The following commit has been merged into the perf/core branch of tip:

Commit-ID:     cf76553aaa363620f58a6b6409bf544f4bcfa8de
Gitweb:        https://git.kernel.org/tip/cf76553aaa363620f58a6b6409bf544f4bcfa8de
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Wed, 05 Nov 2025 11:00:14 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 05 Nov 2025 13:57:32 +01:00

entry,unwind/deferred: Fix unwind_reset_info() placement

Stephen reported that on KASAN builds he's seeing:

vmlinux.o: warning: objtool: user_exc_vmm_communication+0x15a: call to __kasan_check_read() leaves .noinstr.text section
vmlinux.o: warning: objtool: exc_debug_user+0x182: call to __kasan_check_read() leaves .noinstr.text section
vmlinux.o: warning: objtool: exc_int3+0x123: call to __kasan_check_read() leaves .noinstr.text section
vmlinux.o: warning: objtool: noist_exc_machine_check+0x17a: call to __kasan_check_read() leaves .noinstr.text section
vmlinux.o: warning: objtool: fred_exc_machine_check+0x17e: call to __kasan_check_read() leaves .noinstr.text section

This turns out to be atomic ops from unwind_reset_info() that have
explicit instrumentation. Place unwind_reset_info() in the preceding
instrumentation_begin() section.

Fixes: c6439bfaabf2 ("Merge tag 'trace-deferred-unwind-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251105100014.GY4068168@noisy.programming.kicks-ass.net
---
 include/linux/irq-entry-common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/irq-entry-common.h b/include/linux/irq-entry-common.h
index d643c7c..ba1ed42 100644
--- a/include/linux/irq-entry-common.h
+++ b/include/linux/irq-entry-common.h
@@ -253,11 +253,11 @@ static __always_inline void exit_to_user_mode_prepare(struct pt_regs *regs)
 static __always_inline void exit_to_user_mode(void)
 {
 	instrumentation_begin();
+	unwind_reset_info();
 	trace_hardirqs_on_prepare();
 	lockdep_hardirqs_on_prepare();
 	instrumentation_end();
 
-	unwind_reset_info();
 	user_enter_irqoff();
 	arch_exit_to_user_mode();
 	lockdep_hardirqs_on(CALLER_ADDR0);