[GIT PULL] tracing/syscalls: Arch code shrinks, easier arch integration

[GIT PULL] tracing/syscalls: Arch code shrinks, easier arch integration

[Frederic Weisbecker]

Ingo,

This patchset moves most of the arch syscalls tracing code to core,
since most of it has become pretty generic since the latest changes.

Note: I haven't tested the s390 changes.

Please pull from the tracing/syscalls branch which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/syscalls

Thanks,
Frederic.

Frederic Weisbecker (2):
      tracing: Move syscalls metadata handling from arch to core
      tracing: Document HAVE_FTRACE_SYSCALLS needs

 Documentation/trace/ftrace-design.txt |   11 ++++-
 arch/s390/kernel/ftrace.c             |   67 +--------------------------
 arch/x86/kernel/ftrace.c              |   76 +------------------------------
 include/trace/syscall.h               |    2 +-
 kernel/trace/trace_syscalls.c         |   80 +++++++++++++++++++++++++++++++++
 5 files changed, 95 insertions(+), 141 deletions(-)

[PATCH 1/2] tracing: Move syscalls metadata handling from arch to core

[Frederic Weisbecker]

Most of the syscalls metadata processing is done from arch.
But these operations are mostly generic accross archs. Especially now
that we have a common variable name that expresses the number of
syscalls supported by an arch: NR_syscalls, the only remaining bits
that need to reside in arch is the syscall nr to addr translation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
---
 arch/s390/kernel/ftrace.c     |   67 +---------------------------------
 arch/x86/kernel/ftrace.c      |   76 +-------------------------------------
 include/trace/syscall.h       |    2 +-
 kernel/trace/trace_syscalls.c |   80 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 85 insertions(+), 140 deletions(-)

diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 57bdcb1..7c5752c 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -206,73 +206,10 @@ out:
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 
-extern unsigned long __start_syscalls_metadata[];
-extern unsigned long __stop_syscalls_metadata[];
 extern unsigned int sys_call_table[];
 
-static struct syscall_metadata **syscalls_metadata;
-
-struct syscall_metadata *syscall_nr_to_meta(int nr)
-{
-	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
-		return NULL;
-
-	return syscalls_metadata[nr];
-}
-
-int syscall_name_to_nr(char *name)
-{
-	int i;
-
-	if (!syscalls_metadata)
-		return -1;
-	for (i = 0; i < NR_syscalls; i++)
-		if (syscalls_metadata[i])
-			if (!strcmp(syscalls_metadata[i]->name, name))
-				return i;
-	return -1;
-}
-
-void set_syscall_enter_id(int num, int id)
-{
-	syscalls_metadata[num]->enter_id = id;
-}
-
-void set_syscall_exit_id(int num, int id)
+unsigned long __init arch_syscall_addr(int nr)
 {
-	syscalls_metadata[num]->exit_id = id;
-}
-
-static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
-{
-	struct syscall_metadata *start;
-	struct syscall_metadata *stop;
-	char str[KSYM_SYMBOL_LEN];
-
-	start = (struct syscall_metadata *)__start_syscalls_metadata;
-	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
-	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
-
-	for ( ; start < stop; start++) {
-		if (start->name && !strcmp(start->name + 3, str + 3))
-			return start;
-	}
-	return NULL;
-}
-
-static int __init arch_init_ftrace_syscalls(void)
-{
-	struct syscall_metadata *meta;
-	int i;
-	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) * NR_syscalls,
-				    GFP_KERNEL);
-	if (!syscalls_metadata)
-		return -ENOMEM;
-	for (i = 0; i < NR_syscalls; i++) {
-		meta = find_syscall_meta((unsigned long)sys_call_table[i]);
-		syscalls_metadata[i] = meta;
-	}
-	return 0;
+	return (unsigned long)sys_call_table[nr];
 }
-arch_initcall(arch_init_ftrace_syscalls);
 #endif
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 9dbb527..4adb867 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -468,82 +468,10 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 
-extern unsigned long __start_syscalls_metadata[];
-extern unsigned long __stop_syscalls_metadata[];
 extern unsigned long *sys_call_table;
 
