Re: [Qemu-devel] [PATCH 4/5] linux-user: Add access to TLS registers

[Laurent Desnogues <laurent.desnogues@gmail.com>]

On Tue, Jan 26, 2010 at 5:00 PM, Riku Voipio <riku.voipio@iki.fi> wrote:
> From: Riku Voipio <riku.voipio@nokia.com>
>
> If you compile applications with gcc -mtp=cp15, __thread
> access's will generate an abort. Implement accessing allowed
> cp15.c13 registers on ARMv6K+ in linux-user.
>
> Signed-off-by: Riku Voipio <riku.voipio@nokia.com>
> ---
>  target-arm/helper.c |   27 ++++++++++++++++++++++++++-
>  1 files changed, 26 insertions(+), 1 deletions(-)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index b3aec99..68578ce 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -505,13 +505,38 @@ uint32_t HELPER(get_cp)(CPUState *env, uint32_t insn)
>
>  void HELPER(set_cp15)(CPUState *env, uint32_t insn, uint32_t val)
>  {
> +    int op2;
> +
> +    op2 = (insn >> 5) & 7;
> +    /* Allow write access to CP15 User RW Thread ID Register */
> +    if (arm_feature (env, ARM_FEATURE_V6K) && ((insn >> 16) & 0xf) == 13) {
> +        switch (op2) {
> +        case 2:
> +            env->cp15.c13_tls1 = val;
> +            return;
> +        }
> +    }
>     cpu_abort(env, "cp15 insn %08x\n", insn);
>  }
>
>  uint32_t HELPER(get_cp15)(CPUState *env, uint32_t insn)
>  {
> +    int op2;
> +    /* Allow read access to CP15 User RW and RO Thread ID Registers */
> +
> +    op2 = (insn >> 5) & 7;
> +    if (arm_feature (env, ARM_FEATURE_V6K) && ((insn >> 16) & 0xf) == 13) {
> +        switch (op2) {
> +        case 2:
> +            return env->cp15.c13_tls1;
> +        case 3:
> +            return env->cp15.c13_tls2;
> +        default:
> +            goto bad_reg;
> +        }
> +    }
> +bad_reg:
>     cpu_abort(env, "cp15 insn %08x\n", insn);
> -    return 0;
>  }
>
>  /* These should probably raise undefined insn exceptions.  */

Most of the checks you do here could be done in translate.c.
Wouldn't it be better to do them there?


Laurent