diff options
| -rw-r--r-- | target/i386/tcg/translate.c | 82 | ||||
| -rw-r--r-- | tests/tcg/x86_64/Makefile.target | 1 | ||||
| -rw-r--r-- | tests/tcg/x86_64/cmpxchg.c | 42 |
3 files changed, 99 insertions, 26 deletions
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index 28a4e6dc1d..dbd6492778 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -439,32 +439,51 @@ static inline MemOp mo_b_d32(int b, MemOp ot) return b & 1 ? (ot == MO_16 ? MO_16 : MO_32) : MO_8; } -static void gen_op_mov_reg_v(DisasContext *s, MemOp ot, int reg, TCGv t0) +/* Compute the result of writing t0 to the OT-sized register REG. + * + * If DEST is NULL, store the result into the register and return the + * register's TCGv. + * + * If DEST is not NULL, store the result into DEST and return the + * register's TCGv. + */ +static TCGv gen_op_deposit_reg_v(DisasContext *s, MemOp ot, int reg, TCGv dest, TCGv t0) { switch(ot) { case MO_8: - if (!byte_reg_is_xH(s, reg)) { - tcg_gen_deposit_tl(cpu_regs[reg], cpu_regs[reg], t0, 0, 8); - } else { - tcg_gen_deposit_tl(cpu_regs[reg - 4], cpu_regs[reg - 4], t0, 8, 8); + if (byte_reg_is_xH(s, reg)) { + dest = dest ? dest : cpu_regs[reg - 4]; + tcg_gen_deposit_tl(dest, cpu_regs[reg - 4], t0, 8, 8); + return cpu_regs[reg - 4]; } + dest = dest ? dest : cpu_regs[reg]; + tcg_gen_deposit_tl(dest, cpu_regs[reg], t0, 0, 8); break; case MO_16: - tcg_gen_deposit_tl(cpu_regs[reg], cpu_regs[reg], t0, 0, 16); + dest = dest ? dest : cpu_regs[reg]; + tcg_gen_deposit_tl(dest, cpu_regs[reg], t0, 0, 16); break; case MO_32: /* For x86_64, this sets the higher half of register to zero. For i386, this is equivalent to a mov. */ - tcg_gen_ext32u_tl(cpu_regs[reg], t0); + dest = dest ? dest : cpu_regs[reg]; + tcg_gen_ext32u_tl(dest, t0); break; #ifdef TARGET_X86_64 case MO_64: - tcg_gen_mov_tl(cpu_regs[reg], t0); + dest = dest ? dest : cpu_regs[reg]; + tcg_gen_mov_tl(dest, t0); break; #endif default: tcg_abort(); } + return cpu_regs[reg]; +} + +static void gen_op_mov_reg_v(DisasContext *s, MemOp ot, int reg, TCGv t0) +{ + gen_op_deposit_reg_v(s, ot, reg, NULL, t0); } static inline @@ -3747,7 +3766,7 @@ static bool disas_insn(DisasContext *s, CPUState *cpu) case 0x1b0: case 0x1b1: /* cmpxchg Ev, Gv */ { - TCGv oldv, newv, cmpv; + TCGv oldv, newv, cmpv, dest; ot = mo_b_d(b, dflag); modrm = x86_ldub_code(env, s); @@ -3758,7 +3777,7 @@ static bool disas_insn(DisasContext *s, CPUState *cpu) cmpv = tcg_temp_new(); gen_op_mov_v_reg(s, ot, newv, reg); tcg_gen_mov_tl(cmpv, cpu_regs[R_EAX]); - + gen_extu(ot, cmpv); if (s->prefix & PREFIX_LOCK) { if (mod == 3) { goto illegal_op; @@ -3766,32 +3785,43 @@ static bool disas_insn(DisasContext *s, CPUState *cpu) gen_lea_modrm(env, s, modrm); tcg_gen_atomic_cmpxchg_tl(oldv, s->A0, cmpv, newv, s->mem_index, ot | MO_LE); - gen_op_mov_reg_v(s, ot, R_EAX, oldv); } else { if (mod == 3) { rm = (modrm & 7) | REX_B(s); gen_op_mov_v_reg(s, ot, oldv, rm); + gen_extu(ot, oldv); + + /* + * Unlike the memory case, where "the destination operand receives + * a