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    Subject[PATCH 5.4 76/90] parisc: add support for cmpxchg on u8 pointers
    Date
    From: Liam Beguin <liambeguin@gmail.com>

    [ Upstream commit b344d6a83d01c52fddbefa6b3b4764da5b1022a0 ]

    The kernel test bot reported[1] that using set_mask_bits on a u8 causes
    the following issue on parisc:

    hppa-linux-ld: drivers/phy/ti/phy-tusb1210.o: in function `tusb1210_probe':
    >> (.text+0x2f4): undefined reference to `__cmpxchg_called_with_bad_pointer'
    >> hppa-linux-ld: (.text+0x324): undefined reference to `__cmpxchg_called_with_bad_pointer'
    hppa-linux-ld: (.text+0x354): undefined reference to `__cmpxchg_called_with_bad_pointer'

    Add support for cmpxchg on u8 pointers.

    [1] https://lore.kernel.org/patchwork/patch/1272617/#1468946

    Reported-by: kernel test robot <lkp@intel.com>
    Signed-off-by: Liam Beguin <liambeguin@gmail.com>
    Tested-by: Dave Anglin <dave.anglin@bell.net>
    Signed-off-by: Helge Deller <deller@gmx.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/parisc/include/asm/cmpxchg.h | 2 ++
    arch/parisc/lib/bitops.c | 12 ++++++++++++
    2 files changed, 14 insertions(+)

    diff --git a/arch/parisc/include/asm/cmpxchg.h b/arch/parisc/include/asm/cmpxchg.h
    index ab5c215cf46c3..0689585758717 100644
    --- a/arch/parisc/include/asm/cmpxchg.h
    +++ b/arch/parisc/include/asm/cmpxchg.h
    @@ -60,6 +60,7 @@ extern void __cmpxchg_called_with_bad_pointer(void);
    extern unsigned long __cmpxchg_u32(volatile unsigned int *m, unsigned int old,
    unsigned int new_);
    extern u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 new_);
    +extern u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new_);

    /* don't worry...optimizer will get rid of most of this */
    static inline unsigned long
    @@ -71,6 +72,7 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
    #endif
    case 4: return __cmpxchg_u32((unsigned int *)ptr,
    (unsigned int)old, (unsigned int)new_);
    + case 1: return __cmpxchg_u8((u8 *)ptr, (u8)old, (u8)new_);
    }
    __cmpxchg_called_with_bad_pointer();
    return old;
    diff --git a/arch/parisc/lib/bitops.c b/arch/parisc/lib/bitops.c
    index 70ffbcf889b8e..2e4d1f05a9264 100644
    --- a/arch/parisc/lib/bitops.c
    +++ b/arch/parisc/lib/bitops.c
    @@ -79,3 +79,15 @@ unsigned long __cmpxchg_u32(volatile unsigned int *ptr, unsigned int old, unsign
    _atomic_spin_unlock_irqrestore(ptr, flags);
    return (unsigned long)prev;
    }
    +
    +u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new)
    +{
    + unsigned long flags;
    + u8 prev;
    +
    + _atomic_spin_lock_irqsave(ptr, flags);
    + if ((prev = *ptr) == old)
    + *ptr = new;
    + _atomic_spin_unlock_irqrestore(ptr, flags);
    + return prev;
    +}
    --
    2.25.1


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