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SubjectRe: [PATCH v8 2/3] rseq/selftests: add rseq_offset_deref_addv
----- On Sep 23, 2020, at 7:36 PM, Peter Oskolkov posk@google.com wrote:

The patch title should state that it only adds rseq_offset_deref_addv
to x86-64. Considering that other architecture maintainers will look
at it as inspiration for other architectures, we should also state in
the commit message that architectures implementing it should define
"RSEQ_ARCH_HAS_OFFSET_DEREF_ADDV".

Thanks,

Mathieu

> This patch adds rseq_offset_deref_addv function to
> tools/testing/selftests/rseq/rseq-x86.h, to be used
> in a selftest in the next patch in the patchset.
>
> v7->v8: this patch split out of the v7 selftest patch.
>
> Signed-off-by: Peter Oskolkov <posk@google.com>
> ---
> tools/testing/selftests/rseq/rseq-x86.h | 57 +++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/tools/testing/selftests/rseq/rseq-x86.h
> b/tools/testing/selftests/rseq/rseq-x86.h
> index b2da6004fe30..640411518e46 100644
> --- a/tools/testing/selftests/rseq/rseq-x86.h
> +++ b/tools/testing/selftests/rseq/rseq-x86.h
> @@ -279,6 +279,63 @@ int rseq_addv(intptr_t *v, intptr_t count, int cpu)
> #endif
> }
>
> +#define RSEQ_ARCH_HAS_OFFSET_DEREF_ADDV
> +
> +/*
> + * pval = *(ptr+off)
> + * *pval += inc;
> + */
> +static inline __attribute__((always_inline))
> +int rseq_offset_deref_addv(intptr_t *ptr, off_t off, intptr_t inc, int cpu)
> +{
> + RSEQ_INJECT_C(9)
> +
> + __asm__ __volatile__ goto (
> + RSEQ_ASM_DEFINE_TABLE(3, 1f, 2f, 4f) /* start, commit, abort */
> +#ifdef RSEQ_COMPARE_TWICE
> + RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error1])
> +#endif
> + /* Start rseq by storing table entry pointer into rseq_cs. */
> + RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
> + RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
> + RSEQ_INJECT_ASM(3)
> +#ifdef RSEQ_COMPARE_TWICE
> + RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
> +#endif
> + /* get p+v */
> + "movq %[ptr], %%rbx\n\t"
> + "addq %[off], %%rbx\n\t"
> + /* get pv */
> + "movq (%%rbx), %%rcx\n\t"
> + /* *pv += inc */
> + "addq %[inc], (%%rcx)\n\t"
> + "2:\n\t"
> + RSEQ_INJECT_ASM(4)
> + RSEQ_ASM_DEFINE_ABORT(4, "", abort)
> + : /* gcc asm goto does not allow outputs */
> + : [cpu_id] "r" (cpu),
> + [rseq_abi] "r" (&__rseq_abi),
> + /* final store input */
> + [ptr] "m" (*ptr),
> + [off] "er" (off),
> + [inc] "er" (inc)
> + : "memory", "cc", "rax", "rbx", "rcx"
> + RSEQ_INJECT_CLOBBER
> + : abort
> +#ifdef RSEQ_COMPARE_TWICE
> + , error1
> +#endif
> + );
> + return 0;
> +abort:
> + RSEQ_INJECT_FAILED
> + return -1;
> +#ifdef RSEQ_COMPARE_TWICE
> +error1:
> + rseq_bug("cpu_id comparison failed");
> +#endif
> +}
> +
> static inline __attribute__((always_inline))
> int rseq_cmpeqv_trystorev_storev(intptr_t *v, intptr_t expect,
> intptr_t *v2, intptr_t newv2,
> --
> 2.28.0.709.gb0816b6eb0-goog

--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

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