write cycle without regard to the result of the comparison", + * rm must not be touched altogether if the write fails, including + * not zero-extending it on 64-bit processors. So, precompute + * the result of a successful writeback and perform the movcond + * directly on cpu_regs. Also need to write accumulator first, in + * case rm is part of RAX too. + */ + dest = gen_op_deposit_reg_v(s, ot, rm, newv, newv); + tcg_gen_movcond_tl(TCG_COND_EQ, dest, oldv, cmpv, newv, dest); } else { gen_lea_modrm(env, s, modrm); gen_op_ld_v(s, ot, oldv, s->A0); - rm = 0; /* avoid warning */ - } - gen_extu(ot, oldv); - gen_extu(ot, cmpv); - /* store value = (old == cmp ? new : old); */ - tcg_gen_movcond_tl(TCG_COND_EQ, newv, oldv, cmpv, newv, oldv); - if (mod == 3) { - gen_op_mov_reg_v(s, ot, R_EAX, oldv); - gen_op_mov_reg_v(s, ot, rm, newv); - } else { - /* 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 */ + + /* + * 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 + */ + tcg_gen_movcond_tl(TCG_COND_EQ, newv, oldv, cmpv, newv, oldv); gen_op_st_v(s, ot, newv, s->A0); - gen_op_mov_reg_v(s, ot, R_EAX, oldv); } } + /* + * Write EAX only if the cmpxchg fails; reuse newv as the destination, + * since it's dead here. + */ + dest = gen_op_deposit_reg_v(s, ot, R_EAX, newv, oldv); + tcg_gen_movcond_tl(TCG_COND_EQ, dest, oldv, cmpv, dest, newv); tcg_gen_mov_tl(cpu_cc_src, oldv); tcg_gen_mov_tl(s->cc_srcT, cmpv); tcg_gen_sub_tl(cpu_cc_dst, cmpv, oldv); diff --git a/tests/tcg/x86_64/Makefile.target b/tests/tcg/x86_64/Makefile.target index 6895db1c43..4eac78293f 100644 --- a/tests/tcg/x86_64/Makefile.target +++ b/tests/tcg/x86_64/Makefile.target @@ -11,6 +11,7 @@ include $(SRC_PATH)/tests/tcg/i386/Makefile.target ifeq ($(filter %-linux-user, $(TARGET)),$(TARGET)) X86_64_TESTS += vsyscall X86_64_TESTS += noexec +X86_64_TESTS += cmpxchg TESTS=$(MULTIARCH_TESTS) $(X86_64_TESTS) test-x86_64 else TESTS=$(MULTIARCH_TESTS) diff --git a/tests/tcg/x86_64/cmpxchg.c b/tests/tcg/x86_64/cmpxchg.c new file mode 100644 index 0000000000..5891735161 --- /dev/null +++ b/tests/tcg/x86_64/cmpxchg.c @@ -0,0 +1,42 @@ +#include <assert.h> + +static int mem; + +static unsigned long test_cmpxchgb(unsigned long orig) +{ + unsigned long ret; + mem = orig; + asm("cmpxchgb %b[cmp],%[mem]" + : [ mem ] "+m"(mem), [ rax ] "=a"(ret) + : [ cmp ] "r"(0x77), "a"(orig)); + return ret; +} + +static unsigned long test_cmpxchgw(unsigned long orig) +{ + unsigned long ret; + mem = orig; + asm("cmpxchgw %w[cmp],%[mem]" + : [ mem ] "+m"(mem), [ rax ] "=a"(ret) + : [ cmp ] "r"(0x7777), "a"(orig)); + return ret; +} + +static unsigned long test_cmpxchgl(unsigned long orig) +{ + unsigned long ret; + mem = orig; + asm("cmpxchgl %[cmp],%[mem]" + : [ mem ] "+m"(mem), [ rax ] "=a"(ret) + : [ cmp ] "r"(0x77777777u), "a"(orig)); + return ret; +} + +int main() +{ + unsigned long test = 0xdeadbeef12345678ull; + assert(test == test_cmpxchgb(test)); + assert(test == test_cmpxchgw(test)); + assert(test == test_cmpxchgl(test)); + return 0; +} |