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target/nios2: Update helper_eret for shadow registers

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When CRS = 0, we restore from estatus; otherwise from sstatus.
Update for the new CRS.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-56-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-04-21 08:17:26 -07:00
parent 3a03087019
commit 6bcc59cafa
3 changed files with 16 additions and 8 deletions
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1
target/nios2/cpu.h
View File

@ -82,6 +82,7 @@ enum {
R_FP = 28,
R_EA = 29,
R_BA = 30,
R_SSTATUS = 30,
R_RA = 31,
};

10
target/nios2/op_helper.c
View File

@ -73,14 +73,18 @@ void helper_eret(CPUNios2State *env, uint32_t new_status, uint32_t new_pc)
}
/*
* Both estatus and bstatus have no constraints on write;
* None of estatus, bstatus, or sstatus have constraints on write;
* do not allow reserved fields in status to be set.
* TODO: more than this is required for shadow registers.
* When shadow registers are enabled, eret *does* restore CRS.
* Rather than testing eic_present to decide, mask CRS out of
* the set of readonly fields.
*/
new_status &= cpu->cr_state[CR_STATUS].writable;
new_status &= cpu->cr_state[CR_STATUS].writable |
(cpu->cr_state[CR_STATUS].readonly & R_CR_STATUS_CRS_MASK);
env->ctrl[CR_STATUS] = new_status;
env->pc = new_pc;
nios2_update_crs(env);
cpu_loop_exit(cs);
}

13
target/nios2/translate.c
View File

@ -496,11 +496,14 @@ static void eret(DisasContext *dc, uint32_t code, uint32_t flags)
#ifdef CONFIG_USER_ONLY
g_assert_not_reached();
#else
TCGv tmp = tcg_temp_new();
tcg_gen_ld_tl(tmp, cpu_env, offsetof(CPUNios2State, ctrl[CR_ESTATUS]));
gen_helper_eret(cpu_env, tmp, load_gpr(dc, R_EA));
tcg_temp_free(tmp);
if (FIELD_EX32(dc->tb_flags, TBFLAGS, CRS0)) {
TCGv tmp = tcg_temp_new();
tcg_gen_ld_tl(tmp, cpu_env, offsetof(CPUNios2State, ctrl[CR_ESTATUS]));
gen_helper_eret(cpu_env, tmp, load_gpr(dc, R_EA));
tcg_temp_free(tmp);
} else {
gen_helper_eret(cpu_env, load_gpr(dc, R_SSTATUS), load_gpr(dc, R_EA));
}
dc->base.is_jmp = DISAS_NORETURN;
#endif
}