| Message ID | 1450498655-3820-1-git-send-email-apinski@cavium.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: > The problem here is that GCC 6 and above emits .arch now > for each function so now the global .arch_extension has > no effect. This fixes the problem by putting > .arch_extension inside ARM64_LSE_ATOMIC_INSN so > it is enabled for each place where LSE is used. Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. .arch_extension is used for virt, mp and sec over there, and it may be tricky to isolate the actual instruction usage (at least, virt looks lost in kvm/arm.c). Why can't gas have an option to accept all instruction encodings that it knows about, inspite of any .arch directives? Will > Signed-off-by: Andrew Pinski <apinski@cavium.com> > --- > arch/arm64/include/asm/lse.h | 4 +--- > 1 files changed, 1 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h > index 3de42d6..625601f 100644 > --- a/arch/arm64/include/asm/lse.h > +++ b/arch/arm64/include/asm/lse.h > @@ -17,8 +17,6 @@ > > #else /* __ASSEMBLER__ */ > > -__asm__(".arch_extension lse"); > - > /* Move the ll/sc atomics out-of-line */ > #define __LL_SC_INLINE > #define __LL_SC_PREFIX(x) __ll_sc_##x > @@ -29,7 +27,7 @@ __asm__(".arch_extension lse"); > > /* In-line patching at runtime */ > #define ARM64_LSE_ATOMIC_INSN(llsc, lse) \ > - ALTERNATIVE(llsc, lse, ARM64_HAS_LSE_ATOMICS) > + ALTERNATIVE(".arch_extension lse\n" llsc, lse, ARM64_HAS_LSE_ATOMICS) > > #endif /* __ASSEMBLER__ */ > #else /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */ > -- > 1.7.2.5 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On 21 December 2015 at 13:38, Will Deacon <will.deacon@arm.com> wrote: > On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: >> The problem here is that GCC 6 and above emits .arch now >> for each function so now the global .arch_extension has >> no effect. This fixes the problem by putting >> .arch_extension inside ARM64_LSE_ATOMIC_INSN so >> it is enabled for each place where LSE is used. > > Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. > .arch_extension is used for virt, mp and sec over there, and it may be > tricky to isolate the actual instruction usage (at least, virt looks > lost in kvm/arm.c). > > Why can't gas have an option to accept all instruction encodings that it > knows about, inspite of any .arch directives? > Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it probably makes sense to pass that on the command line when building for v7 (or +sec only for v6) if the assembler is found to support it at build time. >> Signed-off-by: Andrew Pinski <apinski@cavium.com> >> --- >> arch/arm64/include/asm/lse.h | 4 +--- >> 1 files changed, 1 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h >> index 3de42d6..625601f 100644 >> --- a/arch/arm64/include/asm/lse.h >> +++ b/arch/arm64/include/asm/lse.h >> @@ -17,8 +17,6 @@ >> >> #else /* __ASSEMBLER__ */ >> >> -__asm__(".arch_extension lse"); >> - >> /* Move the ll/sc atomics out-of-line */ >> #define __LL_SC_INLINE >> #define __LL_SC_PREFIX(x) __ll_sc_##x >> @@ -29,7 +27,7 @@ __asm__(".arch_extension lse"); >> >> /* In-line patching at runtime */ >> #define ARM64_LSE_ATOMIC_INSN(llsc, lse) \ >> - ALTERNATIVE(llsc, lse, ARM64_HAS_LSE_ATOMICS) >> + ALTERNATIVE(".arch_extension lse\n" llsc, lse, ARM64_HAS_LSE_ATOMICS) >> >> #endif /* __ASSEMBLER__ */ >> #else /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */ >> -- >> 1.7.2.5 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Mon, Dec 21, 2015 at 01:46:22PM +0100, Ard Biesheuvel wrote: > On 21 December 2015 at 13:38, Will Deacon <will.deacon@arm.com> wrote: > > On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: > >> The problem here is that GCC 6 and above emits .arch now > >> for each function so now the global .arch_extension has > >> no effect. This fixes the problem by putting > >> .arch_extension inside ARM64_LSE_ATOMIC_INSN so > >> it