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Merge tag 'or1k-pull-request-20230513' of https://github.com/stffrdhr… 
…n/qemu into staging

OpenRISC FPU Updates for 8.1

A few fixes and updates to bring OpenRISC inline with the latest
architecture spec updates:

 - Allow FPCSR to be accessed in user mode
 - Select tininess detection before rounding
 - Fix FPE Exception PC value

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* tag 'or1k-pull-request-20230513' of https://github.com/stffrdhrn/qemu:
  target/openrisc: Setup FPU for detecting tininess before rounding
  target/openrisc: Set PC to cpu state on FPU exception
  target/openrisc: Allow fpcsr access in user mode

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@rth7680
rth7680 committed May 13, 2023
2 parents debca86 + 874c529 commit 8844bb8
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Showing 4 changed files with 81 additions and 53 deletions.
4 changes: 4 additions & 0 deletions target/openrisc/cpu.c
View file
Expand Up @@ -22,6 +22,7 @@
#include "qemu/qemu-print.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "fpu/softfloat-helpers.h"
#include "tcg/tcg.h"

static void openrisc_cpu_set_pc(CPUState *cs, vaddr value)
Expand Down Expand Up @@ -90,6 +91,9 @@ static void openrisc_cpu_reset_hold(Object *obj)
s->exception_index = -1;
cpu_set_fpcsr(&cpu->env, 0);

set_float_detect_tininess(float_tininess_before_rounding,
&cpu->env.fp_status);

#ifndef CONFIG_USER_ONLY
cpu->env.picmr = 0x00000000;
cpu->env.picsr = 0x00000000;
Expand Down
13 changes: 11 additions & 2 deletions target/openrisc/fpu_helper.c
View file
Expand Up @@ -20,8 +20,8 @@

#include "qemu/osdep.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "exec/helper-proto.h"
#include "exception.h"
#include "fpu/softfloat.h"

static int ieee_ex_to_openrisc(int fexcp)
Expand All @@ -45,6 +45,15 @@ static int ieee_ex_to_openrisc(int fexcp)
return ret;
}

static G_NORETURN
void do_fpe(CPUOpenRISCState *env, uintptr_t pc)
{
CPUState *cs = env_cpu(env);

cs->exception_index = EXCP_FPE;
cpu_loop_exit_restore(cs, pc);
}

void HELPER(update_fpcsr)(CPUOpenRISCState *env)
{
int tmp = get_float_exception_flags(&env->fp_status);
Expand All @@ -55,7 +64,7 @@ void HELPER(update_fpcsr)(CPUOpenRISCState *env)
if (tmp) {
env->fpcsr |= tmp;
if (env->fpcsr & FPCSR_FPEE) {
helper_exception(env, EXCP_FPE);
do_fpe(env, GETPC());
}
}
}
Expand Down
45 changes: 34 additions & 11 deletions target/openrisc/sys_helper.c
View file
Expand Up @@ -29,17 +29,37 @@

#define TO_SPR(group, number) (((group) << 11) + (number))

static inline bool is_user(CPUOpenRISCState *env)
{
#ifdef CONFIG_USER_ONLY
return true;
#else
return (env->sr & SR_SM) == 0;
#endif
}

void HELPER(mtspr)(CPUOpenRISCState *env, target_ulong spr, target_ulong rb)
{
#ifndef CONFIG_USER_ONLY
OpenRISCCPU *cpu = env_archcpu(env);
#ifndef CONFIG_USER_ONLY
CPUState *cs = env_cpu(env);
target_ulong mr;
int idx;
#endif

/* Handle user accessible SPRs first. */
switch (spr) {
case TO_SPR(0, 20): /* FPCSR */
cpu_set_fpcsr(env, rb);
return;
}

if (is_user(env)) {
raise_exception(cpu, EXCP_ILLEGAL);
}

#ifndef CONFIG_USER_ONLY
switch (spr) {
case TO_SPR(0, 11): /* EVBAR */
env->evbar = rb;
break;
Expand Down Expand Up @@ -187,27 +207,33 @@ void HELPER(mtspr)(CPUOpenRISCState *env, target_ulong spr, target_ulong rb)
cpu_openrisc_timer_update(cpu);
qemu_mutex_unlock_iothread();
break;
#endif

case TO_SPR(0, 20): /* FPCSR */
cpu_set_fpcsr(env, rb);
break;
}
#endif
}

target_ulong HELPER(mfspr)(CPUOpenRISCState *env, target_ulong rd,
target_ulong spr)
{
OpenRISCCPU *cpu = env_archcpu(env);
#ifndef CONFIG_USER_ONLY
uint64_t data[TARGET_INSN_START_WORDS];
MachineState *ms = MACHINE(qdev_get_machine());
OpenRISCCPU *cpu = env_archcpu(env);
CPUState *cs = env_cpu(env);
int idx;
#endif

