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target/sh4: Use cmpxchg for movco when parallel_cpus

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As for other targets, cmpxchg isn't quite right for ll/sc,
suffering from an ABA race, but is sufficient to implement
portable atomic operations.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20170907185057.23421-2-richard.henderson@linaro.org>
[aurel32: fix whitespace]
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Richard Henderson 2017-09-07 11:50:53 -07:00 committed by Aurelien Jarno
parent 6d56fc6cc3
commit f85da3081d
4 changed files with 79 additions and 27 deletions
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19
linux-user/main.c
View File

@ -2679,6 +2679,8 @@ void cpu_loop(CPUSH4State *env)
target_siginfo_t info;
while (1) {
bool arch_interrupt = true;
cpu_exec_start(cs);
trapnr = cpu_exec(cs);
cpu_exec_end(cs);
@ -2710,13 +2712,14 @@ void cpu_loop(CPUSH4State *env)
int sig;
sig = gdb_handlesig(cs, TARGET_SIGTRAP);
if (sig)
{
if (sig) {
info.si_signo = sig;
info.si_errno = 0;
info.si_code = TARGET_TRAP_BRKPT;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
}
} else {
arch_interrupt = false;
}
}
break;
case 0xa0:
@ -2727,9 +2730,9 @@ void cpu_loop(CPUSH4State *env)
info._sifields._sigfault._addr = env->tea;
queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
break;
case EXCP_ATOMIC:
cpu_exec_step_atomic(cs);
arch_interrupt = false;
break;
default:
printf ("Unhandled trap: 0x%x\n", trapnr);
@ -2737,6 +2740,14 @@ void cpu_loop(CPUSH4State *env)
exit(EXIT_FAILURE);
}
process_pending_signals (env);
/* Most of the traps imply an exception or interrupt, which
implies an REI instruction has been executed. Which means
that LDST (aka LOK_ADDR) should be cleared. But there are
a few exceptions for traps internal to QEMU. */
if (arch_interrupt) {
env->lock_addr = -1;
}
}
}
#endif

4
target/sh4/cpu.h
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@ -188,7 +188,9 @@ typedef struct CPUSH4State {
tlb_t itlb[ITLB_SIZE]; /* instruction translation table */
tlb_t utlb[UTLB_SIZE]; /* unified translation table */
uint32_t ldst;
/* LDST = LOCK_ADDR != -1. */
uint32_t lock_addr;
uint32_t lock_value;
/* Fields up to this point are cleared by a CPU reset */
struct {} end_reset_fields;

1
target/sh4/helper.c
View File

@ -171,6 +171,7 @@ void superh_cpu_do_interrupt(CPUState *cs)
env->spc = env->pc;
env->sgr = env->gregs[15];
env->sr |= (1u << SR_BL) | (1u << SR_MD) | (1u << SR_RB);
env->lock_addr = -1;
if (env->flags & DELAY_SLOT_MASK) {
/* Branch instruction should be executed again before delay slot. */

