[PATCH v2 3/6] s390: Add ftrace_stub_graph

From: Heiko Carstens

Date: Mon Jul 27 2026 - 10:43:28 EST


This is the s390 variant of commit f3a0c23f2539 ("riscv: Add
ftrace_stub_graph"):

"Commit 883bbbffa5a4 ("ftrace,kcfi: Separate ftrace_stub() and
ftrace_stub_graph()") added a separate ftrace_stub_graph function for
CFI_CLANG. Add the stub to fix FUNCTION_GRAPH_TRACER compatibility
with CFI."

Reviewed-by: Jens Remus <jremus@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
---
arch/s390/kernel/mcount.S | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 1fec370fecf4..6bc44c767642 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -4,6 +4,7 @@
*
*/

+#include <linux/cfi_types.h>
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>
@@ -34,10 +35,16 @@

.section .kprobes.text, "ax"

-SYM_FUNC_START(ftrace_stub)
+SYM_TYPED_FUNC_START(ftrace_stub)
BR_EX %r14
SYM_FUNC_END(ftrace_stub)

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+SYM_TYPED_FUNC_START(ftrace_stub_graph)
+ BR_EX %r14
+SYM_FUNC_END(ftrace_stub_graph)
+#endif
+
SYM_CODE_START(ftrace_stub_direct_tramp)
lgr %r1, %r0
BR_EX %r1
--
2.53.0