Groups > linux.kernel > #1345464 > unrolled thread

[PATCH v19 00/10] Compile-time stack metadata validation

Started by	Josh Poimboeuf <jpoimboe@redhat.com>
First post	2016-02-29 05:30 +0100
Last post	2016-02-29 12:10 +0100
Articles	17 — 3 participants

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  [PATCH v19 00/10] Compile-time stack metadata validation Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
    [PATCH v19 06/10] sched: always inline context_switch() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] sched: Always inline context_switch() tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:10 +0100
    [PATCH v19 09/10] objtool: Add CONFIG_STACK_VALIDATION option Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:10 +0100
        Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option Sebastian Andrzej Siewior <sebastian@breakpoint.cc> - 2016-03-03 15:20 +0100
          Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option Josh Poimboeuf <jpoimboe@redhat.com> - 2016-03-03 16:00 +0100
    [PATCH v19 01/10] objtool: Mark non-standard files and directories Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] objtool: Mark non-standard object files and  directories tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:00 +0100
    [PATCH v19 07/10] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] x86/kprobes: Mark kretprobe_trampoline() stack  frame as non-standard tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:10 +0100
    [PATCH v19 10/10] objtool: Enable stack metadata validation on x86_64 Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] objtool: Enable stack metadata validation on  64-bit x86 tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:10 +0100
    [PATCH v19 04/10] bpf: Mark __bpf_prog_run() stack frame as non-standard Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] bpf: Mark __bpf_prog_run() stack frame as  non-standard tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:10 +0100
    [PATCH v19 03/10] x86/xen: Mark xen_cpuid() stack frame as non-standard Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-29 05:30 +0100
      [tip:core/objtool] x86/xen: Mark xen_cpuid() stack frame as  non-standard tip-bot for Josh Poimboeuf <tipbot@zytor.com> - 2016-02-29 12:10 +0100

#1345464 — [PATCH v19 00/10] Compile-time stack metadata validation

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 00/10] Compile-time stack metadata validation
Message-ID	<r7nD4-5hw-5@gated-at.bofh.it>

This is v19 of the compile-time stack metadata validation patch set.

It's based on tip:core/objtool.

v18 can be found here:

  https://lkml.kernel.org/r/cover.1456440439.git.jpoimboe@redhat.com

For more information about the motivation behind this patch set, and
more details about what it does, see the patch 8 changelog and
tools/objtool/Documentation/stack-validation.txt.

Patches 1-7 mark various directories, files, and functions as
"non-standard" in preparation for objtool.

Patches 8-10 add objtool and integrate it into the kernel build.

v19:
- add support for CONFIG_GCOV_KERNEL, CONFIG_KASAN, CONFIG_UBSAN
- always inline context_switch() to prevent gcov inline changes
- add main() return value in objtool.c
- change warning output format to mimic gcc warnings

v18:
- include/linux/objtool.h -> include/linux/frame.h
- __objtool_ignore_func -> __func_stack_frame_non_standard
- reword commit messages and comments a bit
- reorder patches

v17:
- __ex_table fix
- rename stacktool -> objtool
- STACKTOOL_IGNORE_FUNCTION -> STACK_FRAME_NON_STANDARD
- 'STACKTOOL := n' -> 'OBJECT_FILES_NON_STANDARD := y'
- updated global_noreturns list

v16:
- fix all allyesconfig warnings, except for staging
- get rid of STACKTOOL_IGNORE_INSN which is no longer needed
- remove several whitelists in favor of automatically whitelisting any
  function with a special instruction like ljmp, lret, or vmrun
- split up stacktool patch into 3 parts as suggested by Ingo
- update the global noreturn function list
- detect noreturn function fallthroughs
- skip weak functions in noreturn call detection logic
- add empty function check to noreturn logic
- allow non-section rela symbols for __ex_table sections
- support rare switch table case with jmpq *[addr](%rip)
- don't warn on frame pointer restore without save
- rearrange patch order a bit

v15:
- restructure code for a new cmdline interface "stacktool check" using
  the new subcommand framework in tools/lib/subcmd
- fix 32 bit build fail (put __sp at end) in paravirt_types.h patch 10
  which was reported by 0day

v14:
- make tools/include/linux/list.h self-sufficient
- create FRAME_OFFSET to allow 32-bit code to be able to access function
  arguments on the stack
- add FRAME_OFFSET usage in crypto patch 14/24: "Create stack frames in
  aesni-intel_asm.S"
- rename "index" -> "idx" to fix build with some compilers

v13:
- LDFLAGS order fix from Chris J Arges
- new warning fix patches from Chris J Arges
- "--frame-pointer" -> "--check-frame-pointer"

v12:
- rename "stackvalidate" -> "stacktool"
- move from scripts/ to tools/:
  - makefile rework
  - make a copy of the x86 insn code (and warn if the code diverges)
  - use tools/include/linux/list.h
- move warning macros to a new warn.h file
- change wording: "stack validation" -> "stack metadata validation"

v11:
- attempt to answer the "why" question better in the documentation and
  commit message
- s/FP_SAVE/FRAME_BEGIN/ in documentation

v10:
- add scripts/mod to directory ignores
- remove circular dependencies for ignored objects which are built
  before stackvalidate
- fix CONFIG_MODVERSIONS incompatibility

v9:
- rename FRAME/ENDFRAME -> FRAME_BEGIN/FRAME_END
- fix jump table issue for when the original instruction is a jump
- drop paravirt thunk alignment patch
- add maintainers to CC for proposed warning fixes

v8:
- add proposed fixes for warnings
- fix all memory leaks
- process ignores earlier and add more ignore checks
- always assume POPCNT alternative is enabled
- drop hweight inline asm fix
- drop __schedule() ignore patch
- change .Ltemp_\@ to .Lstackvalidate_ignore_\@ in asm macro
- fix CONFIG_* checks in asm macros
- add C versions of ignore macros and frame macros
- change ";" to "\n" in C macros
- add ifdef CONFIG_STACK_VALIDATION checks in C ignore macros
- use numbered label in C ignore macro
- add missing break in switch case statement in arch-x86.c

v7:
- sibling call support
- document proposed solution for inline asm() frame pointer issues
- say "kernel entry/exit" instead of "context switch"
- clarify the checking of switch statement jump tables
- discard __stackvalidate_ignore_* sections in linker script
- use .Ltemp_\@ to get a unique label instead of static 3-digit number
- change STACKVALIDATE_IGNORE_FUNC variable to a static
- move STACKVALIDATE_IGNORE_INSN to arch-specific .h file

v6:
- rename asmvalidate -> stackvalidate (again)
- gcc-generated object file support
- recursive branch state analysis
- external jump support
- fixup/exception table support
- jump label support
- switch statement jump table support
- added documentation
- detection of "noreturn" dead end functions
- added a Kbuild mechanism for skipping files and dirs
- moved frame pointer macros to arch/x86/include/asm/frame.h
- moved ignore macros to include/linux/stackvalidate.h

v5:
- stackvalidate -> asmvalidate
- frame pointers only required for non-leaf functions
- check for the use of the FP_SAVE/RESTORE macros instead of manually
  analyzing code to detect frame pointer usage
- additional checks to ensure each function doesn't leave its boundaries
- make the macros simpler and more flexible
- support for analyzing ALTERNATIVE macros
- simplified the arch interfaces in scripts/asmvalidate/arch.h
- fixed some asmvalidate warnings
- rebased onto latest tip asm cleanups
- many more small changes

v4:
- Changed the default to CONFIG_STACK_VALIDATION=n, until all the asm
  code can get cleaned up.
- Fixed a stackvalidate error path exit code issue found by Michal
  Marek.

