LoongArch: ftrace: Add direct call trampoline samples support

The ftrace samples need per-architecture trampoline implementations to
save and restore argument registers around the calls to my_direct_func*
and to restore polluted registers (e.g: ra).
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/Kconfig

@@ -120,6 +120,8 @@ config LOONGARCH
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RSEQ
+	select HAVE_SAMPLE_FTRACE_DIRECT
+	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
 	select HAVE_SETUP_PER_CPU_AREA if NUMA
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS

samples/ftrace/ftrace-direct-modify.c

@@ -96,6 +96,40 @@ asm (
 
 #endif /* CONFIG_S390 */
 
+#ifdef CONFIG_LOONGARCH
+
+asm (
+"	.pushsection    .text, \"ax\", @progbits\n"
+"	.type		my_tramp1, @function\n"
+"	.globl		my_tramp1\n"
+"   my_tramp1:\n"
+"	addi.d	$sp, $sp, -16\n"
+"	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"
+"	addi.d	$sp, $sp, 16\n"
+"	jr	$t0\n"
+"	.size		my_tramp1, .-my_tramp1\n"
+
+"	.type		my_tramp2, @function\n"
+"	.globl		my_tramp2\n"
+"   my_tramp2:\n"
+"	addi.d	$sp, $sp, -16\n"
+"	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"
+"	addi.d	$sp, $sp, 16\n"
+"	jr	$t0\n"
+"	.size		my_tramp2, .-my_tramp2\n"
+"	.popsection\n"
+);
+
+#endif /* CONFIG_LOONGARCH */
+
 static unsigned long my_tramp = (unsigned long)my_tramp1;
 static unsigned long tramps[2] = {
 	(unsigned long)my_tramp1,

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

@@ -103,6 +103,47 @@ asm (
 
 #endif /* CONFIG_S390 */
 
+#ifdef CONFIG_LOONGARCH
+#include <asm/asm.h>
+
+asm (
+"	.pushsection    .text, \"ax\", @progbits\n"
+"	.type		my_tramp1, @function\n"
+"	.globl		my_tramp1\n"
+"   my_tramp1:\n"
+"	addi.d	$sp, $sp, -32\n"
+"	st.d	$a0, $sp, 0\n"
+"	st.d	$t0, $sp, 8\n"
+"	st.d	$ra, $sp, 16\n"
+"	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"
+"	addi.d	$sp, $sp, 32\n"
+"	jr	$t0\n"
+"	.size		my_tramp1, .-my_tramp1\n"
+
+"	.type		my_tramp2, @function\n"
+"	.globl		my_tramp2\n"
+"   my_tramp2:\n"
+"	addi.d	$sp, $sp, -32\n"
+"	st.d	$a0, $sp, 0\n"
+"	st.d	$t0, $sp, 8\n"
+"	st.d	$ra, $sp, 16\n"
+"	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"
+"	addi.d	$sp, $sp, 32\n"
+"	jr	$t0\n"
+"	.size		my_tramp2, .-my_tramp2\n"
+"	.popsection\n"
+);
+
+#endif /* CONFIG_LOONGARCH */
+
 static unsigned long my_tramp = (unsigned long)my_tramp1;
 static unsigned long tramps[2] = {
 	(unsigned long)my_tramp1,

samples/ftrace/ftrace-direct-multi.c

@@ -66,6 +66,31 @@ asm (
 
 #endif /* CONFIG_S390 */
 
+#ifdef CONFIG_LOONGARCH
+
+#include <asm/asm.h>
+asm (
+"	.pushsection	.text, \"ax\", @progbits\n"
+"	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
+"   my_tramp:\n"
+"	addi.d	$sp, $sp, -32\n"
+"	st.d	$a0, $sp, 0\n"
+"	st.d	$t0, $sp, 8\n"
+"	st.d	$ra, $sp, 16\n"
+"	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"
+"	addi.d	$sp, $sp, 32\n"
+"	jr	$t0\n"
+"	.size		my_tramp, .-my_tramp\n"
+"	.popsection\n"
+);
+
+#endif /* CONFIG_LOONGARCH */
+
 static struct ftrace_ops direct;
 
 static int __init ftrace_direct_multi_init(void)

samples/ftrace/ftrace-direct-too.c

@@ -70,6 +70,33 @@ asm (
 
 #endif /* CONFIG_S390 */
 
+#ifdef CONFIG_LOONGARCH
+
+asm (
+"	.pushsection	.text, \"ax\", @progbits\n"
+"	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
+"   my_tramp:\n"
+"	addi.d	$sp, $sp, -48\n"
+"	st.d	$a0, $sp, 0\n"
+"	st.d	$a1, $sp, 8\n"
+"	st.d	$a2, $sp, 16\n"
+"	st.d	$t0, $sp, 24\n"
+"	st.d	$ra, $sp, 32\n"
+"	bl	my_direct_func\n"
+"	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"
+"	addi.d	$sp, $sp, 48\n"
+"	jr	$t0\n"
+"	.size		my_tramp, .-my_tramp\n"
+"	.popsection\n"
+);
+
+#endif /* CONFIG_LOONGARCH */
+
 static int __init ftrace_direct_init(void)
 {
 	return register_ftrace_direct((unsigned long)handle_mm_fault,

samples/ftrace/ftrace-direct.c

@@ -63,6 +63,29 @@ asm (
 
 #endif /* CONFIG_S390 */
 
+#ifdef CONFIG_LOONGARCH
+
+asm (
+"	.pushsection	.text, \"ax\", @progbits\n"
+"	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
+"   my_tramp:\n"
+"	addi.d	$sp, $sp, -32\n"
+"	st.d	$a0, $sp, 0\n"
+"	st.d	$t0, $sp, 8\n"
+"	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"
+"	addi.d	$sp, $sp, 32\n"
+"	jr	$t0\n"
+"	.size		my_tramp, .-my_tramp\n"
+"	.popsection\n"
+);
+
+#endif /* CONFIG_LOONGARCH */
+
 static int __init ftrace_direct_init(void)
 {
 	return register_ftrace_direct((unsigned long)wake_up_process,