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Re: [Qemu-devel] [PATCH 4/8] tcg: Init TB's direct jumps before making i
From: |
Sergey Fedorov |
Subject: |
Re: [Qemu-devel] [PATCH 4/8] tcg: Init TB's direct jumps before making it visible |
Date: |
Thu, 24 Mar 2016 18:58:13 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 24/03/16 18:40, Alex Bennée wrote:
> 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.
The other way around: 'tb->jmp_reset_offset[n]' are reset before calling
tcg_gen_code() and are set during tcg_gen_code() execution.
Kind regards,
Sergey
[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