linux-kernel - Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

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: <20241108193204.GC38972@noisy.programming.kicks-ass.net>
Date: Fri, 8 Nov 2024 20:32:04 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Colton Lewis <coltonlewis@...gle.com>
Cc: kvm@...r.kernel.org, oliver.upton@...ux.dev, seanjc@...gle.com,
	mingo@...hat.com, acme@...nel.org, namhyung@...nel.org,
	mark.rutland@....com, alexander.shishkin@...ux.intel.com,
	jolsa@...nel.org, irogers@...gle.com, adrian.hunter@...el.com,
	kan.liang@...ux.intel.com, will@...nel.org, linux@...linux.org.uk,
	catalin.marinas@....com, mpe@...erman.id.au, npiggin@...il.com,
	christophe.leroy@...roup.eu, naveen@...nel.org, hca@...ux.ibm.com,
	gor@...ux.ibm.com, agordeev@...ux.ibm.com,
	borntraeger@...ux.ibm.com, svens@...ux.ibm.com, tglx@...utronix.de,
	bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
	hpa@...or.com, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org
Subject: Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

On Fri, Nov 08, 2024 at 08:20:44PM +0100, Peter Zijlstra wrote:

> Isn't the below more or less what you want?
> 
> static unsigned long misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags = 0;
> 
> 	if (regs->flags & PERF_EFLAGS_EXACT)
> 		flags |= PERF_RECORD_MISC_EXACT_IP;
> 
> 	return flags;
> }
> 
> static unsigned long native_flags(struct pt_regs *regs)
> {
> 	unsigned long flags = 0;
> 
> 	if (user_mode(regs))
> 		flags |= PERF_RECORD_MISC_USER;
> 	else
> 		flags |= PERF_RECORD_MISC_KERNEL;
> 
> 	return flags;
> }
> 
> static unsigned long guest_flags(struct pt_regs *regs)
> {
> 	unsigned long guest_state = perf_guest_state();
> 	unsigned long flags = 0;
> 
> 	if (guest_state & PERF_GUEST_ACTIVE) {
> 		if (guest_state & PERF_GUEST_USER)
> 			flags |= PERF_RECORD_MISC_GUEST_USER;
> 		else
> 			flags |= PERF_RECORD_MISC_GUEST_KERNEL;
> 	}
> 
> 	return flags;
> }
> 
> unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags;
> 
> 	flags = misc_flags(regs);
> 	flags |= guest_flags(regs);
> 
> 	return flags;
> }
> 
> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
> {
> 	unsigned long flags;
> 	unsigned long guest;
> 
> 	flags = misc_flags(regs);
> 	guest = guest_flags(regs);
> 	if (guest)
> 		flags |= guest;
> 	else
> 		flags |= native_flags(regs);
> 
> 	return flags;
> }

This last can be written more concise:

unsigned long perf_arch_misc_flags(struct pt_regs *regs)
{
	unsigned long flags;

	flags = guest_flags(regs);
	if (!flags)
		flags |= native_flags(regs);

	flgs |= misc_flags(regs);

	return flags;
}