| Message ID | 20180930222230.24167-1-stefan@agner.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: disable ARMv6 for Clang older than 8.0 | expand |
On Mon, 2018-10-01 at 00:22 +0200, Stefan Agner wrote: > The kernel passes the ArmV6K architecture to the compiler when > using the multi platform selection and enabling ARMv6. Clang > older than version 8.0 emit assembly with an non-existing CPU, > which then makes the assembler fail. Prevent the user from > selecting ARMv6 when using Clang before 8.0. > > Signed-off-by: Stefan Agner <stefan@agner.ch> > Link: https://github.com/ClangBuiltLinux/linux/issues/55 > --- > arch/arm/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index e8cd55a5b04c..8da160757381 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -671,6 +671,7 @@ config ARCH_MULTI_V4_V5 > > config ARCH_MULTI_V6 > bool "ARMv6 based platforms (ARM11)" > + depends on !CC_IS_CLANG || CLANG_VERSION>=80000 > select ARCH_MULTI_V6_V7 > select CPU_V6K > Perhaps it'd be better to avoid this in selection criteria in Kconfig and instead add this to include/linux/compiler_clang.h --- include/linux/compiler-clang.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index b1ce500fe8b3..90fd16c85359 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -3,6 +3,10 @@ #error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead." #endif +#if defined(CONFIG_ARCH_MULTI_V6) && CLANG_VERSION < 80000 +# error Sorry, your compiler is too old - please upgrade it. +#endif + /* Some compiler specific definitions are overwritten here * for Clang compiler */
On Sun, Sep 30, 2018 at 04:48:20PM -0700, Joe Perches wrote: > On Mon, 2018-10-01 at 00:22 +0200, Stefan Agner wrote: > > The kernel passes the ArmV6K architecture to the compiler when > > using the multi platform selection and enabling ARMv6. Clang > > older than version 8.0 emit assembly with an non-existing CPU, > > which then makes the assembler fail. Prevent the user from > > selecting ARMv6 when using Clang before 8.0. > > > > Signed-off-by: Stefan Agner <stefan@agner.ch> > > Link: https://github.com/ClangBuiltLinux/linux/issues/55 > > --- > > arch/arm/Kconfig | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > > index e8cd55a5b04c..8da160757381 100644 > > --- a/arch/arm/Kconfig > > +++ b/arch/arm/Kconfig > > @@ -671,6 +671,7 @@ config ARCH_MULTI_V4_V5 > > > > config ARCH_MULTI_V6 > > bool "ARMv6 based platforms (ARM11)" > > + depends on !CC_IS_CLANG || CLANG_VERSION>=80000 > > select ARCH_MULTI_V6_V7 > > select CPU_V6K > > > > Perhaps it'd be better to avoid this in selection > criteria in Kconfig and instead add this to > include/linux/compiler_clang.h > --- > include/linux/compiler-clang.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h > index b1ce500fe8b3..90fd16c85359 100644 > --- a/include/linux/compiler-clang.h > +++ b/include/linux/compiler-clang.h > @@ -3,6 +3,10 @@ > #error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead." > #endif > > +#if defined(CONFIG_ARCH_MULTI_V6) && CLANG_VERSION < 80000 > +# error Sorry, your compiler is too old - please upgrade it. > +#endif (a) does it makes sense to have arch CONFIG_* in linux/*.h? It could instead go in arch/arm/kernel/asm-offsets.c, where we have the other tests similar to this for GCC. (b) do we get far enough that the #error will be generated before the reported assembler error happens? IOW, would the assembler error mask this #error? I think it needs confirmation that a #error for this problem results in the desired behaviour.