-static struct syscall_metadata **syscalls_metadata;
-
-static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
-{
-	struct syscall_metadata *start;
-	struct syscall_metadata *stop;
-	char str[KSYM_SYMBOL_LEN];
-
-
-	start = (struct syscall_metadata *)__start_syscalls_metadata;
-	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
-	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
-
-	for ( ; start < stop; start++) {
-		if (start->name && !strcmp(start->name, str))
-			return start;
-	}
-	return NULL;
-}
-
-struct syscall_metadata *syscall_nr_to_meta(int nr)
-{
-	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
-		return NULL;
-
-	return syscalls_metadata[nr];
-}
-
-int syscall_name_to_nr(char *name)
-{
-	int i;
-
-	if (!syscalls_metadata)
-		return -1;
-
-	for (i = 0; i < NR_syscalls; i++) {
-		if (syscalls_metadata[i]) {
-			if (!strcmp(syscalls_metadata[i]->name, name))
-				return i;
-		}
-	}
-	return -1;
-}
-
-void set_syscall_enter_id(int num, int id)
-{
-	syscalls_metadata[num]->enter_id = id;
-}
-
-void set_syscall_exit_id(int num, int id)
+unsigned long __init arch_syscall_addr(int nr)
 {
-	syscalls_metadata[num]->exit_id = id;
-}
-
-static int __init arch_init_ftrace_syscalls(void)
-{
-	int i;
-	struct syscall_metadata *meta;
-	unsigned long **psys_syscall_table = &sys_call_table;
-
-	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
-					NR_syscalls, GFP_KERNEL);
-	if (!syscalls_metadata) {
-		WARN_ON(1);
-		return -ENOMEM;
-	}
-
-	for (i = 0; i < NR_syscalls; i++) {
-		meta = find_syscall_meta(psys_syscall_table[i]);
-		syscalls_metadata[i] = meta;
-	}
-	return 0;
+	return (unsigned long)(&sys_call_table)[nr];
 }
-arch_initcall(arch_init_ftrace_syscalls);
 #endif
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 5dc283b..e972f0a 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -33,7 +33,7 @@ struct syscall_metadata {
 };
 
 #ifdef CONFIG_FTRACE_SYSCALLS
-extern struct syscall_metadata *syscall_nr_to_meta(int nr);
+extern unsigned long arch_syscall_addr(int nr);
 extern int syscall_name_to_nr(char *name);
 void set_syscall_enter_id(int num, int id);
 void set_syscall_exit_id(int num, int id);
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 8712ce3..e281fd7 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -14,6 +14,63 @@ static int sys_refcount_exit;
 static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
 static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
 
+extern unsigned long __start_syscalls_metadata[];
+extern unsigned long __stop_syscalls_metadata[];
+
+static struct syscall_metadata **syscalls_metadata;
+
+static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
+{
+	struct syscall_metadata *start;
+	struct syscall_metadata *stop;
+	char str[KSYM_SYMBOL_LEN];
+
+
+	start = (struct syscall_metadata *)__start_syscalls_metadata;
+	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
+	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
+
+	for ( ; start < stop; start++) {
+		if (start->name && !strcmp(start->name, str))
+			return start;
+	}
+	return NULL;
+}
+
+static struct syscall_metadata *syscall_nr_to_meta(int nr)
+{
+	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
+		return NULL;
+
+	return syscalls_metadata[nr];
+}
+
+int syscall_name_to_nr(char *name)
+{
+	int i;
+
+	if (!syscalls_metadata)
+		return -1;
+
+	for (i = 0; i < NR_syscalls; i++) {
+		if (syscalls_metadata[i]) {
+			if (!strcmp(syscalls_metadata[i]->name, name))
+				return i;
+		}
+	}
+	return -1;
+}
+
+void set_syscall_enter_id(int num, int id)
+{
+	syscalls_metadata[num]->enter_id = id;
+}
+
+void set_syscall_exit_id(int num, int id)
+{
+	syscalls_metadata[num]->exit_id = id;
+}
+
 enum print_line_t
 print_syscall_enter(struct trace_iterator *iter, int flags)
 {
@@ -375,6 +432,29 @@ struct trace_event event_syscall_exit = {
 	.trace			= print_syscall_exit,
 };
 
+int __init init_ftrace_syscalls(void)
+{
+	struct syscall_metadata *meta;
+	unsigned long addr;
+	int i;
+
+	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
+					NR_syscalls, GFP_KERNEL);
+	if (!syscalls_metadata) {
+		WARN_ON(1);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < NR_syscalls; i++) {
+		addr = arch_syscall_addr(i);
+		meta = find_syscall_meta(addr);
+		syscalls_metadata[i] = meta;
+	}
+
+	return 0;
+}
+core_initcall(init_ftrace_syscalls);
+
 #ifdef CONFIG_EVENT_PROFILE
 
 static DECLARE_BITMAP(enabled_prof_enter_syscalls, NR_syscalls);
-- 
1.6.2.3

Re: [PATCH 1/2] tracing: Move syscalls metadata handling from arch to core

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Most of the syscalls metadata processing is done from arch. But these 
> operations are mostly generic accross archs. Especially now that we 
> have a common variable name that expresses the number of syscalls 
> supported by an arch: NR_syscalls, the only remaining bits that need 
> to reside in arch is the syscall nr to addr translation.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Jason Baron <jbaron@redhat.com>
> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Paul Mundt <lethal@linux-sh.org>
> ---
>  arch/s390/kernel/ftrace.c     |   67 +---------------------------------
>  arch/x86/kernel/ftrace.c      |   76 +-------------------------------------
>  include/trace/syscall.h       |    2 +-
>  kernel/trace/trace_syscalls.c |   80 +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 85 insertions(+), 140 deletions(-)

Martin, Heiko, would this cleanup be fine with you?

