| Message ID | 20240604210006.668912-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] arm64/io: add constant-argument check | expand |
On Tue, Jun 04, 2024 at 10:59:57PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > In some configurations __const_iowrite32_copy() does not get inlined > and gcc runs into the BUILD_BUG(): > > In file included from <command-line>: > In function '__const_memcpy_toio_aligned32', > inlined from '__const_iowrite32_copy' at arch/arm64/include/asm/io.h:203:3, > inlined from '__const_iowrite32_copy' at arch/arm64/include/asm/io.h:199:20: > include/linux/compiler_types.h:487:45: error: call to '__compiletime_assert_538' declared with attribute error: BUILD_BUG failed > 487 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^ > include/linux/compiler_types.h:468:25: note: in definition of macro '__compiletime_assert' > 468 | prefix ## suffix(); \ > | ^~~~~~ > include/linux/compiler_types.h:487:9: note: in expansion of macro '_compiletime_assert' > 487 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^~~~~~~~~~~~~~~~~~~ > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > | ^~~~~~~~~~~~~~~~~~ > include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG' > 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") > | ^~~~~~~~~~~~~~~~ > arch/arm64/include/asm/io.h:193:17: note: in expansion of macro 'BUILD_BUG' > 193 | BUILD_BUG(); > | ^~~~~~~~~ > > Move the check for constant arguments into the inline function to ensure > it is still constant if the compiler decides against inlining it, and > mark them as __always_inline to override the logic that sometimes leads > to the compiler not producing the simplified output. > > Note that either the __always_inline annotation or the check for a > constant value are sufficient here, but combining the two looks cleaner > as it also avoids the macro. With clang-8 and older, the macro was still > needed, but all versions of gcc and clang can reliably perform constant > folding here. > > Fixes: ead79118dae6 ("arm64/io: Provide a WC friendly __iowriteXX_copy()") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> I have a trivial nit below, but either way this looks good to me, so regardless of that: Reviewed-by: Mark Rutland <mark.rutland@arm.com> > +static __always_inline void > +__iowrite32_copy(void __iomem *to, const void *from, size_t count) > { > - if (count == 8 || count == 4 || count == 2 || count == 1) { > + if (__builtin_constant_p(count) && > + (count == 8 || count == 4 || count == 2 || count == 1)) { > __const_memcpy_toio_aligned32(to, from, count); > dgh(); > } else { > __iowrite32_copy_full(to, from, count); > } > } > +#define __iowrite32_copy(to, from, count) __iowrite32_copy(to, from, count) Normally we'd make this: #define __iowrite32_copy __iowrite32_copy ... so that it's clear it's just providing the preprocessor symbol, and doesn't have to be updated if the prototype changes. [...] > +#define __iowrite64_copy(to, from, count) __iowrite64_copy(to, from, count) Likewise here. Mark.
On Wed, Jun 05, 2024 at 10:15:38AM +0100, Mark Rutland wrote: > On Tue, Jun 04, 2024 at 10:59:57PM +0200, Arnd Bergmann wrote: > > Move the check for constant arguments into the inline function to ensure > > it is still constant if the compiler decides against inlining it, and > > mark them as __always_inline to override the logic that sometimes leads > > to the compiler not producing the simplified output. > > > > Note that either the __always_inline annotation or the check for a > > constant value are sufficient here, but combining the two looks cleaner > > as it also avoids the macro. With clang-8 and older, the macro was still > > needed, but all versions of gcc and clang can reliably perform constant > > folding here. > > > > Fixes: ead79118dae6 ("arm64/io: Provide a WC friendly __iowriteXX_copy()") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > I have a trivial nit below, but either way this looks good to me, so > regardless of that: > > Reviewed-by: Mark Rutland <mark.rutland@arm.com> > > > +static __always_inline void > > +__iowrite32_copy(void __iomem *to, const void *from, size_t count) > > { > > - if (count == 8 || count == 4 || count == 2 || count == 1) { > > + if (__builtin_constant_p(count) && > > + (count == 8 || count == 4 || count == 2 || count == 1)) { > > __const_memcpy_toio_aligned32(to, from, count); > > dgh(); > > } else { > > __iowrite32_copy_full(to, from, count); > > } > > } > > +#define __iowrite32_copy(to, from, count) __iowrite32_copy(to, from, count) > > Normally we'd make this: > > #define __iowrite32_copy __iowrite32_copy > > ... so that it's clear it's just providing the preprocessor symbol, and > doesn't have to be updated if the prototype changes. > > [...] > > > +#define __iowrite64_copy(to, from, count) __iowrite64_copy(to, from, count) > > Likewise here. I can fold these two changes in. Will
On Wed, Jun 5, 2024, at 13:10, Will Deacon wrote: > On Wed, Jun 05, 2024 at 10:15:38AM +0100, Mark Rutland wrote: >> > +#define __iowrite32_copy(to, from, count) __iowrite32_copy(to, from, count) >> >> Normally we'd make this: >> >> #define __iowrite32_copy __iowrite32_copy >> > > I can fold these two changes in. Sounds good, thanks! Arnd
