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target/nios2: Split out helper for eret instruction 

The implementation of eret will become much more complex
with the introduction of shadow registers.

[rth: Split out of a larger patch for shadow register sets.
      Directly exit to the cpu loop from the helper.]

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Amir Gonnen <amir.gonnen@neuroblade.ai>
Message-Id: <20220303153906.2024748-3-amir.gonnen@neuroblade.ai>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-18-richard.henderson@linaro.org>
This commit is contained in:
Amir Gonnen 2022-04-21 08:16:48 -07:00 committed by Richard Henderson
parent 17a406eec5
commit 8d855c89d1
3 changed files with 16 additions and 4 deletions
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1
target/nios2/helper.h
View File

@ -21,6 +21,7 @@
DEF_HELPER_FLAGS_2(raise_exception, TCG_CALL_NO_WG, noreturn, env, i32)
#if !defined(CONFIG_USER_ONLY)
DEF_HELPER_3(eret, noreturn, env, i32, i32)
DEF_HELPER_2(mmu_write_tlbacc, void, env, i32)
DEF_HELPER_2(mmu_write_tlbmisc, void, env, i32)
DEF_HELPER_2(mmu_write_pteaddr, void, env, i32)

9
target/nios2/op_helper.c
View File

@ -30,3 +30,12 @@ void helper_raise_exception(CPUNios2State *env, uint32_t index)
cs->exception_index = index;
cpu_loop_exit(cs);
}
#ifndef CONFIG_USER_ONLY
void helper_eret(CPUNios2State *env, uint32_t new_status, uint32_t new_pc)
{
env->regs[CR_STATUS] = new_status;
env->pc = new_pc;
cpu_loop_exit(env_cpu(env));
}
#endif /* !CONFIG_USER_ONLY */

10
target/nios2/translate.c
View File

@ -391,10 +391,12 @@ static void eret(DisasContext *dc, uint32_t code, uint32_t flags)
return;
}
tcg_gen_mov_tl(cpu_R[CR_STATUS], cpu_R[CR_ESTATUS]);
tcg_gen_mov_tl(cpu_pc, cpu_R[R_EA]);
dc->base.is_jmp = DISAS_JUMP;
#ifdef CONFIG_USER_ONLY
g_assert_not_reached();
#else
gen_helper_eret(cpu_env, cpu_R[CR_ESTATUS], cpu_R[R_EA]);
dc->base.is_jmp = DISAS_NORETURN;
#endif
}
/* PC <- ra */