[RFC PATCH 14/14] samples/ftrace: Add powerpc support for ftrace direct samples
Naveen N. Rao
naveen.n.rao at linux.vnet.ibm.com
Fri Nov 27 05:08:51 AEDT 2020
Add a simple powerpc trampoline to demonstrate use of ftrace direct on
powerpc.
Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
---
samples/Kconfig | 2 +-
samples/ftrace/ftrace-direct-modify.c | 58 +++++++++++++++++++++++++++
samples/ftrace/ftrace-direct-too.c | 48 ++++++++++++++++++++--
samples/ftrace/ftrace-direct.c | 45 +++++++++++++++++++--
4 files changed, 144 insertions(+), 9 deletions(-)
diff --git a/samples/Kconfig b/samples/Kconfig
index 0ed6e4d71d87b1..fdc9e44dba3b95 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -26,7 +26,7 @@ config SAMPLE_TRACE_PRINTK
config SAMPLE_FTRACE_DIRECT
tristate "Build register_ftrace_direct() example"
depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS && m
- depends on X86_64 # has x86_64 inlined asm
+ depends on X86_64 || PPC64 # has inlined asm
help
This builds an ftrace direct function example
that hooks to wake_up_process and prints the parameters.
diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
index c13a5bc5095bea..89d66a12d300e1 100644
--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -2,6 +2,7 @@
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/ftrace.h>
+#include <linux/kprobes.h>
void my_direct_func1(void)
{
@@ -18,6 +19,7 @@ extern void my_tramp2(void *);
static unsigned long my_ip = (unsigned long)schedule;
+#ifdef CONFIG_X86
asm (
" .pushsection .text, \"ax\", @progbits\n"
" .type my_tramp1, @function\n"
@@ -38,6 +40,58 @@ asm (
" .size my_tramp2, .-my_tramp2\n"
" .popsection\n"
);
+#elif CONFIG_PPC64
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp1, @function\n"
+" .global my_tramp1\n"
+" my_tramp1:\n"
+" std 0, 16(1)\n"
+" stdu 1, -480(1)\n"
+" std 2, 24(1)\n"
+" mflr 7\n"
+" std 7, 368(1)\n"
+" bcl 20, 31, 1f\n"
+"1: mflr 12\n"
+" ld 2, (3f - 1b)(12)\n"
+" bl my_direct_func1\n"
+" nop\n"
+" ld 2, 24(1)\n"
+" ld 7, 368(1)\n"
+" mtctr 7\n"
+" addi 1, 1, 480\n"
+" ld 0, 16(1)\n"
+" mtlr 0\n"
+" bctr\n"
+" .size my_tramp1, .-my_tramp1\n"
+" nop\n"
+" .type my_tramp2, @function\n"
+" .global my_tramp2\n"
+" my_tramp2:\n"
+" std 0, 16(1)\n"
+" stdu 1, -480(1)\n"
+" std 2, 24(1)\n"
+" mflr 7\n"
+" std 7, 368(1)\n"
+" bcl 20, 31, 2f\n"
+"2: mflr 12\n"
+" ld 2, (3f - 2b)(12)\n"
+" bl my_direct_func2\n"
+" nop\n"
+" ld 2, 24(1)\n"
+" ld 7, 368(1)\n"
+" mtctr 7\n"
+" addi 1, 1, 480\n"
+" ld 0, 16(1)\n"
+" mtlr 0\n"
+" bctr\n"
+" .size my_tramp2, .-my_tramp2\n"
+"3:\n"
+" .quad .TOC. at tocbase\n"
+" .popsection\n"
+);
+#endif
+
static unsigned long my_tramp = (unsigned long)my_tramp1;
static unsigned long tramps[2] = {
@@ -72,6 +126,10 @@ static int __init ftrace_direct_init(void)
{
int ret;
+#ifdef CONFIG_PPC64
+ my_ip = ppc_function_entry((void *)my_ip) + 4;
+#endif
+
ret = register_ftrace_direct(my_ip, my_tramp);
if (!ret)
simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn");
diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
index d5c5022be66429..9a82abecbe0dcc 100644
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -3,6 +3,7 @@
#include <linux/mm.h> /* for handle_mm_fault() */
#include <linux/ftrace.h>
+#include <linux/kprobes.h>
void my_direct_func(struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
