Messages in this thread | | | From | Marco Elver <> | Date | Thu, 22 Jul 2021 09:21:04 +0200 | Subject | Re: [PATCH] locking/atomic: simplify non-atomic wrappers |
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On Wed, 21 Jul 2021 at 17:58, Mark Rutland <mark.rutland@arm.com> wrote: > > Since the non-atomic arch_*() bitops use plain accesses, they are > implicitly instrumnted by the compiler, and we work around this in the > instrumented wrappers to avoid double instrumentation. > > It's simpler to avoid the wrappers entirely, and use the preprocessor to > alias the arch_*() bitops to their regular versions, removing the need > for checks in the instrumented wrappers. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Suggested-by: Marco Elver <elver@google.com> > Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Marco Elver <elver@google.com>
Thank you!
> --- > .../asm-generic/bitops/instrumented-non-atomic.h | 21 +++++++-------------- > include/asm-generic/bitops/non-atomic.h | 16 +++++++--------- > 2 files changed, 14 insertions(+), 23 deletions(-) > > Hi Peter, > > Are you happy to take this atop your queue/locking/core branch? > > This was suggested by Marco in [1], and also sidesteps some particularly bad > stack spills as in [2]. > > [1] https://lore.kernel.org/r/CANpmjNNVn4UxBCMg1ke9xaQNv52OMuQjr17GxUXojZKwiAFzzg@mail.gmail.com > [2] https://lore.kernel.org/r/20210719100719.GB12806@C02TD0UTHF1T.local/ > > Thanks, > Mark. > > diff --git a/include/asm-generic/bitops/instrumented-non-atomic.h b/include/asm-generic/bitops/instrumented-non-atomic.h > index e6c1540965d6..37363d570b9b 100644 > --- a/include/asm-generic/bitops/instrumented-non-atomic.h > +++ b/include/asm-generic/bitops/instrumented-non-atomic.h > @@ -24,8 +24,7 @@ > */ > static inline void __set_bit(long nr, volatile unsigned long *addr) > { > - if (!__is_defined(arch___set_bit_uses_plain_access)) > - instrument_write(addr + BIT_WORD(nr), sizeof(long)); > + instrument_write(addr + BIT_WORD(nr), sizeof(long)); > arch___set_bit(nr, addr); > } > > @@ -40,8 +39,7 @@ static inline void __set_bit(long nr, volatile unsigned long *addr) > */ > static inline void __clear_bit(long nr, volatile unsigned long *addr) > { > - if (!__is_defined(arch___clear_bit_uses_plain_access)) > - instrument_write(addr + BIT_WORD(nr), sizeof(long)); > + instrument_write(addr + BIT_WORD(nr), sizeof(long)); > arch___clear_bit(nr, addr); > } > > @@ -56,8 +54,7 @@ static inline void __clear_bit(long nr, volatile unsigned long *addr) > */ > static inline void __change_bit(long nr, volatile unsigned long *addr) > { > - if (!__is_defined(arch___change_bit_uses_plain_access)) > - instrument_write(addr + BIT_WORD(nr), sizeof(long)); > + instrument_write(addr + BIT_WORD(nr), sizeof(long)); > arch___change_bit(nr, addr); > } > > @@ -95,8 +92,7 @@ static inline void __instrument_read_write_bitop(long nr, volatile unsigned long > */ > static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr) > { > - if (!__is_defined(arch___test_and_set_bit_uses_plain_access)) > - __instrument_read_write_bitop(nr, addr); > + __instrument_read_write_bitop(nr, addr); > return arch___test_and_set_bit(nr, addr); > } > > @@ -110,8 +106,7 @@ static inline bool __test_and_set_bit(long nr, volatile unsigned long *addr) > */ > static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr) > { > - if (!__is_defined(arch___test_and_clear_bit_uses_plain_access)) > - __instrument_read_write_bitop(nr, addr); > + __instrument_read_write_bitop(nr, addr); > return arch___test_and_clear_bit(nr, addr); > } > > @@ -125,8 +120,7 @@ static inline bool __test_and_clear_bit(long nr, volatile unsigned long *addr) > */ > static inline bool __test_and_change_bit(long nr, volatile unsigned long *addr) > { > - if (!__is_defined(arch___test_and_change_bit_uses_plain_access)) > - __instrument_read_write_bitop(nr, addr); > + __instrument_read_write_bitop(nr, addr); > return arch___test_and_change_bit(nr, addr); > } > > @@ -137,8 +131,7 @@ static inline bool __test_and_change_bit(long nr, volatile unsigned long *addr) > */ > static inline bool test_bit(long nr, const volatile unsigned long *addr) > { > - if (!__is_defined(arch_test_bit_uses_plain_access)) > - instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long)); > + instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long)); > return arch_test_bit(nr, addr); > } > > diff --git a/include/asm-generic/bitops/non-atomic.h b/include/asm-generic/bitops/non-atomic.h > index c8149cd52730..365377fb104b 100644 > --- a/include/asm-generic/bitops/non-atomic.h > +++ b/include/asm-generic/bitops/non-atomic.h > @@ -21,7 +21,7 @@ arch___set_bit(int nr, volatile unsigned long *addr) > > *p |= mask; > } > -#define arch___set_bit_uses_plain_access > +#define __set_bit arch___set_bit > > static __always_inline void > arch___clear_bit(int nr, volatile unsigned long *addr) > @@ -31,7 +31,7 @@ arch___clear_bit(int nr, volatile unsigned long *addr) > > *p &= ~mask; > } > -#define arch___clear_bit_uses_plain_access > +#define __clear_bit arch___clear_bit > > /** > * arch___change_bit - Toggle a bit in memory > @@ -50,7 +50,7 @@ void arch___change_bit(int nr, volatile unsigned long *addr) > > *p ^= mask; > } > -#define arch___change_bit_uses_plain_access > +#define __change_bit arch___change_bit > > /** > * arch___test_and_set_bit - Set a bit and return its old value > @@ -71,7 +71,7 @@ arch___test_and_set_bit(int nr, volatile unsigned long *addr) > *p = old | mask; > return (old & mask) != 0; > } > -#define arch___test_and_set_bit_uses_plain_access > +#define __test_and_set_bit arch___test_and_set_bit > > /** > * arch___test_and_clear_bit - Clear a bit and return its old value > @@ -92,7 +92,7 @@ arch___test_and_clear_bit(int nr, volatile unsigned long *addr) > *p = old & ~mask; > return (old & mask) != 0; > } > -#define arch___test_and_clear_bit_uses_plain_access > +#define __test_and_clear_bit arch___test_and_clear_bit > > /* WARNING: non atomic and it can be reordered! */ > static __always_inline int > @@ -105,7 +105,7 @@ arch___test_and_change_bit(int nr, volatile unsigned long *addr) > *p = old ^ mask; > return (old & mask) != 0; > } > -#define arch___test_and_change_bit_uses_plain_access > +#define __test_and_change_bit arch___test_and_change_bit > > /** > * arch_test_bit - Determine whether a bit is set > @@ -117,8 +117,6 @@ arch_test_bit(int nr, const volatile unsigned long *addr) > { > return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); > } > -#define arch_test_bit_uses_plain_access > - > -#include <asm-generic/bitops/instrumented-non-atomic.h> > +#define test_bit arch_test_bit > > #endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */ > -- > 2.11.0 >
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