	Ingo

Re: [PATCH 1/2] tracing: Move syscalls metadata handling from arch to core

[Heiko Carstens]

On Sat, Sep 19, 2009 at 07:39:16AM +0200, Frederic Weisbecker wrote:
> Most of the syscalls metadata processing is done from arch.
> But these operations are mostly generic accross archs. Especially now
> that we have a common variable name that expresses the number of
> syscalls supported by an arch: NR_syscalls, the only remaining bits
> that need to reside in arch is the syscall nr to addr translation.

That won't work in its current form, since there is a small difference
between x86 and s390:

> diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
> index 57bdcb1..7c5752c 100644
> --- a/arch/s390/kernel/ftrace.c
> +++ b/arch/s390/kernel/ftrace.c
> -static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
> -{
> -	struct syscall_metadata *start;
> -	struct syscall_metadata *stop;
> -	char str[KSYM_SYMBOL_LEN];
> -
> -	start = (struct syscall_metadata *)__start_syscalls_metadata;
> -	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
> -	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
> -
> -	for ( ; start < stop; start++) {
> -		if (start->name && !strcmp(start->name + 3, str + 3))
                                           ^^^^^^^^^^^^^^^^^^^^^^^^
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 9dbb527..4adb867 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> -static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
> -{
> -	struct syscall_metadata *start;
> -	struct syscall_metadata *stop;
> -	char str[KSYM_SYMBOL_LEN];
> -
> -
> -	start = (struct syscall_metadata *)__start_syscalls_metadata;
> -	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
> -	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
> -
> -	for ( ; start < stop; start++) {
> -		if (start->name && !strcmp(start->name, str))
                                           ^^^^^^^^^^^^^^^^
> -			return start;
> -	}
> -	return NULL;

The reason for the "+ 3 " is that architectures with syscall wrappers have
alias function names which also show up in kallsysms:

000000000001c788 t show_cpuinfo
000000000001c9e0 T SyS_s390_personality
000000000001c9e0 T sys_s390_personality
000000000001ca48 T SyS_s390_newuname
000000000001ca48 T sys_s390_newuname
000000000001cac8 T SyS_ipc
000000000001cac8 T sys_ipc
000000000001cd00 T SyS_s390_old_mmap
000000000001cd00 T sys_s390_old_mmap
000000000001ce68 T SyS_mmap2
000000000001ce68 T sys_mmap2
000000000001cfc4 t FixPerRegisters

So kallsyms_lookup(...) would currently always return a string that starts
with "SyS" instead of "sys". Since the metadata syscall names start with
"sys" there is no match.
If you could change the generic version so it also contains a "+ 3" it
should work for all architectures.
Might be worth a comment that I didn't add back then :)

Hmm... maybe it's even possible to throw out the "SyS" variants out of
the kallsyms table and only keep the alias names?
That would shrink the kernel image a bit.

Re: [PATCH 1/2] tracing: Move syscalls metadata handling from arch to core

[Frederic Weisbecker]

On Sat, Sep 19, 2009 at 09:48:16AM +0200, Heiko Carstens wrote:
> On Sat, Sep 19, 2009 at 07:39:16AM +0200, Frederic Weisbecker wrote:
> > Most of the syscalls metadata processing is done from arch.
> > But these operations are mostly generic accross archs. Especially now
> > that we have a common variable name that expresses the number of
> > syscalls supported by an arch: NR_syscalls, the only remaining bits
> > that need to reside in arch is the syscall nr to addr translation.
> 
> That won't work in its current form, since there is a small difference
> between x86 and s390:
> 
> > diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
> > index 57bdcb1..7c5752c 100644
> > --- a/arch/s390/kernel/ftrace.c
> > +++ b/arch/s390/kernel/ftrace.c
> > -static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
> > -{
> > -	struct syscall_metadata *start;
> > -	struct syscall_metadata *stop;
> > -	char str[KSYM_SYMBOL_LEN];
> > -
> > -	start = (struct syscall_metadata *)__start_syscalls_metadata;
> > -	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
> > -	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
> > -
> > -	for ( ; start < stop; start++) {
> > -		if (start->name && !strcmp(start->name + 3, str + 3))
>                                            ^^^^^^^^^^^^^^^^^^^^^^^^



Oh, I thought it was to zap the "sys" prefix comparison.



> > diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> > index 9dbb527..4adb867 100644
> > --- a/arch/x86/kernel/ftrace.c
> > +++ b/arch/x86/kernel/ftrace.c
> > -static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
> > -{
> > -	struct syscall_metadata *start;
> > -	struct syscall_metadata *stop;
> > -	char str[KSYM_SYMBOL_LEN];
> > -
> > -
> > -	start = (struct syscall_metadata *)__start_syscalls_metadata;
> > -	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
> > -	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
> > -
> > -	for ( ; start < stop; start++) {
> > -		if (start->name && !strcmp(start->name, str))
>                                            ^^^^^^^^^^^^^^^^
> > -			return start;
> > -	}
> > -	return NULL;
> 
> The reason for the "+ 3 " is that architectures with syscall wrappers have
> alias function names which also show up in kallsysms:
> 
> 000000000001c788 t show_cpuinfo
> 000000000001c9e0 T SyS_s390_personality
> 000000000001c9e0 T sys_s390_personality
> 000000000001ca48 T SyS_s390_newuname
> 000000000001ca48 T sys_s390_newuname
> 000000000001cac8 T SyS_ipc
> 000000000001cac8 T sys_ipc
> 000000000001cd00 T SyS_s390_old_mmap
> 000000000001cd00 T sys_s390_old_mmap
> 000000000001ce68 T SyS_mmap2
> 000000000001ce68 T sys_mmap2
> 000000000001cfc4 t FixPerRegisters
> 
> So kallsyms_lookup(...) would currently always return a string that starts
> with "SyS" instead of "sys". Since the metadata syscall names start with
> "sys" there is no match.
> If you could change the generic version so it also contains a "+ 3" it
> should work for all architectures.
> Might be worth a comment that I didn't add back then :)



Ah ok. So the fix is easy.
Thanks for the tip!


> Hmm... maybe it's even possible to throw out the "SyS" variants out of
> the kallsyms table and only keep the alias names?
> That would shrink the kernel image a bit.


Yeah, unless someone finds strong reasons to keep them.

Thanks!

[PATCH 2/2] tracing: Document HAVE_FTRACE_SYSCALLS needs

[Frederic Weisbecker]

Document the arch needed requirements to get the support for syscalls
tracing.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
---
 Documentation/trace/ftrace-design.txt |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 7003e10..04ab61c 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -216,7 +216,16 @@ If you can't trace NMI functions, then skip this option.
 HAVE_FTRACE_SYSCALLS
 ---------------------
 
-<details to be filled>
+You need very few things to get the syscalls tracing in an arch.
+
+- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
+  of syscalls supported by the arch.
+- Implement arch_syscall_addr() that resolves a syscall address from a
+  syscall number.
+- Support the TIF_SYSCALL_TRACEPOINT thread flags
+- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
+  in the ptrace syscalls tracing path.
+- Tag this arch as HAVE_FTRACE_SYSCALLS.
 
 
 HAVE_FTRACE_MCOUNT_RECORD
-- 
1.6.2.3

Re: [PATCH 2/2] tracing: Document HAVE_FTRACE_SYSCALLS needs

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Document the arch needed requirements to get the support for syscalls
> tracing.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Masami Hiramatsu <mhiramat@redhat.com>
> Cc: Jason Baron <jbaron@redhat.com>
> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Paul Mundt <lethal@linux-sh.org>
> ---
>  Documentation/trace/ftrace-design.txt |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
> index 7003e10..04ab61c 100644
> --- a/Documentation/trace/ftrace-design.txt
> +++ b/Documentation/trace/ftrace-design.txt
> @@ -216,7 +216,16 @@ If you can't trace NMI functions, then skip this option.
>  HAVE_FTRACE_SYSCALLS
>  ---------------------
>  
> -<details to be filled>
> +You need very few things to get the syscalls tracing in an arch.
> +
> +- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
> +  of syscalls supported by the arch.
> +- Implement arch_syscall_addr() that resolves a syscall address from a
> +  syscall number.
> +- Support the TIF_SYSCALL_TRACEPOINT thread flags
> +- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
> +  in the ptrace syscalls tracing path.
> +- Tag this arch as HAVE_FTRACE_SYSCALLS.

HAVE_FTRACE_SYSCALLS is not actually used anywhere.

	Ingo

Re: [PATCH 2/2] tracing: Document HAVE_FTRACE_SYSCALLS needs

[Frederic Weisbecker]

On Sat, Sep 19, 2009 at 09:17:12AM +0200, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > Document the arch needed requirements to get the support for syscalls
> > tracing.
> > 
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > Cc: Ingo Molnar <mingo@elte.hu>
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Cc: Li Zefan <lizf@cn.fujitsu.com>
> > Cc: Masami Hiramatsu <mhiramat@redhat.com>
> > Cc: Jason Baron <jbaron@redhat.com>
> > Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> > Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > Cc: Paul Mundt <lethal@linux-sh.org>
> > ---
> >  Documentation/trace/ftrace-design.txt |   11 ++++++++++-
> >  1 files changed, 10 insertions(+), 1 deletions(-)
> > 
> > diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
> > index 7003e10..04ab61c 100644
> > --- a/Documentation/trace/ftrace-design.txt
> > +++ b/Documentation/trace/ftrace-design.txt
> > @@ -216,7 +216,16 @@ If you can't trace NMI functions, then skip this option.
> >  HAVE_FTRACE_SYSCALLS
> >  ---------------------
> >  
> > -<details to be filled>
> > +You need very few things to get the syscalls tracing in an arch.
> > +
> > +- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
> > +  of syscalls supported by the arch.
> > +- Implement arch_syscall_addr() that resolves a syscall address from a
> > +  syscall number.
> > +- Support the TIF_SYSCALL_TRACEPOINT thread flags
> > +- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
> > +  in the ptrace syscalls tracing path.
> > +- Tag this arch as HAVE_FTRACE_SYSCALLS.
> 
> HAVE_FTRACE_SYSCALLS is not actually used anywhere.
> 
> 	Ingo


Ah, that has been renamed HAVE_SYSCALL_TRACEPOINTS recently.
What do you prefer? A delta patch or a rebase?

