[PATCH 6.9 132/374] s390/stacktrace: Skip first user stack frame

Greg Kroah-Hartman
2024-06-06T14:09:23Z

From: Heiko Carstens <hca@linux.ibm.com>

[ Upstream commit 87eceb17a987802aeee718be4decd19b56fc8e33 ]

When walking user stack frames the first stack frame (where the stack
pointer points to) should be skipped: the return address of the current
function is saved in the previous stack frame, not the current stack frame,
which is allocated for to be called functions.

Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support")
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kernel/stacktrace.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index e580d4cd2729a..1c9e3b7739a22 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -95,6 +95,10 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
while (1) {
if (__get_user(sp, &sf->back_chain))
break;
+ /* Sanity check: ABI requires SP to be 8 byte aligned. */
+ if (!sp || sp & 0x7)
+ break;
+ sf = (void __user *)sp;
if (__get_user(ip, &sf->gprs[8]))
break;
if (ip & 0x1) {
@@ -110,10 +114,6 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
}
if (!store_ip(consume_entry, cookie, entry, perf, ip))
return;
- /* Sanity check: ABI requires SP to be aligned 8 bytes. */
- if (!sp || sp & 0x7)
- break;
- sf = (void __user *)sp;
first = false;
}
pagefault_enable();
--
2.43.0