diff options
author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-04-12 13:47:12 -0500 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2017-04-14 10:20:06 +0200 |
commit | a8b7a92318b6d7779f6d8e9aa6ba0e3de01a8943 (patch) | |
tree | 6f71ebbdd24bbccb023f8d47b4c7a317b0658ba5 /arch/x86/kernel/unwind_frame.c | |
parent | 6bcdf9d51b9892dd5c6892d50cf5e9628efb8062 (diff) | |
download | linux-stable-a8b7a92318b6d7779f6d8e9aa6ba0e3de01a8943.tar.gz linux-stable-a8b7a92318b6d7779f6d8e9aa6ba0e3de01a8943.tar.bz2 linux-stable-a8b7a92318b6d7779f6d8e9aa6ba0e3de01a8943.zip |
x86/unwind: Silence entry-related warnings
A few people have reported unwinder warnings like the following:
WARNING: kernel stack frame pointer at ffffc90000fe7ff0 in rsync:1157 has bad value (null)
unwind stack type:0 next_sp: (null) mask:2 graph_idx:0
ffffc90000fe7f98: ffffc90000fe7ff0 (0xffffc90000fe7ff0)
ffffc90000fe7fa0: ffffffffb7000f56 (trace_hardirqs_off_thunk+0x1a/0x1c)
ffffc90000fe7fa8: 0000000000000246 (0x246)
ffffc90000fe7fb0: 0000000000000000 ...
ffffc90000fe7fc0: 00007ffe3af639bc (0x7ffe3af639bc)
ffffc90000fe7fc8: 0000000000000006 (0x6)
ffffc90000fe7fd0: 00007f80af433fc5 (0x7f80af433fc5)
ffffc90000fe7fd8: 00007ffe3af638e0 (0x7ffe3af638e0)
ffffc90000fe7fe0: 00007ffe3af638e0 (0x7ffe3af638e0)
ffffc90000fe7fe8: 00007ffe3af63970 (0x7ffe3af63970)
ffffc90000fe7ff0: 0000000000000000 ...
ffffc90000fe7ff8: ffffffffb7b74b9a (entry_SYSCALL_64_after_swapgs+0x17/0x4f)
This warning can happen when unwinding a code path where an interrupt
occurred in x86 entry code before it set up the first stack frame.
Silently ignore any warnings for this case.
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: c32c47c68a0a ("x86/unwind: Warn on bad frame pointer")
Link: http://lkml.kernel.org/r/dbd6838826466a60dc23a52098185bc973ce2f1e.1492020577.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/unwind_frame.c')
-rw-r--r-- | arch/x86/kernel/unwind_frame.c | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index c67a059c6655..c4611359b617 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -1,6 +1,8 @@ #include <linux/sched.h> #include <linux/sched/task.h> #include <linux/sched/task_stack.h> +#include <linux/interrupt.h> +#include <asm/sections.h> #include <asm/ptrace.h> #include <asm/bitops.h> #include <asm/stacktrace.h> @@ -72,6 +74,21 @@ static size_t regs_size(struct pt_regs *regs) return sizeof(*regs); } +static bool in_entry_code(unsigned long ip) +{ + char *addr = (char *)ip; + + if (addr >= __entry_text_start && addr < __entry_text_end) + return true; + +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN) + if (addr >= __irqentry_text_start && addr < __irqentry_text_end) + return true; +#endif + + return false; +} + #ifdef CONFIG_X86_32 #define GCC_REALIGN_WORDS 3 #else @@ -144,6 +161,7 @@ static bool update_stack_state(struct unwind_state *state, if (regs) { frame = (unsigned long *)regs; len = regs_size(regs); + state->got_irq = true; } else { frame = next_bp; len = FRAME_HEADER_SIZE; @@ -239,16 +257,8 @@ bool unwind_next_frame(struct unwind_state *state) next_bp = (unsigned long *)READ_ONCE_TASK_STACK(state->task, *state->bp); /* Move to the next frame if it's safe: */ - if (!update_stack_state(state, next_bp)) { - /* - * Don't warn on bad regs->bp. An interrupt in entry code - * might cause a false positive warning. - */ - if (state->regs) - goto the_end; - + if (!update_stack_state(state, next_bp)) goto bad_address; - } return true; @@ -263,6 +273,13 @@ bad_address: if (state->task != current) goto the_end; + /* + * Don't warn if the unwinder got lost due to an interrupt in entry + * code before the stack was set up: + */ + if (state->got_irq && in_entry_code(state->ip)) + goto the_end; + if (state->regs) { printk_deferred_once(KERN_WARNING "WARNING: kernel stack regs at %p in %s:%d has bad 'bp' value %p\n", @@ -289,6 +306,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task, memset(state, 0, sizeof(*state)); state->task = task; + state->got_irq = (regs); /* Don't even attempt to start from user mode regs: */ if (regs && user_mode(regs)) { |