On Mon, Nov 28, 2016 at 03:04:33PM +0000, Catalin Marinas wrote:
> On Thu, Nov 24, 2016 at 06:58:05PM +0900, AKASHI Takahiro wrote:
> > diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
> > index 04744dc..b5168e8 100644
> > --- a/arch/arm64/include/asm/kexec.h
> > +++ b/arch/arm64/include/asm/kexec.h
> > @@ -40,7 +40,47 @@
> > static inline void crash_setup_regs(struct pt_regs *newregs,
> > struct pt_regs *oldregs)
> > {
> > - /* Empty routine needed to avoid build errors. */
> > + if (oldregs) {
> > + memcpy(newregs, oldregs, sizeof(*newregs));
> > + } else {
> > + u64 tmp1, tmp2;
> > +
> > + __asm__ __volatile__ (
> > + "stp x0, x1, [%2, #16 * 0]\n"
> > + "stp x2, x3, [%2, #16 * 1]\n"
> > + "stp x4, x5, [%2, #16 * 2]\n"
> > + "stp x6, x7, [%2, #16 * 3]\n"
> > + "stp x8, x9, [%2, #16 * 4]\n"
> > + "stp x10, x11, [%2, #16 * 5]\n"
> > + "stp x12, x13, [%2, #16 * 6]\n"
> > + "stp x14, x15, [%2, #16 * 7]\n"
> > + "stp x16, x17, [%2, #16 * 8]\n"
> > + "stp x18, x19, [%2, #16 * 9]\n"
> > + "stp x20, x21, [%2, #16 * 10]\n"
> > + "stp x22, x23, [%2, #16 * 11]\n"
> > + "stp x24, x25, [%2, #16 * 12]\n"
> > + "stp x26, x27, [%2, #16 * 13]\n"
> > + "stp x28, x29, [%2, #16 * 14]\n"
> > + "mov %0, sp\n"
> > + "stp x30, %0, [%2, #16 * 15]\n"
> > +
> > + "/* faked current PSTATE */\n"
> > + "mrs %0, CurrentEL\n"
> > + "mrs %1, SPSEL\n"
> > + "orr %0, %0, %1\n"
> > + "mrs %1, DAIF\n"
> > + "orr %0, %0, %1\n"
> > + "mrs %1, NZCV\n"
> > + "orr %0, %0, %1\n"
> > + /* pc */
> > + "adr %1, 1f\n"
> > + "1:\n"
> > + "stp %1, %0, [%2, #16 * 16]\n"
> > + : "+r" (tmp1), "+r" (tmp2)
> > + : "r" (newregs)
> > + : "memory"
>
> tmp1 and tmp2 are not input arguments here, so you should use the "=&"
> modifier. With my compiler, I get warnings of these variables being used
> uninitialised.
Thank you for this heads-up.
(I misunderstood "+" a bit.)
With this change applied, I confirmed that kdump still works.
-Takahiro AKASHI
> --
> Catalin
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