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SubjectRe: [PATCH v2 11/23] x86,xen: Remove .fixup usage
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On 10.11.21 11:01, Peter Zijlstra wrote:
> Employ the fancy new EX_TYPE_IMM_REG to store -EFAULT in the return
> register and use this to remove some Xen .fixup usage.
>
> All callers of these functions only test for 0 return, so the actual
> return value change from -1 to -EFAULT is immaterial.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/x86/include/asm/xen/page.h | 14 +++-----------
> 1 file changed, 3 insertions(+), 11 deletions(-)
>
> --- a/arch/x86/include/asm/xen/page.h
> +++ b/arch/x86/include/asm/xen/page.h
> @@ -96,11 +96,7 @@ static inline int xen_safe_write_ulong(u
>
> asm volatile("1: mov %[val], %[ptr]\n"
> "2:\n"
> - ".section .fixup, \"ax\"\n"
> - "3: sub $1, %[ret]\n"
> - " jmp 2b\n"
> - ".previous\n"
> - _ASM_EXTABLE(1b, 3b)
> + _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %[ret])
> : [ret] "+r" (ret), [ptr] "=m" (*addr)
> : [val] "r" (val));
>
> @@ -110,16 +106,12 @@ static inline int xen_safe_write_ulong(u
> static inline int xen_safe_read_ulong(const unsigned long *addr,
> unsigned long *val)
> {
> - int ret = 0;
> unsigned long rval = ~0ul;
> + int ret = 0;

Spurious change.

>
> asm volatile("1: mov %[ptr], %[rval]\n"
> "2:\n"
> - ".section .fixup, \"ax\"\n"
> - "3: sub $1, %[ret]\n"
> - " jmp 2b\n"
> - ".previous\n"
> - _ASM_EXTABLE(1b, 3b)
> + _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAUL_REG, %[ret])

I guess you didn't compile that? There is a typo: s/EFAUL/EFAULT/

> : [ret] "+r" (ret), [rval] "+r" (rval)
> : [ptr] "m" (*addr));
> *val = rval;
>
>


Juergen
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