Re: [Qemu-devel] [PATCH v3 31/34] linux-user: remove handling of aarch64's EXCP_STREX

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

Richard Henderson <rth@twiddle.net> writes:

> From: "Emilio G. Cota" <cota@braap.org>
>
> The exception is not emitted anymore.
>
> Signed-off-by: Emilio G. Cota <cota@braap.org>
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> Message-Id: <1467054136-10430-30-git-send-email-cota@braap.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  linux-user/main.c | 125 ------------------------------------------------------
>  1 file changed, 125 deletions(-)
>
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 256382a..64838bf 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -868,124 +868,6 @@ void cpu_loop(CPUARMState *env)
>
>  #else
>
> -/*
> - * Handle AArch64 store-release exclusive
> - *
> - * rs = gets the status result of store exclusive
> - * rt = is the register that is stored
> - * rt2 = is the second register store (in STP)
> - *
> - */
> -static int do_strex_a64(CPUARMState *env)
> -{
> -    uint64_t val;
> -    int size;
> -    bool is_pair;
> -    int rc = 1;
> -    int segv = 0;
> -    uint64_t addr;
> -    int rs, rt, rt2;
> -
> -    start_exclusive();
> -    /* size | is_pair << 2 | (rs << 4) | (rt << 9) | (rt2 << 14)); */
> -    size = extract32(env->exclusive_info, 0, 2);
> -    is_pair = extract32(env->exclusive_info, 2, 1);
> -    rs = extract32(env->exclusive_info, 4, 5);
> -    rt = extract32(env->exclusive_info, 9, 5);
> -    rt2 = extract32(env->exclusive_info, 14, 5);
> -
> -    addr = env->exclusive_addr;
> -
> -    if (addr != env->exclusive_test) {
> -        goto finish;
> -    }
> -
> -    switch (size) {
> -    case 0:
> -        segv = get_user_u8(val, addr);
> -        break;
> -    case 1:
> -        segv = get_user_u16(val, addr);
> -        break;
> -    case 2:
> -        segv = get_user_u32(val, addr);
> -        break;
> -    case 3:
> -        segv = get_user_u64(val, addr);
> -        break;
> -    default:
> -        abort();
> -    }
> -    if (segv) {
> -        env->exception.vaddress = addr;
> -        goto error;
> -    }
> -    if (val != env->exclusive_val) {
> -        goto finish;
> -    }
> -    if (is_pair) {
> -        if (size == 2) {
> -            segv = get_user_u32(val, addr + 4);
> -        } else {
> -            segv = get_user_u64(val, addr + 8);
> -        }
> -        if (segv) {
> -            env->exception.vaddress = addr + (size == 2 ? 4 : 8);
> -            goto error;
> -        }
> -        if (val != env->exclusive_high) {
> -            goto finish;
> -        }
> -    }
> -    /* handle the zero register */
> -    val = rt == 31 ? 0 : env->xregs[rt];
> -    switch (size) {
> -    case 0:
> -        segv = put_user_u8(val, addr);
> -        break;
> -    case 1:
> -        segv = put_user_u16(val, addr);
> -        break;
> -    case 2:
> -        segv = put_user_u32(val, addr);
> -        break;
> -    case 3:
> -        segv = put_user_u64(val, addr);
> -        break;
> -    }
> -    if (segv) {
> -        goto error;
> -    }
> -    if (is_pair) {
> -        /* handle the zero register */
> -        val = rt2 == 31 ? 0 : env->xregs[rt2];
> -        if (size == 2) {
> -            segv = put_user_u32(val, addr + 4);
> -        } else {
> -            segv = put_user_u64(val, addr + 8);
> -        }
> -        if (segv) {
> -            env->exception.vaddress = addr + (size == 2 ? 4 : 8);
> -            goto error;
> -        }
> -    }
> -    rc = 0;
> -finish:
> -    env->pc += 4;
> -    /* rs == 31 encodes a write to the ZR, thus throwing away
> -     * the status return. This is rather silly but valid.
> -     */
> -    if (rs < 31) {
> -        env->xregs[rs] = rc;
> -    }
> -error:
> -    /* instruction faulted, PC does not advance */
> -    /* either way a strex releases any exclusive lock we have */
> -    env->exclusive_addr = -1;
> -    end_exclusive();
> -    return segv;
> -}
> -
>  /* AArch64 main loop */
>  void cpu_loop(CPUARMState *env)
>  {
> @@ -1026,11 +908,6 @@ void cpu_loop(CPUARMState *env)
>              info._sifields._sigfault._addr = env->pc;
>              queue_signal(env, info.si_signo, &info);
>              break;
> -        case EXCP_STREX:
> -            if (!do_strex_a64(env)) {
> -                break;
> -            }
> -            /* fall through for segv */
>          case EXCP_PREFETCH_ABORT:
>          case EXCP_DATA_ABORT:
>              info.si_signo = TARGET_SIGSEGV;
> @@ -1066,8 +943,6 @@ void cpu_loop(CPUARMState *env)
>          process_pending_signals(env);
>          /* Exception return on AArch64 always clears the exclusive monitor,
>           * so any return to running guest code implies this.
> -         * A strex (successful or otherwise) also clears the monitor, so
> -         * we don't need to specialcase EXCP_STREX.
>           */
>          env->exclusive_addr = -1;
>      }


--
Alex Bennée