Thanks.

Re: [PATCH 2/2] tracing: Document HAVE_FTRACE_SYSCALLS needs

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> On Sat, Sep 19, 2009 at 09:17:12AM +0200, Ingo Molnar wrote:
> > 
> > * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > 
> > > Document the arch needed requirements to get the support for syscalls
> > > tracing.
> > > 
> > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > > Cc: Ingo Molnar <mingo@elte.hu>
> > > Cc: Steven Rostedt <rostedt@goodmis.org>
> > > Cc: Li Zefan <lizf@cn.fujitsu.com>
> > > Cc: Masami Hiramatsu <mhiramat@redhat.com>
> > > Cc: Jason Baron <jbaron@redhat.com>
> > > Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> > > Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> > > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > > Cc: Paul Mundt <lethal@linux-sh.org>
> > > ---
> > >  Documentation/trace/ftrace-design.txt |   11 ++++++++++-
> > >  1 files changed, 10 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
> > > index 7003e10..04ab61c 100644
> > > --- a/Documentation/trace/ftrace-design.txt
> > > +++ b/Documentation/trace/ftrace-design.txt
> > > @@ -216,7 +216,16 @@ If you can't trace NMI functions, then skip this option.
> > >  HAVE_FTRACE_SYSCALLS
> > >  ---------------------
> > >  
> > > -<details to be filled>
> > > +You need very few things to get the syscalls tracing in an arch.
> > > +
> > > +- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
> > > +  of syscalls supported by the arch.
> > > +- Implement arch_syscall_addr() that resolves a syscall address from a
> > > +  syscall number.
> > > +- Support the TIF_SYSCALL_TRACEPOINT thread flags
> > > +- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
> > > +  in the ptrace syscalls tracing path.
> > > +- Tag this arch as HAVE_FTRACE_SYSCALLS.
> > 
> > HAVE_FTRACE_SYSCALLS is not actually used anywhere.
> > 
> > 	Ingo
> 
> Ah, that has been renamed HAVE_SYSCALL_TRACEPOINTS recently. What do 
> you prefer? A delta patch or a rebase?

We need the acks from Martin/Heiko so lets wait for that and do a new 
tree then?

	Ingo

Re: [PATCH 2/2] tracing: Document HAVE_FTRACE_SYSCALLS needs

[Frederic Weisbecker]

On Sat, Sep 19, 2009 at 09:28:27AM +0200, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > On Sat, Sep 19, 2009 at 09:17:12AM +0200, Ingo Molnar wrote:
> > > 
> > > * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > > 
> > > > Document the arch needed requirements to get the support for syscalls
> > > > tracing.
> > > > 
> > > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > > > Cc: Ingo Molnar <mingo@elte.hu>
> > > > Cc: Steven Rostedt <rostedt@goodmis.org>
> > > > Cc: Li Zefan <lizf@cn.fujitsu.com>
> > > > Cc: Masami Hiramatsu <mhiramat@redhat.com>
> > > > Cc: Jason Baron <jbaron@redhat.com>
> > > > Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> > > > Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> > > > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > > > Cc: Paul Mundt <lethal@linux-sh.org>
> > > > ---
> > > >  Documentation/trace/ftrace-design.txt |   11 ++++++++++-
> > > >  1 files changed, 10 insertions(+), 1 deletions(-)
> > > > 
> > > > diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
> > > > index 7003e10..04ab61c 100644
> > > > --- a/Documentation/trace/ftrace-design.txt
> > > > +++ b/Documentation/trace/ftrace-design.txt
> > > > @@ -216,7 +216,16 @@ If you can't trace NMI functions, then skip this option.
> > > >  HAVE_FTRACE_SYSCALLS
> > > >  ---------------------
> > > >  
> > > > -<details to be filled>
> > > > +You need very few things to get the syscalls tracing in an arch.
> > > > +
> > > > +- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
> > > > +  of syscalls supported by the arch.
> > > > +- Implement arch_syscall_addr() that resolves a syscall address from a
> > > > +  syscall number.
> > > > +- Support the TIF_SYSCALL_TRACEPOINT thread flags
> > > > +- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
> > > > +  in the ptrace syscalls tracing path.
> > > > +- Tag this arch as HAVE_FTRACE_SYSCALLS.
> > > 
> > > HAVE_FTRACE_SYSCALLS is not actually used anywhere.
> > > 
> > > 	Ingo
> > 
> > Ah, that has been renamed HAVE_SYSCALL_TRACEPOINTS recently. What do 
> > you prefer? A delta patch or a rebase?
> 
> We need the acks from Martin/Heiko so lets wait for that and do a new 
> tree then?
> 
> 	Ingo


Ok.

