From 71945968d8b128c955204baa33ec03bdd91bdc26 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 8 Nov 2023 14:12:15 +0800 Subject: [PATCH] LoongArch: Mark __percpu functions as always inline A recent change to the optimization pipeline in LLVM reveals some fragility around the inlining of LoongArch's __percpu functions, which manifests as a BUILD_BUG() failure: In file included from kernel/sched/build_policy.c:17: In file included from include/linux/sched/cputime.h:5: In file included from include/linux/sched/signal.h:5: In file included from include/linux/rculist.h:11: In file included from include/linux/rcupdate.h:26: In file included from include/linux/irqflags.h:18: arch/loongarch/include/asm/percpu.h:97:3: error: call to '__compiletime_assert_51' declared with 'error' attribute: BUILD_BUG failed 97 | BUILD_BUG(); | ^ include/linux/build_bug.h:59:21: note: expanded from macro 'BUILD_BUG' 59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") | ^ include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG' 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) | ^ include/linux/compiler_types.h:425:2: note: expanded from macro 'compiletime_assert' 425 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) | ^ include/linux/compiler_types.h:413:2: note: expanded from macro '_compiletime_assert' 413 | __compiletime_assert(condition, msg, prefix, suffix) | ^ include/linux/compiler_types.h:406:4: note: expanded from macro '__compiletime_assert' 406 | prefix ## suffix(); \ | ^ :86:1: note: expanded from here 86 | __compiletime_assert_51 | ^ 1 error generated. If these functions are not inlined (which the compiler is free to do even with functions marked with the standard 'inline' keyword), the BUILD_BUG() in the default case cannot be eliminated since the compiler cannot prove it is never used, resulting in a build failure due to the error attribute. Mark these functions as __always_inline to guarantee inlining so that the BUILD_BUG() only triggers when the default case genuinely cannot be eliminated due to an unexpected size. Cc: Closes: https://github.com/ClangBuiltLinux/linux/issues/1955 Fixes: 46859ac8af52 ("LoongArch: Add multi-processor (SMP) support") Link: https://github.com/llvm/llvm-project/commit/1a2e77cf9e11dbf56b5720c607313a566eebb16e Suggested-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Signed-off-by: Huacai Chen --- arch/loongarch/include/asm/percpu.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/loongarch/include/asm/percpu.h b/arch/loongarch/include/asm/percpu.h index b9f567e66016..ed5da02b1cf6 100644 --- a/arch/loongarch/include/asm/percpu.h +++ b/arch/loongarch/include/asm/percpu.h @@ -32,7 +32,7 @@ static inline void set_my_cpu_offset(unsigned long off) #define __my_cpu_offset __my_cpu_offset #define PERCPU_OP(op, asm_op, c_op) \ -static inline unsigned long __percpu_##op(void *ptr, \ +static __always_inline unsigned long __percpu_##op(void *ptr, \ unsigned long val, int size) \ { \ unsigned long ret; \ @@ -63,7 +63,7 @@ PERCPU_OP(and, and, &) PERCPU_OP(or, or, |) #undef PERCPU_OP -static inline unsigned long __percpu_read(void *ptr, int size) +static __always_inline unsigned long __percpu_read(void *ptr, int size) { unsigned long ret; @@ -100,7 +100,7 @@ static inline unsigned long __percpu_read(void *ptr, int size) return ret; } -static inline void __percpu_write(void *ptr, unsigned long val, int size) +static __always_inline void __percpu_write(void *ptr, unsigned long val, int size) { switch (size) { case 1: @@ -132,8 +132,8 @@ static inline void __percpu_write(void *ptr, unsigned long val, int size) } } -static inline unsigned long __percpu_xchg(void *ptr, unsigned long val, - int size) +static __always_inline unsigned long __percpu_xchg(void *ptr, unsigned long val, + int size) { switch (size) { case 1: