[PATCH] ftrace: nmi safe code clean ups

Steven Rostedt
2008-10-31T04:03:34Z

This patch cleans up the NMI safe code for dynamic ftrace as suggested
by Andrew Morton.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
arch/arm/include/asm/ftrace.h | 4 ++--
arch/powerpc/include/asm/ftrace.h | 4 ++--
arch/sh/include/asm/ftrace.h | 4 ++--
arch/sparc/include/asm/ftrace.h | 4 ++--
arch/x86/include/asm/ftrace.h | 10 +++++-----
arch/x86/kernel/ftrace.c | 16 ++++++++--------
include/linux/ftrace.h | 3 +++
kernel/trace/trace.c | 9 ++++-----
8 files changed, 28 insertions(+), 26 deletions(-)

Index: linux-tip.git/arch/arm/include/asm/ftrace.h
===================================================================
--- linux-tip.git.orig/arch/arm/include/asm/ftrace.h 2008-10-30 10:27:09.000000000 -0400
+++ linux-tip.git/arch/arm/include/asm/ftrace.h 2008-10-30 23:24:18.000000000 -0400
@@ -2,8 +2,8 @@
#define _ASM_ARM_FTRACE

#ifndef __ASSEMBLY__
-#define ftrace_nmi_enter() do { } while (0)
-#define ftrace_nmi_exit() do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
#endif

#ifdef CONFIG_FUNCTION_TRACER
Index: linux-tip.git/arch/powerpc/include/asm/ftrace.h
===================================================================
--- linux-tip.git.orig/arch/powerpc/include/asm/ftrace.h 2008-10-30 10:27:09.000000000 -0400
+++ linux-tip.git/arch/powerpc/include/asm/ftrace.h 2008-10-30 23:24:30.000000000 -0400
@@ -2,8 +2,8 @@
#define _ASM_POWERPC_FTRACE

#ifndef __ASSEMBLY__
-#define ftrace_nmi_enter() do { } while (0)
-#define ftrace_nmi_exit() do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
#endif

#ifdef CONFIG_FUNCTION_TRACER
Index: linux-tip.git/arch/sh/include/asm/ftrace.h
===================================================================
--- linux-tip.git.orig/arch/sh/include/asm/ftrace.h 2008-10-30 10:27:09.000000000 -0400
+++ linux-tip.git/arch/sh/include/asm/ftrace.h 2008-10-30 23:24:43.000000000 -0400
@@ -2,8 +2,8 @@
#define __ASM_SH_FTRACE_H

#ifndef __ASSEMBLY__
-#define ftrace_nmi_enter() do { } while (0)
-#define ftrace_nmi_exit() do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
#endif

#ifndef __ASSEMBLY__
Index: linux-tip.git/arch/sparc/include/asm/ftrace.h
===================================================================
--- linux-tip.git.orig/arch/sparc/include/asm/ftrace.h 2008-10-30 10:27:09.000000000 -0400
+++ linux-tip.git/arch/sparc/include/asm/ftrace.h 2008-10-30 23:24:50.000000000 -0400
@@ -2,8 +2,8 @@
#define _ASM_SPARC64_FTRACE

#ifndef __ASSEMBLY__
-#define ftrace_nmi_enter() do { } while (0)
-#define ftrace_nmi_exit() do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
#endif

#ifdef CONFIG_MCOUNT
Index: linux-tip.git/arch/x86/include/asm/ftrace.h
===================================================================
--- linux-tip.git.orig/arch/x86/include/asm/ftrace.h 2008-10-30 13:16:22.000000000 -0400
+++ linux-tip.git/arch/x86/include/asm/ftrace.h 2008-10-30 23:25:26.000000000 -0400
@@ -22,16 +22,16 @@ static inline unsigned long ftrace_call_
extern void ftrace_nmi_enter(void);
extern void ftrace_nmi_exit(void);
#else
-#define ftrace_nmi_enter() do { } while (0)
-#define ftrace_nmi_exit() do { } while (0)
-#endif
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
#endif
+#endif /* __ASSEMBLY__ */

