From: Richard Henderson <richard.henderson@linaro.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [PATCH v2 19/23] target/i386: Use gen_jmp_rel for gen_jcc
Date: Sat, 1 Oct 2022 06:58:43 -0700 [thread overview]
Message-ID: <d7f6e229-c836-9140-ab83-ff9abb425850@linaro.org> (raw)
In-Reply-To: <CABgObfYAQQ5hVg0iDdU+Lro=4_Q=tbPS7=4MtpvJvUVp=QJynQ@mail.gmail.com>
On 10/1/22 00:03, Paolo Bonzini wrote:
> On Sat, Oct 1, 2022 at 3:04 AM Richard Henderson
> <richard.henderson@linaro.org> wrote:
>>
>> On 9/21/22 06:09, Paolo Bonzini wrote:
>>> On Tue, Sep 6, 2022 at 12:09 PM Richard Henderson
>>> <richard.henderson@linaro.org> wrote:
>>>> + gen_jcc1(s, b, l1);
>>>> + gen_jmp_rel(s, ot, 0, 1);
>>>> + gen_set_label(l1);
>>>> + gen_jmp_rel(s, ot, diff, 0);
>>>
>>> Might be worth a comment that jumps with 16-bit operand size truncate
>>> EIP even if the jump is not taken.
>>
>> Hmm. But is that correct? That's not reflected by the pseudocode for Jcc.
>
> No, it's not:
>
> int main() {
> asm("clc; data16 jc 1f; 1:");
> }
>
> does not crash (it does with stc) on real hardware, but it does with
> this series applied. So the various occurrences of gen_jmp_rel(s, ot,
> 0, 1) or gen_jmp_rel(s, MO_32, 0, 1) should stay as gen_jmp_tb(s,
> s->pc - s->cs_base, 1).
Nice test. I had an idea this would be the case, so I had already added a helper to
perform the jump with truncation to the "current code size". It turned out that I needed
that in other places too, like rep.
New patch set coming up.
r~
next prev parent reply other threads:[~2022-10-01 14:01 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-06 10:09 [PATCH v2 00/23] target/i386: pc-relative translation blocks Richard Henderson
2022-09-06 10:09 ` [PATCH v2 01/23] target/i386: Remove pc_start Richard Henderson
2022-09-21 11:49 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 02/23] target/i386: Return bool from disas_insn Richard Henderson
2022-09-06 14:42 ` Philippe Mathieu-Daudé via
2022-09-08 12:14 ` Richard Henderson
2022-09-21 17:51 ` Philippe Mathieu-Daudé via
2022-09-06 10:09 ` [PATCH v2 03/23] target/i386: Remove cur_eip argument to gen_exception Richard Henderson
2022-09-06 14:44 ` Philippe Mathieu-Daudé via
2022-09-21 11:51 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 04/23] target/i386: Remove cur_eip, next_eip arguments to gen_interrupt Richard Henderson
2022-09-06 14:46 ` Philippe Mathieu-Daudé via
2022-09-21 11:51 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 05/23] target/i386: Create gen_update_eip_cur Richard Henderson
2022-09-21 11:58 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 06/23] target/i386: Create gen_update_eip_next Richard Henderson
2022-09-21 12:04 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 07/23] target/i386: Introduce DISAS_EOB* Richard Henderson
2022-09-21 12:05 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 08/23] target/i386: Use DISAS_EOB* in gen_movl_seg_T0 Richard Henderson
2022-09-21 12:09 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 09/23] target/i386: Use DISAS_EOB_NEXT Richard Henderson
2022-09-21 12:25 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 10/23] target/i386: USe DISAS_EOB_ONLY Richard Henderson
2022-09-21 12:10 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 11/23] target/i386: Create cur_insn_len, cur_insn_len_i32 Richard Henderson
2022-09-06 14:49 ` Philippe Mathieu-Daudé via
2022-09-21 12:25 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 12/23] target/i386: Remove cur_eip, next_eip arguments to gen_repz* Richard Henderson
2022-09-21 12:26 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 13/23] target/i386: Introduce DISAS_JUMP Richard Henderson
2022-09-21 12:28 ` Paolo Bonzini
2022-09-21 23:27 ` Richard Henderson
2022-09-06 10:09 ` [PATCH v2 14/23] target/i386: Truncate values for lcall_real to i32 Richard Henderson
2022-09-21 12:29 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 15/23] target/i386: Create eip_next_* Richard Henderson
2022-09-21 12:34 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 16/23] target/i386: Use DISAS_TOO_MANY to exit after gen_io_start Richard Henderson
2022-09-21 12:38 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 17/23] target/i386: Create gen_jmp_rel Richard Henderson
2022-09-21 13:06 ` Paolo Bonzini
2022-10-01 0:53 ` Richard Henderson
2022-10-01 6:54 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 18/23] target/i386: Use gen_jmp_rel for loop and jecxz insns Richard Henderson
2022-09-21 13:06 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 19/23] target/i386: Use gen_jmp_rel for gen_jcc Richard Henderson
2022-09-21 13:09 ` Paolo Bonzini
2022-10-01 1:04 ` Richard Henderson
2022-10-01 7:03 ` Paolo Bonzini
2022-10-01 13:58 ` Richard Henderson [this message]
2022-09-06 10:09 ` [PATCH v2 20/23] target/i386: Use gen_jmp_rel for gen_repz* Richard Henderson
2022-09-21 13:10 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 21/23] target/i386: Use gen_jmp_rel for DISAS_TOO_MANY Richard Henderson
2022-09-21 13:11 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 22/23] target/i386: Create gen_eip_cur Richard Henderson
2022-09-06 14:50 ` Philippe Mathieu-Daudé via
2022-09-21 13:12 ` Paolo Bonzini
2022-09-06 10:09 ` [PATCH v2 23/23] target/i386: Enable TARGET_TB_PCREL Richard Henderson
2022-09-21 13:31 ` Paolo Bonzini
2022-10-01 1:51 ` Richard Henderson
2022-09-21 13:32 ` [PATCH v2 00/23] target/i386: pc-relative translation blocks Paolo Bonzini
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