linux-kernel - Re: linux-next: build warnings after merge of the tip tree

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: <Yjis6hJKUj/WrSwK@hirez.programming.kicks-ass.net>
Date:   Mon, 21 Mar 2022 17:50:50 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        mhiramat@...nel.org, ast@...nel.org, hjl.tools@...il.com,
        rick.p.edgecombe@...el.com, rppt@...nel.org,
        linux-toolchains@...r.kernel.org, Andrew.Cooper3@...rix.com,
        ndesaulniers@...gle.com
Subject: Re: linux-next: build warnings after merge of the tip tree

On Mon, Mar 21, 2022 at 12:45:51PM -0400, Steven Rostedt wrote:
> On Mon, 21 Mar 2022 17:40:32 +0100
> Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > func_B:
> > 	call __fentry__	/* push func_B */
> > 	...
> > 	call __fexit__	/* pop 1 + tails */
> > 	ret
> > 
> > func_A:
> > 	call __fentry__ /* push func_A */
> > 	...
> > 	call __ftail__  /* mark func_A tail */
> > 	jmp func_B
> > 
> > func_C:
> > 	call __fentry__ /* push func_C */
> > 	call func_A;
> > 	...
> > 	call __fexit__  /* pop 1 + tails */
> > 	ret;
> 
> This also assumes that we need to trace everything that is marked. I
> mentioned in another email, what do we do if we only trace funcA?

Like I said later on; if we inhibit tail-calls to notrace, this goes
away.