[PATCH] arm64/signal: Clean up SVE/SME feature checking inconsistency

[PATCH] arm64/signal: Clean up SVE/SME feature checking inconsistency

[Mark Brown]

Currently when restoring signal state we check to see if SVE is supported
in restore_sigframe() but check to see if SVE is supported inside
restore_sve_fpsimd_context(). This makes no real difference since SVE is
always supported in systems with SME but looks a bit untidy and makes
things slightly harder to follow, move the SVE check next to the SME one
in restore_sve_fpsimd_context().

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/signal.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 23dd4c3bcfed..0d5a9eb43085 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -281,6 +281,9 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user)
 
 		vl = task_get_sme_vl(current);
 	} else {
+		if (!system_supports_sve())
+			return -EINVAL;
+
 		vl = task_get_sve_vl(current);
 	}
 
@@ -652,14 +655,10 @@ static int restore_sigframe(struct pt_regs *regs,
 		if (!user.fpsimd)
 			return -EINVAL;
 
-		if (user.sve) {
-			if (!system_supports_sve())
-				return -EINVAL;
-
+		if (user.sve)
 			err = restore_sve_fpsimd_context(&user);
-		} else {
+		else
 			err = restore_fpsimd_context(user.fpsimd);
-		}
 	}
 
 	if (err == 0 && system_supports_sme() && user.za)
-- 
2.30.2


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Re: [PATCH] arm64/signal: Clean up SVE/SME feature checking inconsistency

[Will Deacon]

On Mon, Jun 13, 2022 at 10:01:33PM +0100, Mark Brown wrote:
> Currently when restoring signal state we check to see if SVE is supported
> in restore_sigframe() but check to see if SVE is supported inside
> restore_sve_fpsimd_context(). This makes no real difference since SVE is
> always supported in systems with SME but looks a bit untidy and makes
> things slightly harder to follow, move the SVE check next to the SME one
> in restore_sve_fpsimd_context().
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  arch/arm64/kernel/signal.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> index 23dd4c3bcfed..0d5a9eb43085 100644
> --- a/arch/arm64/kernel/signal.c
> +++ b/arch/arm64/kernel/signal.c
> @@ -281,6 +281,9 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user)
>  
>  		vl = task_get_sme_vl(current);
>  	} else {
> +		if (!system_supports_sve())
> +			return -EINVAL;
> +
>  		vl = task_get_sve_vl(current);
>  	}
>  
> @@ -652,14 +655,10 @@ static int restore_sigframe(struct pt_regs *regs,
>  		if (!user.fpsimd)
>  			return -EINVAL;
>  
> -		if (user.sve) {
> -			if (!system_supports_sve())
> -				return -EINVAL;
> -
> +		if (user.sve)
>  			err = restore_sve_fpsimd_context(&user);

This breaks the allnoconfig build for me:

ld.lld: error: undefined symbol: restore_sve_fpsimd_context
>>> referenced by signal.c
>>>               kernel/signal.o:(__arm64_sys_rt_sigreturn) in archive arch/arm64/built-in.a
make: *** [Makefile:1164: vmlinux] Error 1

Will

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Re: [PATCH] arm64/signal: Clean up SVE/SME feature checking inconsistency

[Mark Brown]

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On Thu, Jun 23, 2022 at 06:47:38PM +0100, Will Deacon wrote:

> This breaks the allnoconfig build for me:

> ld.lld: error: undefined symbol: restore_sve_fpsimd_context
> >>> referenced by signal.c
> >>>               kernel/signal.o:(__arm64_sys_rt_sigreturn) in archive arch/arm64/built-in.a
> make: *** [Makefile:1164: vmlinux] Error 1

I can't reproduce that here - could you confirm exactly what tree you
applied against and what toolchain you're using?  I'm normally using
clang 15 at the minute, 14 seems fine too, and applied against both
-next and v5.19-rc3 all of which are building an allnoconfig happily for
me.

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Re: [PATCH] arm64/signal: Clean up SVE/SME feature checking inconsistency

[Will Deacon]

On Fri, Jun 24, 2022 at 02:28:07PM +0100, Mark Brown wrote:
> On Thu, Jun 23, 2022 at 06:47:38PM +0100, Will Deacon wrote:
> 
> > This breaks the allnoconfig build for me:
> 
> > ld.lld: error: undefined symbol: restore_sve_fpsimd_context
> > >>> referenced by signal.c
> > >>>               kernel/signal.o:(__arm64_sys_rt_sigreturn) in archive arch/arm64/built-in.a
> > make: *** [Makefile:1164: vmlinux] Error 1
> 
> I can't reproduce that here - could you confirm exactly what tree you
> applied against and what toolchain you're using?  I'm normally using
> clang 15 at the minute, 14 seems fine too, and applied against both
> -next and v5.19-rc3 all of which are building an allnoconfig happily for
> me.

I can reproduce the issue with just this patch applied on top of -rc3.
I'll give your v2 a try, bu FWIW I'm using clang 12.0.6 and building
using:

$ make LLVM=1 ARCH=arm64 mrproper allnoconfig
$ make LLVM=1 ARCH=arm64 -j100

Will

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Re: [PATCH] arm64/signal: Clean up SVE/SME feature checking inconsistency

[Mark Brown]

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On Fri, Jun 24, 2022 at 03:10:46PM +0100, Will Deacon wrote:
> On Fri, Jun 24, 2022 at 02:28:07PM +0100, Mark Brown wrote:

> > I can't reproduce that here - could you confirm exactly what tree you
> > applied against and what toolchain you're using?  I'm normally using
> > clang 15 at the minute, 14 seems fine too, and applied against both
> > -next and v5.19-rc3 all of which are building an allnoconfig happily for
> > me.

> I can reproduce the issue with just this patch applied on top of -rc3.
> I'll give your v2 a try, bu FWIW I'm using clang 12.0.6 and building
> using:

Ah, clang 12 is pretty old by clang standards and that .6 suggests it's
probably some Android version.  I can reproduce with upstream clang 12,
my fix does seem to work for me.

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