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    Subject[PATCH v8 1/3] x86/asm: Add suffix macro for GEN_*_RMWcc()
    Date
    The coming x86 refcount protection needs to be able to add trailing
    instructions to the GEN_*_RMWcc() operations. This extracts the
    difference between the goto/non-goto cases so the helper macros
    can be defined outside the #ifdef cases. Additionally adds argument
    naming to the resulting asm for referencing from suffixed
    instructions, and adds clobbers for "cc", and "cx" to let suffixes
    use _ASM_CX, and retain any set flags.

    Signed-off-by: Kees Cook <keescook@chromium.org>
    ---
    arch/x86/include/asm/rmwcc.h | 37 ++++++++++++++++++++++++-------------
    1 file changed, 24 insertions(+), 13 deletions(-)

    diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
    index 661dd305694a..045f99211a99 100644
    --- a/arch/x86/include/asm/rmwcc.h
    +++ b/arch/x86/include/asm/rmwcc.h
    @@ -1,45 +1,56 @@
    #ifndef _ASM_X86_RMWcc
    #define _ASM_X86_RMWcc

    +#define __CLOBBERS_MEM "memory"
    +#define __CLOBBERS_MEM_CC_CX "memory", "cc", "cx"
    +
    #if !defined(__GCC_ASM_FLAG_OUTPUTS__) && defined(CC_HAVE_ASM_GOTO)

    /* Use asm goto */

    -#define __GEN_RMWcc(fullop, var, cc, ...) \
    +#define __GEN_RMWcc(fullop, var, cc, clobbers, ...) \
    do { \
    asm_volatile_goto (fullop "; j" #cc " %l[cc_label]" \
    - : : "m" (var), ## __VA_ARGS__ \
    - : "memory" : cc_label); \
    + : : [counter] "m" (var), ## __VA_ARGS__ \
    + : clobbers : cc_label); \
    return 0; \
    cc_label: \
    return 1; \
    } while (0)

    -#define GEN_UNARY_RMWcc(op, var, arg0, cc) \
    - __GEN_RMWcc(op " " arg0, var, cc)
    +#define __BINARY_RMWcc_ARG " %1, "

    -#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc) \
    - __GEN_RMWcc(op " %1, " arg0, var, cc, vcon (val))

    #else /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */

    /* Use flags output or a set instruction */

    -#define __GEN_RMWcc(fullop, var, cc, ...) \
    +#define __GEN_RMWcc(fullop, var, cc, clobbers, ...) \
    do { \
    bool c; \
    asm volatile (fullop ";" CC_SET(cc) \
    - : "+m" (var), CC_OUT(cc) (c) \
    - : __VA_ARGS__ : "memory"); \
    + : [counter] "+m" (var), CC_OUT(cc) (c) \
    + : __VA_ARGS__ : clobbers); \
    return c; \
    } while (0)

    +#define __BINARY_RMWcc_ARG " %2, "
    +
    +#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
    +
    #define GEN_UNARY_RMWcc(op, var, arg0, cc) \
    - __GEN_RMWcc(op " " arg0, var, cc)
    + __GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM)
    +
    +#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc) \
    + __GEN_RMWcc(op " " arg0 "\n\t" suffix, var, cc, \
    + __CLOBBERS_MEM_CC_CX)

    #define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc) \
    - __GEN_RMWcc(op " %2, " arg0, var, cc, vcon (val))
    + __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0, var, cc, \
    + __CLOBBERS_MEM, vcon (val))

    -#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
    +#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc) \
    + __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0 "\n\t" suffix, var, cc, \
    + __CLOBBERS_MEM_CC_CX, vcon (val))

    #endif /* _ASM_X86_RMWcc */
    --
    2.7.4
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