Commit ee213fc7 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar

kprobes/x86: Set up frame pointer in kprobe trampoline

Richard Weinberger saw an unwinder warning when running bcc's opensnoop:

  WARNING: kernel stack frame pointer at ffff99ef4076bea0 in opensnoop:2008 has bad value 0000000000000008
  unwind stack type:0 next_sp:          (null) mask:0x2 graph_idx:0
  ...
  ffff99ef4076be88: ffff99ef4076bea0 (0xffff99ef4076bea0)
  ffff99ef4076be90: ffffffffac442721 (optimized_callback +0x81/0x90)
  ...

A lockdep stack trace was initiated from inside a kprobe handler, when
the unwinder noticed a bad frame pointer on the stack.  The bad frame
pointer is related to the fact that the kprobe optprobe trampoline
doesn't save the frame pointer before calling into optimized_callback().
Reported-and-tested-by: default avatarRichard Weinberger <richard@sigma-star.at>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/7aef2f8ecd75c2f505ef9b80490412262cf4a44c.1507038547.git.jpoimboe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9e66317d
...@@ -3,6 +3,15 @@ ...@@ -3,6 +3,15 @@
/* Kprobes and Optprobes common header */ /* Kprobes and Optprobes common header */
#include <asm/asm.h>
#ifdef CONFIG_FRAME_POINTER
# define SAVE_RBP_STRING " push %" _ASM_BP "\n" \
" mov %" _ASM_SP ", %" _ASM_BP "\n"
#else
# define SAVE_RBP_STRING " push %" _ASM_BP "\n"
#endif
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
#define SAVE_REGS_STRING \ #define SAVE_REGS_STRING \
/* Skip cs, ip, orig_ax. */ \ /* Skip cs, ip, orig_ax. */ \
...@@ -17,7 +26,7 @@ ...@@ -17,7 +26,7 @@
" pushq %r10\n" \ " pushq %r10\n" \
" pushq %r11\n" \ " pushq %r11\n" \
" pushq %rbx\n" \ " pushq %rbx\n" \
" pushq %rbp\n" \ SAVE_RBP_STRING \
" pushq %r12\n" \ " pushq %r12\n" \
" pushq %r13\n" \ " pushq %r13\n" \
" pushq %r14\n" \ " pushq %r14\n" \
...@@ -48,7 +57,7 @@ ...@@ -48,7 +57,7 @@
" pushl %es\n" \ " pushl %es\n" \
" pushl %ds\n" \ " pushl %ds\n" \
" pushl %eax\n" \ " pushl %eax\n" \
" pushl %ebp\n" \ SAVE_RBP_STRING \
" pushl %edi\n" \ " pushl %edi\n" \
" pushl %esi\n" \ " pushl %esi\n" \
" pushl %edx\n" \ " pushl %edx\n" \
......
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