Re: [Qemu-devel] [RFC 01/10] target-arm: protect cpu_exclusive_*.

["Alex Bennée" <alex.bennee@linaro.org>]

fred.konrad@greensocs.com writes:

> From: KONRAD Frederic <fred.konrad@greensocs.com>
>
> This adds a lock to avoid multiple exclusive access at the same time in case of
> TCG multithread.
>
> Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
>
> V1 -> V2:
>   Removed qemu_mutex_destroy().
> ---
>  target-arm/cpu.c       | 14 ++++++++++++++
>  target-arm/cpu.h       |  3 +++
>  target-arm/helper.h    |  3 +++
>  target-arm/op_helper.c | 10 ++++++++++
>  target-arm/translate.c |  6 ++++++
>  5 files changed, 36 insertions(+)
>
<snip>
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index bdfcdf1..513d151 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -7381,6 +7381,7 @@ static void gen_load_exclusive(DisasContext *s, int rt, int rt2,
>          abort();
>      }
>  
> +    gen_helper_exclusive_lock();
>      if (size == 3) {
>          TCGv_i32 tmp2 = tcg_temp_new_i32();
>          TCGv_i32 tmp3 = tcg_temp_new_i32();
> @@ -7396,11 +7397,14 @@ static void gen_load_exclusive(DisasContext *s, int rt, int rt2,
>  
>      store_reg(s, rt, tmp);
>      tcg_gen_extu_i32_i64(cpu_exclusive_addr, addr);
> +    gen_helper_exclusive_unlock();
>  }
>  
>  static void gen_clrex(DisasContext *s)
>  {
> +    gen_helper_exclusive_lock();
>      tcg_gen_movi_i64(cpu_exclusive_addr, -1);
> +    gen_helper_exclusive_unlock();
>  }
>  
>  #ifdef CONFIG_USER_ONLY
> @@ -7431,6 +7435,7 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
>      done_label = gen_new_label();
>      extaddr = tcg_temp_new_i64();
>      tcg_gen_extu_i32_i64(extaddr, addr);
> +    gen_helper_exclusive_lock();
>      tcg_gen_brcond_i64(TCG_COND_NE, extaddr, cpu_exclusive_addr, fail_label);
>      tcg_temp_free_i64(extaddr);
>  
> @@ -7495,6 +7500,7 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
>      tcg_gen_movi_i32(cpu_R[rd], 1);
>      gen_set_label(done_label);
>      tcg_gen_movi_i64(cpu_exclusive_addr, -1);
> +    gen_helper_exclusive_unlock();
>  }
>  #endif

As the aarch64 code shares a lot of helper code with arm it is probably
worth adding the locks to both translate and translate-a64.c.

-- 
Alex Bennée