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target-i386: emulate LOCK'ed cmpxchg using cmpxchg helpers

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The diff here is uglier than necessary. All this does is to turn

FOO

into:

if (s->prefix & PREFIX_LOCK) {
BAR
} else {
FOO
}

where FOO is the original implementation of an unlocked cmpxchg.

Backports commit ae03f8de45427042ecd10b0941a005f21ecc064c from qemu
This commit is contained in:
Emilio G. Cota 2018-02-27 22:33:16 -05:00 committed by Lioncash
parent b48508a6c1
commit a386368f82
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7
3 changed files with 168 additions and 68 deletions
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2
qemu/target-i386/helper.h
View file

@ -76,8 +76,10 @@ DEF_HELPER_3(boundw, void, env, tl, int)
DEF_HELPER_3(boundl, void, env, tl, int)
DEF_HELPER_1(rsm, void, env)
DEF_HELPER_2(into, void, env, int)
DEF_HELPER_2(cmpxchg8b_unlocked, void, env, tl)
DEF_HELPER_2(cmpxchg8b, void, env, tl)
#ifdef TARGET_X86_64
DEF_HELPER_2(cmpxchg16b_unlocked, void, env, tl)
DEF_HELPER_2(cmpxchg16b, void, env, tl)
#endif
DEF_HELPER_1(single_step, void, env)

