linux-kernel - Re: [PATCH v3 21/26] arm64: Introduce asm/vdso/arch

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: <20200315183151.GE32205@mbp>
Date:   Sun, 15 Mar 2020 18:32:16 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Vincenzo Frascino <vincenzo.frascino@....com>
Cc:     linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        clang-built-linux@...glegroups.com, x86@...nel.org,
        Will Deacon <will.deacon@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Russell King <linux@...linux.org.uk>,
        Paul Burton <paul.burton@...s.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Stephen Boyd <sboyd@...nel.org>,
        Mark Salyzyn <salyzyn@...roid.com>,
        Kees Cook <keescook@...omium.org>,
        Peter Collingbourne <pcc@...gle.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Andrei Vagin <avagin@...nvz.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Marc Zyngier <maz@...nel.org>,
        Mark Rutland <Mark.Rutland@....com>,
        Will Deacon <will@...nel.org>
Subject: Re: [PATCH v3 21/26] arm64: Introduce asm/vdso/arch_timer.h

On Fri, Mar 13, 2020 at 03:43:40PM +0000, Vincenzo Frascino wrote:
> The vDSO library should only include the necessary headers required for
> a userspace library (UAPI and a minimal set of kernel headers). To make
> this possible it is necessary to isolate from the kernel headers the
> common parts that are strictly necessary to build the library.
> 
> Introduce asm/vdso/arch_timer.h to contain all the arm64 specific
> code. This allows to replace the second isb() in __arch_get_hw_counter()
> with a fake dependent stack read of the counter which improves the vdso
> library peformances of ~4.5%. Below the results of vdsotest [1] ran for
> 100 iterations.

The subject seems to imply a non-functional change but as you read, it
gets a lot more complicated. Could you keep the functional change
separate from the header clean-up, maybe submit it as an independent
patch? And it shouldn't go in without Will's ack ;).

-- 
Catalin