On 01.10.2018 18:53, Russell King - ARM Linux wrote: > On Sun, Sep 30, 2018 at 04:48:20PM -0700, Joe Perches wrote: >> On Mon, 2018-10-01 at 00:22 +0200, Stefan Agner wrote: >> > The kernel passes the ArmV6K architecture to the compiler when >> > using the multi platform selection and enabling ARMv6. Clang >> > older than version 8.0 emit assembly with an non-existing CPU, >> > which then makes the assembler fail. Prevent the user from >> > selecting ARMv6 when using Clang before 8.0. >> > >> > Signed-off-by: Stefan Agner <stefan@agner.ch> >> > Link: https://github.com/ClangBuiltLinux/linux/issues/55 >> > --- >> > arch/arm/Kconfig | 1 + >> > 1 file changed, 1 insertion(+) >> > >> > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> > index e8cd55a5b04c..8da160757381 100644 >> > --- a/arch/arm/Kconfig >> > +++ b/arch/arm/Kconfig >> > @@ -671,6 +671,7 @@ config ARCH_MULTI_V4_V5 >> > >> > config ARCH_MULTI_V6 >> > bool "ARMv6 based platforms (ARM11)" >> > + depends on !CC_IS_CLANG || CLANG_VERSION>=80000 >> > select ARCH_MULTI_V6_V7 >> > select CPU_V6K >> > >> >> Perhaps it'd be better to avoid this in selection >> criteria in Kconfig and instead add this to >> include/linux/compiler_clang.h >> --- >> include/linux/compiler-clang.h | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h >> index b1ce500fe8b3..90fd16c85359 100644 >> --- a/include/linux/compiler-clang.h >> +++ b/include/linux/compiler-clang.h >> @@ -3,6 +3,10 @@ >> #error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead." >> #endif >> >> +#if defined(CONFIG_ARCH_MULTI_V6) && CLANG_VERSION < 80000 >> +# error Sorry, your compiler is too old - please upgrade it. >> +#endif > > (a) does it makes sense to have arch CONFIG_* in linux/*.h? It could > instead go in arch/arm/kernel/asm-offsets.c, where we have the other > tests similar to this for GCC. > > (b) do we get far enough that the #error will be generated before the > reported assembler error happens? IOW, would the assembler error > mask this #error? > > I think it needs confirmation that a #error for this problem results > in the desired behaviour. Adding the above #error errors out before the assembler error happen in both cases. However, adding it to include/linux/compiler-clang.h leads to a bunch of warnings too: ... CC kernel/bounds.s In file included from <built-in>:2: In file included from ././include/linux/compiler_types.h:59: ./include/linux/compiler-clang.h:7:2: error: "Sorry, your compiler is too old - please upgrade it." #error "Sorry, your compiler is too old - please upgrade it." ^ In file included from kernel/bounds.c:10: In file included from ./include/linux/page-flags.h:10: In file included from ./include/linux/bug.h:5: In file included from ./arch/arm/include/asm/bug.h:60: In file included from ./include/asm-generic/bug.h:18: In file included from ./include/linux/kernel.h:11: ./include/linux/bitops.h:53:41: warning: shift count >= width of type [-Wshift-count-overflow] return sizeof(w) == 4 ? hweight32(w) : hweight64(w); ^~~~~~~~~~~~ ./include/asm-generic/bitops/const_hweight.h:29:49: note: expanded from macro 'hweight64' #define hweight64(w) (__builtin_constant_p(w) ? __const_hweight64(w) : __arch_hweight64(w)) ^~~~~~~~~~~~~~~~~~~~ ./include/asm-generic/bitops/const_hweight.h:21:76: note: expanded from macro '__const_hweight64' #define __const_hweight64(w) (__const_hweight32(w) + __const_hweight32((w) >> 32)) ^ ~~ ./include/asm-generic/bitops/const_hweight.h:20:49: note: expanded from macro '__const_hweight32' #define __const_hweight32(w) (__const_hweight16(w) + __const_hweight16((w) >> 16)) ^ ./include/asm-generic/bitops/const_hweight.h:19:48: note: expanded from macro '__const_hweight16' #define __const_hweight16(w) (__const_hweight8(w) + __const_hweight8((w) >> 8 )) ^ ./include/asm-generic/bitops/const_hweight.h:10:9: note: expanded from macro '__const_hweight8' ((!!((w) & (1ULL << 0))) + \ ^ Including it to arch/arm/kernel/asm-offsets.c does not lead to those warnings: ... CC kernel/bounds.s UPD include/generated/bounds.h CC arch/arm/kernel/asm-offsets.s arch/arm/kernel/asm-offsets.c:51:2: error: "Sorry, your compiler is too old - please upgrade it." #error "Sorry, your compiler is too old - please upgrade it." ^ 1 error generated. make[1]: *** [Kbuild:56: arch/arm/kernel/asm-offsets.s] Error 1 make: *** [Makefile:1100: prepare0] Error 2 -- Stefan
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index e8cd55a5b04c..8da160757381 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -671,6 +671,7 @@ config ARCH_MULTI_V4_V5 config ARCH_MULTI_V6 bool "ARMv6 based platforms (ARM11)" + depends on !CC_IS_CLANG || CLANG_VERSION>=80000 select ARCH_MULTI_V6_V7 select CPU_V6K
The kernel passes the ArmV6K architecture to the compiler when using the multi platform selection and enabling ARMv6. Clang older than version 8.0 emit assembly with an non-existing CPU, which then makes the assembler fail. Prevent the user from selecting ARMv6 when using Clang before 8.0. Signed-off-by: Stefan Agner <stefan@agner.ch> Link: https://github.com/ClangBuiltLinux/linux/issues/55 --- arch/arm/Kconfig | 1 + 1 file changed, 1 insertion(+)