From bb056c0f080a3d15c2a9ad9057a8b542d45e4ba0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 19 Nov 2022 01:34:50 +0000 Subject: [PATCH] tools: KVM: selftests: Convert clear/set_bit() to actual atomics Convert {clear,set}_bit() to atomics as KVM's ucall implementation relies on clear_bit() being atomic, they are defined in atomic.h, and the same helpers in the kernel proper are atomic. KVM's ucall infrastructure is the only user of clear_bit() in tools/, and there are no true set_bit() users. tools/testing/nvdimm/ does make heavy use of set_bit(), but that code builds into a kernel module of sorts, i.e. pulls in all of the kernel's header and so is already getting the kernel's atomic set_bit(). Signed-off-by: Sean Christopherson Message-Id: <20221119013450.2643007-10-seanjc@google.com> Signed-off-by: Paolo Bonzini --- tools/arch/x86/include/asm/atomic.h | 5 +++++ tools/include/asm-generic/atomic-gcc.h | 11 +++++++++++ tools/include/asm-generic/bitops/atomic.h | 15 ++++++--------- 3 files changed, 22 insertions(+), 9 deletions(-) diff --git a/tools/arch/x86/include/asm/atomic.h b/tools/arch/x86/include/asm/atomic.h index a42733af7d51..365cf182df12 100644 --- a/tools/arch/x86/include/asm/atomic.h +++ b/tools/arch/x86/include/asm/atomic.h @@ -76,4 +76,9 @@ static inline int test_and_set_bit(long nr, unsigned long *addr) GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(bts), *addr, "Ir", nr, "%0", "c"); } +static inline int test_and_clear_bit(long nr, unsigned long *addr) +{ + GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(btc), *addr, "Ir", nr, "%0", "c"); +} + #endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */ diff --git a/tools/include/asm-generic/atomic-gcc.h b/tools/include/asm-generic/atomic-gcc.h index 37ef522aaac4..9b3c528bab92 100644 --- a/tools/include/asm-generic/atomic-gcc.h +++ b/tools/include/asm-generic/atomic-gcc.h @@ -81,4 +81,15 @@ static inline int test_and_set_bit(long nr, unsigned long *addr) return !!(old & mask); } +static inline int test_and_clear_bit(long nr, unsigned long *addr) +{ + unsigned long mask = BIT_MASK(nr); + long old; + + addr += BIT_WORD(nr); + + old = __sync_fetch_and_and(addr, ~mask); + return !!(old & mask); +} + #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */ diff --git a/tools/include/asm-generic/bitops/atomic.h b/tools/include/asm-generic/bitops/atomic.h index f64b049d236c..ab37a221b41a 100644 --- a/tools/include/asm-generic/bitops/atomic.h +++ b/tools/include/asm-generic/bitops/atomic.h @@ -5,14 +5,11 @@ #include #include -static inline void set_bit(unsigned long nr, unsigned long *addr) -{ - addr[nr / __BITS_PER_LONG] |= 1UL << (nr % __BITS_PER_LONG); -} - -static inline void clear_bit(unsigned long nr, unsigned long *addr) -{ - addr[nr / __BITS_PER_LONG] &= ~(1UL << (nr % __BITS_PER_LONG)); -} +/* + * Just alias the test versions, all of the compiler built-in atomics "fetch", + * and optimizing compile-time constants on x86 isn't worth the complexity. + */ +#define set_bit test_and_set_bit +#define clear_bit test_and_clear_bit #endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS_ATOMIC_H_ */ -- 2.11.0