v3:
- Added a patch to make the push/pop CFI macros arch-independent, as
  suggested by H. Peter Anvin

v2:
- Fixed memory leaks reported by Petr Mladek

Cc: linux-kernel@vger.kernel.org
Cc: live-patching@vger.kernel.org
Cc: Michal Marek <mmarek@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>

Josh Poimboeuf (10):
  objtool: Mark non-standard files and directories
  objtool: Add STACK_FRAME_NON_STANDARD macro
  x86/xen: Mark xen_cpuid() stack frame as non-standard
  bpf: Mark __bpf_prog_run() stack frame as non-standard
  sched: Mark __schedule() stack frame as non-standard
  sched: always inline context_switch()
  x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard
  objtool: Compile-time stack metadata validation
  objtool: Add CONFIG_STACK_VALIDATION option
  objtool: Enable stack metadata validation on x86_64

 MAINTAINERS                                       |    5 +
 Makefile                                          |    5 +-
 arch/Kconfig                                      |    6 +
 arch/x86/Kconfig                                  |    1 +
 arch/x86/boot/Makefile                            |    3 +-
 arch/x86/boot/compressed/Makefile                 |    3 +-
 arch/x86/entry/Makefile                           |    4 +
 arch/x86/entry/vdso/Makefile                      |    6 +-
 arch/x86/kernel/Makefile                          |   11 +-
 arch/x86/kernel/kprobes/core.c                    |    2 +
 arch/x86/kernel/vmlinux.lds.S                     |    5 +-
 arch/x86/platform/efi/Makefile                    |    2 +
 arch/x86/purgatory/Makefile                       |    2 +
 arch/x86/realmode/Makefile                        |    4 +-
 arch/x86/realmode/rm/Makefile                     |    3 +-
 arch/x86/xen/enlighten.c                          |    3 +-
 drivers/firmware/efi/libstub/Makefile             |    1 +
 include/linux/frame.h                             |   23 +
 kernel/bpf/core.c                                 |    2 +
 kernel/sched/core.c                               |    4 +-
 lib/Kconfig.debug                                 |   12 +
 scripts/Makefile.build                            |   39 +-
 scripts/mod/Makefile                              |    2 +
 tools/Makefile                                    |   14 +-
 tools/objtool/.gitignore                          |    2 +
 tools/objtool/Build                               |   13 +
 tools/objtool/Documentation/stack-validation.txt  |  342 +++++++
 tools/objtool/Makefile                            |   60 ++
 tools/objtool/arch.h                              |   44 +
 tools/objtool/arch/x86/Build                      |   12 +
 tools/objtool/arch/x86/decode.c                   |  172 ++++
 tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk |  387 ++++++++
 tools/objtool/arch/x86/insn/inat.c                |   97 ++
 tools/objtool/arch/x86/insn/inat.h                |  221 +++++
 tools/objtool/arch/x86/insn/inat_types.h          |   29 +
 tools/objtool/arch/x86/insn/insn.c                |  594 ++++++++++++
 tools/objtool/arch/x86/insn/insn.h                |  201 ++++
 tools/objtool/arch/x86/insn/x86-opcode-map.txt    |  984 +++++++++++++++++++
 tools/objtool/builtin-check.c                     | 1072 +++++++++++++++++++++
 tools/objtool/builtin.h                           |   22 +
 tools/objtool/elf.c                               |  403 ++++++++
 tools/objtool/elf.h                               |   79 ++
 tools/objtool/objtool.c                           |  136 +++
 tools/objtool/special.c                           |  193 ++++
 tools/objtool/special.h                           |   42 +
 tools/objtool/warn.h                              |   60 ++
 46 files changed, 5304 insertions(+), 23 deletions(-)
 create mode 100644 include/linux/frame.h
 create mode 100644 tools/objtool/.gitignore
 create mode 100644 tools/objtool/Build
 create mode 100644 tools/objtool/Documentation/stack-validation.txt
 create mode 100644 tools/objtool/Makefile
 create mode 100644 tools/objtool/arch.h
 create mode 100644 tools/objtool/arch/x86/Build
 create mode 100644 tools/objtool/arch/x86/decode.c
 create mode 100644 tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk
 create mode 100644 tools/objtool/arch/x86/insn/inat.c
 create mode 100644 tools/objtool/arch/x86/insn/inat.h
 create mode 100644 tools/objtool/arch/x86/insn/inat_types.h
 create mode 100644 tools/objtool/arch/x86/insn/insn.c
 create mode 100644 tools/objtool/arch/x86/insn/insn.h
 create mode 100644 tools/objtool/arch/x86/insn/x86-opcode-map.txt
 create mode 100644 tools/objtool/builtin-check.c
 create mode 100644 tools/objtool/builtin.h
 create mode 100644 tools/objtool/elf.c
 create mode 100644 tools/objtool/elf.h
 create mode 100644 tools/objtool/objtool.c
 create mode 100644 tools/objtool/special.c
 create mode 100644 tools/objtool/special.h
 create mode 100644 tools/objtool/warn.h

-- 
2.4.3

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#1345465 — [PATCH v19 06/10] sched: always inline context_switch()

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 06/10] sched: always inline context_switch()
Message-ID	<r7nD4-5hw-11@gated-at.bofh.it>
In reply to	#1345464

When CONFIG_GCOV is enabled, gcc decides to put context_switch()
out-of-line, which is inconsistent with its normal behavior.