On Wed, Jun 05, 2024 at 10:15:38AM +0100, Mark Rutland wrote: > On Tue, Jun 04, 2024 at 10:59:57PM +0200, Arnd Bergmann wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > > > In some configurations __const_iowrite32_copy() does not get inlined > > and gcc runs into the BUILD_BUG(): > > > > In file included from <command-line>: > > In function '__const_memcpy_toio_aligned32', > > inlined from '__const_iowrite32_copy' at arch/arm64/include/asm/io.h:203:3, > > inlined from '__const_iowrite32_copy' at arch/arm64/include/asm/io.h:199:20: > > include/linux/compiler_types.h:487:45: error: call to '__compiletime_assert_538' declared with attribute error: BUILD_BUG failed > > 487 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > > | ^ > > include/linux/compiler_types.h:468:25: note: in definition of macro '__compiletime_assert' > > 468 | prefix ## suffix(); \ > > | ^~~~~~ > > include/linux/compiler_types.h:487:9: note: in expansion of macro '_compiletime_assert' > > 487 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > > | ^~~~~~~~~~~~~~~~~~~ > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > | ^~~~~~~~~~~~~~~~~~ > > include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG' > > 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") > > | ^~~~~~~~~~~~~~~~ > > arch/arm64/include/asm/io.h:193:17: note: in expansion of macro 'BUILD_BUG' > > 193 | BUILD_BUG(); > > | ^~~~~~~~~ > > > > Move the check for constant arguments into the inline function to ensure > > it is still constant if the compiler decides against inlining it, and > > mark them as __always_inline to override the logic that sometimes leads > > to the compiler not producing the simplified output. > > > > Note that either the __always_inline annotation or the check for a > > constant value are sufficient here, but combining the two looks cleaner > > as it also avoids the macro. With clang-8 and older, the macro was still > > needed, but all versions of gcc and clang can reliably perform constant > > folding here. > > > > Fixes: ead79118dae6 ("arm64/io: Provide a WC friendly __iowriteXX_copy()") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > I have a trivial nit below, but either way this looks good to me, so > regardless of that: > > Reviewed-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Still codegens what I expect on clang-17 at least, agree with Mark's note Thanks, Jason
On Tue, 04 Jun 2024 22:59:57 +0200, Arnd Bergmann wrote: > In some configurations __const_iowrite32_copy() does not get inlined > and gcc runs into the BUILD_BUG(): > > In file included from <command-line>: > In function '__const_memcpy_toio_aligned32', > inlined from '__const_iowrite32_copy' at arch/arm64/include/asm/io.h:203:3, > inlined from '__const_iowrite32_copy' at arch/arm64/include/asm/io.h:199:20: > include/linux/compiler_types.h:487:45: error: call to '__compiletime_assert_538' declared with attribute error: BUILD_BUG failed > 487 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^ > include/linux/compiler_types.h:468:25: note: in definition of macro '__compiletime_assert' > 468 | prefix ## suffix(); \ > | ^~~~~~ > include/linux/compiler_types.h:487:9: note: in expansion of macro '_compiletime_assert' > 487 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) > | ^~~~~~~~~~~~~~~~~~~ > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > | ^~~~~~~~~~~~~~~~~~ > include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG' > 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") > | ^~~~~~~~~~~~~~~~ > arch/arm64/include/asm/io.h:193:17: note: in expansion of macro 'BUILD_BUG' > 193 | BUILD_BUG(); > | ^~~~~~~~~ > > [...] Applied to arm64 (for-next/fixes), thanks! [1/1] arm64/io: add constant-argument check https://git.kernel.org/arm64/c/5c40e428aea6 Cheers,
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 4ff0ae3f6d66..bc239371323a 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -153,8 +153,9 @@ extern void __memset_io(volatile void __iomem *, int, size_t); * emit the large TLP from the CPU. */ -static inline void __const_memcpy_toio_aligned32(volatile u32 __iomem *to, - const u32 *from, size_t count) +static __always_inline void +__const_memcpy_toio_aligned32(volatile u32 __iomem *to, const u32 *from, + size_t count) { switch (count) { case 8: @@ -196,24 +197,22 @@ static inline void __const_memcpy_toio_aligned32(volatile u32 __iomem *to, void __iowrite32_copy_full(void __iomem *to, const void *from, size_t count); -static inline void __const_iowrite32_copy(void __iomem *to, const void *from, - size_t count) +static __always_inline void +__iowrite32_copy(void __iomem *to, const void *from, size_t count) { - if (count == 8 || count == 4 || count == 2 || count == 1) { + if (__builtin_constant_p(count) && + (count == 8 || count == 4 || count == 2 || count == 1)) { __const_memcpy_toio_aligned32(to, from, count); dgh(); } else { __iowrite32_copy_full(to, from, count); } } +#define __iowrite32_copy(to, from, count) __iowrite32_copy(to, from, count) -#define __iowrite32_copy(to, from, count) \ - (__builtin_constant_p(count) ? \ - __const_iowrite32_copy(to, from, count) : \ - __iowrite32_copy_full(to, from, count)) - -static inline void __const_memcpy_toio_aligned64(volatile u64 __iomem *to, - const u64 *from, size_t count) +static __always_inline void +__const_memcpy_toio_aligned64(volatile u64 __iomem *to, const u64 *from, + size_t count) { switch (count) { case 8: @@ -255,21 +254,18 @@ static inline void __const_memcpy_toio_aligned64(volatile u64 __iomem *to, void __iowrite64_copy_full(void __iomem *to, const void *from, size_t count); -static inline void __const_iowrite64_copy(void __iomem *to, const void *from, - size_t count) +static __always_inline void +__iowrite64_copy(void __iomem *to, const void *from, size_t count) { - if (count == 8 || count == 4 || count == 2 || count == 1) { + if (__builtin_constant_p(count) && + (count == 8 || count == 4 || count == 2 || count == 1)) { __const_memcpy_toio_aligned64(to, from, count); dgh(); } else { __iowrite64_copy_full(to, from, count); } } - -#define __iowrite64_copy(to, from, count) \ - (__builtin_constant_p(count) ? \ - __const_iowrite64_copy(to, from, count) : \ - __iowrite64_copy_full(to, from, count)) +#define __iowrite64_copy(to, from, count) __iowrite64_copy(to, from, count) /* * I/O memory mapping functions.