Commit bb85d206 authored Dec 31, 2025 by Chenghao Duan Committed by Huacai Chen Dec 31, 2025

samples/ftrace: Adjust LoongArch register restore order in direct calls



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: 9cdc3b6a ("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>

parent 73721d86

samples/ftrace/ftrace-direct-modify.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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"

samples/ftrace/ftrace-direct-multi-modify.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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"

samples/ftrace/ftrace-direct-multi.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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"

samples/ftrace/ftrace-direct-too.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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"

samples/ftrace/ftrace-direct.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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"