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target/arm: only update pc after semihosting completes

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Before we introduce blocking semihosting calls we need to ensure we
can restart the system on semi hosting exception. To be able to do
this the EXCP_SEMIHOST operation should be idempotent until it finally
completes. Practically this means ensureing we only update the pc
after the semihosting call has completed.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Tested-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Alex Bennée 2019-12-17 15:08:57 +00:00
parent b906acbb3a
commit 4ff5ef9e91
6 changed files with 9 additions and 4 deletions
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1
linux-user/aarch64/cpu_loop.c
View File

@ -130,6 +130,7 @@ void cpu_loop(CPUARMState *env)
break;
case EXCP_SEMIHOST:
env->xregs[0] = do_arm_semihosting(env);
env->pc += 4;
break;
case EXCP_YIELD:
/* nothing to do here for user-mode, just resume guest code */

1
linux-user/arm/cpu_loop.c
View File

@ -377,6 +377,7 @@ void cpu_loop(CPUARMState *env)
break;
case EXCP_SEMIHOST:
env->regs[0] = do_arm_semihosting(env);
env->regs[15] += env->thumb ? 2 : 4;
break;
case EXCP_INTERRUPT:
/* just indicate that signals should be handled asap */

2
target/arm/helper.c
View File

@ -8614,11 +8614,13 @@ static void handle_semihosting(CPUState *cs)
"...handling as semihosting call 0x%" PRIx64 "\n",
env->xregs[0]);
env->xregs[0] = do_arm_semihosting(env);
env->pc += 4;
} else {
qemu_log_mask(CPU_LOG_INT,
"...handling as semihosting call 0x%x\n",
env->regs[0]);
env->regs[0] = do_arm_semihosting(env);
env->regs[15] += env->thumb ? 2 : 4;
}
}
#endif

1
target/arm/m_helper.c
View File

@ -2185,6 +2185,7 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
"...handling as semihosting call 0x%x\n",
env->regs[0]);
env->regs[0] = do_arm_semihosting(env);
env->regs[15] += env->thumb ? 2 : 4;
return;
case EXCP_BKPT:
armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_DEBUG, false);

2
target/arm/translate-a64.c
View File

@ -1937,7 +1937,7 @@ static void disas_exc(DisasContext *s, uint32_t insn)
break;
}
#endif
gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
gen_exception_internal_insn(s, s->pc_curr, EXCP_SEMIHOST);
} else {
unsupported_encoding(s, insn);
}

6
target/arm/translate.c
View File

@ -1124,7 +1124,7 @@ static inline void gen_hlt(DisasContext *s, int imm)
s->current_el != 0 &&
#endif
(imm == (s->thumb ? 0x3c : 0xf000))) {
gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
gen_exception_internal_insn(s, s->pc_curr, EXCP_SEMIHOST);
return;
}
@ -8457,7 +8457,7 @@ static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
!IS_USER(s) &&
#endif
(a->imm == 0xab)) {
gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
gen_exception_internal_insn(s, s->pc_curr, EXCP_SEMIHOST);
} else {
gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
}
@ -10266,7 +10266,7 @@ static bool trans_SVC(DisasContext *s, arg_SVC *a)
!IS_USER(s) &&
#endif
(a->imm == semihost_imm)) {
gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
gen_exception_internal_insn(s, s->pc_curr, EXCP_SEMIHOST);
} else {
gen_set_pc_im(s, s->base.pc_next);
s->svc_imm = a->imm;