/* Handle user accessible SPRs first. */
switch (spr) {
case TO_SPR(0, 20): /* FPCSR */
return env->fpcsr;
}

if (is_user(env)) {
raise_exception(cpu, EXCP_ILLEGAL);
}

#ifndef CONFIG_USER_ONLY
switch (spr) {
case TO_SPR(0, 0): /* VR */
return env->vr;

Expand Down Expand Up @@ -324,11 +350,8 @@ target_ulong HELPER(mfspr)(CPUOpenRISCState *env, target_ulong rd,
cpu_openrisc_count_update(cpu);
qemu_mutex_unlock_iothread();
return cpu_openrisc_count_get(cpu);
#endif

case TO_SPR(0, 20): /* FPCSR */
return env->fpcsr;
}
#endif

/* for rd is passed in, if rd unchanged, just keep it back. */
return rd;
Expand Down
72 changes: 32 additions & 40 deletions target/openrisc/translate.c
View file
Expand Up @@ -819,57 +819,49 @@ static bool trans_l_xori(DisasContext *dc, arg_rri *a)

static bool trans_l_mfspr(DisasContext *dc, arg_l_mfspr *a)
{
check_r0_write(dc, a->d);

if (is_user(dc)) {
gen_illegal_exception(dc);
} else {
TCGv spr = tcg_temp_new();

if (tb_cflags(dc->base.tb) & CF_USE_ICOUNT) {
gen_io_start();
if (dc->delayed_branch) {
tcg_gen_mov_tl(cpu_pc, jmp_pc);
tcg_gen_discard_tl(jmp_pc);
} else {
tcg_gen_movi_tl(cpu_pc, dc->base.pc_next + 4);
}
dc->base.is_jmp = DISAS_EXIT;
}
TCGv spr = tcg_temp_new();

tcg_gen_ori_tl(spr, cpu_R(dc, a->a), a->k);
gen_helper_mfspr(cpu_R(dc, a->d), cpu_env, cpu_R(dc, a->d), spr);
}
return true;
}

static bool trans_l_mtspr(DisasContext *dc, arg_l_mtspr *a)
{
if (is_user(dc)) {
gen_illegal_exception(dc);
} else {
TCGv spr;
check_r0_write(dc, a->d);

if (tb_cflags(dc->base.tb) & CF_USE_ICOUNT) {
gen_io_start();
}
/* For SR, we will need to exit the TB to recognize the new
* exception state. For NPC, in theory this counts as a branch
* (although the SPR only exists for use by an ICE). Save all
* of the cpu state first, allowing it to be overwritten.
*/
if (tb_cflags(dc->base.tb) & CF_USE_ICOUNT) {
gen_io_start();
if (dc->delayed_branch) {
tcg_gen_mov_tl(cpu_pc, jmp_pc);
tcg_gen_discard_tl(jmp_pc);
} else {
tcg_gen_movi_tl(cpu_pc, dc->base.pc_next + 4);
}
dc->base.is_jmp = DISAS_EXIT;
}

tcg_gen_ori_tl(spr, cpu_R(dc, a->a), a->k);
gen_helper_mfspr(cpu_R(dc, a->d), cpu_env, cpu_R(dc, a->d), spr);
return true;
}

static bool trans_l_mtspr(DisasContext *dc, arg_l_mtspr *a)
{
TCGv spr = tcg_temp_new();

spr = tcg_temp_new();
tcg_gen_ori_tl(spr, cpu_R(dc, a->a), a->k);
gen_helper_mtspr(cpu_env, spr, cpu_R(dc, a->b));
if (tb_cflags(dc->base.tb) & CF_USE_ICOUNT) {
gen_io_start();
}
/*
* For SR, we will need to exit the TB to recognize the new
* exception state. For NPC, in theory this counts as a branch
* (although the SPR only exists for use by an ICE). Save all
* of the cpu state first, allowing it to be overwritten.
*/
if (dc->delayed_branch) {
tcg_gen_mov_tl(cpu_pc, jmp_pc);
tcg_gen_discard_tl(jmp_pc);
} else {
tcg_gen_movi_tl(cpu_pc, dc->base.pc_next + 4);
}
dc->base.is_jmp = DISAS_EXIT;

tcg_gen_ori_tl(spr, cpu_R(dc, a->a), a->k);
gen_helper_mtspr(cpu_env, spr, cpu_R(dc, a->b));
return true;
}

Expand Down

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