Messages in this thread Patch in this message | | | From | Josh Poimboeuf <> | Subject | [PATCH urgent] Revert "x86/unwind: Detect bad stack return address" | Date | Thu, 22 Dec 2016 09:02:49 -0600 |
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This reverts commit b6959a362177 ("x86/unwind: Detect bad stack return address").
Andrey Konovalov reported an unwinder warning:
WARNING: unrecognized kernel stack return address ffffffffa0000001 at ffff88006377fa18 in a.out:4467
The unwind was initiated from an interrupt which occurred while running in the generated code for a kprobe. The unwinder printed the warning because it expected regs->ip to point to a valid text address, but instead it pointed to the generated code.
Eventually we may want come up with a way to identify generated kprobe code so the unwinder can know that it's a valid return address. Until then, just remove the warning.
Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- arch/x86/kernel/unwind_frame.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-)
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index 20d4b4e..4443e49 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -51,16 +51,7 @@ unsigned long unwind_get_return_address(struct unwind_state *state) addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, *addr_p, addr_p); - if (!__kernel_text_address(addr)) { - printk_deferred_once(KERN_WARNING - "WARNING: unrecognized kernel stack return address %p at %p in %s:%d\n", - (void *)addr, addr_p, state->task->comm, - state->task->pid); - unwind_dump(state, addr_p); - return 0; - } - - return addr; + return __kernel_text_address(addr) ? addr : 0; } EXPORT_SYMBOL_GPL(unwind_get_return_address); -- 2.7.4
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