* [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections
@ 2020-10-28 13:33 Ard Biesheuvel
2020-10-28 15:12 ` Will Deacon
2020-10-28 15:56 ` Kees Cook
0 siblings, 2 replies; 5+ messages in thread
From: Ard Biesheuvel @ 2020-10-28 13:33 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Kees Cook, catalin.marinas, Nick Desaulniers, Geert Uytterhoeven,
Jessica Yu, will, Ard Biesheuvel
Now that we started making the linker warn about orphan sections
(input sections that are not explicitly consumed by an output section),
some configurations produce the following warning:
aarch64-linux-gnu-ld: warning: orphan section `.igot.plt' from
`arch/arm64/kernel/head.o' being placed in section `.igot.plt'
It could be any file that triggers this - head.o is simply the first
input file in the link - and the resulting .igot.plt section never
actually appears in vmlinux as it turns out to be empty.
So let's add .igot.plt to our collection of input sections to disregard
unless they are empty.
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/kernel/vmlinux.lds.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 6567d80dd15f..48b222f1c700 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -278,7 +278,7 @@ SECTIONS
* explicitly check instead of blindly discarding.
*/
.plt : {
- *(.plt) *(.plt.*) *(.iplt) *(.igot)
+ *(.plt) *(.plt.*) *(.iplt) *(.igot .igot.plt)
}
ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!")
--
2.17.1
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^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections
2020-10-28 13:33 [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections Ard Biesheuvel
@ 2020-10-28 15:12 ` Will Deacon
2020-10-28 15:56 ` Kees Cook
1 sibling, 0 replies; 5+ messages in thread
From: Will Deacon @ 2020-10-28 15:12 UTC (permalink / raw)
To: Ard Biesheuvel, linux-arm-kernel
Cc: Kees Cook, Will Deacon, catalin.marinas, Nick Desaulniers,
Geert Uytterhoeven, Jessica Yu, kernel-team
On Wed, 28 Oct 2020 14:33:32 +0100, Ard Biesheuvel wrote:
> Now that we started making the linker warn about orphan sections
> (input sections that are not explicitly consumed by an output section),
> some configurations produce the following warning:
>
> aarch64-linux-gnu-ld: warning: orphan section `.igot.plt' from
> `arch/arm64/kernel/head.o' being placed in section `.igot.plt'
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] arm64: vmlinux.lds: account for spurious empty .igot.plt sections
https://git.kernel.org/arm64/c/5f692a81b4e9
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections
2020-10-28 13:33 [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections Ard Biesheuvel
2020-10-28 15:12 ` Will Deacon
@ 2020-10-28 15:56 ` Kees Cook
2020-10-28 15:58 ` Ard Biesheuvel
2020-10-28 17:47 ` Will Deacon
1 sibling, 2 replies; 5+ messages in thread
From: Kees Cook @ 2020-10-28 15:56 UTC (permalink / raw)
To: Ard Biesheuvel
Cc: catalin.marinas, Nick Desaulniers, Geert Uytterhoeven, Jessica Yu,
will, linux-arm-kernel
On Wed, Oct 28, 2020 at 02:33:32PM +0100, Ard Biesheuvel wrote:
> Now that we started making the linker warn about orphan sections
> (input sections that are not explicitly consumed by an output section),
> some configurations produce the following warning:
>
> aarch64-linux-gnu-ld: warning: orphan section `.igot.plt' from
> `arch/arm64/kernel/head.o' being placed in section `.igot.plt'
>
> It could be any file that triggers this - head.o is simply the first
> input file in the link - and the resulting .igot.plt section never
> actually appears in vmlinux as it turns out to be empty.
>
> So let's add .igot.plt to our collection of input sections to disregard
> unless they are empty.
typo: "non-empty"?
> Cc: Jessica Yu <jeyu@kernel.org>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Thanks! Any idea what causes this?
Reviewed-by: Kees Cook <keescook@chromium.org>
Though I think Will already snagged the patch :)
--
Kees Cook
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections
2020-10-28 15:56 ` Kees Cook
@ 2020-10-28 15:58 ` Ard Biesheuvel
2020-10-28 17:47 ` Will Deacon
1 sibling, 0 replies; 5+ messages in thread
From: Ard Biesheuvel @ 2020-10-28 15:58 UTC (permalink / raw)
To: Kees Cook
Cc: Catalin Marinas, Nick Desaulniers, Geert Uytterhoeven, Jessica Yu,
Will Deacon, Linux ARM
On Wed, 28 Oct 2020 at 16:56, Kees Cook <keescook@chromium.org> wrote:
>
> On Wed, Oct 28, 2020 at 02:33:32PM +0100, Ard Biesheuvel wrote:
> > Now that we started making the linker warn about orphan sections
> > (input sections that are not explicitly consumed by an output section),
> > some configurations produce the following warning:
> >
> > aarch64-linux-gnu-ld: warning: orphan section `.igot.plt' from
> > `arch/arm64/kernel/head.o' being placed in section `.igot.plt'
> >
> > It could be any file that triggers this - head.o is simply the first
> > input file in the link - and the resulting .igot.plt section never
> > actually appears in vmlinux as it turns out to be empty.
> >
> > So let's add .igot.plt to our collection of input sections to disregard
> > unless they are empty.
>
> typo: "non-empty"?
>
Indeed.
> > Cc: Jessica Yu <jeyu@kernel.org>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> > Cc: Nick Desaulniers <ndesaulniers@google.com>
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
>
> Thanks! Any idea what causes this?
>
Not a clue.
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
Thanks,
> Though I think Will already snagged the patch :)
>
> --
> Kees Cook
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections
2020-10-28 15:56 ` Kees Cook
2020-10-28 15:58 ` Ard Biesheuvel
@ 2020-10-28 17:47 ` Will Deacon
1 sibling, 0 replies; 5+ messages in thread
From: Will Deacon @ 2020-10-28 17:47 UTC (permalink / raw)
To: Kees Cook
Cc: catalin.marinas, Nick Desaulniers, Geert Uytterhoeven, Jessica Yu,
Ard Biesheuvel, linux-arm-kernel
On Wed, Oct 28, 2020 at 08:56:14AM -0700, Kees Cook wrote:
> On Wed, Oct 28, 2020 at 02:33:32PM +0100, Ard Biesheuvel wrote:
> > Now that we started making the linker warn about orphan sections
> > (input sections that are not explicitly consumed by an output section),
> > some configurations produce the following warning:
> >
> > aarch64-linux-gnu-ld: warning: orphan section `.igot.plt' from
> > `arch/arm64/kernel/head.o' being placed in section `.igot.plt'
> >
> > It could be any file that triggers this - head.o is simply the first
> > input file in the link - and the resulting .igot.plt section never
> > actually appears in vmlinux as it turns out to be empty.
> >
> > So let's add .igot.plt to our collection of input sections to disregard
> > unless they are empty.
>
> typo: "non-empty"?
>
> > Cc: Jessica Yu <jeyu@kernel.org>
> > Cc: Kees Cook <keescook@chromium.org>
> > Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> > Cc: Nick Desaulniers <ndesaulniers@google.com>
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
>
> Thanks! Any idea what causes this?
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> Though I think Will already snagged the patch :)
Yeah, sorry -- I was keen to get rid of that annoying warning!
Will
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2020-10-28 13:33 [PATCH] arm64: vmlinux.lds: account for spurious empty .igot.plt sections Ard Biesheuvel
2020-10-28 15:12 ` Will Deacon
2020-10-28 15:56 ` Kees Cook
2020-10-28 15:58 ` Ard Biesheuvel
2020-10-28 17:47 ` Will Deacon
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