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.hender...@linaro.org> --- This may be too late for 8.2; if not, then 8.2.1 and 8.1.next. I think I have found all forms of pc <-> eip, but another set of eyes would be appreciated. r~ --- target/i386/cpu.h | 9 +++++++-- target/i386/tcg/tcg-cpu.c | 4 +++- target/i386/tcg/translate.c | 23 +++++++++++++++++------ 3 files changed, 27 insertions(+), 9 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index cd2e295bd6..ef987f344c 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -2324,10 +2324,15 @@ static inline int cpu_mmu_index_kernel(CPUX86State *env) 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 2c6a12c835..eb05a69f79 100644 --- a/target/i386/tcg/tcg-cpu.c +++ b/target/i386/tcg/tcg-cpu.c @@ -66,8 +66,10 @@ static void x86_restore_state_to_opc(CPUState *cs, 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 587d88692a..037bc47e7c 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -552,8 +552,10 @@ static void gen_update_eip_cur(DisasContext *s) 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 @@ static void gen_update_eip_next(DisasContext *s) 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 @@ 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)); } } @@ -622,8 +628,10 @@ 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)); } } @@ -2837,6 +2845,10 @@ 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); @@ -2854,8 +2866,7 @@ 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 (!(tb_cflags(s->base.tb) & CF_PCREL)) { -- 2.34.1
