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    SubjectRe: [PATCH v4 1/5] x86/asm: move the raw asm in iosubmit_cmds512() to special_insns.h
    > Subject: Re: [PATCH v4 1/5] x86/asm: move the raw asm in iosubmit_cmds512() to special_insns.h

    Start patch name with a capital letter: "Move the asm definition.."

    Also, calling stuff "raw" and "core" is misleading in the kernel context
    - you wanna say simply: "Carve out a generic movdir64b() helper... "

    On Thu, Sep 17, 2020 at 02:15:16PM -0700, Dave Jiang wrote:
    > diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
    > index 59a3e13204c3..7bc8e714f37e 100644
    > --- a/arch/x86/include/asm/special_insns.h
    > +++ b/arch/x86/include/asm/special_insns.h
    > @@ -234,6 +234,23 @@ static inline void clwb(volatile void *__p)
    >
    > #define nop() asm volatile ("nop")
    >
    > +static inline void movdir64b(void *__dst, const void *src)

    Make __dst be the function local variable name and keep "dst", i.e.,
    without the underscores, the function parameter name.

    > + /*
    > + * Note that this isn't an "on-stack copy", just definition of "dst"
    > + * as a pointer to 64-bytes of stuff that is going to be overwritten.
    > + * In the MOVDIR64B case that may be needed as you can use the
    > + * MOVDIR64B instruction to copy arbitrary memory around. This trick
    > + * lets the compiler know how much gets clobbered.
    > + */
    > + volatile struct { char _[64]; } *dst = __dst;
    > +
    > + /* MOVDIR64B [rdx], rax */
    > + asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
    > + : "=m" (dst)
    > + : "d" (src), "a" (dst));
    > +}
    > +
    > #endif /* __KERNEL__ */
    >
    > #endif /* _ASM_X86_SPECIAL_INSNS_H */
    >

    --
    Regards/Gruss,
    Boris.

    https://people.kernel.org/tglx/notes-about-netiquette

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