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Subject[PATCH 3/7][RFC] powerpc64, tracing: add function graph tracer with dynamic tracing
From: Steven Rostedt <srostedt@redhat.com>

This is the port of the function graph tracer to PowerPC with
dynamic tracing.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
arch/powerpc/Kconfig | 2 +-
arch/powerpc/kernel/entry_64.S | 8 ++++++-
arch/powerpc/kernel/ftrace.c | 47 ++++++++++++++++++++++++++++++++++-----
3 files changed, 49 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ca4647e..6e1ee1b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -111,7 +111,7 @@ config PPC
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_DYNAMIC_FTRACE
select HAVE_FUNCTION_TRACER
- select HAVE_FUNCTION_GRAPH_TRACER if !DYNAMIC_FTRACE && PPC64
+ select HAVE_FUNCTION_GRAPH_TRACER if PPC64
select ARCH_WANT_OPTIONAL_GPIOLIB
select HAVE_IDE
select HAVE_IOREMAP_PROT
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index a32699e..9f61fd6 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -908,6 +908,12 @@ _GLOBAL(ftrace_caller)
ftrace_call:
bl ftrace_stub
nop
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+.globl ftrace_graph_call
+ftrace_graph_call:
+ b ftrace_graph_stub
+_GLOBAL(ftrace_graph_stub)
+#endif
ld r0, 128(r1)
mtlr r0
addi r1, r1, 112
@@ -946,7 +952,7 @@ _GLOBAL(ftrace_stub)
#endif /* CONFIG_DYNAMIC_FTRACE */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-ftrace_graph_caller:
+_GLOBAL(ftrace_graph_caller)
/* load r4 with local address */
ld r4, 128(r1)
subi r4, r4, MCOUNT_INSN_SIZE
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index c9b1547..7538b94 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -43,7 +43,8 @@ static unsigned char *ftrace_nop_replace(void)
return (char *)&ftrace_nop;
}

-static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+static unsigned char *
+ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
{
static unsigned int op;

@@ -55,8 +56,9 @@ static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
*/
addr = GET_ADDR(addr);

- /* Set to "bl addr" */
- op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc);
+ /* if (link) set op to 'bl' else 'b' */
+ op = 0x48000000 | (link ? 1 : 0);
+ op |= (ftrace_calc_offset(ip, addr) & 0x03fffffc);

/*
* No locking needed, this must be called via kstop_machine
@@ -344,7 +346,7 @@ int ftrace_make_nop(struct module *mod,
*/
if (test_24bit_addr(ip, addr)) {
/* within range */
- old = ftrace_call_replace(ip, addr);
+ old = ftrace_call_replace(ip, addr, 1);
new = ftrace_nop_replace();
return ftrace_modify_code(ip, old, new);
}
@@ -484,7 +486,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
if (test_24bit_addr(ip, addr)) {
/* within range */
old = ftrace_nop_replace();
- new = ftrace_call_replace(ip, addr);
+ new = ftrace_call_replace(ip, addr, 1);
return ftrace_modify_code(ip, old, new);
}

@@ -513,7 +515,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
int ret;

memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
- new = ftrace_call_replace(ip, (unsigned long)func);
+ new = ftrace_call_replace(ip, (unsigned long)func, 1);
ret = ftrace_modify_code(ip, old, new);

return ret;
@@ -532,6 +534,39 @@ int __init ftrace_dyn_arch_init(void *data)

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void ftrace_graph_call(void);
+extern void ftrace_graph_stub(void);
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ unsigned long ip = (unsigned long)(&ftrace_graph_call);
+ unsigned long addr = (unsigned long)(&ftrace_graph_caller);
+ unsigned long stub = (unsigned long)(&ftrace_graph_stub);
+ unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+ new = ftrace_call_replace(ip, stub, 0);
+ memcpy(old, new, MCOUNT_INSN_SIZE);
+ new = ftrace_call_replace(ip, addr, 0);
+
+ return ftrace_modify_code(ip, old, new);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ unsigned long ip = (unsigned long)(&ftrace_graph_call);
+ unsigned long addr = (unsigned long)(&ftrace_graph_caller);
+ unsigned long stub = (unsigned long)(&ftrace_graph_stub);
+ unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+ new = ftrace_call_replace(ip, addr, 0);
+ memcpy(old, new, MCOUNT_INSN_SIZE);
+ new = ftrace_call_replace(ip, stub, 0);
+
+ return ftrace_modify_code(ip, old, new);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
/*
* Hook the return address and push it in the stack of return addrs
* in current thread info.
--
1.5.6.5
--


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