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Groups > linux.kernel > #1207312 > unrolled thread
| Started by | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| First post | 2015-08-14 05:20 +0200 |
| Last post | 2015-08-19 12:10 +0200 |
| Articles | 5 — 3 participants |
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[PATCH v10 00/20] Compile-time stack validation Josh Poimboeuf <jpoimboe@redhat.com> - 2015-08-14 05:20 +0200
[PATCH v10 04/20] x86/stackvalidate: Add file and directory ignores Josh Poimboeuf <jpoimboe@redhat.com> - 2015-08-14 05:20 +0200
Re: [PATCH v10 03/20] x86/stackvalidate: Compile-time stack validation Andrew Morton <akpm@linux-foundation.org> - 2015-08-15 09:30 +0200
Re: [PATCH v10 03/20] x86/stackvalidate: Compile-time stack validation Josh Poimboeuf <jpoimboe@redhat.com> - 2015-08-15 14:50 +0200
Re: [PATCH v10 03/20] x86/stackvalidate: Compile-time stack validation Ingo Molnar <mingo@kernel.org> - 2015-08-19 12:10 +0200
| From | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| Date | 2015-08-14 05:20 +0200 |
| Subject | [PATCH v10 00/20] Compile-time stack validation |
| Message-ID | <pXdHb-6tK-3@gated-at.bofh.it> |
This is v10 of the compile-time stack validation patch set, along with
proposed fixes for many of the warnings it found. It's based on the
tip/master branch.
The frame pointer macros have been renamed from FRAME/ENDFRAME to
FRAME_BEGIN/FRAME_END.
v9 can be found here:
https://lkml.kernel.org/r/cover.1438963009.git.jpoimboe@redhat.com
For more information about the motivation behind this patch set, and
more details about what it does, please see the changelog in patch 3.
Patches 1-5 are the stackvalidate tool and some related macros.
Patches 6-20 are some proposed fixes for several of the warnings
reported by stackvalidate. They've been compile-tested and boot tested
in a VM, but I haven't attempted any meaningful testing for many of
them.
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: 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: live-patching@vger.kernel.org
Josh Poimboeuf (20):
x86/asm: Frame pointer macro cleanup
x86/asm: Add C versions of frame pointer macros
x86/stackvalidate: Compile-time stack validation
x86/stackvalidate: Add file and directory ignores
x86/stackvalidate: Add ignore macros
x86/xen: Add stack frame dependency to hypercall inline asm calls
x86/paravirt: Add stack frame dependency to PVOP inline asm calls
x86/paravirt: Create a stack frame in PV_CALLEE_SAVE_REGS_THUNK
x86/amd: Set ELF function type for vide()
x86/reboot: Add ljmp instructions to stackvalidate whitelist
x86/xen: Add xen_cpuid() and xen_setup_gdt() to stackvalidate
whitelists
x86/asm/crypto: Create stack frames in aesni-intel_asm.S
x86/asm/crypto: Move .Lbswap_mask data to .rodata section
x86/asm/crypto: Move jump_table to .rodata section
x86/asm/crypto: Create stack frames in clmul_ghash_mul/update()
x86/asm/entry: Create stack frames in thunk functions
x86/asm/acpi: Create a stack frame in do_suspend_lowlevel()
x86/asm: Create stack frames in rwsem functions
x86/asm/efi: Create a stack frame in efi_call()
x86/asm/power: Create stack frames in hibernate_asm_64.S
Documentation/stack-validation.txt | 193 ++++++
MAINTAINERS | 8 +
arch/Kconfig | 6 +
arch/x86/Kconfig | 1 +
arch/x86/Makefile | 6 +-
arch/x86/boot/Makefile | 3 +-
arch/x86/boot/compressed/Makefile | 3 +-
arch/x86/crypto/aesni-intel_asm.S | 21 +
arch/x86/crypto/crc32c-pcl-intel-asm_64.S | 8 +-
arch/x86/crypto/ghash-clmulni-intel_asm.S | 5 +
arch/x86/entry/thunk_64.S | 4 +
arch/x86/entry/vdso/Makefile | 5 +-
arch/x86/include/asm/frame.h | 51 +-
arch/x86/include/asm/paravirt.h | 9 +-
arch/x86/include/asm/paravirt_types.h | 18 +-
arch/x86/include/asm/stackvalidate.h | 45 ++
arch/x86/include/asm/xen/hypercall.h | 5 +-
arch/x86/kernel/acpi/wakeup_64.S | 3 +
arch/x86/kernel/cpu/amd.c | 5 +-
arch/x86/kernel/reboot.c | 7 +-
arch/x86/kernel/vmlinux.lds.S | 5 +-
arch/x86/lib/rwsem.S | 11 +-
arch/x86/platform/efi/efi_stub_64.S | 3 +
arch/x86/power/hibernate_asm_64.S | 7 +
arch/x86/purgatory/Makefile | 2 +
arch/x86/realmode/Makefile | 4 +-
arch/x86/realmode/rm/Makefile | 3 +-
arch/x86/xen/enlighten.c | 4 +-
drivers/firmware/efi/libstub/Makefile | 1 +
include/linux/stackvalidate.h | 28 +
lib/Kconfig.debug | 11 +
scripts/Makefile | 1 +
