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target/nios2: Advance pc when raising exceptions 

The exception return address for nios2 is the instruction
after the one that was executing at the time of the exception.

We have so far implemented this by advancing the pc during the
process of raising the exception.  It is perhaps a little less
confusing to do this advance in the translator (and helpers)
when raising the exception in the first place, so that we may
more closely match kernel sources.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220421151735.31996-58-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-04-21 08:17:28 -07:00
parent a25c4eff32
commit e84f176844
5 changed files with 30 additions and 17 deletions
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8
linux-user/nios2/cpu_loop.c
View File

@ -39,6 +39,8 @@ void cpu_loop(CPUNios2State *env)
break;
case EXCP_DIV:
/* Match kernel's handle_diverror_c(). */
env->pc -= 4;
force_sig_fault(TARGET_SIGFPE, TARGET_FPE_INTDIV, env->pc);
break;
@ -49,12 +51,6 @@ void cpu_loop(CPUNios2State *env)
break;
case EXCP_TRAP:
/*
* TODO: This advance should be done in the translator, as
* hardware produces an advanced pc as part of all exceptions.
*/
env->pc += 4;
switch (env->error_code) {
case 0:
qemu_log_mask(CPU_LOG_INT, "\nSyscall\n");

2
target/nios2/cpu.h
View File

@ -266,6 +266,8 @@ hwaddr nios2_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
G_NORETURN void nios2_cpu_do_unaligned_access(CPUState *cpu, vaddr addr,
MMUAccessType access_type, int mmu_idx,
uintptr_t retaddr);
G_NORETURN void nios2_cpu_loop_exit_advance(CPUNios2State *env,
uintptr_t retaddr);
void do_nios2_semihosting(CPUNios2State *env);

13
target/nios2/helper.c
View File

@ -49,7 +49,7 @@ static void do_exception(Nios2CPU *cpu, uint32_t exception_addr,
cr_es = CR_BSTATUS;
}
env->ctrl[cr_es] = old_status;
env->regs[r_ea] = env->pc + 4;
env->regs[r_ea] = env->pc;
if (cpu->mmu_present) {
new_status |= CR_STATUS_EH;
@ -113,7 +113,7 @@ static void do_eic_irq(Nios2CPU *cpu)
}
env->shadow_regs[new_rs][R_SSTATUS] = old_status;
}
env->shadow_regs[new_rs][R_EA] = env->pc + 4;
env->shadow_regs[new_rs][R_EA] = env->pc;
}
env->ctrl[CR_STATUS] = new_status;
@ -187,6 +187,8 @@ void nios2_cpu_do_interrupt(CPUState *cs)
switch (cs->exception_index) {
case EXCP_IRQ:
/* Note that PC is advanced for interrupts as well. */
env->pc += 4;
if (cpu->eic_present) {
do_eic_irq(cpu);
} else {
@ -249,7 +251,6 @@ void nios2_cpu_do_interrupt(CPUState *cs)
break;
case EXCP_SEMIHOST:
env->pc += 4;
do_nios2_semihosting(env);
break;
@ -291,7 +292,7 @@ void nios2_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
env->ctrl[CR_BADADDR] = addr;
cs->exception_index = EXCP_UNALIGN;
cpu_loop_exit_restore(cs, retaddr);
nios2_cpu_loop_exit_advance(env, retaddr);
}
bool nios2_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
@ -330,7 +331,7 @@ bool nios2_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
cs->exception_index = (access_type == MMU_INST_FETCH
? EXCP_SUPERA_X : EXCP_SUPERA_D);
env->ctrl[CR_BADADDR] = address;
cpu_loop_exit_restore(cs, retaddr);
nios2_cpu_loop_exit_advance(env, retaddr);
}
}
@ -367,5 +368,5 @@ bool nios2_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
cs->exception_index = excp;
env->ctrl[CR_BADADDR] = address;
cpu_loop_exit_restore(cs, retaddr);
nios2_cpu_loop_exit_advance(env, retaddr);
}

18
target/nios2/op_helper.c
View File

@ -31,6 +31,20 @@ void helper_raise_exception(CPUNios2State *env, uint32_t index)
cpu_loop_exit(cs);
}
void nios2_cpu_loop_exit_advance(CPUNios2State *env, uintptr_t retaddr)
{
CPUState *cs = env_cpu(env);
/*
* Note that PC is advanced for all hardware exceptions.
* Do this here, rather than in restore_state_to_opc(),
* lest we affect QEMU internal exceptions, like EXCP_DEBUG.
*/
cpu_restore_state(cs, retaddr, true);
env->pc += 4;
cpu_loop_exit(cs);
}
static void maybe_raise_div(CPUNios2State *env, uintptr_t ra)
{
Nios2CPU *cpu = env_archcpu(env);
@ -38,7 +52,7 @@ static void maybe_raise_div(CPUNios2State *env, uintptr_t ra)
if (cpu->diverr_present) {
cs->exception_index = EXCP_DIV;
cpu_loop_exit_restore(cs, ra);
nios2_cpu_loop_exit_advance(env, ra);
}
}
@ -69,7 +83,7 @@ void helper_eret(CPUNios2State *env, uint32_t new_status, uint32_t new_pc)
if (unlikely(new_pc & 3)) {
env->ctrl[CR_BADADDR] = new_pc;
cs->exception_index = EXCP_UNALIGND;
cpu_loop_exit_restore(cs, GETPC());
nios2_cpu_loop_exit_advance(env, GETPC());
}
/*

6
target/nios2/translate.c
View File

@ -202,10 +202,10 @@ static TCGv dest_gpr(DisasContext *dc, unsigned reg)
#endif
}
static void t_gen_helper_raise_exception(DisasContext *dc,
uint32_t index)
static void t_gen_helper_raise_exception(DisasContext *dc, uint32_t index)
{
tcg_gen_movi_tl(cpu_pc, dc->pc);
/* Note that PC is advanced for all hardware exceptions. */
tcg_gen_movi_tl(cpu_pc, dc->base.pc_next);
gen_helper_raise_exception(cpu_env, tcg_constant_i32(index));
dc->base.is_jmp = DISAS_NORETURN;
}