136
qemu/target-i386/mem_helper.c
View file

@ -22,6 +22,8 @@
#include "exec/helper-proto.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#include "qemu/int128.h"
#include "tcg.h"
#include "uc_priv.h"
@ -35,53 +37,141 @@ void helper_unlock(CPUX86State *env)
{
}
void helper_cmpxchg8b(CPUX86State *env, target_ulong a0)
void helper_cmpxchg8b_unlocked(CPUX86State *env, target_ulong a0)
{
uint64_t d;
uintptr_t ra = GETPC();
uint64_t oldv, cmpv, newv;
int eflags;
eflags = cpu_cc_compute_all(env, CC_OP);
d = cpu_ldq_data_ra(env, a0, GETPC());
if (d == (((uint64_t)env->regs[R_EDX] << 32) | (uint32_t)env->regs[R_EAX])) {
cpu_stq_data_ra(env, a0, ((uint64_t)env->regs[R_ECX] << 32)
| (uint32_t)env->regs[R_EBX], GETPC());
cmpv = deposit64(env->regs[R_EAX], 32, 32, env->regs[R_EDX]);
newv = deposit64(env->regs[R_EBX], 32, 32, env->regs[R_ECX]);
oldv = cpu_ldq_data_ra(env, a0, ra);
newv = (cmpv == oldv ? newv : oldv);
/* always do the store */
cpu_stq_data_ra(env, a0, newv, ra);
if (oldv == cmpv) {
eflags |= CC_Z;
} else {
/* always do the store */
cpu_stq_data_ra(env, a0, d, GETPC());
env->regs[R_EDX] = (uint32_t)(d >> 32);
env->regs[R_EAX] = (uint32_t)d;
env->regs[R_EAX] = (uint32_t)oldv;
env->regs[R_EDX] = (uint32_t)(oldv >> 32);
eflags &= ~CC_Z;
}
CC_SRC = eflags;
}
#ifdef TARGET_X86_64
void helper_cmpxchg16b(CPUX86State *env, target_ulong a0)
void helper_cmpxchg8b(CPUX86State *env, target_ulong a0)
{
uint64_t d0, d1;
#ifdef CONFIG_ATOMIC64
uint64_t oldv, cmpv, newv;
int eflags;
eflags = cpu_cc_compute_all(env, CC_OP);
cmpv = deposit64(env->regs[R_EAX], 32, 32, env->regs[R_EDX]);
newv = deposit64(env->regs[R_EBX], 32, 32, env->regs[R_ECX]);
#ifdef CONFIG_USER_ONLY
{
uint64_t *haddr = g2h(a0);
cmpv = cpu_to_le64(cmpv);
newv = cpu_to_le64(newv);
oldv = atomic_cmpxchg__nocheck(haddr, cmpv, newv);
oldv = le64_to_cpu(oldv);
}
#else
{
uintptr_t ra = GETPC();
int mem_idx = cpu_mmu_index(env, false);
TCGMemOpIdx oi = make_memop_idx(MO_TEQ, mem_idx);
oldv = helper_atomic_cmpxchgq_le_mmu(env, a0, cmpv, newv, oi, ra);
}
#endif
if (oldv == cmpv) {
eflags |= CC_Z;
} else {
env->regs[R_EAX] = (uint32_t)oldv;
env->regs[R_EDX] = (uint32_t)(oldv >> 32);
eflags &= ~CC_Z;
}
CC_SRC = eflags;
#else
cpu_loop_exit_atomic(ENV_GET_CPU(env), GETPC());
#endif /* CONFIG_ATOMIC64 */
}
#ifdef TARGET_X86_64
void helper_cmpxchg16b_unlocked(CPUX86State *env, target_ulong a0)
{
uintptr_t ra = GETPC();
Int128 oldv, cmpv, newv;
uint64_t o0, o1;
int eflags;
bool success;
if ((a0 & 0xf) != 0) {
raise_exception_ra(env, EXCP0D_GPF, GETPC());
}
eflags = cpu_cc_compute_all(env, CC_OP);
d0 = cpu_ldq_data_ra(env, a0, GETPC());
d1 = cpu_ldq_data_ra(env, a0 + 8, GETPC());
if (d0 == env->regs[R_EAX] && d1 == env->regs[R_EDX]) {
cpu_stq_data_ra(env, a0, env->regs[R_EBX], GETPC());
cpu_stq_data_ra(env, a0 + 8, env->regs[R_ECX], GETPC());
cmpv = int128_make128(env->regs[R_EAX], env->regs[R_EDX]);
newv = int128_make128(env->regs[R_EBX], env->regs[R_ECX]);
o0 = cpu_ldq_data_ra(env, a0 + 0, ra);
o1 = cpu_ldq_data_ra(env, a0 + 8, ra);
oldv = int128_make128(o0, o1);
success = int128_eq(oldv, cmpv);
if (!success) {
newv = oldv;
}
cpu_stq_data_ra(env, a0 + 0, int128_getlo(newv), ra);
cpu_stq_data_ra(env, a0 + 8, int128_gethi(newv), ra);
if (success) {
eflags |= CC_Z;
} else {
/* always do the store */
cpu_stq_data_ra(env, a0, d0, GETPC());
cpu_stq_data_ra(env, a0 + 8, d1, GETPC());
env->regs[R_EDX] = d1;
env->regs[R_EAX] = d0;
env->regs[R_EAX] = int128_getlo(oldv);
env->regs[R_EDX] = int128_gethi(oldv);
eflags &= ~CC_Z;
}
CC_SRC = eflags;
}
void helper_cmpxchg16b(CPUX86State *env, target_ulong a0)
{
uintptr_t ra = GETPC();
if ((a0 & 0xf) != 0) {
raise_exception_ra(env, EXCP0D_GPF, ra);
} else {
#ifndef CONFIG_ATOMIC128
cpu_loop_exit_atomic(ENV_GET_CPU(env), ra);
#else
int eflags = cpu_cc_compute_all(env, CC_OP);
Int128 cmpv = int128_make128(env->regs[R_EAX], env->regs[R_EDX]);
Int128 newv = int128_make128(env->regs[R_EBX], env->regs[R_ECX]);
int mem_idx = cpu_mmu_index(env, false);
TCGMemOpIdx oi = make_memop_idx(MO_TEQ | MO_ALIGN_16, mem_idx);
Int128 oldv = helper_atomic_cmpxchgo_le_mmu(env, a0, cmpv,
newv, oi, ra);
if (int128_eq(oldv, cmpv)) {
eflags |= CC_Z;
} else {
env->regs[R_EAX] = int128_getlo(oldv);
env->regs[R_EDX] = int128_gethi(oldv);
eflags &= ~CC_Z;
}
CC_SRC = eflags;
#endif
}
}
#endif
void helper_boundw(CPUX86State *env, target_ulong a0, int v)