[GIT PULL v2] tracing/syscalls: Arch code shrinks, easier arch integration

[Frederic Weisbecker]

Ingo, Heiko,

I've updated the patches following your reviews.
Please tell me if you see another troubles.

The new tree can be pulled from:

  git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
	tracing/syscalls-v2

Thanks,
	Frederic.

Frederic Weisbecker (2):
      tracing: Move syscalls metadata handling from arch to core
      tracing: Document HAVE_SYSCALL_TRACEPOINTS needs

 Documentation/trace/ftrace-design.txt |   13 ++++-
 arch/s390/kernel/ftrace.c             |   67 +-------------------------
 arch/x86/kernel/ftrace.c              |   76 +----------------------------
 include/trace/syscall.h               |    2 +-
 kernel/trace/trace_syscalls.c         |   86 +++++++++++++++++++++++++++++++++
 5 files changed, 102 insertions(+), 142 deletions(-)

Re: [GIT PULL v2] tracing/syscalls: Arch code shrinks, easier arch integration

[Frederic Weisbecker]

On Sat, Sep 19, 2009 at 11:08:56AM +0200, Frederic Weisbecker wrote:
> Ingo, Heiko,
> 
> I've updated the patches following your reviews.
> Please tell me if you see another troubles.
> 
> The new tree can be pulled from:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> 	tracing/syscalls-v2
> 
> Thanks,
> 	Frederic.


Ingo,

I wonder if you have forgotten this pull request, or if there is a
problem with it.

It's still cleanly mergeable into tip:/tracing/core.

Thanks.



 
> Frederic Weisbecker (2):
>       tracing: Move syscalls metadata handling from arch to core
>       tracing: Document HAVE_SYSCALL_TRACEPOINTS needs
> 
>  Documentation/trace/ftrace-design.txt |   13 ++++-
>  arch/s390/kernel/ftrace.c             |   67 +-------------------------
>  arch/x86/kernel/ftrace.c              |   76 +----------------------------
>  include/trace/syscall.h               |    2 +-
>  kernel/trace/trace_syscalls.c         |   86 +++++++++++++++++++++++++++++++++
>  5 files changed, 102 insertions(+), 142 deletions(-)

Re: [GIT PULL v2] tracing/syscalls: Arch code shrinks, easier arch integration

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> On Sat, Sep 19, 2009 at 11:08:56AM +0200, Frederic Weisbecker wrote:
> > Ingo, Heiko,
> > 
> > I've updated the patches following your reviews.
> > Please tell me if you see another troubles.
> > 
> > The new tree can be pulled from:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> > 	tracing/syscalls-v2
> > 
> > Thanks,
> > 	Frederic.
> 
> 
> Ingo,
> 
> I wonder if you have forgotten this pull request, or if there is a
> problem with it.
> 
> It's still cleanly mergeable into tip:/tracing/core.
> 
> Thanks.
> 
> 
> 
>  
> > Frederic Weisbecker (2):
> >       tracing: Move syscalls metadata handling from arch to core
> >       tracing: Document HAVE_SYSCALL_TRACEPOINTS needs
> > 
> >  Documentation/trace/ftrace-design.txt |   13 ++++-
> >  arch/s390/kernel/ftrace.c             |   67 +-------------------------

I skipped it because the s390 bit needs the ack of at least one of these 
gents:

 S390
 M:      Martin Schwidefsky <schwidefsky@de.ibm.com>
 M:      Heiko Carstens <heiko.carstens@de.ibm.com>

Thanks,

	Ingo

Re: [GIT PULL v2] tracing/syscalls: Arch code shrinks, easier arch integration

[Heiko Carstens]

On Wed, Oct 14, 2009 at 08:18:40AM +0200, Ingo Molnar wrote:
> 
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > On Sat, Sep 19, 2009 at 11:08:56AM +0200, Frederic Weisbecker wrote:
> > > Ingo, Heiko,
> > > 
> > > I've updated the patches following your reviews.
> > > Please tell me if you see another troubles.
> > > 
> > > The new tree can be pulled from:
> > > 
> > >   git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> > > 	tracing/syscalls-v2
> > Ingo,
> > 
> > I wonder if you have forgotten this pull request, or if there is a
> > problem with it.
> > 
> > It's still cleanly mergeable into tip:/tracing/core.
> > > Frederic Weisbecker (2):
> > >       tracing: Move syscalls metadata handling from arch to core
> > >       tracing: Document HAVE_SYSCALL_TRACEPOINTS needs
> > > 
> > >  Documentation/trace/ftrace-design.txt |   13 ++++-
> > >  arch/s390/kernel/ftrace.c             |   67 +-------------------------
> 
> I skipped it because the s390 bit needs the ack of at least one of these 
> gents:
> 
>  S390
>  M:      Martin Schwidefsky <schwidefsky@de.ibm.com>
>  M:      Heiko Carstens <heiko.carstens@de.ibm.com>

Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>

[PATCH 1/2 v2] tracing: Move syscalls metadata handling from arch to core

[Frederic Weisbecker]

Most of the syscalls metadata processing is done from arch.
But these operations are mostly generic accross archs. Especially now
that we have a common variable name that expresses the number of
syscalls supported by an arch: NR_syscalls, the only remaining bits
that need to reside in arch is the syscall nr to addr translation.

v2: Compare syscalls symbols only after the "sys" prefix so that we
    avoid spurious mismatches with archs that have syscalls wrappers,
    in which case syscalls symbols have "SyS" prefixed aliases.
    (Reported by: Heiko Carstens)

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
---
 arch/s390/kernel/ftrace.c     |   67 +-------------------------------
 arch/x86/kernel/ftrace.c      |   76 +-----------------------------------
 include/trace/syscall.h       |    2 +-
 kernel/trace/trace_syscalls.c |   86 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 91 insertions(+), 140 deletions(-)

diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 57bdcb1..7c5752c 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -206,73 +206,10 @@ out:
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 
-extern unsigned long __start_syscalls_metadata[];
-extern unsigned long __stop_syscalls_metadata[];
 extern unsigned int sys_call_table[];
 
-static struct syscall_metadata **syscalls_metadata;
-
-struct syscall_metadata *syscall_nr_to_meta(int nr)
-{
-	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
-		return NULL;
-
-	return syscalls_metadata[nr];
-}
-
-int syscall_name_to_nr(char *name)
-{
-	int i;
-
-	if (!syscalls_metadata)
-		return -1;
-	for (i = 0; i < NR_syscalls; i++)
-		if (syscalls_metadata[i])
-			if (!strcmp(syscalls_metadata[i]->name, name))
-				return i;
-	return -1;
-}
-
-void set_syscall_enter_id(int num, int id)
-{
-	syscalls_metadata[num]->enter_id = id;
-}
-
-void set_syscall_exit_id(int num, int id)
+unsigned long __init arch_syscall_addr(int nr)
 {
-	syscalls_metadata[num]->exit_id = id;
-}
-
-static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
-{
-	struct syscall_metadata *start;
-	struct syscall_metadata *stop;
-	char str[KSYM_SYMBOL_LEN];
-
-	start = (struct syscall_metadata *)__start_syscalls_metadata;
-	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
-	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
-
-	for ( ; start < stop; start++) {
-		if (start->name && !strcmp(start->name + 3, str + 3))
-			return start;
-	}
-	return NULL;
-}
-
-static int __init arch_init_ftrace_syscalls(void)
-{
-	struct syscall_metadata *meta;
-	int i;
-	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) * NR_syscalls,
-				    GFP_KERNEL);
-	if (!syscalls_metadata)
-		return -ENOMEM;
-	for (i = 0; i < NR_syscalls; i++) {
-		meta = find_syscall_meta((unsigned long)sys_call_table[i]);
-		syscalls_metadata[i] = meta;
-	}
-	return 0;
+	return (unsigned long)sys_call_table[nr];
 }
-arch_initcall(arch_init_ftrace_syscalls);
 #endif
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 9dbb527..4adb867 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -468,82 +468,10 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 
 #ifdef CONFIG_FTRACE_SYSCALLS
 
-extern unsigned long __start_syscalls_metadata[];
-extern unsigned long __stop_syscalls_metadata[];
 extern unsigned long *sys_call_table;
 
-static struct syscall_metadata **syscalls_metadata;
-
-static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
-{
-	struct syscall_metadata *start;
-	struct syscall_metadata *stop;
-	char str[KSYM_SYMBOL_LEN];
-
-
-	start = (struct syscall_metadata *)__start_syscalls_metadata;
-	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
-	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
-
-	for ( ; start < stop; start++) {
-		if (start->name && !strcmp(start->name, str))
-			return start;
-	}
-	return NULL;
-}
-
-struct syscall_metadata *syscall_nr_to_meta(int nr)
-{
-	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
-		return NULL;
-
-	return syscalls_metadata[nr];
-}
-
-int syscall_name_to_nr(char *name)
-{
-	int i;
-
-	if (!syscalls_metadata)
-		return -1;
-
-	for (i = 0; i < NR_syscalls; i++) {
-		if (syscalls_metadata[i]) {
-			if (!strcmp(syscalls_metadata[i]->name, name))
-				return i;
-		}
-	}
-	return -1;
-}
-
-void set_syscall_enter_id(int num, int id)
-{
-	syscalls_metadata[num]->enter_id = id;
-}
-
-void set_syscall_exit_id(int num, int id)
+unsigned long __init arch_syscall_addr(int nr)
 {
-	syscalls_metadata[num]->exit_id = id;
-}
-
-static int __init arch_init_ftrace_syscalls(void)
-{
-	int i;
-	struct syscall_metadata *meta;
-	unsigned long **psys_syscall_table = &sys_call_table;
-
-	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
-					NR_syscalls, GFP_KERNEL);
-	if (!syscalls_metadata) {
-		WARN_ON(1);
-		return -ENOMEM;
-	}
-
-	for (i = 0; i < NR_syscalls; i++) {
-		meta = find_syscall_meta(psys_syscall_table[i]);
-		syscalls_metadata[i] = meta;
-	}
-	return 0;
+	return (unsigned long)(&sys_call_table)[nr];
 }
-arch_initcall(arch_init_ftrace_syscalls);
 #endif
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 5dc283b..e972f0a 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -33,7 +33,7 @@ struct syscall_metadata {
 };
 