@@ -13,6 +14,9 @@ void my_direct_func(struct vm_area_struct *vma,
extern void my_tramp(void *);
+static unsigned long my_ip = (unsigned long)handle_mm_fault;
+
+#ifdef CONFIG_X86
asm (
" .pushsection .text, \"ax\", @progbits\n"
" .type my_tramp, @function\n"
@@ -31,18 +35,54 @@ asm (
" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);
+#elif CONFIG_PPC64
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .global my_tramp\n"
+" my_tramp:\n"
+" std 0, 16(1)\n"
+" stdu 1, -480(1)\n"
+" std 2, 24(1)\n"
+" std 3, 136(1)\n"
+" std 4, 144(1)\n"
+" std 5, 152(1)\n"
+" mflr 7\n"
+" std 7, 368(1)\n"
+" bcl 20, 31, 1f\n"
+"1: mflr 12\n"
+" ld 2, (2f - 1b)(12)\n"
+" bl my_direct_func\n"
+" nop\n"
+" ld 5, 152(1)\n"
+" ld 4, 144(1)\n"
+" ld 3, 136(1)\n"
+" ld 2, 24(1)\n"
+" ld 7, 368(1)\n"
+" mtctr 7\n"
+" addi 1, 1, 480\n"
+" ld 0, 16(1)\n"
+" mtlr 0\n"
+" bctr\n"
+" .size my_tramp, .-my_tramp\n"
+"2:\n"
+" .quad .TOC. at tocbase\n"
+" .popsection\n"
+);
+#endif
static int __init ftrace_direct_init(void)
{
- return register_ftrace_direct((unsigned long)handle_mm_fault,
- (unsigned long)my_tramp);
+#ifdef CONFIG_PPC64
+ my_ip = ppc_function_entry((void *)my_ip) + 4;
+#endif
+ return register_ftrace_direct(my_ip, (unsigned long)my_tramp);
}
static void __exit ftrace_direct_exit(void)
{
- unregister_ftrace_direct((unsigned long)handle_mm_fault,
- (unsigned long)my_tramp);
+ unregister_ftrace_direct(my_ip, (unsigned long)my_tramp);
}
module_init(ftrace_direct_init);
diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
index 63ca06d42c803f..da67b6217f91d2 100644
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -3,6 +3,7 @@
#include <linux/sched.h> /* for wake_up_process() */
#include <linux/ftrace.h>
+#include <linux/kprobes.h> /* for ppc_function_entry() */
void my_direct_func(struct task_struct *p)
{
@@ -11,6 +12,9 @@ void my_direct_func(struct task_struct *p)
extern void my_tramp(void *);
+static unsigned long my_ip = (unsigned long)wake_up_process;
+
+#ifdef CONFIG_X86
asm (
" .pushsection .text, \"ax\", @progbits\n"
" .type my_tramp, @function\n"
@@ -25,18 +29,51 @@ asm (
" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);
+#elif CONFIG_PPC64
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .global my_tramp\n"
+" my_tramp:\n"
+" std 0, 16(1)\n"
+" stdu 1, -480(1)\n"
+" std 2, 24(1)\n"
+" std 3, 136(1)\n"
+" mflr 7\n"
+" std 7, 368(1)\n"
+" bcl 20, 31, 1f\n"
+"1: mflr 12\n"
+" ld 2, (2f - 1b)(12)\n"
+" bl my_direct_func\n"
+" nop\n"
+" ld 3, 136(1)\n"
+" ld 2, 24(1)\n"
+" ld 7, 368(1)\n"
+" mtctr 7\n"
+" addi 1, 1, 480\n"
+" ld 0, 16(1)\n"
+" mtlr 0\n"
+" bctr\n"
+" .size my_tramp, .-my_tramp\n"
+"2:\n"
+" .quad .TOC. at tocbase\n"
+" .popsection\n"
+);
+#endif
static int __init ftrace_direct_init(void)
{
- return register_ftrace_direct((unsigned long)wake_up_process,
- (unsigned long)my_tramp);
+#ifdef CONFIG_PPC64
+ /* Ftrace location is (usually) the second instruction at a function's local entry point */
+ my_ip = ppc_function_entry((void *)my_ip) + 4;
+#endif
+ return register_ftrace_direct(my_ip, (unsigned long)my_tramp);
}
static void __exit ftrace_direct_exit(void)
{
- unregister_ftrace_direct((unsigned long)wake_up_process,
- (unsigned long)my_tramp);
+ unregister_ftrace_direct(my_ip, (unsigned long)my_tramp);
}
module_init(ftrace_direct_init);
--
2.25.4
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