Re: [Qemu-devel] [PATCH 10/11] tcg/mips: Make direct jump patching thread-safe

[Paolo Bonzini]

On 07/04/2016 17:53, Sergey Fedorov wrote:
> Ensure direct jump patching in MIPS is atomic by using
> atomic_read()/atomic_set() for code patching.
> 
> Signed-off-by: Sergey Fedorov <address@hidden>
> Signed-off-by: Sergey Fedorov <address@hidden>
> ---
>  tcg/mips/tcg-target.inc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tcg/mips/tcg-target.inc.c b/tcg/mips/tcg-target.inc.c
> index 682e19897db0..e65835d2096b 100644
> --- a/tcg/mips/tcg-target.inc.c
> +++ b/tcg/mips/tcg-target.inc.c
> @@ -1886,6 +1886,7 @@ static void tcg_target_init(TCGContext *s)
>  void tb_set_jmp_target1(uintptr_t jmp_addr, uintptr_t addr)
>  {
>      uint32_t *ptr = (uint32_t *)jmp_addr;
> -    *ptr = deposit32(*ptr, 0, 26, addr >> 2);
> +    uint32_t insn = atomic_read(ptr);
> +    atomic_write(ptr, deposit32(insn, 0, 26, addr >> 2));

Oops. :)

Paolo

>      flush_icache_range(jmp_addr, jmp_addr + 4);
>  }