[v2,5/8] ftrace: Add swap_func to ftrace_process_locs()

Commit Message

Mike Rapoport Aug. 26, 2024, 6:55 a.m. UTC

From: Song Liu <[e-mail]>

ftrace_process_locs sorts module mcount, which is inside RO memory. Add a
ftrace_swap_func so that archs can use RO-memory-poke function to do the
sorting.

Signed-off-by: Song Liu <[e-mail]>
Signed-off-by: Mike Rapoport (Microsoft) <[e-mail]>
---
 include/linux/ftrace.h |  2 ++
 kernel/trace/ftrace.c  | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

Comments

Steven Rostedt Aug. 26, 2024, 5:29 p.m. UTC | #1

On Mon, 26 Aug 2024 09:55:29 +0300
Mike Rapoport <[e-mail]> wrote:

> From: Song Liu <[e-mail]>
> 
> ftrace_process_locs sorts module mcount, which is inside RO memory. Add a
> ftrace_swap_func so that archs can use RO-memory-poke function to do the
> sorting.

Can you add the above as a comment above the ftrace_swap_func() function?

Thanks,

-- Steve

> 
> Signed-off-by: Song Liu <[e-mail]>
> Signed-off-by: Mike Rapoport (Microsoft) <[e-mail]>
> ---
>  include/linux/ftrace.h |  2 ++
>  kernel/trace/ftrace.c  | 13 ++++++++++++-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index fd5e84d0ec47..b794dcb7cae8 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -1188,4 +1188,6 @@ unsigned long arch_syscall_addr(int nr);
>  
>  #endif /* CONFIG_FTRACE_SYSCALLS */
>  
> +void ftrace_swap_func(void *a, void *b, int n);
> +
>  #endif /* _LINUX_FTRACE_H */
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 4c28dd177ca6..9829979f3a46 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -6989,6 +6989,17 @@ static void test_is_sorted(unsigned long *start,
> unsigned long count) }
>  #endif
>  
> +void __weak ftrace_swap_func(void *a, void *b, int n)
> +{
> +	unsigned long t;
> +
> +	WARN_ON_ONCE(n != sizeof(t));
> +
> +	t = *((unsigned long *)a);
> +	*(unsigned long *)a = *(unsigned long *)b;
> +	*(unsigned long *)b = t;
> +}
> +
>  static int ftrace_process_locs(struct module *mod,
>  			       unsigned long *start,
>  			       unsigned long *end)
> @@ -7016,7 +7027,7 @@ static int ftrace_process_locs(struct module *mod,
>  	 */
>  	if (!IS_ENABLED(CONFIG_BUILDTIME_MCOUNT_SORT) || mod) {
>  		sort(start, count, sizeof(*start),
> -		     ftrace_cmp_ips, NULL);
> +		     ftrace_cmp_ips, ftrace_swap_func);
>  	} else {
>  		test_is_sorted(start, count);
>  	}

Mike Rapoport Aug. 27, 2024, 3:40 p.m. UTC | #2

On Mon, Aug 26, 2024 at 01:29:09PM -0400, Steven Rostedt wrote:
> On Mon, 26 Aug 2024 09:55:29 +0300
> Mike Rapoport <[e-mail]> wrote:
> 
> > From: Song Liu <[e-mail]>
> > 
> > ftrace_process_locs sorts module mcount, which is inside RO memory. Add a
> > ftrace_swap_func so that archs can use RO-memory-poke function to do the
> > sorting.
> 
> Can you add the above as a comment above the ftrace_swap_func() function?

Sure.
 
> Thanks,
> 
> -- Steve
> 
> > 
> > Signed-off-by: Song Liu <[e-mail]>
> > Signed-off-by: Mike Rapoport (Microsoft) <[e-mail]>
> > ---
> >  include/linux/ftrace.h |  2 ++
> >  kernel/trace/ftrace.c  | 13 ++++++++++++-
> >  2 files changed, 14 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> > index fd5e84d0ec47..b794dcb7cae8 100644
> > --- a/include/linux/ftrace.h
> > +++ b/include/linux/ftrace.h
> > @@ -1188,4 +1188,6 @@ unsigned long arch_syscall_addr(int nr);
> >  
> >  #endif /* CONFIG_FTRACE_SYSCALLS */
> >  
> > +void ftrace_swap_func(void *a, void *b, int n);
> > +
> >  #endif /* _LINUX_FTRACE_H */
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index 4c28dd177ca6..9829979f3a46 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -6989,6 +6989,17 @@ static void test_is_sorted(unsigned long *start,
> > unsigned long count) }
> >  #endif
> >  
> > +void __weak ftrace_swap_func(void *a, void *b, int n)
> > +{
> > +	unsigned long t;
> > +
> > +	WARN_ON_ONCE(n != sizeof(t));
> > +
> > +	t = *((unsigned long *)a);
> > +	*(unsigned long *)a = *(unsigned long *)b;
> > +	*(unsigned long *)b = t;
> > +}
> > +
> >  static int ftrace_process_locs(struct module *mod,
> >  			       unsigned long *start,
> >  			       unsigned long *end)
> > @@ -7016,7 +7027,7 @@ static int ftrace_process_locs(struct module *mod,
> >  	 */
> >  	if (!IS_ENABLED(CONFIG_BUILDTIME_MCOUNT_SORT) || mod) {
> >  		sort(start, count, sizeof(*start),
> > -		     ftrace_cmp_ips, NULL);
> > +		     ftrace_cmp_ips, ftrace_swap_func);
> >  	} else {
> >  		test_is_sorted(start, count);
> >  	}
>

Patch

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index fd5e84d0ec47..b794dcb7cae8 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1188,4 +1188,6 @@  unsigned long arch_syscall_addr(int nr);
 
 #endif /* CONFIG_FTRACE_SYSCALLS */
 
+void ftrace_swap_func(void *a, void *b, int n);
+
 #endif /* _LINUX_FTRACE_H */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4c28dd177ca6..9829979f3a46 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6989,6 +6989,17 @@  static void test_is_sorted(unsigned long *start, unsigned long count)
 }
 #endif
 
+void __weak ftrace_swap_func(void *a, void *b, int n)
+{
+	unsigned long t;
+
+	WARN_ON_ONCE(n != sizeof(t));
+
+	t = *((unsigned long *)a);
+	*(unsigned long *)a = *(unsigned long *)b;
+	*(unsigned long *)b = t;
+}
+
 static int ftrace_process_locs(struct module *mod,
 			       unsigned long *start,
 			       unsigned long *end)
@@ -7016,7 +7027,7 @@  static int ftrace_process_locs(struct module *mod,
 	 */
 	if (!IS_ENABLED(CONFIG_BUILDTIME_MCOUNT_SORT) || mod) {
 		sort(start, count, sizeof(*start),
-		     ftrace_cmp_ips, NULL);
+		     ftrace_cmp_ips, ftrace_swap_func);
 	} else {
 		test_is_sorted(start, count);
 	}