[PATCH 6.12 444/567] samples/ftrace: Adjust LoongArch register restore order in direct calls

Greg Kroah-Hartman
2026-01-06T17:38:48Z

From: Chenghao Duan <duanchenghao@kylinos.cn>

commit bb85d206be208bbf834883e948125a35ac59993a upstream.

Ensure that in the ftrace direct call logic, the CPU register state
(with ra = parent return address) is restored to the correct state after
the execution of the custom trampoline function and before returning to
the traced function. Additionally, guarantee the correctness of the jump
logic for jr t0 (traced function address).

Cc: stable@vger.kernel.org
Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support")
Reported-by: Youling Tang <tangyouling@kylinos.cn>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
samples/ftrace/ftrace-direct-modify.c | 8 ++++----
samples/ftrace/ftrace-direct-multi-modify.c | 8 ++++----
samples/ftrace/ftrace-direct-multi.c | 4 ++--
samples/ftrace/ftrace-direct-too.c | 4 ++--
samples/ftrace/ftrace-direct.c | 4 ++--
5 files changed, 14 insertions(+), 14 deletions(-)

--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -176,8 +176,8 @@ asm (
" st.d $t0, $sp, 0\n"
" st.d $ra, $sp, 8\n"
" bl my_direct_func1\n"
-" ld.d $t0, $sp, 0\n"
-" ld.d $ra, $sp, 8\n"
+" ld.d $ra, $sp, 0\n"
+" ld.d $t0, $sp, 8\n"
" addi.d $sp, $sp, 16\n"
" jr $t0\n"
" .size my_tramp1, .-my_tramp1\n"
@@ -189,8 +189,8 @@ asm (
" st.d $t0, $sp, 0\n"
" st.d $ra, $sp, 8\n"
" bl my_direct_func2\n"
-" ld.d $t0, $sp, 0\n"
-" ld.d $ra, $sp, 8\n"
+" ld.d $ra, $sp, 0\n"
+" ld.d $t0, $sp, 8\n"
" addi.d $sp, $sp, 16\n"
" jr $t0\n"
" .size my_tramp2, .-my_tramp2\n"
--- a/samples/ftrace/ftrace-direct-multi-modify.c
+++ b/samples/ftrace/ftrace-direct-multi-modify.c
@@ -199,8 +199,8 @@ asm (
" move $a0, $t0\n"
" bl my_direct_func1\n"
" ld.d $a0, $sp, 0\n"
-" ld.d $t0, $sp, 8\n"
-" ld.d $ra, $sp, 16\n"
+" ld.d $ra, $sp, 8\n"
+" ld.d $t0, $sp, 16\n"
" addi.d $sp, $sp, 32\n"
" jr $t0\n"
" .size my_tramp1, .-my_tramp1\n"
@@ -215,8 +215,8 @@ asm (
" move $a0, $t0\n"
" bl my_direct_func2\n"
" ld.d $a0, $sp, 0\n"
-" ld.d $t0, $sp, 8\n"
-" ld.d $ra, $sp, 16\n"
+" ld.d $ra, $sp, 8\n"
+" ld.d $t0, $sp, 16\n"
" addi.d $sp, $sp, 32\n"
" jr $t0\n"
" .size my_tramp2, .-my_tramp2\n"
--- a/samples/ftrace/ftrace-direct-multi.c
+++ b/samples/ftrace/ftrace-direct-multi.c
@@ -131,8 +131,8 @@ asm (
" move $a0, $t0\n"
" bl my_direct_func\n"
" ld.d $a0, $sp, 0\n"
-" ld.d $t0, $sp, 8\n"
-" ld.d $ra, $sp, 16\n"
+" ld.d $ra, $sp, 8\n"
+" ld.d $t0, $sp, 16\n"
" addi.d $sp, $sp, 32\n"
" jr $t0\n"
" .size my_tramp, .-my_tramp\n"
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -143,8 +143,8 @@ asm (
" ld.d $a0, $sp, 0\n"
" ld.d $a1, $sp, 8\n"
" ld.d $a2, $sp, 16\n"
-" ld.d $t0, $sp, 24\n"
-" ld.d $ra, $sp, 32\n"
+" ld.d $ra, $sp, 24\n"
+" ld.d $t0, $sp, 32\n"
" addi.d $sp, $sp, 48\n"
" jr $t0\n"
" .size my_tramp, .-my_tramp\n"
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -124,8 +124,8 @@ asm (
" st.d $ra, $sp, 16\n"
" bl my_direct_func\n"
" ld.d $a0, $sp, 0\n"
-" ld.d $t0, $sp, 8\n"
-" ld.d $ra, $sp, 16\n"
+" ld.d $ra, $sp, 8\n"
+" ld.d $t0, $sp, 16\n"
" addi.d $sp, $sp, 32\n"
" jr $t0\n"
" .size my_tramp, .-my_tramp\n"