It also causes an objtool warning because __schedule() no longer inlines
context_switch(), so the "STACK_FRAME_NON_STANDARD(__schedule)"
statement loses its effect.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 641043d..bb0daab 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2763,7 +2763,7 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev)
 /*
  * context_switch - switch to the new MM and the new thread's register state.
  */
-static inline struct rq *
+static __always_inline struct rq *
 context_switch(struct rq *rq, struct task_struct *prev,
 	       struct task_struct *next)
 {
-- 
2.4.3

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#1345667 — [tip:core/objtool] sched: Always inline context_switch()

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:10 +0100
Subject	[tip:core/objtool] sched: Always inline context_switch()
Message-ID	<r7tSc-2et-51@gated-at.bofh.it>
In reply to	#1345465

Commit-ID:  049369487e2068294b61cee19233be0ffac7d243
Gitweb:     http://git.kernel.org/tip/049369487e2068294b61cee19233be0ffac7d243
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:39 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:11 +0100

sched: Always inline context_switch()

When CONFIG_GCOV is enabled, gcc decides to put context_switch()
out-of-line, which is inconsistent with its normal behavior.

It also causes an objtool warning because __schedule() no longer inlines
context_switch(), so the "STACK_FRAME_NON_STANDARD(__schedule)"
statement loses its effect.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/d62aee926b6e303394e34a06999a964dc2773cf6.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 641043d..bb0daab 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2763,7 +2763,7 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev)
 /*
  * context_switch - switch to the new MM and the new thread's register state.
  */
-static inline struct rq *
+static __always_inline struct rq *
 context_switch(struct rq *rq, struct task_struct *prev,
 	       struct task_struct *next)
 {

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#1345467 — [PATCH v19 09/10] objtool: Add CONFIG_STACK_VALIDATION option

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 09/10] objtool: Add CONFIG_STACK_VALIDATION option
Message-ID	<r7nD4-5hw-13@gated-at.bofh.it>
In reply to	#1345464

Add a CONFIG_STACK_VALIDATION option which will run "objtool check" for
each .o file to ensure the validity of its stack metadata.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 Makefile               |  5 ++++-
 arch/Kconfig           |  6 ++++++
 lib/Kconfig.debug      | 12 ++++++++++++
 scripts/Makefile.build | 39 +++++++++++++++++++++++++++++++++++----
 4 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index fbe1b92..62be03b 100644
--- a/Makefile
+++ b/Makefile
@@ -993,7 +993,10 @@ prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..
-prepare: prepare0
+prepare: prepare0 prepare-objtool
+
+PHONY += prepare-objtool
+prepare-objtool: $(if $(CONFIG_STACK_VALIDATION), tools/objtool FORCE)
 
 # Generate some files
 # ---------------------------------------------------------------------------
diff --git a/arch/Kconfig b/arch/Kconfig
index f6b649d..81869a5 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -583,6 +583,12 @@ config HAVE_COPY_THREAD_TLS
 	  normal C parameter passing, rather than extracting the syscall
 	  argument from pt_regs.
 
+config HAVE_STACK_VALIDATION
+	bool
+	help
+	  Architecture supports the 'objtool check' host tool command, which
+	  performs compile-time stack metadata validation.
+
 #
 # ABI hall of shame
 #
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8bfd1ac..8552656 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -342,6 +342,18 @@ config FRAME_POINTER
 	  larger and slower, but it gives very useful debugging information
 	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
 
+config STACK_VALIDATION
+	bool "Compile-time stack metadata validation"
+	depends on HAVE_STACK_VALIDATION
+	default n
+	help
+	  Add compile-time checks to validate stack metadata, including frame
+	  pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
+	  that runtime stack traces are more reliable.
+
+	  For more information, see
+	  tools/objtool/Documentation/stack-validation.txt.
+
 config DEBUG_FORCE_WEAK_PER_CPU
 	bool "Force weak per-cpu definitions"
 	depends on DEBUG_KERNEL
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2c47f9c..130a452 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -241,10 +241,32 @@ cmd_record_mcount =						\
 	fi;
 endif
 
+ifdef CONFIG_STACK_VALIDATION
+
+__objtool_obj := $(objtree)/tools/objtool/objtool
+
+objtool_args = check
+ifndef CONFIG_FRAME_POINTER
+objtool_args += --no-fp
+endif
+
+# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
+# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
+# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
+cmd_objtool = $(if $(patsubst y%,, \
+	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
+	$(__objtool_obj) $(objtool_args) "$(@)";)
+objtool_obj = $(if $(patsubst y%,, \
+	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
+	$(__objtool_obj))
+
+endif # CONFIG_STACK_VALIDATION
+
 define rule_cc_o_c
 	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
 	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
 	$(cmd_modversions)						  \
+	$(cmd_objtool)						  \
 	$(call echo-cmd,record_mcount)					  \
 	$(cmd_record_mcount)						  \
 	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
@@ -253,14 +275,23 @@ define rule_cc_o_c
 	mv -f $(dot-target).tmp $(dot-target).cmd
 endef
 
+define rule_as_o_S
+	$(call echo-cmd,as_o_S) $(cmd_as_o_S);				  \
+	$(cmd_objtool)						  \
+	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' >    \
+	                                              $(dot-target).tmp;  \
+	rm -f $(depfile);						  \
+	mv -f $(dot-target).tmp $(dot-target).cmd
+endef
+
 # Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 
 # Single-part modules are special since we need to mark them in $(MODVERDIR)
 
-$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
@@ -290,8 +321,8 @@ $(obj)/%.s: $(src)/%.S FORCE
 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<
 
-$(obj)/%.o: $(src)/%.S FORCE
-	$(call if_changed_dep,as_o_S)
+$(obj)/%.o: $(src)/%.S $(objtool_obj) FORCE
+	$(call if_changed_rule,as_o_S)
 
 targets += $(real-objs-y) $(real-objs-m) $(lib-y)
 targets += $(extra-y) $(MAKECMDGOALS) $(always)
-- 
2.4.3

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#1345654 — [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:10 +0100
Subject	[tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option
Message-ID	<r7tSa-2et-19@gated-at.bofh.it>
In reply to	#1345467

Commit-ID:  b9ab5ebb14ec389bd80f66613f1fe3f8f65f2521
Gitweb:     http://git.kernel.org/tip/b9ab5ebb14ec389bd80f66613f1fe3f8f65f2521
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:42 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:13 +0100

objtool: Add CONFIG_STACK_VALIDATION option

Add a CONFIG_STACK_VALIDATION option which will run "objtool check" for
each .o file to ensure the validity of its stack metadata.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/92baab69a6bf9bc7043af0bfca9fb964a1d45546.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 Makefile               |  5 ++++-
 arch/Kconfig           |  6 ++++++
 lib/Kconfig.debug      | 12 ++++++++++++
 scripts/Makefile.build | 39 +++++++++++++++++++++++++++++++++++----
 4 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index fbe1b92..62be03b 100644
--- a/Makefile
+++ b/Makefile
@@ -993,7 +993,10 @@ prepare0: archprepare FORCE
 	$(Q)$(MAKE) $(build)=.
 
