linux-kernel - Re: [PATCH] ftrace: x86: Fix a compile error about get_kernel

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: <20250206205449.5f83a585945ae6eb0cc15483@kernel.org>
Date: Thu, 6 Feb 2025 20:54:49 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>, Gabriel de Perthuis
 <g2p.code@...il.com>, Haiyue Wang <haiyuewa@....com>, Sami Tolvanen
 <samitolvanen@...gle.com>, Mark Rutland <mark.rutland@....com>, Thomas
 Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav
 Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
 linux-trace-kernel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ftrace: x86: Fix a compile error about
 get_kernel_nofault()

On Thu, 6 Feb 2025 09:12:25 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> 
> > +#ifdef CONFIG_HAVE_FENTRY
> > +/* Convert fentry address to the symbol address. */
> > +unsigned long arch_ftrace_get_symaddr(unsigned long fentry_ip)
> > +{
> > +#ifdef CONFIG_X86_KERNEL_IBT
> > +	u32 instr;
> > +
> > +	/* We want to be extra safe in case entry ip is on the page edge,
> > +	 * but otherwise we need to avoid get_kernel_nofault()'s overhead.
> > +	 */
> > +	if ((fentry_ip & ~PAGE_MASK) < ENDBR_INSN_SIZE) {
> > +		if (get_kernel_nofault(instr, (u32 *)(fentry_ip - ENDBR_INSN_SIZE)))
> > +			return fentry_ip;
> > +	} else {
> > +		instr = *(u32 *)(fentry_ip - ENDBR_INSN_SIZE);
> > +	}
> > +	if (is_endbr(instr))
> > +		fentry_ip -= ENDBR_INSN_SIZE;
> > +#endif
> > +	return fentry_ip;
> > +}
> > +#endif
> 
> Urgh, that reminds, me. I have a pile of patches cleaning up this mess.
> Let me go find them.

Thanks for cleaning up! So would it change the location of ENDBR and
symbol address?

Thanks,

-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>