linux-kernel - Re: [PATCH v3 44/64] x86/jump_label: Define ELF section entry size for jump labels

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

Message-ID: <dhuk7aokj2hpqy3q65uqpv7bz4pwvg2zhngyfh44y7gmiujg4y@h6s354xixgf2>
Date: Fri, 27 Jun 2025 09:55:30 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, 
	Petr Mladek <pmladek@...e.com>, Miroslav Benes <mbenes@...e.cz>, 
	Joe Lawrence <joe.lawrence@...hat.com>, live-patching@...r.kernel.org, Song Liu <song@...nel.org>, 
	laokz <laokz@...mail.com>, Jiri Kosina <jikos@...nel.org>, 
	Marcos Paulo de Souza <mpdesouza@...e.com>, Weinan Liu <wnliu@...gle.com>, 
	Fazla Mehrab <a.mehrab@...edance.com>, Chen Zhongjin <chenzhongjin@...wei.com>, 
	Puranjay Mohan <puranjay@...nel.org>, Dylan Hatch <dylanbhatch@...gle.com>
Subject: Re: [PATCH v3 44/64] x86/jump_label: Define ELF section entry size
 for jump labels

On Fri, Jun 27, 2025 at 12:48:18PM +0200, Peter Zijlstra wrote:
> > +#define JUMP_TABLE_ENTRY(key, label)				\
> > +	".pushsection __jump_table,  \"aM\", @progbits, "	\
> > +	__stringify(JUMP_ENTRY_SIZE) "\n\t"			\
> 
> Argh, can you please not do this line-break. Yes it'll be long, but this
> is most confusing.

Yeah, I'll go indent that like the extable one.

> > @@ -29,6 +30,9 @@ int main(void)
> >  #else
> >  	DEFINE(LRU_GEN_WIDTH, 0);
> >  	DEFINE(__LRU_REFS_WIDTH, 0);
> > +#endif
> > +#if defined(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE) && defined(CONFIG_JUMP_LABEL)
> 
> How is HAVE_ARCH_JUMP_LABEL_RELATIVE relevant here?

#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE

struct jump_entry {
	s32 code;
	s32 target;
	long key;	// key may be far away from the core kernel under KASLR
};

-- 
Josh