Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1680131

[PATCH 4.11 67/84] Revert "x86/entry: Fix the end of the stack for newly forked tasks"

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.11 67/84] Revert "x86/entry: Fix the end of the stack for newly forked tasks"
Date 2017-07-03 16:00 +0200
Message-ID <tZa3p-2gz-33@gated-at.bofh.it> (permalink)
References <tZ9TH-2c1-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Josh Poimboeuf <jpoimboe@redhat.com>

commit ebd574994c63164d538a197172157318f58ac647 upstream.

Petr Mladek reported the following warning when loading the livepatch
sample module:

  WARNING: CPU: 1 PID: 3699 at arch/x86/kernel/stacktrace.c:132 save_stack_trace_tsk_reliable+0x133/0x1a0
  ...
  Call Trace:
   __schedule+0x273/0x820
   schedule+0x36/0x80
   kthreadd+0x305/0x310
   ? kthread_create_on_cpu+0x80/0x80
   ? icmp_echo.part.32+0x50/0x50
   ret_from_fork+0x2c/0x40

That warning means the end of the stack is no longer recognized as such
for newly forked tasks.  The problem was introduced with the following
commit:

  ff3f7e2475bb ("x86/entry: Fix the end of the stack for newly forked tasks")

... which was completely misguided.  It only partially fixed the
reported issue, and it introduced another bug in the process.  None of
the other entry code saves the frame pointer before calling into C code,
so it doesn't make sense for ret_from_fork to do so either.

Contrary to what I originally thought, the original issue wasn't related
to newly forked tasks.  It was actually related to ftrace.  When entry
code calls into a function which then calls into an ftrace handler, the
stack frame looks different than normal.

The original issue will be fixed in the unwinder, in a subsequent patch.

Reported-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: live-patching@vger.kernel.org
Fixes: ff3f7e2475bb ("x86/entry: Fix the end of the stack for newly forked tasks")
Link: http://lkml.kernel.org/r/f350760f7e82f0750c8d1dd093456eb212751caa.1495553739.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/entry/entry_32.S |   30 +++++++++++++++++++-----------
 arch/x86/entry/entry_64.S |   11 ++++-------
 2 files changed, 23 insertions(+), 18 deletions(-)

--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -255,6 +255,23 @@ ENTRY(__switch_to_asm)
 END(__switch_to_asm)
 
 /*
+ * The unwinder expects the last frame on the stack to always be at the same
+ * offset from the end of the page, which allows it to validate the stack.
+ * Calling schedule_tail() directly would break that convention because its an
+ * asmlinkage function so its argument has to be pushed on the stack.  This
+ * wrapper creates a proper "end of stack" frame header before the call.
+ */
+ENTRY(schedule_tail_wrapper)
+	FRAME_BEGIN
+
+	pushl	%eax
+	call	schedule_tail
+	popl	%eax
+
+	FRAME_END
+	ret
+ENDPROC(schedule_tail_wrapper)
+/*
  * A newly forked process directly context switches into this address.
  *
  * eax: prev task we switched from
@@ -262,24 +279,15 @@ END(__switch_to_asm)
  * edi: kernel thread arg
  */
 ENTRY(ret_from_fork)
-	FRAME_BEGIN		/* help unwinder find end of stack */
-
-	/*
-	 * schedule_tail() is asmlinkage so we have to put its 'prev' argument
-	 * on the stack.
-	 */
-	pushl	%eax
-	call	schedule_tail
-	popl	%eax
+	call	schedule_tail_wrapper
 
 	testl	%ebx, %ebx
 	jnz	1f		/* kernel threads are uncommon */
 
 2:
 	/* When we fork, we trace the syscall return in the child, too. */
-	leal	FRAME_OFFSET(%esp), %eax
+	movl    %esp, %eax
 	call    syscall_return_slowpath
-	FRAME_END
 	jmp     restore_all
 
 	/* kernel thread */
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -36,7 +36,6 @@
 #include <asm/smap.h>
 #include <asm/pgtable_types.h>
 #include <asm/export.h>
-#include <asm/frame.h>
 #include <linux/err.h>
 
 .code64
@@ -409,19 +408,17 @@ END(__switch_to_asm)
  * r12: kernel thread arg
  */
 ENTRY(ret_from_fork)
-	FRAME_BEGIN			/* help unwinder find end of stack */
 	movq	%rax, %rdi
-	call	schedule_tail		/* rdi: 'prev' task parameter */
+	call	schedule_tail			/* rdi: 'prev' task parameter */
 
-	testq	%rbx, %rbx		/* from kernel_thread? */
-	jnz	1f			/* kernel threads are uncommon */
+	testq	%rbx, %rbx			/* from kernel_thread? */
+	jnz	1f				/* kernel threads are uncommon */
 
 2:
-	leaq	FRAME_OFFSET(%rsp),%rdi	/* pt_regs pointer */
+	movq	%rsp, %rdi
 	call	syscall_return_slowpath	/* returns with IRQs disabled */
 	TRACE_IRQS_ON			/* user mode is traced as IRQS on */
 	SWAPGS
-	FRAME_END
 	jmp	restore_regs_and_iret
 
 1:

