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author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-12-31 19:18:06 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2018-01-03 18:14:46 +0300 |
commit | a9cdbe72c4e8bf3b38781c317a79326e2e1a230d (patch) | |
tree | 68cdaf511eb0f093cebb50d201d5ee8f399549cd /arch/x86/include | |
parent | 52994c256df36fda9a715697431cba9daecb6b11 (diff) | |
download | linux-a9cdbe72c4e8bf3b38781c317a79326e2e1a230d.tar.xz |
x86/dumpstack: Fix partial register dumps
The show_regs_safe() logic is wrong. When there's an iret stack frame,
it prints the entire pt_regs -- most of which is random stack data --
instead of just the five registers at the end.
show_regs_safe() is also poorly named: the on_stack() checks aren't for
safety. Rename the function to show_regs_if_on_stack() and add a
comment to explain why the checks are needed.
These issues were introduced with the "partial register dump" feature of
the following commit:
b02fcf9ba121 ("x86/unwinder: Handle stack overflows more gracefully")
That patch had gone through a few iterations of development, and the
above issues were artifacts from a previous iteration of the patch where
'regs' pointed directly to the iret frame rather than to the (partially
empty) pt_regs.
Tested-by: Alexander Tsoy <alexander@tsoy.me>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toralf Förster <toralf.foerster@gmx.de>
Cc: stable@vger.kernel.org
Fixes: b02fcf9ba121 ("x86/unwinder: Handle stack overflows more gracefully")
Link: http://lkml.kernel.org/r/5b05b8b344f59db2d3d50dbdeba92d60f2304c54.1514736742.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include')
-rw-r--r-- | arch/x86/include/asm/unwind.h | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h index c1688c2d0a12..1f86e1b0a5cd 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -56,18 +56,27 @@ void unwind_start(struct unwind_state *state, struct task_struct *task, #if defined(CONFIG_UNWINDER_ORC) || defined(CONFIG_UNWINDER_FRAME_POINTER) /* - * WARNING: The entire pt_regs may not be safe to dereference. In some cases, - * only the iret frame registers are accessible. Use with caution! + * If 'partial' returns true, only the iret frame registers are valid. */ -static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) +static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state, + bool *partial) { if (unwind_done(state)) return NULL; + if (partial) { +#ifdef CONFIG_UNWINDER_ORC + *partial = !state->full_regs; +#else + *partial = false; +#endif + } + return state->regs; } #else -static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) +static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state, + bool *partial) { return NULL; } |