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SubjectRe: [PATCH] riscv: vdso: fix section overlapping under some conditions
On Tue, Nov 01, 2022 at 10:19:42AM +0100, Andrew Jones wrote:
> 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@intel.com/#r
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > ---
> > 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,

Hi Andrew,

>
> 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

To be honest, I dunno. The hardcoded 0x800 was there from day1, maybe
Palmer knew the details.

> 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

Aha, I think align text to 4byte is fine. In my old memories, I was
told to align function entry at 16byte boundary, I'm not sure this
is still true.

PS: I just sent out v2 of this fix. The fix method is different and
think v2 is the correct fix while this v1 is an improvement.

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