82
target/sh4/translate.c
View File

@ -69,7 +69,8 @@ static TCGv cpu_gregs[32];
static TCGv cpu_sr, cpu_sr_m, cpu_sr_q, cpu_sr_t;
static TCGv cpu_pc, cpu_ssr, cpu_spc, cpu_gbr;
static TCGv cpu_vbr, cpu_sgr, cpu_dbr, cpu_mach, cpu_macl;
static TCGv cpu_pr, cpu_fpscr, cpu_fpul, cpu_ldst;
static TCGv cpu_pr, cpu_fpscr, cpu_fpul;
static TCGv cpu_lock_addr, cpu_lock_value;
static TCGv cpu_fregs[32];
/* internal register indexes */
@ -147,8 +148,12 @@ void sh4_translate_init(void)
offsetof(CPUSH4State,
delayed_cond),
"_delayed_cond_");
cpu_ldst = tcg_global_mem_new_i32(cpu_env,
offsetof(CPUSH4State, ldst), "_ldst_");
cpu_lock_addr = tcg_global_mem_new_i32(cpu_env,
offsetof(CPUSH4State, lock_addr),
"_lock_addr_");
cpu_lock_value = tcg_global_mem_new_i32(cpu_env,
offsetof(CPUSH4State, lock_value),
"_lock_value_");
for (i = 0; i < 32; i++)
cpu_fregs[i] = tcg_global_mem_new_i32(cpu_env,
@ -1549,31 +1554,64 @@ static void _decode_opc(DisasContext * ctx)
return;
case 0x0073:
/* MOVCO.L
LDST -> T
If (T == 1) R0 -> (Rn)
0 -> LDST
*/
* LDST -> T
* If (T == 1) R0 -> (Rn)
* 0 -> LDST
*
* The above description doesn't work in a parallel context.
* Since we currently support no smp boards, this implies user-mode.
* But we can still support the official mechanism while user-mode
* is single-threaded. */
CHECK_SH4A
{
TCGLabel *label = gen_new_label();
tcg_gen_mov_i32(cpu_sr_t, cpu_ldst);
tcg_gen_brcondi_i32(TCG_COND_EQ, cpu_ldst, 0, label);
tcg_gen_qemu_st_i32(REG(0), REG(B11_8), ctx->memidx, MO_TEUL);
gen_set_label(label);
tcg_gen_movi_i32(cpu_ldst, 0);
return;
TCGLabel *fail = gen_new_label();
TCGLabel *done = gen_new_label();
if ((tb_cflags(ctx->tb) & CF_PARALLEL)) {
TCGv tmp;
tcg_gen_brcond_i32(TCG_COND_NE, REG(B11_8),
cpu_lock_addr, fail);
tmp = tcg_temp_new();
tcg_gen_atomic_cmpxchg_i32(tmp, REG(B11_8), cpu_lock_value,
REG(0), ctx->memidx, MO_TEUL);
tcg_gen_setcond_i32(TCG_COND_EQ, cpu_sr_t, tmp, cpu_lock_value);
tcg_temp_free(tmp);
} else {
tcg_gen_brcondi_i32(TCG_COND_EQ, cpu_lock_addr, -1, fail);
tcg_gen_qemu_st_i32(REG(0), REG(B11_8), ctx->memidx, MO_TEUL);
tcg_gen_movi_i32(cpu_sr_t, 1);
}
tcg_gen_br(done);
gen_set_label(fail);
tcg_gen_movi_i32(cpu_sr_t, 0);
gen_set_label(done);
tcg_gen_movi_i32(cpu_lock_addr, -1);
}
return;
case 0x0063:
/* MOVLI.L @Rm,R0
1 -> LDST
(Rm) -> R0
When interrupt/exception
occurred 0 -> LDST
*/
* 1 -> LDST
* (Rm) -> R0
* When interrupt/exception
* occurred 0 -> LDST
*
* In a parallel context, we must also save the loaded value
* for use with the cmpxchg that we'll use with movco.l. */
CHECK_SH4A
tcg_gen_movi_i32(cpu_ldst, 0);
tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx, MO_TESL);
tcg_gen_movi_i32(cpu_ldst, 1);
if ((tb_cflags(ctx->tb) & CF_PARALLEL)) {
TCGv tmp = tcg_temp_new();
tcg_gen_mov_i32(tmp, REG(B11_8));
tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx, MO_TESL);
tcg_gen_mov_i32(cpu_lock_value, REG(0));
tcg_gen_mov_i32(cpu_lock_addr, tmp);
tcg_temp_free(tmp);
} else {
tcg_gen_qemu_ld_i32(REG(0), REG(B11_8), ctx->memidx, MO_TESL);
tcg_gen_movi_i32(cpu_lock_addr, 0);
}
return;
case 0x0093: /* ocbi @Rn */
{