 # All the preparing..
-prepare: prepare0
+prepare: prepare0 prepare-objtool
+
+PHONY += prepare-objtool
+prepare-objtool: $(if $(CONFIG_STACK_VALIDATION), tools/objtool FORCE)
 
 # Generate some files
 # ---------------------------------------------------------------------------
diff --git a/arch/Kconfig b/arch/Kconfig
index f6b649d..81869a5 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -583,6 +583,12 @@ config HAVE_COPY_THREAD_TLS
 	  normal C parameter passing, rather than extracting the syscall
 	  argument from pt_regs.
 
+config HAVE_STACK_VALIDATION
+	bool
+	help
+	  Architecture supports the 'objtool check' host tool command, which
+	  performs compile-time stack metadata validation.
+
 #
 # ABI hall of shame
 #
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8bfd1ac..8552656 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -342,6 +342,18 @@ config FRAME_POINTER
 	  larger and slower, but it gives very useful debugging information
 	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
 
+config STACK_VALIDATION
+	bool "Compile-time stack metadata validation"
+	depends on HAVE_STACK_VALIDATION
+	default n
+	help
+	  Add compile-time checks to validate stack metadata, including frame
+	  pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
+	  that runtime stack traces are more reliable.
+
+	  For more information, see
+	  tools/objtool/Documentation/stack-validation.txt.
+
 config DEBUG_FORCE_WEAK_PER_CPU
 	bool "Force weak per-cpu definitions"
 	depends on DEBUG_KERNEL
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2c47f9c..130a452 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -241,10 +241,32 @@ cmd_record_mcount =						\
 	fi;
 endif
 
+ifdef CONFIG_STACK_VALIDATION
+
+__objtool_obj := $(objtree)/tools/objtool/objtool
+
+objtool_args = check
+ifndef CONFIG_FRAME_POINTER
+objtool_args += --no-fp
+endif
+
+# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
+# 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file
+# 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
+cmd_objtool = $(if $(patsubst y%,, \
+	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
+	$(__objtool_obj) $(objtool_args) "$(@)";)
+objtool_obj = $(if $(patsubst y%,, \
+	$(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
+	$(__objtool_obj))
+
+endif # CONFIG_STACK_VALIDATION
+
 define rule_cc_o_c
 	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
 	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);				  \
 	$(cmd_modversions)						  \
+	$(cmd_objtool)						  \
 	$(call echo-cmd,record_mcount)					  \
 	$(cmd_record_mcount)						  \
 	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
@@ -253,14 +275,23 @@ define rule_cc_o_c
 	mv -f $(dot-target).tmp $(dot-target).cmd
 endef
 
+define rule_as_o_S
+	$(call echo-cmd,as_o_S) $(cmd_as_o_S);				  \
+	$(cmd_objtool)						  \
+	scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' >    \
+	                                              $(dot-target).tmp;  \
+	rm -f $(depfile);						  \
+	mv -f $(dot-target).tmp $(dot-target).cmd
+endef
+
 # Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 
 # Single-part modules are special since we need to mark them in $(MODVERDIR)
 
-$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE
 	$(call cmd,force_checksrc)
 	$(call if_changed_rule,cc_o_c)
 	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
@@ -290,8 +321,8 @@ $(obj)/%.s: $(src)/%.S FORCE
 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
 cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<
 
-$(obj)/%.o: $(src)/%.S FORCE
-	$(call if_changed_dep,as_o_S)
+$(obj)/%.o: $(src)/%.S $(objtool_obj) FORCE
+	$(call if_changed_rule,as_o_S)
 
 targets += $(real-objs-y) $(real-objs-m) $(lib-y)
 targets += $(extra-y) $(MAKECMDGOALS) $(always)

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#1349198 — Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option

From	Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Date	2016-03-03 15:20 +0100
Subject	Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option
Message-ID	<r8CgG-8cy-21@gated-at.bofh.it>
In reply to	#1345654

On 2016-02-29 03:01:35 [-0800], tip-bot for Josh Poimboeuf wrote:
> Gitweb:     http://git.kernel.org/tip/b9ab5ebb14ec389bd80f66613f1fe3f8f65f2521
> Author:     Josh Poimboeuf <jpoimboe@redhat.com>
> objtool: Add CONFIG_STACK_VALIDATION option
> 
> Add a CONFIG_STACK_VALIDATION option which will run "objtool check" for
> each .o file to ensure the validity of its stack metadata.

|./mk-x86-64.sh -j1
|make[1]: Entering directory '/home/bigeasy/linux-tip/build/linux-x8664'
|  CHK     include/config/kernel.release
|  Using /home/bigeasy/linux-tip as source for kernel
|  GEN     ./Makefile
|  CHK     include/generated/uapi/linux/version.h
|  CHK     include/generated/utsrelease.h
|  CHK     include/generated/bounds.h
|  CHK     include/generated/timeconst.h
|  CHK     include/generated/asm-offsets.h
|  CALL    /home/bigeasy/linux-tip/scripts/checksyscalls.sh
|scripts/Makefile.include:3: *** O=build/linux-x8664 does not exist.  Stop.
|/home/bigeasy/linux-tip/Makefile:1518: recipe for target 'tools/objtool' failed
|make[1]: *** [tools/objtool] Error 2
|make[1]: Leaving directory '/home/bigeasy/linux-tip/build/linux-x8664'
|Makefile:146: recipe for target 'sub-make' failed
|make: *** [sub-make] Error 2

with
|$ cat mk-x86-64.sh 
|#!/bin/sh
|export PATH=/usr/lib/ccache/:$PATH
|exec make O=build/linux-x8664 -j 8 $*

Is this know? I tried the TIP tree as of now. It works with
CONFIG_STACK_VALIDATION=n

Sebastian

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#1349251 — Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-03-03 16:00 +0100
Subject	Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option
Message-ID	<r8CTo-8sH-15@gated-at.bofh.it>
In reply to	#1349198

On Thu, Mar 03, 2016 at 03:12:01PM +0100, Sebastian Andrzej Siewior wrote:
> On 2016-02-29 03:01:35 [-0800], tip-bot for Josh Poimboeuf wrote:
> > Gitweb:     http://git.kernel.org/tip/b9ab5ebb14ec389bd80f66613f1fe3f8f65f2521
> > Author:     Josh Poimboeuf <jpoimboe@redhat.com>
> > objtool: Add CONFIG_STACK_VALIDATION option
> > 
> > Add a CONFIG_STACK_VALIDATION option which will run "objtool check" for
> > each .o file to ensure the validity of its stack metadata.
> 
> |./mk-x86-64.sh -j1
> |make[1]: Entering directory '/home/bigeasy/linux-tip/build/linux-x8664'
> |  CHK     include/config/kernel.release
> |  Using /home/bigeasy/linux-tip as source for kernel
> |  GEN     ./Makefile
> |  CHK     include/generated/uapi/linux/version.h
> |  CHK     include/generated/utsrelease.h
> |  CHK     include/generated/bounds.h
> |  CHK     include/generated/timeconst.h
> |  CHK     include/generated/asm-offsets.h
> |  CALL    /home/bigeasy/linux-tip/scripts/checksyscalls.sh
> |scripts/Makefile.include:3: *** O=build/linux-x8664 does not exist.  Stop.
> |/home/bigeasy/linux-tip/Makefile:1518: recipe for target 'tools/objtool' failed
> |make[1]: *** [tools/objtool] Error 2
> |make[1]: Leaving directory '/home/bigeasy/linux-tip/build/linux-x8664'
> |Makefile:146: recipe for target 'sub-make' failed
> |make: *** [sub-make] Error 2
> 
> with
> |$ cat mk-x86-64.sh 
> |#!/bin/sh
> |export PATH=/usr/lib/ccache/:$PATH
> |exec make O=build/linux-x8664 -j 8 $*
> 
> Is this know? I tried the TIP tree as of now. It works with
> CONFIG_STACK_VALIDATION=n
> 
> Sebastian

