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: <20250206081225.GI7145@noisy.programming.kicks-ass.net>
Date: Thu, 6 Feb 2025 09:12:25 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.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, Feb 06, 2025 at 12:12:42PM +0900, Masami Hiramatsu (Google) 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.