#else /* CONFIG_FUNCTION_TRACER */

#ifndef __ASSEMBLY__
-#define ftrace_nmi_enter() do { } while (0)
-#define ftrace_nmi_exit() do { } while (0)
+static inline void ftrace_nmi_enter(void) { }
+static inline void ftrace_nmi_exit(void) { }
#endif

#endif /* CONFIG_FUNCTION_TRACER */
Index: linux-tip.git/arch/x86/kernel/ftrace.c
===================================================================
--- linux-tip.git.orig/arch/x86/kernel/ftrace.c 2008-10-30 16:07:05.000000000 -0400
+++ linux-tip.git/arch/x86/kernel/ftrace.c 2008-10-30 23:30:19.000000000 -0400
@@ -67,7 +67,7 @@ unsigned char *ftrace_call_replace(unsig
*
* Two buffers are added: An IP buffer and a "code" buffer.
*
- * 1) Put in the instruction pointer into the IP buffer
+ * 1) Put the instruction pointer into the IP buffer
* and the new code into the "code" buffer.
* 2) Set a flag that says we are modifying code
* 3) Wait for any running NMIs to finish.
@@ -85,14 +85,14 @@ unsigned char *ftrace_call_replace(unsig
* are the same as what exists.
*/

-static atomic_t in_nmi;
-static int mod_code_status;
-static int mod_code_write;
-static void *mod_code_ip;
-static void *mod_code_newcode;
+static atomic_t in_nmi = ATOMIC_INIT(0);
+static int mod_code_status; /* holds return value of text write */
+static int mod_code_write; /* set when NMI should do the write */
+static void *mod_code_ip; /* holds the IP to write to */
+static void *mod_code_newcode; /* holds the text to write to the IP */

-static int nmi_wait_count;
-static atomic_t nmi_update_count;
+static unsigned nmi_wait_count;
+static atomic_t nmi_update_count = ATOMIC_INIT(0);

int ftrace_arch_read_dyn_info(char *buf, int size)
{
Index: linux-tip.git/include/linux/ftrace.h
===================================================================
--- linux-tip.git.orig/include/linux/ftrace.h 2008-10-30 10:27:07.000000000 -0400
+++ linux-tip.git/include/linux/ftrace.h 2008-10-30 23:31:33.000000000 -0400
@@ -74,6 +74,9 @@ extern void ftrace_caller(void);
extern void ftrace_call(void);
extern void mcount_call(void);

+/* May be defined in arch */
+extern int ftrace_arch_read_dyn_info(char *buf, int size);
+
/**
* ftrace_modify_code - modify code segment
* @ip: the address of the code segment
Index: linux-tip.git/kernel/trace/trace.c
===================================================================
--- linux-tip.git.orig/kernel/trace/trace.c 2008-10-30 16:07:05.000000000 -0400
+++ linux-tip.git/kernel/trace/trace.c 2008-10-30 23:33:41.000000000 -0400
@@ -2837,10 +2837,6 @@ static struct file_operations tracing_ma

#ifdef CONFIG_DYNAMIC_FTRACE

-#define DYN_INFO_BUF_SIZE 1023
-static char ftrace_dyn_info_buffer[DYN_INFO_BUF_SIZE+1];
-static DEFINE_MUTEX(dyn_info_mutex);
-
int __weak ftrace_arch_read_dyn_info(char *buf, int size)
{
return 0;
@@ -2850,14 +2846,17 @@ static ssize_t
tracing_read_dyn_info(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
+ static char ftrace_dyn_info_buffer[1024];
+ static DEFINE_MUTEX(dyn_info_mutex);
unsigned long *p = filp->private_data;
char *buf = ftrace_dyn_info_buffer;
+ int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
int r;

mutex_lock(&dyn_info_mutex);
r = sprintf(buf, "%ld ", *p);

- r += ftrace_arch_read_dyn_info(buf+r, DYN_INFO_BUF_SIZE-r);
+ r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
buf[r++] = '\n';

r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);