From 5d1ceb3969b6b2e47e2df6d17790a7c5a20fcbb4 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 22 Oct 2021 16:53:02 +0200 Subject: [PATCH] x86: Fix __get_wchan() for !STACKTRACE Use asm/unwind.h to implement wchan, since we cannot always rely on STACKTRACE=y. Fixes: bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder") Reported-by: Stephen Rothwell Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20211022152104.137058575@infradead.org --- arch/x86/kernel/process.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index a69885a9d711..8fb6bd4cbc50 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -43,6 +43,7 @@ #include #include #include +#include #include "process.h" @@ -944,10 +945,20 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) */ unsigned long __get_wchan(struct task_struct *p) { - unsigned long entry = 0; + struct unwind_state state; + unsigned long addr = 0; - stack_trace_save_tsk(p, &entry, 1, 0); - return entry; + for (unwind_start(&state, p, NULL, NULL); !unwind_done(&state); + unwind_next_frame(&state)) { + addr = unwind_get_return_address(&state); + if (!addr) + break; + if (in_sched_functions(addr)) + continue; + break; + } + + return addr; } long do_arch_prctl_common(struct task_struct *task, int option, -- 2.20.1