Hi Sebastian,

This bug happens when using a relative path for 'O=' with
CONFIG_STACK_VALIDATION.  I posted a patch to fix it:

  https://lkml.kernel.org/r/94a078c6c998fac9f01a14f574008bf7dff40191.1457016803.git.jpoimboe@redhat.com

-- 
Josh

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#1345468 — [PATCH v19 01/10] objtool: Mark non-standard files and directories

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 01/10] objtool: Mark non-standard files and directories
Message-ID	<r7nD5-5hw-19@gated-at.bofh.it>
In reply to	#1345464

Code which runs outside the kernel's normal mode of operation often does
unusual things which can cause a static analysis tool like objtool to
emit false positive warnings:

- boot image
- vdso image
- relocation
- realmode
- efi
- head
- purgatory
- modpost

Set OBJECT_FILES_NON_STANDARD for their related files and directories,
which will tell objtool to skip checking them.  It's ok to skip them
because they don't affect runtime stack traces.

Also skip the following code which does the right thing with respect to
frame pointers, but is too "special" to be validated by a tool:

- entry
- mcount

Also skip the test_nx module because it modifies its exception handling
table at runtime, which objtool can't understand.  Fortunately it's
just a test module so it doesn't matter much.

Currently objtool is the only user of OBJECT_FILES_NON_STANDARD, but it
might eventually be useful for other tools.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/boot/Makefile                |  3 ++-
 arch/x86/boot/compressed/Makefile     |  3 ++-
 arch/x86/entry/Makefile               |  4 ++++
 arch/x86/entry/vdso/Makefile          |  6 ++++--
 arch/x86/kernel/Makefile              | 11 ++++++++---
 arch/x86/platform/efi/Makefile        |  2 ++
 arch/x86/purgatory/Makefile           |  2 ++
 arch/x86/realmode/Makefile            |  4 +++-
 arch/x86/realmode/rm/Makefile         |  3 ++-
 drivers/firmware/efi/libstub/Makefile |  1 +
 scripts/mod/Makefile                  |  2 ++
 11 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index bbe1a62..0bf6749 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -9,7 +9,8 @@
 # Changed by many, many contributors over the years.
 #
 
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 # If you want to preset the SVGA mode, uncomment the next line and
 # set SVGA_MODE to whatever number you want.
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index f9ce75d..5e1d26e 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -16,7 +16,8 @@
 #	(see scripts/Makefile.lib size_append)
 #	compressed vmlinux.bin.all + u32 size of vmlinux.bin.all
 
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
 	vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4
diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile
index bd55ded..fe91c25 100644
--- a/arch/x86/entry/Makefile
+++ b/arch/x86/entry/Makefile
@@ -1,6 +1,10 @@
 #
 # Makefile for the x86 low level entry code
 #
+
+OBJECT_FILES_NON_STANDARD_entry_$(BITS).o   := y
+OBJECT_FILES_NON_STANDARD_entry_64_compat.o := y
+
 obj-y				:= entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o
 obj-y				+= common.o
 
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index c854541..f9fb859 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -3,8 +3,9 @@
 #
 
 KBUILD_CFLAGS += $(DISABLE_LTO)
-KASAN_SANITIZE := n
-UBSAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+UBSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 VDSO64-$(CONFIG_X86_64)		:= y
 VDSOX32-$(CONFIG_X86_X32_ABI)	:= y
@@ -16,6 +17,7 @@ vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
 
 # files to link into kernel
 obj-y				+= vma.o
+OBJECT_FILES_NON_STANDARD_vma.o	:= n
 
 # vDSO images to build
 vdso_img-$(VDSO64-y)		+= 64
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index b1b78ff..d5fb087 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -16,9 +16,14 @@ CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_early_printk.o = -pg
 endif
 
-KASAN_SANITIZE_head$(BITS).o := n
-KASAN_SANITIZE_dumpstack.o := n
-KASAN_SANITIZE_dumpstack_$(BITS).o := n
+KASAN_SANITIZE_head$(BITS).o				:= n
+KASAN_SANITIZE_dumpstack.o				:= n
+KASAN_SANITIZE_dumpstack_$(BITS).o			:= n
+
+OBJECT_FILES_NON_STANDARD_head_$(BITS).o		:= y
+OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o	:= y
+OBJECT_FILES_NON_STANDARD_mcount_$(BITS).o		:= y
+OBJECT_FILES_NON_STANDARD_test_nx.o			:= y
 
 CFLAGS_irq.o := -I$(src)/../include/asm/trace
 
diff --git a/arch/x86/platform/efi/Makefile b/arch/x86/platform/efi/Makefile
index 2846aaa..066619b 100644
--- a/arch/x86/platform/efi/Makefile
+++ b/arch/x86/platform/efi/Makefile
@@ -1,3 +1,5 @@
+OBJECT_FILES_NON_STANDARD_efi_thunk_$(BITS).o := y
+
 obj-$(CONFIG_EFI) 		+= quirks.o efi.o efi_$(BITS).o efi_stub_$(BITS).o
 obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
 obj-$(CONFIG_EARLY_PRINTK_EFI)	+= early_printk.o
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 2c835e3..92e3e1d 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -1,3 +1,5 @@
+OBJECT_FILES_NON_STANDARD := y
+
 purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string.o
 
 targets += $(purgatory-y)
diff --git a/arch/x86/realmode/Makefile b/arch/x86/realmode/Makefile
index e02c2c6..682c895 100644
--- a/arch/x86/realmode/Makefile
+++ b/arch/x86/realmode/Makefile
@@ -6,7 +6,9 @@
 # for more details.
 #
 #
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
+
 subdir- := rm
 
 obj-y += init.o
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 3e75fcf..053abe7b0 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -6,7 +6,8 @@
 # for more details.
 #
 #
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 always := realmode.bin realmode.relocs
 
