linux-kernel - Re: [RFC PATCH 2/2] objtool/LoongArch: Fix unreachable instruction warnings about head.S

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <l7l2ik5b2inhwbxmlae7ozrlxi7hbdjbrhjsrykjgotlhflah6@jebephhvtxki>
Date: Tue, 26 Aug 2025 16:43:49 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc: Huacai Chen <chenhuacai@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Nathan Chancellor <nathan@...nel.org>, loongarch@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] objtool/LoongArch: Fix unreachable instruction
 warnings about head.S

On Tue, Aug 26, 2025 at 08:30:23PM +0800, Tiezhu Yang wrote:
> On 2025/8/26 下午4:26, Huacai Chen wrote:
> > On Tue, Aug 26, 2025 at 2:46 PM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
> > > 
> > > When compiling with LLVM and CONFIG_LTO_CLANG is set, there exist the
> > > following objtool warnings after silencing all of the other warnings:
> 
> ...
> 
> > >   arch/loongarch/kernel/head.S | 8 ++++----
> > >   1 file changed, 4 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> > > index e3865e92a917..566a1dbf5fa0 100644
> > > --- a/arch/loongarch/kernel/head.S
> > > +++ b/arch/loongarch/kernel/head.S
> > > @@ -20,6 +20,7 @@
> > >          __HEAD
> > > 
> > >   _head:
> > > +       UNWIND_HINT_UNDEFINED
> > >          .word   IMAGE_DOS_SIGNATURE     /* "MZ", MS-DOS header */
> > >          .org    0x8
> > >          .dword  _kernel_entry           /* Kernel entry point (physical address) */
> > > @@ -30,6 +31,7 @@ _head:
> > >          .long   pe_header - _head       /* Offset to the PE header */
> > > 
> > >   pe_header:
> > > +       UNWIND_HINT_UNDEFINED
> > >          __EFI_PE_HEADER
> > The efi header is completely not code, the annotations are very strange.
> 
> Yes, I think so too, but the aim is only to not checking for objtool,
> it seems no other better way.

Objtool is only getting confused because there's data in a text section.
Why not put that in a data section?

-- 
Josh