[PATCH] powerpc/ptrace: Add prototype for function pt_regs_check

[PATCH] powerpc/ptrace: Add prototype for function pt_regs_check

[Mathieu Malaterre]

`pt_regs_check` is a dummy function, its purpose is to break the build
if struct pt_regs and struct user_pt_regs don't match.

This function has no functionnal purpose, and will get eliminated at
link time or after init depending on CONFIG_LD_DEAD_CODE_DATA_ELIMINATION

This commit adds a prototype to fix warning at W=1:

  arch/powerpc/kernel/ptrace.c:3339:13: error: no previous prototype for ‘pt_regs_check’ [-Werror=missing-prototypes]

Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
---
 arch/powerpc/kernel/ptrace.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index a398999d0770..341c0060b4c8 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -3338,6 +3338,10 @@ void do_syscall_trace_leave(struct pt_regs *regs)
 	user_enter();
 }
 
+void __init pt_regs_check(void);
+/* dummy function, its purpose is to break the build if struct pt_regs and
+ * struct user_pt_regs don't match.
+ */
 void __init pt_regs_check(void)
 {
 	BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
-- 
2.19.2

Re: [PATCH] powerpc/ptrace: Add prototype for function pt_regs_check

[Mathieu Malaterre]

On Sat, Dec 8, 2018 at 4:46 PM Mathieu Malaterre <malat@debian.org> wrote:
>
> `pt_regs_check` is a dummy function, its purpose is to break the build
> if struct pt_regs and struct user_pt_regs don't match.
>
> This function has no functionnal purpose, and will get eliminated at
> link time or after init depending on CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
>
> This commit adds a prototype to fix warning at W=1:
>
>   arch/powerpc/kernel/ptrace.c:3339:13: error: no previous prototype for ‘pt_regs_check’ [-Werror=missing-prototypes]
>
> Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Signed-off-by: Mathieu Malaterre <malat@debian.org>
> ---
>  arch/powerpc/kernel/ptrace.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> index a398999d0770..341c0060b4c8 100644
> --- a/arch/powerpc/kernel/ptrace.c
> +++ b/arch/powerpc/kernel/ptrace.c
> @@ -3338,6 +3338,10 @@ void do_syscall_trace_leave(struct pt_regs *regs)
>         user_enter();
>  }
>
> +void __init pt_regs_check(void);
> +/* dummy function, its purpose is to break the build if struct pt_regs and
> + * struct user_pt_regs don't match.
> + */

Another trick which seems to work with GCC is:

-void __init pt_regs_check(void)
+static inline void __init pt_regs_check(void)

>  void __init pt_regs_check(void)
>  {
>         BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
> --
> 2.19.2
>

Re: [PATCH] powerpc/ptrace: Add prototype for function pt_regs_check

[Christophe Leroy]

Le 15/02/2019 à 09:11, Mathieu Malaterre a écrit :
> On Sat, Dec 8, 2018 at 4:46 PM Mathieu Malaterre <malat@debian.org> wrote:
>>
>> `pt_regs_check` is a dummy function, its purpose is to break the build
>> if struct pt_regs and struct user_pt_regs don't match.
>>
>> This function has no functionnal purpose, and will get eliminated at
>> link time or after init depending on CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
>>
>> This commit adds a prototype to fix warning at W=1:
>>
>>    arch/powerpc/kernel/ptrace.c:3339:13: error: no previous prototype for ‘pt_regs_check’ [-Werror=missing-prototypes]
>>
>> Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> Signed-off-by: Mathieu Malaterre <malat@debian.org>
>> ---
>>   arch/powerpc/kernel/ptrace.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
>> index a398999d0770..341c0060b4c8 100644
>> --- a/arch/powerpc/kernel/ptrace.c
>> +++ b/arch/powerpc/kernel/ptrace.c
>> @@ -3338,6 +3338,10 @@ void do_syscall_trace_leave(struct pt_regs *regs)
>>          user_enter();
>>   }
>>
>> +void __init pt_regs_check(void);
>> +/* dummy function, its purpose is to break the build if struct pt_regs and
>> + * struct user_pt_regs don't match.
>> + */
> 
> Another trick which seems to work with GCC is:
> 
> -void __init pt_regs_check(void)
> +static inline void __init pt_regs_check(void)

Does this really work ? Did you test to ensure that the BUILD_BUG_ON 
still detect mismatch between struct pt_regs and struct user_pt_regs ?

Christophe

> 
>>   void __init pt_regs_check(void)
>>   {
>>          BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
>> --
>> 2.19.2
>>

Re: [PATCH] powerpc/ptrace: Add prototype for function pt_regs_check

[Mathieu Malaterre]

On Fri, Feb 15, 2019 at 9:21 AM Christophe Leroy
<christophe.leroy@c-s.fr> wrote:
>
>
>
> Le 15/02/2019 à 09:11, Mathieu Malaterre a écrit :
> > On Sat, Dec 8, 2018 at 4:46 PM Mathieu Malaterre <malat@debian.org> wrote:
> >>
> >> `pt_regs_check` is a dummy function, its purpose is to break the build
> >> if struct pt_regs and struct user_pt_regs don't match.
> >>
> >> This function has no functionnal purpose, and will get eliminated at
> >> link time or after init depending on CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> >>
> >> This commit adds a prototype to fix warning at W=1:
> >>
> >>    arch/powerpc/kernel/ptrace.c:3339:13: error: no previous prototype for ‘pt_regs_check’ [-Werror=missing-prototypes]
> >>
> >> Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
> >> Signed-off-by: Mathieu Malaterre <malat@debian.org>
> >> ---
> >>   arch/powerpc/kernel/ptrace.c | 4 ++++
> >>   1 file changed, 4 insertions(+)
> >>
> >> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> >> index a398999d0770..341c0060b4c8 100644
> >> --- a/arch/powerpc/kernel/ptrace.c
> >> +++ b/arch/powerpc/kernel/ptrace.c
> >> @@ -3338,6 +3338,10 @@ void do_syscall_trace_leave(struct pt_regs *regs)
> >>          user_enter();
> >>   }
> >>
> >> +void __init pt_regs_check(void);
> >> +/* dummy function, its purpose is to break the build if struct pt_regs and
> >> + * struct user_pt_regs don't match.
> >> + */
> >
> > Another trick which seems to work with GCC is:
> >
> > -void __init pt_regs_check(void)
> > +static inline void __init pt_regs_check(void)
>
> Does this really work ? Did you test to ensure that the BUILD_BUG_ON
> still detect mismatch between struct pt_regs and struct user_pt_regs ?
>

My bad, I was unaware of GCC behavior for static inline in this case.
Sorry for the noise.
Original ugly patch does work though.
>
> >
> >>   void __init pt_regs_check(void)
> >>   {
> >>          BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
> >> --
> >> 2.19.2
> >>

Re: [PATCH] powerpc/ptrace: Add prototype for function pt_regs_check

[Michael Ellerman]

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On Sat, 2018-12-08 at 15:46:23 UTC, Mathieu Malaterre wrote:
> `pt_regs_check` is a dummy function, its purpose is to break the build
> if struct pt_regs and struct user_pt_regs don't match.
> 
> This function has no functionnal purpose, and will get eliminated at
> link time or after init depending on CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
> 
> This commit adds a prototype to fix warning at W=1:
> 
>   arch/powerpc/kernel/ptrace.c:3339:13: error: no previous prototype for ‘pt_regs_check’ [-Werror=missing-prototypes]
> 
> Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Signed-off-by: Mathieu Malaterre <malat@debian.org>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/5c74f79958682fccd82a6029c53859d1dab3b239

cheers