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index aaf9c0b..68fa977 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -23,6 +23,7 @@ KBUILD_CFLAGS			:= $(cflags-y) -DDISABLE_BRANCH_PROFILING \
 GCOV_PROFILE			:= n
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 lib-y				:= efi-stub-helper.o
 
diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
index c11212f..19d9bca 100644
--- a/scripts/mod/Makefile
+++ b/scripts/mod/Makefile
@@ -1,3 +1,5 @@
+OBJECT_FILES_NON_STANDARD := y
+
 hostprogs-y	:= modpost mk_elfconfig
 always		:= $(hostprogs-y) empty.o
 
-- 
2.4.3

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#1345644 — [tip:core/objtool] objtool: Mark non-standard object files and directories

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:00 +0100
Subject	[tip:core/objtool] objtool: Mark non-standard object files and directories
Message-ID	<r7tIu-1VP-13@gated-at.bofh.it>
In reply to	#1345468

Commit-ID:  c0dd671686b2229e888ede77682ab0633b2a0dd7
Gitweb:     http://git.kernel.org/tip/c0dd671686b2229e888ede77682ab0633b2a0dd7
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:34 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:02 +0100

objtool: Mark non-standard object files and directories

Code which runs outside the kernel's normal mode of operation often does
unusual things which can cause a static analysis tool like objtool to
emit false positive warnings:

 - boot image
 - vdso image
 - relocation
 - realmode
 - efi
 - head
 - purgatory
 - modpost

Set OBJECT_FILES_NON_STANDARD for their related files and directories,
which will tell objtool to skip checking them.  It's ok to skip them
because they don't affect runtime stack traces.

Also skip the following code which does the right thing with respect to
frame pointers, but is too "special" to be validated by a tool:

 - entry
 - mcount

Also skip the test_nx module because it modifies its exception handling
table at runtime, which objtool can't understand.  Fortunately it's
just a test module so it doesn't matter much.

Currently objtool is the only user of OBJECT_FILES_NON_STANDARD, but it
might eventually be useful for other tools.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/366c080e3844e8a5b6a0327dc7e8c2b90ca3baeb.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/boot/Makefile                |  3 ++-
 arch/x86/boot/compressed/Makefile     |  3 ++-
 arch/x86/entry/Makefile               |  4 ++++
 arch/x86/entry/vdso/Makefile          |  6 ++++--
 arch/x86/kernel/Makefile              | 11 ++++++++---
 arch/x86/platform/efi/Makefile        |  2 ++
 arch/x86/purgatory/Makefile           |  2 ++
 arch/x86/realmode/Makefile            |  4 +++-
 arch/x86/realmode/rm/Makefile         |  3 ++-
 drivers/firmware/efi/libstub/Makefile |  1 +
 scripts/mod/Makefile                  |  2 ++
 11 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index bbe1a62..0bf6749 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -9,7 +9,8 @@
 # Changed by many, many contributors over the years.
 #
 
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 # If you want to preset the SVGA mode, uncomment the next line and
 # set SVGA_MODE to whatever number you want.
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index f9ce75d..5e1d26e 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -16,7 +16,8 @@
 #	(see scripts/Makefile.lib size_append)
 #	compressed vmlinux.bin.all + u32 size of vmlinux.bin.all
 
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
 	vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4
diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile
index bd55ded..fe91c25 100644
--- a/arch/x86/entry/Makefile
+++ b/arch/x86/entry/Makefile
@@ -1,6 +1,10 @@
 #
 # Makefile for the x86 low level entry code
 #
+
+OBJECT_FILES_NON_STANDARD_entry_$(BITS).o   := y
+OBJECT_FILES_NON_STANDARD_entry_64_compat.o := y
+
 obj-y				:= entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o
 obj-y				+= common.o
 
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index c854541..f9fb859 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -3,8 +3,9 @@
 #
 
 KBUILD_CFLAGS += $(DISABLE_LTO)
-KASAN_SANITIZE := n
-UBSAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+UBSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 VDSO64-$(CONFIG_X86_64)		:= y
 VDSOX32-$(CONFIG_X86_X32_ABI)	:= y
@@ -16,6 +17,7 @@ vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
 
 # files to link into kernel
 obj-y				+= vma.o
+OBJECT_FILES_NON_STANDARD_vma.o	:= n
 
 # vDSO images to build
 vdso_img-$(VDSO64-y)		+= 64
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index b1b78ff..d5fb087 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -16,9 +16,14 @@ CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_early_printk.o = -pg
 endif
 
-KASAN_SANITIZE_head$(BITS).o := n
-KASAN_SANITIZE_dumpstack.o := n
-KASAN_SANITIZE_dumpstack_$(BITS).o := n
+KASAN_SANITIZE_head$(BITS).o				:= n
+KASAN_SANITIZE_dumpstack.o				:= n
+KASAN_SANITIZE_dumpstack_$(BITS).o			:= n
+
+OBJECT_FILES_NON_STANDARD_head_$(BITS).o		:= y
+OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o	:= y
+OBJECT_FILES_NON_STANDARD_mcount_$(BITS).o		:= y
+OBJECT_FILES_NON_STANDARD_test_nx.o			:= y
 
 CFLAGS_irq.o := -I$(src)/../include/asm/trace
 
diff --git a/arch/x86/platform/efi/Makefile b/arch/x86/platform/efi/Makefile
index 2846aaa..066619b 100644
--- a/arch/x86/platform/efi/Makefile
+++ b/arch/x86/platform/efi/Makefile
@@ -1,3 +1,5 @@
+OBJECT_FILES_NON_STANDARD_efi_thunk_$(BITS).o := y
+
 obj-$(CONFIG_EFI) 		+= quirks.o efi.o efi_$(BITS).o efi_stub_$(BITS).o
 obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
 obj-$(CONFIG_EARLY_PRINTK_EFI)	+= early_printk.o
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 2c835e3..92e3e1d 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -1,3 +1,5 @@
+OBJECT_FILES_NON_STANDARD := y
+
 purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string.o
 
 targets += $(purgatory-y)
diff --git a/arch/x86/realmode/Makefile b/arch/x86/realmode/Makefile
index e02c2c6..682c895 100644
--- a/arch/x86/realmode/Makefile
+++ b/arch/x86/realmode/Makefile
@@ -6,7 +6,9 @@
 # for more details.
 #
 #
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
+
 subdir- := rm
 
 obj-y += init.o
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 3e75fcf..053abe7b0 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -6,7 +6,8 @@
 # for more details.
 #
 #
-KASAN_SANITIZE := n
+KASAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 always := realmode.bin realmode.relocs
 
