Le 07/08/2019 à 01:38, Daniel Axtens a écrit :
In KASAN development I noticed that the powerpc-specific bitops
were not being picked up by the KASAN test suite.

Instrumentation is done via the bitops-instrumented.h header. It
requies 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_waiter constant. This works because it's a preprocessor
macro - so it's only actually evaluated in contexts where PG_waiter
is defined. With instrumentation however, it becomes a static inline
function, and all of a sudden we need the actual value of PG_waiter.
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, but it does obscure the origin a little bit.

Cc: Nicholas Piggin <npig...@gmail.com> # clear_bit_unlock_negative_byte
Signed-off-by: Daniel Axtens <d...@axtens.net>
---
  arch/powerpc/include/asm/bitops.h | 25 ++++++++++++++-----------
  1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/include/asm/bitops.h 
b/arch/powerpc/include/asm/bitops.h
index 603aed229af7..19dc16e62e6a 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;
@@ -186,14 +186,14 @@ static __inline__ unsigned long 
clear_bit_unlock_return_word(int nr,
  }
/* 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))
+#define arch_clear_bit_unlock_is_negative_byte(nr, addr)               \
+       (clear_bit_unlock_return_word(nr, addr) & BIT_MASK(7))

Maybe add a comment reminding that 7 is PG_waiters ?

Christophe

#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 +239,9 @@ unsigned long __arch_hweight64(__u64 w);
#include <asm-generic/bitops/find.h> +/* wrappers that deal with KASAN instrumentation */
+#include <asm-generic/bitops-instrumented.h>
+
  /* Little-endian versions */
  #include <asm-generic/bitops/le.h>

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