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Re: [Qemu-devel] [PATCH 4/8] tcg: Init TB's direct jumps before making i
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 4/8] tcg: Init TB's direct jumps before making it visible |
Date: |
Thu, 24 Mar 2016 15:40:25 +0000 |
User-agent: |
mu4e 0.9.17; emacs 25.0.92.7 |
Sergey Fedorov <address@hidden> writes:
> On 24/03/16 18:11, Alex Bennée wrote:
>> address@hidden writes:
>>> From: Sergey Fedorov <address@hidden>
>>>
>>> diff --git a/translate-all.c b/translate-all.c
>>> index ca01dd325b8d..f68716e1819f 100644
>>> --- a/translate-all.c
>>> +++ b/translate-all.c
>>> @@ -1131,19 +1131,6 @@ static void tb_link_page(TranslationBlock *tb,
>>> tb_page_addr_t phys_pc,
>>> tb->page_addr[1] = -1;
>>> }
>>>
>>> - assert(((uintptr_t)tb & 3) == 0);
>>> - tb->jmp_list_first = (uintptr_t)tb | 2;
>>> - tb->jmp_list_next[0] = (uintptr_t)NULL;
>>> - tb->jmp_list_next[1] = (uintptr_t)NULL;
>>> -
>>> - /* init original jump addresses */
>>> - if (tb->jmp_reset_offset[0] != TB_JMP_RESET_OFFSET_INVALID) {
>>> - tb_reset_jump(tb, 0);
>>> - }
>>> - if (tb->jmp_reset_offset[1] != TB_JMP_RESET_OFFSET_INVALID) {
>>> - tb_reset_jump(tb, 1);
>>> - }
>>> -
>>> #ifdef DEBUG_TB_CHECK
>>> tb_page_check();
>>> #endif
>>> @@ -1251,6 +1238,20 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
>>> ROUND_UP((uintptr_t)gen_code_buf + gen_code_size + search_size,
>>> CODE_GEN_ALIGN);
>>>
>>> + /* init jump list */
>>> + assert(((uintptr_t)tb & 3) == 0);
>>> + tb->jmp_list_first = (uintptr_t)tb | 2;
>>> + tb->jmp_list_next[0] = (uintptr_t)NULL;
>>> + tb->jmp_list_next[1] = (uintptr_t)NULL;
>> maybe these should be further up the function with the other jmp setting
>> code?
>
> I meant to keep them together with the following lines.
>
>>
>>> +
>>> + /* init original jump addresses */
>>> + if (tb->jmp_reset_offset[0] != TB_JMP_RESET_OFFSET_INVALID) {
>>> + tb_reset_jump(tb, 0);
>>> + }
>>> + if (tb->jmp_reset_offset[1] != TB_JMP_RESET_OFFSET_INVALID) {
>>> + tb_reset_jump(tb, 1);
>>> + }
>> Why would tb->jmp_reset_offset[0] == TB_JMP_RESET_OFFSET_INVALID not be
>> the case as it is set a few lines further up.
>
> Because tcg_gen_code() gets called in between and it is passed
> '&tcg_ctx' which holds a pointer to 'tb->jmp_reset_offset'. tcg_out_op()
> is called from tcg_gen_code() and sets 'tb->jmp_reset_offset[n]'
> indirectly, as well as 'tb->jmp_insn_offset[n]'.
OK a quick addition to the comment: "these may have been reset in
tcg_gen_code" would be helpful here.
>
> Kind regards,
> Sergey
--
Alex Bennée
[Qemu-devel] [PATCH 7/8] tcg: Extract removing of jumps to TB from tb_phys_invalidate(), sergey . fedorov, 2016/03/24
Re: [Qemu-devel] [PATCH 0/8] tcg: Direct block chaining clean-up, Paolo Bonzini, 2016/03/24