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From: Andreas Schwab <schwab@linux-m68k.org>
To: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
Cc: linux-riscv <linux-riscv@lists.infradead.org>
Subject: Re: [Request for help] issue when add relative extable support to riscv64
Date: Sun, 10 Oct 2021 18:59:14 +0200	[thread overview]
Message-ID: <87ee8sg6jh.fsf@igel.home> (raw)
In-Reply-To: <20211010235655.35c55e61@xhacker> (Jisheng Zhang's message of "Sun, 10 Oct 2021 23:56:55 +0800")

On Okt 10 2021, Jisheng Zhang wrote:

> a simple code:
>
> 	nop
> 1:
> .section __ex_table,"a"
> 	.align 3
> 	.long (1b - .)
>
> assemble it, then we can see that there are two entries for the above
> label substraction, R_RISCV_ADD32 and R_RISCV_SUB32
>
> Relocation section '.rela__ex_table' at offset 0x108 contains 2 entries:
>   Offset          Info           Type           Sym. Value    Sym. Name + Addend
> 000000000000  000600000023 R_RISCV_ADD32     0000000000000002 .L1^B1 + 0
> 000000000000  000500000027 R_RISCV_SUB32     0000000000000000 .L0  + 0
>
> The 2nd R_RISCV_SUB32 rela entry causes the problem.
>
> Can we prevent assembler from emitting the R_RISCV_SUB32 rela entry?

There is R_RISCV_32_PCREL, but I guess it isn't used here because it was
a late addition.  The assembler uses it only in a very special situation
(FDE initial location).

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
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      reply	other threads:[~2021-10-10 16:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17 15:57 [Request for help] issue when add relative extable support to riscv64 Jisheng Zhang
2021-09-17 16:26 ` Jisheng Zhang
2021-09-18  1:23   ` Kefeng Wang
2021-09-18 14:20     ` Jisheng Zhang
2021-10-10 15:56 ` Jisheng Zhang
2021-10-10 16:59   ` Andreas Schwab [this message]

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