scripts/Makefile.build | 37 +-
scripts/mod/Makefile | 2 +
scripts/stackvalidate/Makefile | 24 +
scripts/stackvalidate/arch-x86.c | 160 +++++
scripts/stackvalidate/arch.h | 44 ++
scripts/stackvalidate/elf.c | 427 +++++++++++++
scripts/stackvalidate/elf.h | 92 +++
scripts/stackvalidate/list.h | 217 +++++++
scripts/stackvalidate/special.c | 199 ++++++
scripts/stackvalidate/special.h | 42 ++
scripts/stackvalidate/stackvalidate.c | 976 ++++++++++++++++++++++++++++++
43 files changed, 2658 insertions(+), 48 deletions(-)
create mode 100644 Documentation/stack-validation.txt
create mode 100644 arch/x86/include/asm/stackvalidate.h
create mode 100644 include/linux/stackvalidate.h
create mode 100644 scripts/stackvalidate/Makefile
create mode 100644 scripts/stackvalidate/arch-x86.c
create mode 100644 scripts/stackvalidate/arch.h
create mode 100644 scripts/stackvalidate/elf.c
create mode 100644 scripts/stackvalidate/elf.h
create mode 100644 scripts/stackvalidate/list.h
create mode 100644 scripts/stackvalidate/special.c
create mode 100644 scripts/stackvalidate/special.h
create mode 100644 scripts/stackvalidate/stackvalidate.c
--
2.4.3
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| From | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| Date | 2015-08-14 05:20 +0200 |
| Subject | [PATCH v10 04/20] x86/stackvalidate: Add file and directory ignores |
| Message-ID | <pXdHc-6tK-17@gated-at.bofh.it> |
| In reply to | #1207312 |
Tell stackvalidate to skip validation of the following code: - boot image - vdso image - kexec purgatory - realmode - efi libstub - scripts/mod They all run outside the kernel's normal mode of operation and they don't affect runtime kernel stack traces, so they're free to skirt the stackvalidate rules. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- arch/x86/boot/Makefile | 3 ++- arch/x86/boot/compressed/Makefile | 3 ++- arch/x86/entry/vdso/Makefile | 5 ++++- 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 ++ 8 files changed, 18 insertions(+), 5 deletions(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 0d553e5..d31808c 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -14,7 +14,8 @@ # Set it to -DSVGA_MODE=NORMAL_VGA if you just want the EGA/VGA mode. # The number is the same as you would ordinarily press at bootup. -KASAN_SANITIZE := n +KASAN_SANITIZE := n +STACKVALIDATE := n SVGA_MODE := -DSVGA_MODE=NORMAL_VGA diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 0a291cd..530a46f 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 +STACKVALIDATE := n 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/vdso/Makefile b/arch/x86/entry/vdso/Makefile index a3d0767..b7cbf61 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -3,7 +3,9 @@ # KBUILD_CFLAGS += $(DISABLE_LTO) -KASAN_SANITIZE := n + +KASAN_SANITIZE := n +STACKVALIDATE := n VDSO64-$(CONFIG_X86_64) := y VDSOX32-$(CONFIG_X86_X32_ABI) := y @@ -15,6 +17,7 @@ vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o # files to link into kernel obj-y += vma.o +STACKVALIDATE_vma.o := y # vDSO images to build vdso_img-$(VDSO64-y) += 64 diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index 2c835e3..a736c19 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile @@ -1,3 +1,5 @@ +STACKVALIDATE := n + 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..7a2d4df 100644 --- a/arch/x86/realmode/Makefile +++ b/arch/x86/realmode/Makefile @@ -6,7 +6,9 @@ # for more details. # # -KASAN_SANITIZE := n +KASAN_SANITIZE := n +STACKVALIDATE := n + subdir- := rm obj-y += init.o diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 2730d77..d462a57 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 +STACKVALIDATE := n always := realmode.bin realmode.relocs diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 816dbe9..b392f3f 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -20,6 +20,7 @@ KBUILD_CFLAGS := $(cflags-y) \ GCOV_PROFILE := n KASAN_SANITIZE := n +STACKVALIDATE := n lib-y := efi-stub-helper.o lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile index c11212f..374c413 100644 --- a/scripts/mod/Makefile +++ b/scripts/mod/Makefile @@ -1,3 +1,5 @@ +STACKVALIDATE := n + hostprogs-y := modpost mk_elfconfig always := $(hostprogs-y) empty.o -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2015-08-15 09:30 +0200 |
| Subject | Re: [PATCH v10 03/20] x86/stackvalidate: Compile-time stack validation |