80
qemu/target-i386/translate.c
View file

@ -5721,57 +5721,57 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
case 0x1b0:
case 0x1b1: /* cmpxchg Ev, Gv */
{
TCGLabel *label1, *label2;
TCGv t0, t1, t2, a0;
TCGv oldv, newv, cmpv;
ot = mo_b_d(b, dflag);
modrm = cpu_ldub_code(env, s->pc++);
reg = ((modrm >> 3) & 7) | rex_r;
mod = (modrm >> 6) & 3;
t0 = tcg_temp_local_new(tcg_ctx);
t1 = tcg_temp_local_new(tcg_ctx);
t2 = tcg_temp_local_new(tcg_ctx);
a0 = tcg_temp_local_new(tcg_ctx);
gen_op_mov_v_reg(tcg_ctx, ot, t1, reg);
oldv = tcg_temp_new(tcg_ctx);
newv = tcg_temp_new(tcg_ctx);
cmpv = tcg_temp_new(tcg_ctx);
gen_op_mov_v_reg(tcg_ctx, ot, newv, reg);
tcg_gen_mov_tl(tcg_ctx, cmpv, tcg_ctx->cpu_regs[R_EAX]);
if (s->prefix & PREFIX_LOCK) {
if (mod == 3) {
goto illegal_op;
}
tcg_gen_atomic_cmpxchg_tl(tcg_ctx, oldv, cpu_A0, cmpv, newv,
s->mem_index, ot | MO_LE);
gen_op_mov_reg_v(tcg_ctx, ot, R_EAX, oldv);
} else {
if (mod == 3) {
rm = (modrm & 7) | REX_B(s);
gen_op_mov_v_reg(tcg_ctx, ot, t0, rm);
gen_op_mov_v_reg(tcg_ctx, ot, oldv, rm);
} else {
gen_lea_modrm(env, s, modrm);
tcg_gen_mov_tl(tcg_ctx, a0, cpu_A0);
gen_op_ld_v(s, ot, t0, a0);
gen_op_ld_v(s, ot, oldv, cpu_A0);
rm = 0; /* avoid warning */
}
label1 = gen_new_label(tcg_ctx);
tcg_gen_mov_tl(tcg_ctx, t2, cpu_regs[R_EAX]);
gen_extu(tcg_ctx, ot, t0);
gen_extu(tcg_ctx, ot, t2);
tcg_gen_brcond_tl(tcg_ctx, TCG_COND_EQ, t2, t0, label1);
label2 = gen_new_label(tcg_ctx);
gen_extu(tcg_ctx, ot, oldv);
gen_extu(tcg_ctx, ot, cmpv);
/* store value = (old == cmp ? new : old); */
tcg_gen_movcond_tl(tcg_ctx, TCG_COND_EQ, newv, oldv, cmpv, newv, oldv);
if (mod == 3) {
gen_op_mov_reg_v(tcg_ctx, ot, R_EAX, t0);
tcg_gen_br(tcg_ctx, label2);
gen_set_label(tcg_ctx, label1);
gen_op_mov_reg_v(tcg_ctx, ot, rm, t1);
gen_op_mov_reg_v(tcg_ctx, ot, R_EAX, oldv);
gen_op_mov_reg_v(tcg_ctx, ot, rm, newv);
} else {
/* perform no-op store cycle like physical cpu; must be
before changing accumulator to ensure idempotency if
the store faults and the instruction is restarted */
gen_op_st_v(s, ot, t0, a0);
gen_op_mov_reg_v(tcg_ctx, ot, R_EAX, t0);
tcg_gen_br(tcg_ctx, label2);
gen_set_label(tcg_ctx, label1);
gen_op_st_v(s, ot, t1, a0);
/* Perform an unconditional store cycle like physical cpu;
must be before changing accumulator to ensure
idempotency if the store faults and the instruction
is restarted */
gen_op_st_v(s, ot, newv, cpu_A0);
gen_op_mov_reg_v(tcg_ctx, ot, R_EAX, oldv);
}
gen_set_label(tcg_ctx, label2);
tcg_gen_mov_tl(tcg_ctx, cpu_cc_src, t0);
tcg_gen_mov_tl(tcg_ctx, cpu_cc_srcT, t2);
tcg_gen_sub_tl(tcg_ctx, cpu_cc_dst, t2, t0);
}
tcg_gen_mov_tl(tcg_ctx, cpu_cc_src, oldv);
tcg_gen_mov_tl(tcg_ctx, cpu_cc_srcT, cmpv);
tcg_gen_sub_tl(tcg_ctx, cpu_cc_dst, cmpv, oldv);
set_cc_op(s, CC_OP_SUBB + ot);
tcg_temp_free(tcg_ctx, t0);
tcg_temp_free(tcg_ctx, t1);
tcg_temp_free(tcg_ctx, t2);
tcg_temp_free(tcg_ctx, a0);
tcg_temp_free(tcg_ctx, oldv);
tcg_temp_free(tcg_ctx, newv);
tcg_temp_free(tcg_ctx, cmpv);
}
break;
case 0x1c7: /* cmpxchg8b */
@ -5784,14 +5784,22 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
if (!(s->cpuid_ext_features & CPUID_EXT_CX16))
goto illegal_op;
gen_lea_modrm(env, s, modrm);
if ((s->prefix & PREFIX_LOCK) && tcg_ctx->uc->parallel_cpus) {
gen_helper_cmpxchg16b(tcg_ctx, cpu_env, cpu_A0);
} else {
gen_helper_cmpxchg16b_unlocked(tcg_ctx, cpu_env, cpu_A0);
}
} else
#endif
{
if (!(s->cpuid_features & CPUID_CX8))
goto illegal_op;
gen_lea_modrm(env, s, modrm);
if ((s->prefix & PREFIX_LOCK) && tcg_ctx->uc->parallel_cpus) {
gen_helper_cmpxchg8b(tcg_ctx, cpu_env, cpu_A0);
} else {
gen_helper_cmpxchg8b_unlocked(tcg_ctx, cpu_env, cpu_A0);
}
}
set_cc_op(s, CC_OP_EFLAGS);
break;