[PATCH v1] powerpc: Make setjmp/longjump signature standard
Thanks you all for the comments. Everything addressed, plus the array vs pointer suggestion from Segher Boessenkool on the other thread, which is only cosmetic and does not change anything wrt behaviour.
Re: [PATCH v1] powerpc: Make setjmp/longjump signature standard
On Fri, Mar 27, 2020 at 06:45:21PM +0100, Christophe Leroy wrote: > Subject line, change longjump to longjmp > > Le 27/03/2020 à 11:07, Clement Courbet a écrit : > > Declaring setjmp()/longjmp() as taking longs makes the signature > > non-standard, and makes clang complain. In the past, this has been > > worked around by adding -ffreestanding to the compile flags. > > > > The implementation looks like it only ever propagates the value > > (in longjmp) or sets it to 1 (in setjmp), and we only call longjmp > > with integer parameters. > > > > This allows removing -ffreestanding from the compilation flags. > > > > Context: > > https://lore.kernel.org/patchwork/patch/1214060 > > https://lore.kernel.org/patchwork/patch/1216174 > > > > Signed-off-by: Clement Courbet > > --- > > arch/powerpc/include/asm/setjmp.h | 6 -- > > arch/powerpc/kexec/Makefile | 3 --- > > 2 files changed, 4 insertions(+), 5 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/setjmp.h > > b/arch/powerpc/include/asm/setjmp.h > > index e9f81bb3f83b..84bb0d140d59 100644 > > --- a/arch/powerpc/include/asm/setjmp.h > > +++ b/arch/powerpc/include/asm/setjmp.h > > @@ -7,7 +7,9 @@ > > #define JMP_BUF_LEN23 > > -extern long setjmp(long *) __attribute__((returns_twice)); > > -extern void longjmp(long *, long) __attribute__((noreturn)); > > +typedef long *jmp_buf; > > Do we need that new opaque typedef ? Why not just keep long * ? Yes, otherwise the warning comes back: In file included from arch/powerpc/kexec/crash.c:25: arch/powerpc/include/asm/setjmp.h:10:12: error: declaration of built-in function 'setjmp' requires the declaration of the 'jmp_buf' type, commonly provided in the header . [-Werror,-Wincomplete-setjmp-declaration] extern int setjmp(long *env) __attribute__((returns_twice)); ^ arch/powerpc/include/asm/setjmp.h:11:13: error: declaration of built-in function 'longjmp' requires the declaration of the 'jmp_buf' type, commonly provided in the header . [-Werror,-Wincomplete-setjmp-declaration] extern void longjmp(long *env, int val) __attribute__((noreturn)); ^ 2 errors generated. > > + > > +extern int setjmp(jmp_buf env) __attribute__((returns_twice)); > > +extern void longjmp(jmp_buf env, int val) __attribute__((noreturn)); > > #endif /* _ASM_POWERPC_SETJMP_H */ > > diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile > > index 378f6108a414..86380c69f5ce 100644 > > --- a/arch/powerpc/kexec/Makefile > > +++ b/arch/powerpc/kexec/Makefile > > @@ -3,9 +3,6 @@ > > # Makefile for the linux kernel. > > # > > -# Avoid clang warnings around longjmp/setjmp declarations > > -CFLAGS_crash.o += -ffreestanding > > - > > obj-y += core.o crash.o core_$(BITS).o > > obj-$(CONFIG_PPC32) += relocate_32.o > > > > Christophe
Re: [PATCH v1] powerpc: Make setjmp/longjump signature standard
Subject line, change longjump to longjmp Le 27/03/2020 à 11:07, Clement Courbet a écrit : Declaring setjmp()/longjmp() as taking longs makes the signature non-standard, and makes clang complain. In the past, this has been worked around by adding -ffreestanding to the compile flags. The implementation looks like it only ever propagates the value (in longjmp) or sets it to 1 (in setjmp), and we only call longjmp with integer parameters. This allows removing -ffreestanding from the compilation flags. Context: https://lore.kernel.org/patchwork/patch/1214060 https://lore.kernel.org/patchwork/patch/1216174 Signed-off-by: Clement Courbet --- arch/powerpc/include/asm/setjmp.h | 6 -- arch/powerpc/kexec/Makefile | 3 --- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/include/asm/setjmp.h b/arch/powerpc/include/asm/setjmp.h index e9f81bb3f83b..84bb0d140d59 100644 --- a/arch/powerpc/include/asm/setjmp.h +++ b/arch/powerpc/include/asm/setjmp.h @@ -7,7 +7,9 @@ #define JMP_BUF_LEN23 -extern long setjmp(long *) __attribute__((returns_twice)); -extern void longjmp(long *, long) __attribute__((noreturn)); +typedef long *jmp_buf; Do we need that new opaque typedef ? Why not just keep long * ? + +extern int setjmp(jmp_buf env) __attribute__((returns_twice)); +extern void longjmp(jmp_buf env, int val) __attribute__((noreturn)); #endif /* _ASM_POWERPC_SETJMP_H */ diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile index 378f6108a414..86380c69f5ce 100644 --- a/arch/powerpc/kexec/Makefile +++ b/arch/powerpc/kexec/Makefile @@ -3,9 +3,6 @@ # Makefile for the linux kernel. # -# Avoid clang warnings around longjmp/setjmp declarations -CFLAGS_crash.o += -ffreestanding - obj-y += core.o crash.o core_$(BITS).o obj-$(CONFIG_PPC32) += relocate_32.o Christophe
Re: [PATCH v1] powerpc: Make setjmp/longjump signature standard
On Fri, Mar 27, 2020 at 10:10:44AM -0700, Nick Desaulniers wrote:
> On Fri, Mar 27, 2020 at 3:08 AM Clement Courbet wrote:
> >
> > Declaring setjmp()/longjmp() as taking longs makes the signature
> > non-standard, and makes clang complain. In the past, this has been
> > worked around by adding -ffreestanding to the compile flags.
