From c280f7736ab26a601932b1ce017a3840dbedcfdc Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Thu, 22 Dec 2016 09:02:49 -0600 Subject: [PATCH] Revert "x86/unwind: Detect bad stack return address" Revert the following commit: b6959a362177 ("x86/unwind: Detect bad stack return address") ... because 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 Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/02f296848fbf49fb72dfeea706413ecbd9d4caf6.1482418739.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- 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 20d4b4e0800c..4443e499f279 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); -- 2.20.1