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Re: [PATCH 62/77] target/microblaze: Try to keep imm and delay slot toge
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From: |
Richard Henderson |
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Subject: |
Re: [PATCH 62/77] target/microblaze: Try to keep imm and delay slot together |
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Date: |
Thu, 27 Aug 2020 14:33:32 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 |
On 8/27/20 12:17 PM, Edgar E. Iglesias wrote:
> On Tue, Aug 25, 2020 at 01:59:35PM -0700, Richard Henderson wrote:
>> If the last insn on a page is imm, or a branch with delay slot,
>> then end a tb early if this has not begun the tb. If it has
>> begun the tb, then we can allow the tb to span two pages as if
>> the imm plus its consumer, or branch plus delay, or imm plus
>> branch plus delay, are a single insn.
>>
>> If the insn in the delay slot faults, then the exception handler
>> will have reset the PC to the beginning of this sequence anyway,
>> via the stored D_FLAG and BIMM_FLAG bits.
>>
>> Disable all of this when single-stepping.
>
>
> Hi Richard,
>
> We've got a Linux boot that fails after applying this patch.
> It goes from always working to only working like 1 out of 3 times.
> It fails deep in user-space so I don't have a good log for it.
Hmm. Let's just put this off for now. I'm not 100% happy with it anyway,
since it adjusts the data structures in weird ways.
r~
- [PATCH 54/77] target/microblaze: Assert no overlap in flags making up tb_flags, (continued)
- [PATCH 54/77] target/microblaze: Assert no overlap in flags making up tb_flags, Richard Henderson, 2020/08/25
- [PATCH 57/77] tcg: Add tcg_get_insn_start_param, Richard Henderson, 2020/08/25
- [PATCH 55/77] target/microblaze: Move bimm to BIMM_FLAG, Richard Henderson, 2020/08/25
- [PATCH 56/77] target/microblaze: Store "current" iflags in insn_start, Richard Henderson, 2020/08/25
- [PATCH 58/77] target/microblaze: Use cc->do_unaligned_access, Richard Henderson, 2020/08/25
- [PATCH 59/77] target/microblaze: Replace clear_imm with tb_flags_to_set, Richard Henderson, 2020/08/25
- [PATCH 60/77] target/microblaze: Replace delayed_branch with tb_flags_to_set, Richard Henderson, 2020/08/25
- [PATCH 61/77] target/microblaze: Tidy mb_cpu_dump_state, Richard Henderson, 2020/08/25
- [PATCH 62/77] target/microblaze: Try to keep imm and delay slot together, Richard Henderson, 2020/08/25
- [PATCH 63/77] target/microblaze: Convert brk and brki to decodetree, Richard Henderson, 2020/08/25
- [PATCH 64/77] target/microblaze: Convert mbar to decodetree, Richard Henderson, 2020/08/25
[PATCH 65/77] target/microblaze: Reorganize branching, Richard Henderson, 2020/08/25
[PATCH 66/77] target/microblaze: Use tcg_gen_lookup_and_goto_ptr, Richard Henderson, 2020/08/25