target/i386: Fix 32-bit wrapping of pc/eip computation
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()")
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index e0771a1..0893b79 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2286,10 +2286,15 @@
static inline void cpu_get_tb_cpu_state(CPUX86State *env, vaddr *pc,
uint64_t *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);
diff --git a/target/i386/tcg/tcg-cpu.c b/target/i386/tcg/tcg-cpu.c
index b942c30..f252e33 100644
--- a/target/i386/tcg/tcg-cpu.c
+++ b/target/i386/tcg/tcg-cpu.c
@@ -52,7 +52,12 @@
/* The instruction pointer is always up to date with CF_PCREL. */
if (!(tb_cflags(tb) & CF_PCREL)) {
CPUX86State *env = cs->env_ptr;
- env->eip = tb->pc - tb->cs_base;
+
+ if (tb->flags & HF_CS64_MASK) {
+ env->eip = tb->pc;
+ } else {
+ env->eip = (uint32_t)(tb->pc - tb->cs_base);
+ }
}
}
@@ -66,8 +71,10 @@
if (tb_cflags(tb) & CF_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;
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index e0a6229..93001fd 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -552,8 +552,10 @@
assert(s->pc_save != -1);
if (tb_cflags(s->base.tb) & CF_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;
}
@@ -563,8 +565,10 @@
assert(s->pc_save != -1);
if (tb_cflags(s->base.tb) & CF_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;
}
@@ -610,8 +614,10 @@
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));
}
}
@@ -622,8 +628,10 @@
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));
}
}
@@ -2859,6 +2867,10 @@
}
}
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);
@@ -2876,8 +2888,7 @@
}
}
- 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 (!(tb_cflags(s->base.tb) & CF_PCREL)) {
