Re: [PATCH] riscv: vdso: fix section overlapping under some conditions

[Andrew Jones]

On Tue, Nov 01, 2022 at 01:58:42AM +0800, Jisheng Zhang wrote:
> lkp reported a build error, I tried the config and can reproduce
> build error as below:
> 
>   VDSOLD  arch/riscv/kernel/vdso/vdso.so.dbg
> ld.lld: error: section .note file range overlaps with .text
> >>> .note range is [0x7C8, 0x803]
> >>> .text range is [0x800, 0x1993]
> 
> ld.lld: error: section .text file range overlaps with .dynamic
> >>> .text range is [0x800, 0x1993]
> >>> .dynamic range is [0x808, 0x937]
> 
> ld.lld: error: section .note virtual address range overlaps with .text
> >>> .note range is [0x7C8, 0x803]
> >>> .text range is [0x800, 0x1993]
> 
> Fix it by removing the hardcoding 0x800 and related comments.
> 
> Link: https://lore.kernel.org/lkml/202210122123.Cc4FPShJ-lkp@xxxxxxxxx/#r
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>
> ---
>  arch/riscv/kernel/vdso/vdso.lds.S | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S
> index 01d94aae5bf5..344209d2e128 100644
> --- a/arch/riscv/kernel/vdso/vdso.lds.S
> +++ b/arch/riscv/kernel/vdso/vdso.lds.S
> @@ -31,13 +31,7 @@ SECTIONS
>  
>  	.rodata		: { *(.rodata .rodata.* .gnu.linkonce.r.*) }
>  
> -	/*
> -	 * This linker script is used both with -r and with -shared.
> -	 * For the layouts to match, we need to skip more than enough
> -	 * space for the dynamic symbol table, etc. If this amount is
> -	 * insufficient, ld -shared will error; simply increase it here.
> -	 */
> -	. = 0x800;

Hi Jisheng,

Removing this hard coded value is a good thing, but I don't understand
why, if it was necessary before, that it's no longer necessary. Can you
please explain that in the commit message? If the linker improved in
this regard, then do we need to document a new minimum linker version?

> +	. = ALIGN(16);

Aligning text to a 4-byte boundary makes sense to me, but I don't
understand the 16-byte boundary requirement. Can you please explain
this for my education?

Thanks,
drew

>  	.text		: { *(.text .text.*) }		:text
>  
>  	.data		: {
> -- 
> 2.37.2
> 
> 
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