 #ifdef CONFIG_FTRACE_SYSCALLS
-extern struct syscall_metadata *syscall_nr_to_meta(int nr);
+extern unsigned long arch_syscall_addr(int nr);
 extern int syscall_name_to_nr(char *name);
 void set_syscall_enter_id(int num, int id);
 void set_syscall_exit_id(int num, int id);
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 8712ce3..965ce55 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -14,6 +14,69 @@ static int sys_refcount_exit;
 static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
 static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
 
+extern unsigned long __start_syscalls_metadata[];
+extern unsigned long __stop_syscalls_metadata[];
+
+static struct syscall_metadata **syscalls_metadata;
+
+static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
+{
+	struct syscall_metadata *start;
+	struct syscall_metadata *stop;
+	char str[KSYM_SYMBOL_LEN];
+
+
+	start = (struct syscall_metadata *)__start_syscalls_metadata;
+	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
+	kallsyms_lookup(syscall, NULL, NULL, NULL, str);
+
+	for ( ; start < stop; start++) {
+		/*
+		 * Only compare after the "sys" prefix. Archs that use
+		 * syscall wrappers may have syscalls symbols aliases prefixed
+		 * with "SyS" instead of "sys", leading to an unwanted
+		 * mismatch.
+		 */
+		if (start->name && !strcmp(start->name + 3, str + 3))
+			return start;
+	}
+	return NULL;
+}
+
+static struct syscall_metadata *syscall_nr_to_meta(int nr)
+{
+	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
+		return NULL;
+
+	return syscalls_metadata[nr];
+}
+
+int syscall_name_to_nr(char *name)
+{
+	int i;
+
+	if (!syscalls_metadata)
+		return -1;
+
+	for (i = 0; i < NR_syscalls; i++) {
+		if (syscalls_metadata[i]) {
+			if (!strcmp(syscalls_metadata[i]->name, name))
+				return i;
+		}
+	}
+	return -1;
+}
+
+void set_syscall_enter_id(int num, int id)
+{
+	syscalls_metadata[num]->enter_id = id;
+}
+
+void set_syscall_exit_id(int num, int id)
+{
+	syscalls_metadata[num]->exit_id = id;
+}
+
 enum print_line_t
 print_syscall_enter(struct trace_iterator *iter, int flags)
 {
@@ -375,6 +438,29 @@ struct trace_event event_syscall_exit = {
 	.trace			= print_syscall_exit,
 };
 
+int __init init_ftrace_syscalls(void)
+{
+	struct syscall_metadata *meta;
+	unsigned long addr;
+	int i;
+
+	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
+					NR_syscalls, GFP_KERNEL);
+	if (!syscalls_metadata) {
+		WARN_ON(1);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < NR_syscalls; i++) {
+		addr = arch_syscall_addr(i);
+		meta = find_syscall_meta(addr);
+		syscalls_metadata[i] = meta;
+	}
+
+	return 0;
+}
+core_initcall(init_ftrace_syscalls);
+
 #ifdef CONFIG_EVENT_PROFILE
 
 static DECLARE_BITMAP(enabled_prof_enter_syscalls, NR_syscalls);
-- 
1.6.2.3

[PATCH 2/2 v2] tracing: Document HAVE_SYSCALL_TRACEPOINTS needs

[Frederic Weisbecker]

Document the arch needed requirements to get the support for syscalls
tracing.

v2: HAVE_FTRACE_SYSCALLS have been changed to HAVE_SYSCALL_TRACEPOINTS
    recently. Update this config name in the documentation then.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
---
 Documentation/trace/ftrace-design.txt |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 7003e10..641a1ef 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -213,10 +213,19 @@ If you can't trace NMI functions, then skip this option.
 <details to be filled>
 
 
-HAVE_FTRACE_SYSCALLS
+HAVE_SYSCALL_TRACEPOINTS
 ---------------------
 
-<details to be filled>
+You need very few things to get the syscalls tracing in an arch.
+
+- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
+  of syscalls supported by the arch.
+- Implement arch_syscall_addr() that resolves a syscall address from a
+  syscall number.
+- Support the TIF_SYSCALL_TRACEPOINT thread flags
+- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
+  in the ptrace syscalls tracing path.
+- Tag this arch as HAVE_SYSCALL_TRACEPOINTS.
 
 
 HAVE_FTRACE_MCOUNT_RECORD
-- 
1.6.2.3