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index aaf9c0b..68fa977 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -23,6 +23,7 @@ KBUILD_CFLAGS			:= $(cflags-y) -DDISABLE_BRANCH_PROFILING \
 GCOV_PROFILE			:= n
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
+OBJECT_FILES_NON_STANDARD	:= y
 
 lib-y				:= efi-stub-helper.o
 
diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
index c11212f..19d9bca 100644
--- a/scripts/mod/Makefile
+++ b/scripts/mod/Makefile
@@ -1,3 +1,5 @@
+OBJECT_FILES_NON_STANDARD := y
+
 hostprogs-y	:= modpost mk_elfconfig
 always		:= $(hostprogs-y) empty.o

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#1345469 — [PATCH v19 07/10] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 07/10] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard
Message-ID	<r7nD5-5hw-21@gated-at.bofh.it>
In reply to	#1345464

objtool reports the following warning for kretprobe_trampoline():

  arch/x86/kernel/kprobes/core.o: warning: objtool: kretprobe_trampoline()+0x20: call without frame pointer save/setup

kretprobes are a special case where the stack is intentionally wrong.
The return address isn't known at the beginning of the trampoline, so
the stack frame can't be set up properly before it calls
trampoline_handler().

Because kretprobe handlers don't sleep, the frame pointer doesn't *have*
to be accurate in the trampoline.  So it's ok to tell objtool to ignore
it.  This results in no actual changes to the generated code.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
---
 arch/x86/kernel/kprobes/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 48acaac..ae703ac 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -49,6 +49,7 @@
 #include <linux/kdebug.h>
 #include <linux/kallsyms.h>
 #include <linux/ftrace.h>
+#include <linux/frame.h>
 
 #include <asm/cacheflush.h>
 #include <asm/desc.h>
@@ -703,6 +704,7 @@ asm(
 	".size kretprobe_trampoline, .-kretprobe_trampoline\n"
 );
 NOKPROBE_SYMBOL(kretprobe_trampoline);
+STACK_FRAME_NON_STANDARD(kretprobe_trampoline);
 
 /*
  * Called from kretprobe_trampoline
-- 
2.4.3

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#1345664 — [tip:core/objtool] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:10 +0100
Subject	[tip:core/objtool] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard
Message-ID	<r7tSb-2et-43@gated-at.bofh.it>
In reply to	#1345469

Commit-ID:  87aaff2ae09036cf699fde20dfd52ce7d3c8eabe
Gitweb:     http://git.kernel.org/tip/87aaff2ae09036cf699fde20dfd52ce7d3c8eabe
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:40 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:12 +0100

x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard

objtool reports the following warning for kretprobe_trampoline():

  arch/x86/kernel/kprobes/core.o: warning: objtool: kretprobe_trampoline()+0x20: call without frame pointer save/setup

kretprobes are a special case where the stack is intentionally wrong.
The return address isn't known at the beginning of the trampoline, so
the stack frame can't be set up properly before it calls
trampoline_handler().

Because kretprobe handlers don't sleep, the frame pointer doesn't *have*
to be accurate in the trampoline.  So it's ok to tell objtool to ignore
it.  This results in no actual changes to the generated code.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/7eaf37de52456ff822ffc86b928edb5d48a40ef1.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/kprobes/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 48acaac..ae703ac 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -49,6 +49,7 @@
 #include <linux/kdebug.h>
 #include <linux/kallsyms.h>
 #include <linux/ftrace.h>
+#include <linux/frame.h>
 
 #include <asm/cacheflush.h>
 #include <asm/desc.h>
@@ -703,6 +704,7 @@ asm(
 	".size kretprobe_trampoline, .-kretprobe_trampoline\n"
 );
 NOKPROBE_SYMBOL(kretprobe_trampoline);
+STACK_FRAME_NON_STANDARD(kretprobe_trampoline);
 
 /*
  * Called from kretprobe_trampoline

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#1345470 — [PATCH v19 10/10] objtool: Enable stack metadata validation on x86_64

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 10/10] objtool: Enable stack metadata validation on x86_64
Message-ID	<r7nD5-5hw-25@gated-at.bofh.it>
In reply to	#1345464

Set HAVE_STACK_VALIDATION to enable stack metadata validation for
x86_64.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c46662f..adc5a6d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -155,6 +155,7 @@ config X86
 	select VIRT_TO_BUS
 	select X86_DEV_DMA_OPS			if X86_64
 	select X86_FEATURE_NAMES		if PROC_FS
+	select HAVE_STACK_VALIDATION		if X86_64
 
 config INSTRUCTION_DECODER
 	def_bool y
-- 
2.4.3

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#1345670 — [tip:core/objtool] objtool: Enable stack metadata validation on 64-bit x86

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:10 +0100
Subject	[tip:core/objtool] objtool: Enable stack metadata validation on 64-bit x86
Message-ID	<r7tSc-2et-53@gated-at.bofh.it>
In reply to	#1345470

Commit-ID:  d4883d5d6b146fd65f762c462b2c6d4a327c7d50
Gitweb:     http://git.kernel.org/tip/d4883d5d6b146fd65f762c462b2c6d4a327c7d50
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:43 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:13 +0100

objtool: Enable stack metadata validation on 64-bit x86

Set HAVE_STACK_VALIDATION to enable stack metadata validation for
x86_64.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/cdaeb6914d00a070c0f455cd06989bf3f787a2f6.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c46662f..adc5a6d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -155,6 +155,7 @@ config X86
 	select VIRT_TO_BUS
 	select X86_DEV_DMA_OPS			if X86_64
 	select X86_FEATURE_NAMES		if PROC_FS
+	select HAVE_STACK_VALIDATION		if X86_64
 
 config INSTRUCTION_DECODER
 	def_bool y

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#1345472 — [PATCH v19 04/10] bpf: Mark __bpf_prog_run() stack frame as non-standard

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 04/10] bpf: Mark __bpf_prog_run() stack frame as non-standard
Message-ID	<r7nD5-5hw-31@gated-at.bofh.it>
In reply to	#1345464

objtool reports the following false positive warnings:

  kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x5c: sibling call from callable instruction with changed frame pointer
  kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x60: function has unreachable instruction
  kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x64: function has unreachable instruction
  [...]

It's confused by the following dynamic jump instruction in
__bpf_prog_run()::

  jmp     *(%r12,%rax,8)

which corresponds to the following line in the C code:

  goto *jumptable[insn->code];

There's no way for objtool to deterministically find all possible
branch targets for a dynamic jump, so it can't verify this code.

