On 2015-06-17 15:42, Pavel Dovgalyuk wrote:
> This patch fixes exception handling in MIPS.
> Instructions generate several types of exceptions.
> When exception is generated, it breaks the execution of the current
> translation
> block. Implementation of the exceptions handling does not correctly
> restore icount for the instruction which caused the exception. In most cases
> icount will be decreased by the value equal to the size of TB.
> This patch passes pointer to the translation block internals to the exception
> handler. It allows correct restoring of the icount value.
>
> Signed-off-by: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
> ---
> target-mips/cpu.h | 28 +++++++
> target-mips/helper.h | 1
> target-mips/msa_helper.c | 5 +
> target-mips/op_helper.c | 183
> ++++++++++++++++++++++------------------------
> target-mips/translate.c | 46 ++++++------
> 5 files changed, 141 insertions(+), 122 deletions(-)
[ snip ]
> diff --git a/target-mips/op_helper.c b/target-mips/op_helper.c
> index 73a8e45..2815c60 100644
> --- a/target-mips/op_helper.c
> +++ b/target-mips/op_helper.c
> @@ -30,41 +30,23 @@ static inline void cpu_mips_tlb_flush (CPUMIPSState *env,
> int flush_global);
>
> /*****************************************************************************/
> /* Exceptions processing helpers */
>
> -static inline void QEMU_NORETURN do_raise_exception_err(CPUMIPSState *env,
> - uint32_t exception,
> - int error_code,
> - uintptr_t pc)
> +void helper_raise_exception_err(CPUMIPSState *env, uint32_t exception,
> + int error_code)
> {
> - CPUState *cs = CPU(mips_env_get_cpu(env));
> -
> - if (exception < EXCP_SC) {
> - qemu_log("%s: %d %d\n", __func__, exception, error_code);
> - }
> - cs->exception_index = exception;
> - env->error_code = error_code;
> -
> - if (pc) {
> - /* now we have a real cpu fault */
> - cpu_restore_state(cs, pc);
> - }
> -
> - cpu_loop_exit(cs);
> + do_raise_exception_err(env, exception, error_code, GETPC());
> }
>
> -static inline void QEMU_NORETURN do_raise_exception(CPUMIPSState *env,
> - uint32_t exception,
> - uintptr_t pc)
> +void helper_raise_exception(CPUMIPSState *env, uint32_t exception)
> {
> - do_raise_exception_err(env, exception, 0, pc);
> + do_raise_exception(env, exception, GETPC());
> }
raise_exception is used to implement the SYSCALL instruction on MIPS.
With this change, this mean that each TB containing a syscall will have
to be translated at least twice, probably more. That's not something
acceptable performance wise.
> diff --git a/target-mips/translate.c b/target-mips/translate.c
> index fd063a2..0de9244 100644
> --- a/target-mips/translate.c
> +++ b/target-mips/translate.c
> @@ -1673,7 +1673,7 @@ generate_exception_err (DisasContext *ctx, int excp,
> int err)
> {
> TCGv_i32 texcp = tcg_const_i32(excp);
> TCGv_i32 terr = tcg_const_i32(err);
> - save_cpu_state(ctx, 1);
> + save_cpu_state(ctx, 0);
If retranslation is used, you don't even need to save the branch status,
restore_state_to_opc can restore it.
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net
