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Date: Tue, 4 Jun 2024 22:59:57 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Nathan Chancellor <nathan@...nel.org>,
Jason Gunthorpe <jgg@...pe.ca>
Cc: Arnd Bergmann <arnd@...db.de>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Bill Wendling <morbo@...gle.com>,
Justin Stitt <justinstitt@...gle.com>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
Baoquan He <bhe@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Mark Rutland <mark.rutland@....com>,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
llvm@...ts.linux.dev
Subject: [PATCH] [v3] arm64/io: add constant-argument check
From: Arnd Bergmann <arnd@...db.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@...db.de>
---
v3:
- also mark functions as __always_inline
v2:
- fix both 32-bit and 64-bit copies
- remove now-redundant macros
---
arch/arm64/include/asm/io.h | 36 ++++++++++++++++--------------------
1 file changed, 16 insertions(+), 20 deletions(-)
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.
--
2.39.2
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