is enabled for each place where LSE is used. > > > > Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. > > .arch_extension is used for virt, mp and sec over there, and it may be > > tricky to isolate the actual instruction usage (at least, virt looks > > lost in kvm/arm.c). > > > > Why can't gas have an option to accept all instruction encodings that it > > knows about, inspite of any .arch directives? > > > > Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it > probably makes sense to pass that on the command line when building > for v7 (or +sec only for v6) if the assembler is found to support it > at build time. Does that override a more restrictive .arch directive emitted by the compiler? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On 21 December 2015 at 13:51, Will Deacon <will.deacon@arm.com> wrote: > On Mon, Dec 21, 2015 at 01:46:22PM +0100, Ard Biesheuvel wrote: >> On 21 December 2015 at 13:38, Will Deacon <will.deacon@arm.com> wrote: >> > On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: >> >> The problem here is that GCC 6 and above emits .arch now >> >> for each function so now the global .arch_extension has >> >> no effect. This fixes the problem by putting >> >> .arch_extension inside ARM64_LSE_ATOMIC_INSN so >> >> it is enabled for each place where LSE is used. >> > >> > Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. >> > .arch_extension is used for virt, mp and sec over there, and it may be >> > tricky to isolate the actual instruction usage (at least, virt looks >> > lost in kvm/arm.c). >> > >> > Why can't gas have an option to accept all instruction encodings that it >> > knows about, inspite of any .arch directives? >> > >> >> Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it >> probably makes sense to pass that on the command line when building >> for v7 (or +sec only for v6) if the assembler is found to support it >> at build time. > > Does that override a more restrictive .arch directive emitted by the > compiler? > It seems to be additive: -march=armv7-a+mp+sec allows a .S file containing a virt arch_extension + both hvc and smc instructions to be assembled. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Mon, Dec 21, 2015 at 01:58:30PM +0100, Ard Biesheuvel wrote: > On 21 December 2015 at 13:51, Will Deacon <will.deacon@arm.com> wrote: > > On Mon, Dec 21, 2015 at 01:46:22PM +0100, Ard Biesheuvel wrote: > >> On 21 December 2015 at 13:38, Will Deacon <will.deacon@arm.com> wrote: > >> > On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: > >> >> The problem here is that GCC 6 and above emits .arch now > >> >> for each function so now the global .arch_extension has > >> >> no effect. This fixes the problem by putting > >> >> .arch_extension inside ARM64_LSE_ATOMIC_INSN so > >> >> it is enabled for each place where LSE is used. > >> > > >> > Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. > >> > .arch_extension is used for virt, mp and sec over there, and it may be > >> > tricky to isolate the actual instruction usage (at least, virt looks > >> > lost in kvm/arm.c). > >> > > >> > Why can't gas have an option to accept all instruction encodings that it > >> > knows about, inspite of any .arch directives? > >> > > >> > >> Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it > >> probably makes sense to pass that on the command line when building > >> for v7 (or +sec only for v6) if the assembler is found to support it > >> at build time. > > > > Does that override a more restrictive .arch directive emitted by the > > compiler? > > > > It seems to be additive: -march=armv7-a+mp+sec allows a .S file > containing a virt arch_extension + both hvc and smc instructions to be > assembled. The problem I'm seeing is if I have something like: .arch_extension lse before something like: .cpu cortex-a57+fp+simd+crc -or- .arch armv8-a+fp+simd+crc then I can no longer assemble lse instructions. So the .cpu/.arch directive is undoing the .arch_extension. We can fix this by following Andrew's suggestion to have .arch_extension before every point of use, but the whole thing would be much simpler if we could just tell gas to assemble harder. Maybe we just need to construct the mother of all -march options based on build-time checks in the Makefile? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On 21 January 2016 at 13:32, Vladimir Murzin <vladimir.murzin@arm.com> wrote: > On 21/12/15 13:37, Will Deacon wrote: >> On Mon, Dec 21, 2015 at 01:58:30PM +0100, Ard Biesheuvel wrote: >>> On 21 December 2015 at 13:51, Will Deacon <will.deacon@arm.com> wrote: >>>> On Mon, Dec 21, 2015 at 01:46:22PM +0100, Ard Biesheuvel wrote: >>>>> On 21 December 2015 at 13:38, Will Deacon <will.deacon@arm.com> wrote: >>>>>> On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: >>>>>>> The problem here is that GCC 6 and above emits .arch now >>>>>>> for each function so now the global .arch_extension has >>>>>>> no effect. This fixes the problem by putting >>>>>>> .arch_extension inside ARM64_LSE_ATOMIC_INSN so >>>>>>> it is enabled for each place where LSE is used. >>>>>> >>>>>> Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. >>>>>> .arch_extension is used for virt, mp and sec over there, and it may be >>>>>> tricky to isolate the actual instruction usage (at least, virt looks >>>>>> lost in kvm/arm.c). >>>>>> >>>>>> Why can't gas have an option to accept all instruction encodings that it >>>>>> knows about, inspite of any .arch directives? >>>>>> >>>>> >>>>> Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it >>>>> probably makes sense to pass that on the command line when building >>>>> for v7 (or +sec only for v6) if the assembler is found to support it >>>>> at build time. >>>> >>>> Does that override a more restrictive .arch directive emitted by the >>>> compiler? >>>> >>> >>> It seems to be additive: -march=armv7-a+mp+sec allows a .S file >>> containing a virt arch_extension + both hvc and smc instructions to be >>> assembled. >> >> The problem I'm seeing is if I have something like: >> >> .arch_extension lse >> >> before something like: >> >> .cpu cortex-a57+fp+simd+crc >> >> -or- >> >> .arch armv8-a+fp+simd+crc >> >> then I can no longer assemble lse instructions. So the .cpu/.arch >> directive is undoing the .arch_extension. We can fix this by following >> Andrew's suggestion to have .arch_extension before every point of use, >> but the whole thing would be much simpler if we could just tell gas to >> assemble harder. >> >> Maybe we just need to construct the mother of all -march options based >> on build-time checks in the Makefile? >> > > Since I've been bitten by this I'm curious what was conclusion on this > topic? > None that I'm aware of
diff --git a/arch/arm64/include/asm/lse.h b/arch/arm64/include/asm/lse.h index 3de42d6..625601f 100644 --- a/arch/arm64/include/asm/lse.h +++ b/arch/arm64/include/asm/lse.h @@ -17,8 +17,6 @@ #else /* __ASSEMBLER__ */ -__asm__(".arch_extension lse"); - /* Move the ll/sc atomics out-of-line */ #define __LL_SC_INLINE #define __LL_SC_PREFIX(x) __ll_sc_##x @@ -29,7 +27,7 @@ __asm__(".arch_extension lse"); /* In-line patching at runtime */ #define ARM64_LSE_ATOMIC_INSN(llsc, lse) \ - ALTERNATIVE(llsc, lse, ARM64_HAS_LSE_ATOMICS) + ALTERNATIVE(".arch_extension lse\n" llsc, lse, ARM64_HAS_LSE_ATOMICS) #endif /* __ASSEMBLER__ */ #else /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */
The problem here is that GCC 6 and above emits .arch now for each function so now the global .arch_extension has no effect. This fixes the problem by putting .arch_extension inside ARM64_LSE_ATOMIC_INSN so it is enabled for each place where LSE is used. Signed-off-by: Andrew Pinski <apinski@cavium.com> --- arch/arm64/include/asm/lse.h | 4 +--- 1 files changed, 1 insertions(+), 3 deletions(-) -- 1.7.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/