On 07/04/16 18:53, Sergey Fedorov wrote:
> From: Sergey Fedorov <serge.f...@gmail.com>
>
> Ensure direct jump patching in AArch64 is atomic by using
> atomic_read()/atomic_set() for code patching.
>
> Signed-off-by: Sergey Fedorov <serge.f...@gmail.com>
> Signed-off-by: Sergey Fedorov <sergey.fedo...@linaro.org>
> ---
> tcg/aarch64/tcg-target.inc.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/tcg/aarch64/tcg-target.inc.c b/tcg/aarch64/tcg-target.inc.c
> index 0ed10a974121..15fdebec921f 100644
> --- a/tcg/aarch64/tcg-target.inc.c
> +++ b/tcg/aarch64/tcg-target.inc.c
> @@ -73,6 +73,18 @@ static inline void reloc_pc26(tcg_insn_unit *code_ptr,
> tcg_insn_unit *target)
> *code_ptr = deposit32(*code_ptr, 0, 26, offset);
> }
>
> +static inline void reloc_pc26_atomic(tcg_insn_unit *code_ptr,
> + tcg_insn_unit *target)
> +{
> + ptrdiff_t offset = target - code_ptr;
> + tcg_insn_unit insn;
> + assert(offset == sextract64(offset, 0, 26));
I'd better use tcg_debug_assert() here as in this patch:
http://patchwork.ozlabs.org/patch/613020/
Kind regards,
Sergey
> + /* read instruction, mask away previous PC_REL26 parameter contents,
> + set the proper offset, then write back the instruction. */
> + insn = atomic_read(code_ptr);
> + atomic_set(code_ptr, deposit32(insn, 0, 26, offset));
> +}
> +
> static inline void reloc_pc19(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
> {
> ptrdiff_t offset = target - code_ptr;
> @@ -835,7 +847,7 @@ void aarch64_tb_set_jmp_target(uintptr_t jmp_addr,
> uintptr_t addr)
> tcg_insn_unit *code_ptr = (tcg_insn_unit *)jmp_addr;
> tcg_insn_unit *target = (tcg_insn_unit *)addr;
>
> - reloc_pc26(code_ptr, target);
> + reloc_pc26_atomic(code_ptr, target);
> flush_icache_range(jmp_addr, jmp_addr + 4);
> }
>