> >
> > The implementation looks like it only ever propagates the value
> > (in longjmp) or sets it to 1 (in setjmp), and we only call longjmp
> > with integer parameters.
> >
> > This allows removing -ffreestanding from the compilation flags.
> >
> > Context:
> > https://lore.kernel.org/patchwork/patch/1214060
> > https://lore.kernel.org/patchwork/patch/1216174
> >
> > Signed-off-by: Clement Courbet
Thanks for fixing this properly, not really sure why I did not think of
this in the first place. I guess my thought was the warning makes it
seem like clang is going to ignore the kernel's implementation of
setjmp/longjmp but I can't truly remember.
> Hi Clement, thanks for the patch! Would you mind sending a V2 that
> included a similar fix to arch/powerpc/xmon/Makefile?
Agreed.
> For context, this was the original patch:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=aea447141c7e7824b81b49acd1bc78
> which was then modified to:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c9029ef9c95765e7b63c4d9aa780674447db1ec0
>
> So on your V2, if you include in the commit message, the line:
>
> Fixes c9029ef9c957 ("powerpc: Avoid clang warnings around setjmp and longjmp")
>
> then that will help our LTS branch maintainers back port it to the
> appropriate branches.
The tags should be:
Cc: sta...@vger.kernel.org # v4.14+
Fixes: c9029ef9c957 ("powerpc: Avoid clang warnings around setjmp and longjmp")
that way it explicitly gets picked up for stable, rather than Sasha's
AUTOSEL process, which could miss it.
With the xmon/Makefile -ffreestanding removed and the tags updated,
consider this:
Reviewed-by: Nathan Chancellor
Tested-by: Nathan Chancellor
Cheers,
Nathan
Re: [PATCH v1] powerpc: Make setjmp/longjump signature standard
On Fri, Mar 27, 2020 at 3:08 AM Clement Courbet wrote:
>
> Declaring setjmp()/longjmp() as taking longs makes the signature
> non-standard, and makes clang complain. In the past, this has been
> worked around by adding -ffreestanding to the compile flags.
>
> The implementation looks like it only ever propagates the value
> (in longjmp) or sets it to 1 (in setjmp), and we only call longjmp
> with integer parameters.
>
> This allows removing -ffreestanding from the compilation flags.
>
> Context:
> https://lore.kernel.org/patchwork/patch/1214060
> https://lore.kernel.org/patchwork/patch/1216174
>
> Signed-off-by: Clement Courbet
Hi Clement, thanks for the patch! Would you mind sending a V2 that
included a similar fix to arch/powerpc/xmon/Makefile?
For context, this was the original patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=aea447141c7e7824b81b49acd1bc78
which was then modified to:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c9029ef9c95765e7b63c4d9aa780674447db1ec0
So on your V2, if you include in the commit message, the line:
Fixes c9029ef9c957 ("powerpc: Avoid clang warnings around setjmp and longjmp")
then that will help our LTS branch maintainers back port it to the
appropriate branches.
>
> ---
> arch/powerpc/include/asm/setjmp.h | 6 --
> arch/powerpc/kexec/Makefile | 3 ---
> 2 files changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/setjmp.h
> b/arch/powerpc/include/asm/setjmp.h
> index e9f81bb3f83b..84bb0d140d59 100644
> --- a/arch/powerpc/include/asm/setjmp.h
> +++ b/arch/powerpc/include/asm/setjmp.h
> @@ -7,7 +7,9 @@
>
> #define JMP_BUF_LEN23
>
> -extern long setjmp(long *) __attribute__((returns_twice));
> -extern void longjmp(long *, long) __attribute__((noreturn));
> +typedef long *jmp_buf;
> +
> +extern int setjmp(jmp_buf env) __attribute__((returns_twice));
> +extern void longjmp(jmp_buf env, int val) __attribute__((noreturn));
>
> #endif /* _ASM_POWERPC_SETJMP_H */
> diff --git a/arch/powerpc/kexec/Makefile b/arch/powerpc/kexec/Makefile
> index 378f6108a414..86380c69f5ce 100644
> --- a/arch/powerpc/kexec/Makefile
> +++ b/arch/powerpc/kexec/Makefile
> @@ -3,9 +3,6 @@
> # Makefile for the linux kernel.
> #
>
> -# Avoid clang warnings around longjmp/setjmp declarations
> -CFLAGS_crash.o += -ffreestanding
> -
> obj-y += core.o crash.o core_$(BITS).o
>
> obj-$(CONFIG_PPC32)+= relocate_32.o
> --
> 2.25.1.696.g5e7596f4ac-goog
>
--
Thanks,
~Nick Desaulniers