| Message-ID | <pXE4G-2Wa-3@gated-at.bofh.it> |
| In reply to | #1207312 |
On Thu, 13 Aug 2015 22:10:24 -0500 Josh Poimboeuf <jpoimboe@redhat.com> wrote: > This adds a CONFIG_STACK_VALIDATION option which enables a host tool > named stackvalidate which runs at compile time. It would be useful to - show example output for a typical error site - describe the consequences of that error (ie: why should we fix these things?) - describe what needs to be done to repair these sites. IOW, what do we gain from merging all this stuff? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| Date | 2015-08-15 14:50 +0200 |
| Subject | Re: [PATCH v10 03/20] x86/stackvalidate: Compile-time stack validation |
| Message-ID | <pXJ4m-1DC-3@gated-at.bofh.it> |
| In reply to | #1208030 |
On Sat, Aug 15, 2015 at 12:23:54AM -0700, Andrew Morton wrote:
> On Thu, 13 Aug 2015 22:10:24 -0500 Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> > This adds a CONFIG_STACK_VALIDATION option which enables a host tool
> > named stackvalidate which runs at compile time.
>
> It would be useful to
>
> - show example output for a typical error site
>
> - describe the consequences of that error (ie: why should we fix
> these things?)
>
> - describe what needs to be done to repair these sites.
>
>
> IOW, what do we gain from merging all this stuff?
I attempted to do all that in Documentation/stack-validation.txt which
is in patch 03/20. Does it address your concerns? Here it is:
Compile-time stack validation
=============================
Overview
--------
The CONFIG_STACK_VALIDATION option enables a host tool named
stackvalidate which runs at compile time. It analyzes every .o file and
ensures the validity of its stack metadata. It enforces a set of rules
on asm code and C inline assembly code so that stack traces can be
reliable.
Currently it only checks frame pointer usage, but there are plans to add
CFI validation for C files and CFI generation for asm files.
For each function, it recursively follows all possible code paths and
validates the correct frame pointer state at each instruction.
It also follows code paths involving special sections, like
.altinstructions, __jump_table, and __ex_table, which can add
alternative execution paths to a given instruction (or set of
instructions). Similarly, it knows how to follow switch statements, for
which gcc sometimes uses jump tables.
Rules
-----
To achieve the validation, stackvalidate enforces the following rules:
1. Each callable function must be annotated as such with the ELF
function type. In asm code, this is typically done using the
ENTRY/ENDPROC macros. If stackvalidate finds a return instruction
outside of a function, it flags an error since that usually indicates
callable code which should be annotated accordingly.
2. Conversely, each section of code which is *not* callable should *not*
be annotated as an ELF function. The ENDPROC macro shouldn't be used
in this case.
3. Each callable function which calls another function must have the
correct frame pointer logic, if required by CONFIG_FRAME_POINTER or
the architecture's back chain rules. This can by done in asm code
with the FRAME_BEGIN/FRAME_END macros.
4. Dynamic jumps and jumps to undefined symbols are only allowed if:
a) the jump is part of a switch statement; or
b) the jump matches sibling call semantics and the frame pointer has
the same value it had on function entry.
5. A callable function may not execute kernel entry/exit instructions.
The only code which needs such instructions is kernel entry code,
which shouldn't be be in callable functions anyway.
Errors in .S files
------------------
If you're getting an error in a compiled .S file which you don't
understand, first make sure that the affected code follows the above
rules.
Here are some examples of common problems and suggestions for how to fix
them.
1. stackvalidate: asm_file.o: func()+0x128: call without frame pointer save/setup
The func() function made a function call without first saving and/or
updating the frame pointer.
If func() is indeed a callable function, add proper frame pointer
logic using the FP_SAVE and FP_RESTORE macros. Otherwise, remove its
ELF function annotation by changing ENDPROC to END.
If you're getting this error in a .c file, see the "Errors in .c
files" section.