In this case the jumps all stay within the function, and there's nothing
unusual going on related to the stack, so we can whitelist the function.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: netdev@vger.kernel.org
---
 kernel/bpf/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 972d9a8..be0abf6 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -27,6 +27,7 @@
 #include <linux/random.h>
 #include <linux/moduleloader.h>
 #include <linux/bpf.h>
+#include <linux/frame.h>
 
 #include <asm/unaligned.h>
 
@@ -649,6 +650,7 @@ load_byte:
 		WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code);
 		return 0;
 }
+STACK_FRAME_NON_STANDARD(__bpf_prog_run); /* jump table */
 
 bool bpf_prog_array_compatible(struct bpf_array *array,
 			       const struct bpf_prog *fp)
-- 
2.4.3

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#1345647 — [tip:core/objtool] bpf: Mark __bpf_prog_run() stack frame as non-standard

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:10 +0100
Subject	[tip:core/objtool] bpf: Mark __bpf_prog_run() stack frame as non-standard
Message-ID	<r7tSa-2et-3@gated-at.bofh.it>
In reply to	#1345472

Commit-ID:  39853cc0cdcf1b11f00f7f81e2f515a4d68ed209
Gitweb:     http://git.kernel.org/tip/39853cc0cdcf1b11f00f7f81e2f515a4d68ed209
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:37 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:11 +0100

bpf: Mark __bpf_prog_run() stack frame as non-standard

objtool reports the following false positive warnings:

  kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x5c: sibling call from callable instruction with changed frame pointer
  kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x60: function has unreachable instruction
  kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x64: function has unreachable instruction
  [...]

It's confused by the following dynamic jump instruction in
__bpf_prog_run()::

  jmp     *(%r12,%rax,8)

which corresponds to the following line in the C code:

  goto *jumptable[insn->code];

There's no way for objtool to deterministically find all possible
branch targets for a dynamic jump, so it can't verify this code.

In this case the jumps all stay within the function, and there's nothing
unusual going on related to the stack, so we can whitelist the function.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/b90e6bf3fdbfb5c4cc1b164b965502e53cf48935.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/bpf/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 972d9a8..be0abf6 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -27,6 +27,7 @@
 #include <linux/random.h>
 #include <linux/moduleloader.h>
 #include <linux/bpf.h>
+#include <linux/frame.h>
 
 #include <asm/unaligned.h>
 
@@ -649,6 +650,7 @@ load_byte:
 		WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code);
 		return 0;
 }
+STACK_FRAME_NON_STANDARD(__bpf_prog_run); /* jump table */
 
 bool bpf_prog_array_compatible(struct bpf_array *array,
 			       const struct bpf_prog *fp)

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#1345474 — [PATCH v19 03/10] x86/xen: Mark xen_cpuid() stack frame as non-standard

From	Josh Poimboeuf <jpoimboe@redhat.com>
Date	2016-02-29 05:30 +0100
Subject	[PATCH v19 03/10] x86/xen: Mark xen_cpuid() stack frame as non-standard
Message-ID	<r7nD6-5hw-35@gated-at.bofh.it>
In reply to	#1345464

objtool reports the following false positive warning:

  arch/x86/xen/enlighten.o: warning: objtool: xen_cpuid()+0x41: can't find jump dest instruction at .text+0x108

The warning is due to xen_cpuid()'s use of XEN_EMULATE_PREFIX to insert
some fake instructions which objtool doesn't know how to decode.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 arch/x86/xen/enlighten.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d09e4c9..5c45a69 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -32,6 +32,7 @@
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/edd.h>
+#include <linux/frame.h>
 
 #ifdef CONFIG_KEXEC_CORE
 #include <linux/kexec.h>
@@ -351,8 +352,8 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 	*cx &= maskecx;
 	*cx |= setecx;
 	*dx &= maskedx;
-
 }
+STACK_FRAME_NON_STANDARD(xen_cpuid); /* XEN_EMULATE_PREFIX */
 
 static bool __init xen_check_mwait(void)
 {
-- 
2.4.3

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#1345653 — [tip:core/objtool] x86/xen: Mark xen_cpuid() stack frame as non-standard

From	tip-bot for Josh Poimboeuf <tipbot@zytor.com>
Date	2016-02-29 12:10 +0100
Subject	[tip:core/objtool] x86/xen: Mark xen_cpuid() stack frame as non-standard
Message-ID	<r7tSa-2et-17@gated-at.bofh.it>
In reply to	#1345474

Commit-ID:  983bb6d254c77aaec581473e11c2eb859294f1f2
Gitweb:     http://git.kernel.org/tip/983bb6d254c77aaec581473e11c2eb859294f1f2
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Sun, 28 Feb 2016 22:22:36 -0600
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 29 Feb 2016 08:35:10 +0100

x86/xen: Mark xen_cpuid() stack frame as non-standard

objtool reports the following false positive warning:

  arch/x86/xen/enlighten.o: warning: objtool: xen_cpuid()+0x41: can't find jump dest instruction at .text+0x108

The warning is due to xen_cpuid()'s use of XEN_EMULATE_PREFIX to insert
some fake instructions which objtool doesn't know how to decode.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/bb88399840406629e3417831dc371ecd2842e2a6.1456719558.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/xen/enlighten.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index d09e4c9..5c45a69 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -32,6 +32,7 @@
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/edd.h>
+#include <linux/frame.h>
 
 #ifdef CONFIG_KEXEC_CORE
 #include <linux/kexec.h>
@@ -351,8 +352,8 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 	*cx &= maskecx;
 	*cx |= setecx;
 	*dx &= maskedx;
-
 }
+STACK_FRAME_NON_STANDARD(xen_cpuid); /* XEN_EMULATE_PREFIX */
 
 static bool __init xen_check_mwait(void)
 {

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csiph-web

[PATCH v19 00/10] Compile-time stack metadata validation

Contents

#1345464 — [PATCH v19 00/10] Compile-time stack metadata validation

#1345465 — [PATCH v19 06/10] sched: always inline context_switch()

#1345667 — [tip:core/objtool] sched: Always inline context_switch()

#1345467 — [PATCH v19 09/10] objtool: Add CONFIG_STACK_VALIDATION option

#1345654 — [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option

#1349198 — Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option

#1349251 — Re: [tip:core/objtool] objtool: Add CONFIG_STACK_VALIDATION option

#1345468 — [PATCH v19 01/10] objtool: Mark non-standard files and directories

#1345644 — [tip:core/objtool] objtool: Mark non-standard object files and directories

#1345469 — [PATCH v19 07/10] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard

#1345664 — [tip:core/objtool] x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard

#1345470 — [PATCH v19 10/10] objtool: Enable stack metadata validation on x86_64

#1345670 — [tip:core/objtool] objtool: Enable stack metadata validation on 64-bit x86

#1345472 — [PATCH v19 04/10] bpf: Mark __bpf_prog_run() stack frame as non-standard

#1345647 — [tip:core/objtool] bpf: Mark __bpf_prog_run() stack frame as non-standard

#1345474 — [PATCH v19 03/10] x86/xen: Mark xen_cpuid() stack frame as non-standard

#1345653 — [tip:core/objtool] x86/xen: Mark xen_cpuid() stack frame as non-standard