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authorJosh Poimboeuf <jpoimboe@redhat.com>2016-11-27 23:13:07 -0600
committerIngo Molnar <mingo@kernel.org>2016-11-28 07:47:54 +0100
commit55f856e640560494518eaf24fe9d2d2089fba71a (patch)
tree196efed69de7c9567795e9f0daf163851eb4b9ac /arch
parentadee8705d2517f0e163ffc45e8d7f9e97a58f1f6 (diff)
x86/unwind: Fix guess-unwinder regression
My attempt at fixing some KASAN false positive warnings was rather brain dead, and it broke the guess unwinder. With frame pointers disabled, /proc/<pid>/stack is broken: # cat /proc/1/stack [<ffffffffffffffff>] 0xffffffffffffffff Restore the code flow to more closely resemble its previous state, while still using READ_ONCE_NOCHECK() macros to silence KASAN false positives. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: c2d75e03d630 ("x86/unwind: Prevent KASAN false positive warnings in guess unwinder") Link: http://lkml.kernel.org/r/b824f92c2c22eca5ec95ac56bd2a7c84cf0b9df9.1480309971.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/unwind_guess.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c
index b80e8bf43cc6..22881ddcbb9f 100644
--- a/arch/x86/kernel/unwind_guess.c
+++ b/arch/x86/kernel/unwind_guess.c
@@ -7,11 +7,13 @@
unsigned long unwind_get_return_address(struct unwind_state *state)
{
- unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
+ unsigned long addr;
if (unwind_done(state))
return 0;
+ addr = READ_ONCE_NOCHECK(*state->sp);
+
return ftrace_graph_ret_addr(state->task, &state->graph_idx,
addr, state->sp);
}
@@ -25,11 +27,12 @@ bool unwind_next_frame(struct unwind_state *state)
return false;
do {
- unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
+ for (state->sp++; state->sp < info->end; state->sp++) {
+ unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
- for (state->sp++; state->sp < info->end; state->sp++)
if (__kernel_text_address(addr))
return true;
+ }
state->sp = info->next_sp;