2. stackvalidate: asm_file.o: .text+0x53: return instruction outside of a callable function
A return instruction was detected, but stackvalidate couldn't find a
way for a callable function to reach the instruction.
If the return instruction is inside (or reachable from) a callable
function, the function needs to be annotated with the ENTRY/ENDPROC
macros.
If you _really_ need a return instruction outside of a function, and
are 100% sure that it won't affect stack traces, you can tell
stackvalidate to ignore it. See the "Adding exceptions" section
below.
3. stackvalidate: asm_file.o: func()+0x9: function has unreachable instruction
The instruction lives inside of a callable function, but there's no
possible control flow path from the beginning of the function to the
instruction.
If the instruction is actually needed, and it's actually in a
callable function, ensure that its function is properly annotated
with ENTRY/ENDPROC.
If it's not actually in a callable function (e.g. kernel entry code),
change ENDPROC to END.
4. stackvalidate: asm_file.o: func(): can't find starting instruction
or
stackvalidate: asm_file.o: func()+0x11dd: can't decode instruction
Did you put data in a text section? If so, that can confuse
stackvalidate's instruction decoder. Move the data to a more
appropriate section like .data or .rodata.
5. stackvalidate: asm_file.o: func()+0x6: kernel entry/exit from callable instruction
This is a kernel entry/exit instruction like sysenter or sysret.
Such instructions aren't allowed in a callable function, and are most
likely part of the kernel entry code.
If the instruction isn't actually in a callable function, change
ENDPROC to END.
6. stackvalidate: asm_file.o: func()+0x26: sibling call from callable instruction with changed frame pointer
This is a dynamic jump or a jump to an undefined symbol.
Stackvalidate assumed it's a sibling call and detected that the frame
pointer wasn't first restored to its original state.
If it's not really a sibling call, you may need to move the
destination code to the local file.
If the instruction is not actually in a callable function (e.g.
kernel entry code), change ENDPROC to END.
7. stackvalidate: asm_file: func()+0x5c: frame pointer state mismatch
The instruction's frame pointer state is inconsistent, depending on
which execution path was taken to reach the instruction.
Make sure the function pushes and sets up the frame pointer (for
x86_64, this means rbp) at the beginning of the function and pops it
at the end of the function. Also make sure that no other code in the
function touches the frame pointer.
Errors in .c files
------------------
If you're getting a stackvalidate error in a compiled .c file, chances
are the file uses an asm() statement which has a "call" instruction. An
asm() statement with a call instruction must declare the use of the
stack pointer in its output operand. For example, on x86_64:
register void *__sp asm("rsp");
asm volatile("call func" : "+r" (__sp));
Otherwise the stack frame may not get created before the call.
Another possible cause for errors in C code is if the Makefile removes
-fno-omit-frame-pointer or adds -fomit-frame-pointer to the gcc options.
Also see the above section for .S file errors for more information what
the individual error messages mean.
Adding exceptions
-----------------
If you _really_ need stackvalidate to ignore something, and are 100%
sure that it won't affect kernel stack traces, you can tell
stackvalidate to ignore it:
- To skip validation of an instruction, use the
STACKVALIDATE_IGNORE_INSN macro immediately before the instruction.
- To skip validation of a function, use the STACKVALIDATE_IGNORE_FUNC
macro.
- To skip validation of a file, add "STACKVALIDATE_filename.o := n" to
the Makefile.
- To skip validation of a directory, add "STACKVALIDATE := n" to the
Makefile.
--
Josh
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| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Date | 2015-08-19 12:10 +0200 |
| Subject | Re: [PATCH v10 03/20] x86/stackvalidate: Compile-time stack validation |
| Message-ID | <pZ8tI-2KG-5@gated-at.bofh.it> |
| In reply to | #1208075 |
* Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Sat, Aug 15, 2015 at 12:23:54AM -0700, Andrew Morton wrote:
> > On Thu, 13 Aug 2015 22:10:24 -0500 Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> >
> > > This adds a CONFIG_STACK_VALIDATION option which enables a host tool
> > > named stackvalidate which runs at compile time.
> >
> > It would be useful to
> >
> > - show example output for a typical error site
> >
> > - describe the consequences of that error (ie: why should we fix
> > these things?)
> >
> > - describe what needs to be done to repair these sites.
> >
> >
> > IOW, what do we gain from merging all this stuff?
>
> I attempted to do all that in Documentation/stack-validation.txt which
> is in patch 03/20. Does it address your concerns? Here it is:
I think it answers the first and third question, but not the second one:
- describe the consequences of that error (ie: why should we fix
these things?)
would be nice to document all that richly.
Thanks,
Ingo
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