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Message-ID: <FBD24A55B409E4DF+71a45adc-2e20-ea3c-a8ea-7341862991c6@tinylab.org>
Date: Thu, 31 Aug 2023 14:55:54 +0800
From: Song Shuai <songshuaishuai@...ylab.org>
To: Andreas Schwab <schwab@...e.de>
Cc: paul.walmsley@...ive.com, palmer@...belt.com,
aou@...s.berkeley.edu, mick@....forth.gr, alex@...ti.fr,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: kexec: Cleanup riscv_kexec_relocate
Hi, Andreas:
在 2023/8/30 15:24, Andreas Schwab 写道:
> On Aug 30 2023, Song Shuai wrote:
>
>> @@ -52,21 +42,27 @@ SYM_CODE_START(riscv_kexec_relocate)
>> * the start of the loop below so that we jump there in
>> * any case.
>> */
>> - la s8, 1f
>> - sub s8, s8, s7
>> - csrw CSR_STVEC, s8
>> + la s6, 1f
>> + sub s6, s6, s4
>> + csrw CSR_STVEC, s6
>> +
>> + /*
>> + * With C-extension, here we get 42 Bytes and the next
>> + * .align directive would pad zeros here up to 44 Bytes.
>> + * So manually put a nop here to avoid zeros padding.
>> + */
>> + nop
>>
>> /* Process entries in a loop */
>> .align 2
>
> While you are at it, I'd suggest being explicit about .palign
> vs. .balign.
>
How about this commemt:
Due to the stvec.BASE 4-byte alignment constraint, the following .align
(alias of .p2align) directive will align the next instruction to
a 4-byte boundary by padding zeros for this .rodata section.
With C-extension, here we get 42 Bytes and would be padded with zeros
up to 44 Bytes. So manually put a nop here to avoid it.
--
Thanks
Song Shuai
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