Re: [PATCH 2/2] powerpc: support KASAN instrumentation of bitops
From: Christophe Leroy <hidden>
Date: 2019-08-19 11:39:18
Also in:
linux-arch, linux-s390
Le 19/08/2019 à 08:28, Daniel Axtens a écrit :
In KASAN development I noticed that the powerpc-specific bitops were not being picked up by the KASAN test suite.
I'm not sure anybody cares about who noticed the problem. This sentence could be rephrased as: The powerpc-specific bitops are not being picked up by the KASAN test suite.
Instrumentation is done via the bitops/instrumented-{atomic,lock}.h
headers. They require that arch-specific versions of bitop functions
are renamed to arch_*. Do this renaming.
For clear_bit_unlock_is_negative_byte, the current implementation
uses the PG_waiters constant. This works because it's a preprocessor
macro - so it's only actually evaluated in contexts where PG_waiters
is defined. With instrumentation however, it becomes a static inline
function, and all of a sudden we need the actual value of PG_waiters.
Because of the order of header includes, it's not available and we
fail to compile. Instead, manually specify that we care about bit 7.
This is still correct: bit 7 is the bit that would mark a negative
byte.
Cc: Nicholas Piggin <npiggin@gmail.com> # clear_bit_unlock_negative_byte
Signed-off-by: Daniel Axtens <redacted>Reviewed-by: Christophe Leroy <redacted> Note that this patch might be an opportunity to replace all the '__inline__' by the standard 'inline' keyword. Some () alignment to be fixes as well, see checkpatch warnings/checks at https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/8601//artifact/linux/checkpatch.log
quoted hunk ↗ jump to hunk
--- arch/powerpc/include/asm/bitops.h | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-)diff --git a/arch/powerpc/include/asm/bitops.h b/arch/powerpc/include/asm/bitops.h index 603aed229af7..8615b2bc35fe 100644 --- a/arch/powerpc/include/asm/bitops.h +++ b/arch/powerpc/include/asm/bitops.h@@ -86,22 +86,22 @@ DEFINE_BITOP(clear_bits, andc, "") DEFINE_BITOP(clear_bits_unlock, andc, PPC_RELEASE_BARRIER) DEFINE_BITOP(change_bits, xor, "") -static __inline__ void set_bit(int nr, volatile unsigned long *addr) +static __inline__ void arch_set_bit(int nr, volatile unsigned long *addr) { set_bits(BIT_MASK(nr), addr + BIT_WORD(nr)); } -static __inline__ void clear_bit(int nr, volatile unsigned long *addr) +static __inline__ void arch_clear_bit(int nr, volatile unsigned long *addr) { clear_bits(BIT_MASK(nr), addr + BIT_WORD(nr)); } -static __inline__ void clear_bit_unlock(int nr, volatile unsigned long *addr) +static __inline__ void arch_clear_bit_unlock(int nr, volatile unsigned long *addr) { clear_bits_unlock(BIT_MASK(nr), addr + BIT_WORD(nr)); } -static __inline__ void change_bit(int nr, volatile unsigned long *addr) +static __inline__ void arch_change_bit(int nr, volatile unsigned long *addr) { change_bits(BIT_MASK(nr), addr + BIT_WORD(nr)); }@@ -138,26 +138,26 @@ DEFINE_TESTOP(test_and_clear_bits, andc, PPC_ATOMIC_ENTRY_BARRIER, DEFINE_TESTOP(test_and_change_bits, xor, PPC_ATOMIC_ENTRY_BARRIER, PPC_ATOMIC_EXIT_BARRIER, 0) -static __inline__ int test_and_set_bit(unsigned long nr, +static __inline__ int arch_test_and_set_bit(unsigned long nr, volatile unsigned long *addr) { return test_and_set_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0; } -static __inline__ int test_and_set_bit_lock(unsigned long nr, +static __inline__ int arch_test_and_set_bit_lock(unsigned long nr, volatile unsigned long *addr) { return test_and_set_bits_lock(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0; } -static __inline__ int test_and_clear_bit(unsigned long nr, +static __inline__ int arch_test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) { return test_and_clear_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0; } -static __inline__ int test_and_change_bit(unsigned long nr, +static __inline__ int arch_test_and_change_bit(unsigned long nr, volatile unsigned long *addr) { return test_and_change_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0;@@ -185,15 +185,18 @@ static __inline__ unsigned long clear_bit_unlock_return_word(int nr, return old; } -/* This is a special function for mm/filemap.c */ -#define clear_bit_unlock_is_negative_byte(nr, addr) \ - (clear_bit_unlock_return_word(nr, addr) & BIT_MASK(PG_waiters)) +/* + * This is a special function for mm/filemap.c + * Bit 7 corresponds to PG_waiters. + */ +#define arch_clear_bit_unlock_is_negative_byte(nr, addr) \ + (clear_bit_unlock_return_word(nr, addr) & BIT_MASK(7)) #endif /* CONFIG_PPC64 */ #include <asm-generic/bitops/non-atomic.h> -static __inline__ void __clear_bit_unlock(int nr, volatile unsigned long *addr) +static __inline__ void arch___clear_bit_unlock(int nr, volatile unsigned long *addr) { __asm__ __volatile__(PPC_RELEASE_BARRIER "" ::: "memory"); __clear_bit(nr, addr);@@ -239,6 +242,10 @@ unsigned long __arch_hweight64(__u64 w); #include <asm-generic/bitops/find.h> +/* wrappers that deal with KASAN instrumentation */ +#include <asm-generic/bitops/instrumented-atomic.h> +#include <asm-generic/bitops/instrumented-lock.h> + /* Little-endian versions */ #include <asm-generic/bitops/le.h>