This is a note to let you know that I've just added the patch titled
x86: Fix __get_wchan() for !STACKTRACE
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fix-__get_wchan-for-stacktrace.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f16b3dd8dcb1f27ad452a55bbf4099c9b0c1ca69
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Fri Oct 22 16:53:02 2021 +0200
x86: Fix __get_wchan() for !STACKTRACE
[ Upstream commit 5d1ceb3969b6b2e47e2df6d17790a7c5a20fcbb4 ]
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 <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20211022152104.137058575@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 266962547b58c..2fe1810e922a9 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -43,6 +43,7 @@
#include <asm/io_bitmap.h>
#include <asm/proto.h>
#include <asm/frame.h>
+#include <asm/unwind.h>
#include "process.h"
@@ -945,10 +946,20 @@ 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,
