linux-kernel - Re: [PATCH] powerpc/vmlinux.lds: Drop .interp description

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Message-ID: <aP8jT3XY3kQUCwFQ@linux.ibm.com>
Date: Mon, 27 Oct 2025 13:16:23 +0530
From: Vishal Chourasia <vishalc@...ux.ibm.com>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
        Bill Wendling <morbo@...gle.com>,
        Justin Stitt <justinstitt@...gle.com>, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] powerpc/vmlinux.lds: Drop .interp description

ping.

what's the status for this patch?

vishalc


On Tue, Oct 21, 2025 at 01:48:31PM +0530, Vishal Chourasia wrote:
> On Sat, Oct 18, 2025 at 06:52:40PM +0100, Nathan Chancellor wrote:
> > Commit da30705c4621 ("arch/powerpc: Remove .interp section in vmlinux")
> > intended to drop the .interp section from vmlinux but even with this
> > change, relocatable kernels linked with ld.lld contain an empty .interp
> > section, which ends up causing crashes in GDB [1].
> > 
> >   $ make -skj"$(nproc)" ARCH=powerpc LLVM=1 clean pseries_le_defconfig vmlinux
> > 
> >   $ llvm-readelf -S vmlinux | grep interp
> >     [44] .interp           PROGBITS        c0000000021ddb34 21edb34 000000 00   A  0   0  1
> > 
> > There appears to be a subtle difference between GNU ld and ld.lld when
> > it comes to discarding sections that specify load addresses [2].
> > 
> > Since '--no-dynamic-linker' prevents emission of the .interp section,
> > there is no need to describe it in the output sections of the vmlinux
> > linker script. Drop the .interp section description from vmlinux.lds.S
> > to avoid this issue altogether.
> > 
> > Link: https://sourceware.org/bugzilla/show_bug.cgi?id=33481 [1]
> > Link: https://github.com/ClangBuiltLinux/linux/issues/2137 [2]
> > Reported-by: Vishal Chourasia <vishalc@...ux.ibm.com>
> > Closes: https://lore.kernel.org/20251013040148.560439-1-vishalc@linux.ibm.com/
> > Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> > ---
> >  arch/powerpc/kernel/vmlinux.lds.S | 1 -
> >  1 file changed, 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
> > index de6ee7d35cff..15850296c0a9 100644
> > --- a/arch/powerpc/kernel/vmlinux.lds.S
> > +++ b/arch/powerpc/kernel/vmlinux.lds.S
> > @@ -330,7 +330,6 @@ SECTIONS
> >  	}
> >  	.hash : AT(ADDR(.hash) - LOAD_OFFSET) { *(.hash) }
> >  	.gnu.hash : AT(ADDR(.gnu.hash) - LOAD_OFFSET) { *(.gnu.hash) }
> > -	.interp : AT(ADDR(.interp) - LOAD_OFFSET) { *(.interp) }
> >  	.rela.dyn : AT(ADDR(.rela.dyn) - LOAD_OFFSET)
> >  	{
> >  		__rela_dyn_start = .;
> > 
> > ---
> > base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
> > change-id: 20251018-ppc-fix-lld-interp-1a78c361cd42
> > 
> 
> With this patch, I don't see .interp section being emitted the final
> vmlinux binary.
> 
> ```
> (i) ❯ make LLVM=1 vmlinux
> (i) ❯ llvm-readelf -p .comment vmlinux
> 
> String dump of section '.comment':
> [     1] clang version 22.0.0git (https://github.com/llvm/llvm-project.git 7314565281ec28b745502c3f429fd431e16673eb)
> [    6d] Linker: LLD 22.0.0 (https://github.com/llvm/llvm-project.git 7314565281ec28b745502c3f429fd431e16673eb)
> 
> (i) ❯ llvm-readelf -p .interp vmlinux
> llvm-readelf: warning: 'vmlinux': could not find section '.interp'
> ```
> 
> Tested-by: Vishal Chourasia <vishalc@...ux.ibm.com>