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target/i386: Fix 32-bit wrapping of pc/eip computation

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In 32-bit mode, pc = eip + cs_base is also 32-bit, and must wrap.
Failure to do so results in incorrect memory exceptions to the guest.
Before 732d548732ed, this was implicitly done via truncation to
target_ulong but only in qemu-system-i386, not qemu-system-x86_64.

To fix this, we must add conditional zero-extensions.
Since we have to test for 32 vs 64-bit anyway, note that cs_base
is always zero in 64-bit mode.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2022
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20231212172510.103305-1-richard.henderson@linaro.org>
(cherry picked from commit b5e0d5d22fbffc3d8f7d3e86d7a2d05a1a974e27)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: context fix in target/i386/tcg/tcg-cpu.c for v8.1.0-1190-gb77af26e97
 "accel/tcg: Replace CPUState.env_ptr with cpu_env()")
(Mjt: fixup in target/i386/tcg/tcg-cpu.c for v7.2.0-1854-g34a39c2443
 "target/i386: Replace `tb_pc()` with `tb->pc`")
This commit is contained in:
Richard Henderson 2023-12-12 09:01:38 -08:00 committed by Michael Tokarev
parent 2ad4ebb350
commit 15e207b9ed
3 changed files with 33 additions and 10 deletions
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9
target/i386/cpu.h
View File

@ -2217,10 +2217,15 @@ static inline int cpu_mmu_index_kernel(CPUX86State *env)
static inline void cpu_get_tb_cpu_state(CPUX86State *env, target_ulong *pc,
target_ulong *cs_base, uint32_t *flags)
{
*cs_base = env->segs[R_CS].base;
*pc = *cs_base + env->eip;
*flags = env->hflags |
(env->eflags & (IOPL_MASK | TF_MASK | RF_MASK | VM_MASK | AC_MASK));
if (env->hflags & HF_CS64_MASK) {
*cs_base = 0;
*pc = env->eip;
} else {
*cs_base = env->segs[R_CS].base;
*pc = (uint32_t)(*cs_base + env->eip);
}
}
void do_cpu_init(X86CPU *cpu);

11
target/i386/tcg/tcg-cpu.c
View File

@ -52,7 +52,12 @@ static void x86_cpu_synchronize_from_tb(CPUState *cs,
/* The instruction pointer is always up to date with TARGET_TB_PCREL. */
if (!TARGET_TB_PCREL) {
CPUX86State *env = cs->env_ptr;
env->eip = tb_pc(tb) - tb->cs_base;
if (tb->flags & HF_CS64_MASK) {
env->eip = tb_pc(tb);
} else {
env->eip = (uint32_t)(tb_pc(tb) - tb->cs_base);
}
}
}
@ -66,8 +71,10 @@ static void x86_restore_state_to_opc(CPUState *cs,
if (TARGET_TB_PCREL) {
env->eip = (env->eip & TARGET_PAGE_MASK) | data[0];
} else if (tb->flags & HF_CS64_MASK) {
env->eip = data[0];
} else {
env->eip = data[0] - tb->cs_base;
env->eip = (uint32_t)(data[0] - tb->cs_base);
}
if (cc_op != CC_OP_DYNAMIC) {
env->cc_op = cc_op;

23
target/i386/tcg/translate.c
View File

@ -547,8 +547,10 @@ static void gen_update_eip_cur(DisasContext *s)
assert(s->pc_save != -1);
if (TARGET_TB_PCREL) {
tcg_gen_addi_tl(cpu_eip, cpu_eip, s->base.pc_next - s->pc_save);
} else if (CODE64(s)) {
tcg_gen_movi_tl(cpu_eip, s->base.pc_next);
} else {
tcg_gen_movi_tl(cpu_eip, s->base.pc_next - s->cs_base);
tcg_gen_movi_tl(cpu_eip, (uint32_t)(s->base.pc_next - s->cs_base));
}
s->pc_save = s->base.pc_next;
}
@ -558,8 +560,10 @@ static void gen_update_eip_next(DisasContext *s)
assert(s->pc_save != -1);
if (TARGET_TB_PCREL) {
tcg_gen_addi_tl(cpu_eip, cpu_eip, s->pc - s->pc_save);
} else if (CODE64(s)) {
tcg_gen_movi_tl(cpu_eip, s->base.pc_next);
} else {
tcg_gen_movi_tl(cpu_eip, s->pc - s->cs_base);
tcg_gen_movi_tl(cpu_eip, (uint32_t)(s->base.pc_next - s->cs_base));
}
s->pc_save = s->pc;
}
@ -605,8 +609,10 @@ static TCGv eip_next_tl(DisasContext *s)
TCGv ret = tcg_temp_new();
tcg_gen_addi_tl(ret, cpu_eip, s->pc - s->pc_save);
return ret;
} else if (CODE64(s)) {
return tcg_constant_tl(s->pc);
} else {
return tcg_constant_tl(s->pc - s->cs_base);
return tcg_constant_tl((uint32_t)(s->pc - s->cs_base));
}
}
@ -617,8 +623,10 @@ static TCGv eip_cur_tl(DisasContext *s)
TCGv ret = tcg_temp_new();
tcg_gen_addi_tl(ret, cpu_eip, s->base.pc_next - s->pc_save);
return ret;
} else if (CODE64(s)) {
return tcg_constant_tl(s->base.pc_next);
} else {
return tcg_constant_tl(s->base.pc_next - s->cs_base);
return tcg_constant_tl((uint32_t)(s->base.pc_next - s->cs_base));
}
}
@ -2875,6 +2883,10 @@ static void gen_jmp_rel(DisasContext *s, MemOp ot, int diff, int tb_num)
}
}
new_eip &= mask;
new_pc = new_eip + s->cs_base;
if (!CODE64(s)) {
new_pc = (uint32_t)new_pc;
}
gen_update_cc_op(s);
set_cc_op(s, CC_OP_DYNAMIC);
@ -2892,8 +2904,7 @@ static void gen_jmp_rel(DisasContext *s, MemOp ot, int diff, int tb_num)
}
}
if (use_goto_tb &&
translator_use_goto_tb(&s->base, new_eip + s->cs_base)) {
if (use_goto_tb && translator_use_goto_tb(&s->base, new_pc)) {
/* jump to same page: we can use a direct jump */
tcg_gen_goto_tb(tb_num);
if (!TARGET_TB_PCREL) {