• James Hogan's avatar
    metag: Fix __cmpxchg_u32 asm constraint for CMP · 6154c187
    James Hogan authored
    The LNKGET based atomic sequence in __cmpxchg_u32 has slightly incorrect
    constraints for the return value which under certain circumstances can
    allow an address unit register to be used as the first operand of a CMP
    instruction. This isn't a valid instruction however as the encodings
    only allow a data unit to be specified. This would result in an
    assembler error like the following:
      Error: failed to assemble instruction: "CMP A0.2,D0Ar6"
    Fix by changing the constraint from "=&da" (assigned, early clobbered,
    data or address unit register) to "=&d" (data unit register only).
    The constraint for the second operand, "bd" (an op2 register where op1
    is a data unit register and the instruction supports O2R) is already
    correct assuming the first operand is a data unit register.
    Other cases of CMP in inline asm have had their constraints checked, and
    appear to all be fine.
    Fixes: 6006c0d8 ("metag: Atomics, locks and bitops")
    Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
    Cc: linux-metag@vger.kernel.org
    Cc: <stable@vger.kernel.org> # 3.9.x-
cmpxchg_lnkget.h 1.72 KB