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 4.11 00/84] 4.11.9-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:50 +0200
  [PATCH 4.11 39/84] MIPS: Fix IRQ tracing & lockdep when rescheduling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:50 +0200
  [PATCH 4.11 13/84] net: tipc: Fix a sleep-in-atomic bug in tipc_msg_reverse Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 15:50 +0200
  [PATCH 4.11 61/84] ARM64: PCI: Fix struct acpi_pci_root_ops allocation failure path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 23/84] ipv6: fix calling in6_ifa_hold incorrectly for dad work Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 64/84] ARM: davinci: PM: Free resources in error handling path in davinci_pm_init Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 80/84] mtd: nand: fsmc: fix NAND width handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 50/84] dm thin: do not queue freed thin mapping for next stage processing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 47/84] x86/intel_rdt: Fix memory leak on mount failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 76/84] iommu/amd: Fix incorrect error handling in amd_iommu_bind_pasid() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 60/84] watchdog: bcm281xx: Fix use of uninitialized spinlock. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 67/84] Revert "x86/entry: Fix the end of the stack for newly forked tasks" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 78/84] infiniband: hns: avoid gcc-7.0.1 warning for uninitialized data Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 36/84] MIPS: head: Reorder instructions missing a delay slot Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 81/84] KVM: x86: fix emulation of RSM and IRET instructions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 58/84] xfrm: NULL dereference on allocation failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 69/84] x86/boot/KASLR: Fix kexec crash due to virt_addr calculation bug Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 75/84] iommu/dma: Dont reserve PCI I/O windows Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 74/84] ocfs2: fix deadlock caused by recursive locking in xattr Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 33/84] netfilter: synproxy: fix conntrackd interaction Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 72/84] x86/mm: Fix flush_tlb_page() on Xen Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 55/84] xfrm6: Fix IPv6 payload_len in xfrm6_transport_finish Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 46/84] gpiolib: fix filtering out unwanted events Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 73/84] ocfs2: o2hb: revert hb threshold to keep compatible Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 66/84] tools arch: Sync arch/x86/lib/memcpy_64.S with the kernel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 79/84] mtd: nand: brcmnand: Check flash #WP pin status before nand erase/program Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 38/84] MIPS: pm-cps: Drop manual cache-line alignment of ready_count Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 65/84] ARM: davinci: PM: Do not free useful resources in normal path in davinci_pm_init Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 34/84] NFSv4.x/callback: Create the callback service through svc_create_pooled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 62/84] ARM64/ACPI: Fix BAD_MADT_GICC_ENTRY() macro implementation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 70/84] perf/x86: Fix spurious NMI with PEBS Load Latency event Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 31/84] ipv6: Do not leak throw route references Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 56/84] xfrm: move xfrm_garbage_collect out of xfrm_policy_flush Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 68/84] x86/mshyperv: Remove excess #includes from mshyperv.h Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 53/84] mm/vmalloc.c: huge-vmap: fail gracefully on unexpected huge vmap mappings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 37/84] MIPS: Avoid accidental raw backtrace Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 40/84] ALSA: hda - Fix endless loop of codec configure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 71/84] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 77/84] iommu/amd: Fix interrupt remapping when disable guest_mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 51/84] x86/mm: Fix boot crash caused by incorrect loop count calculation in sync_global_pgds() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:00 +0200
  [PATCH 4.11 25/84] net/mlx5e: Fix min inline value for VF rep SQs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 16/84] net/mlx5e: Fix wrong indications in DIM due to counter wraparound Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 45/84] ovl: copy-up: dont unlock between lookup and link Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 20/84] igmp: add a missing spin_lock_init() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 01/84] net: dont call strlen on non-terminated string in dev_set_alias() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 22/84] net: dont global ICMP rate limit packets originating from loopback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 06/84] net: Zero ifla_vf_info in rtnl_fill_vfinfo() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 05/84] decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 27/84] net/mlx5: Wait for FW readiness before initializing command interface Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 43/84] NFSv4.1: Fix a race in nfs4_proc_layoutget Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 17/84] net/mlx5: Enable 4K UAR only when page size is bigger than 4K Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 32/84] rtnetlink: add IFLA_GROUP to ifla_policy Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 41/84] ALSA: hda - set input_path bitmap to zero after moving it to new place Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 08/84] net: vrf: Make add_fib_rules per network namespace flag Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 04/84] mac80211: free netdev on dev_alloc_name() error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 19/84] igmp: acquire pmc lock for ip_mc_clear_src() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 02/84] net: Fix inconsistent teardown and release of private netdev state. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 29/84] decnet: always not take dst->__refcnt when inserting dst into hash table Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 44/84] Revert "NFS: nfs_rename() handle -ERESTARTSYS dentry left behind" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 14/84] net/mlx5: Remove several module events out of ethtool stats Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 09/84] af_unix: Add sockaddr length checks before accessing sa_family in bind and connect handlers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 18/84] proc: snmp6: Use correct type in memset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 42/84] NFSv4.2: Dont send mode again in post-EXCLUSIVE4_1 SETATTR with umask Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  [PATCH 4.11 07/84] net: ipv6: Release route when device is unregistering Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-03 16:10 +0200
  Re: [PATCH 4.11 00/84] 4.11.9-stable review Guenter Roeck <linux@roeck-us.net> - 2017-07-03 22:00 +0200
    Re: [PATCH 4.11 00/84] 4.11.9-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-07-04 10:00 +0200

csiph-web