Messages in this thread | | | Date | Mon, 25 Jun 2018 14:10:10 -0400 (EDT) | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 3/3] rseq/selftests: Add support for arm64 |
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----- On Jun 25, 2018, at 1:54 PM, Will Deacon will.deacon@arm.com wrote:
[...]
> +#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip, \ > + post_commit_offset, abort_ip) \ > + " .pushsection __rseq_table, \"aw\"\n" \ > + " .balign 32\n" \ > + __rseq_str(label) ":\n" \ > + " .long " __rseq_str(version) ", " __rseq_str(flags) "\n" \ > + " .quad " __rseq_str(start_ip) ", " \ > + __rseq_str(post_commit_offset) ", " \ > + __rseq_str(abort_ip) "\n" \ > + " .popsection\n" > + > +#define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip) \ > + __RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip, \ > + (post_commit_ip - start_ip), abort_ip) > + > +#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \ > + RSEQ_INJECT_ASM(1) \ > + " adrp " RSEQ_ASM_TMP_REG ", " __rseq_str(cs_label) "\n" \ > + " add " RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG \ > + ", :lo12:" __rseq_str(cs_label) "\n" \ > + " str " RSEQ_ASM_TMP_REG ", %[" __rseq_str(rseq_cs) "]\n" \ > + __rseq_str(label) ":\n" > + > +#define RSEQ_ASM_DEFINE_ABORT(label, abort_label) \ > + " .pushsection __rseq_failure, \"ax\"\n" \ > + " .long " __rseq_str(RSEQ_SIG) "\n" \ > + __rseq_str(label) ":\n" \ > + " b %l[" __rseq_str(abort_label) "]\n" \ > + " .popsection\n"
Thanks Will for porting rseq to arm64 !
I notice you are using the instructions
adrp add str
to implement RSEQ_ASM_STORE_RSEQ_CS(). Did you compare performance-wise with an approach using a literal pool near the instruction pointer like I did on arm32 ?
With that approach, this ends up being simply
adr str
which provides significantly better performance on my test platform over loading a pointer targeting a separate data section.
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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