From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 569F7CA9EA0 for ; Fri, 25 Oct 2019 20:51:52 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id A053C21872 for ; Fri, 25 Oct 2019 20:51:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OMpIHy66" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A053C21872 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17132-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 21691 invoked by uid 550); 25 Oct 2019 20:51:46 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 21673 invoked from network); 25 Oct 2019 20:51:45 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=SOwCMPM2O4ZOlwd3DBrA7iEvzDojcSJWVcNWTrD2V3A=; b=OMpIHy666PHw9erjn8xDTPpke8xQntbqoetTb755EO9PeDOpXuqP6XhDAI7uUr5fO2 xmVL8gs1k0UTMM90x7YH/5ifo3akIvmtUP3P99Y8UkXss+I/VMnYl83cvTyhYTBE+xXo cZnJNJr5EGcHbCKDOw5qzZmWgscClEDk8K70pc2sU5/7TsNOz3qMBup0ghahhpvfFUWg vkZUy83KnTruoWWThCWKQaNjwulexQFfxNHsd7rgNtxCf3BUJ3Swu+Hls5xYOIdyzbqN pTUp3jauqQWIFYhE31Un5fjVTn41lvbrOA703W64zMOhKqcxNHtTJHVm5pwg8QOK9PnF Ba7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SOwCMPM2O4ZOlwd3DBrA7iEvzDojcSJWVcNWTrD2V3A=; b=r1qh50fTbSAMDHj6SghNm/GZgnYdJ6JPifI85uxnmOfF1kcXC8BcyQNrA8rePBfm2Y fVxYNyu7eCG1Z8L6KoYhxkW42m/pW4tSovbFKwYc1X6tVrSC3SvTX6ikYYGXPIcA1Nax 4Z1WoTW8i92ZKKceZAmub8KNoH1rfZ5bIPfgqNPud+LMdM/qaxjNym8zprcUriskmsTg AAwyBBg/OMQRAeyXYSSCnyLkmggQ7AXMvB2VeRuCgmafr4/hlE9wEUM2WklkD9gwQSy9 eXoBo2Nn1DBkBXYL3tXGNtuQQObFOnODLhES6LM9bEm4PAkUAJE9anXZwy2FrQPYm/Zx iikQ== X-Gm-Message-State: APjAAAX+XQSBmZ8nrLO705R2JPrgP3KFHBEJyItnLOmJjfF6RYrJxwQS J1h3A+hZmguXIVFiLF08J9LYE9y5C14mpJ7L8nRF1w== X-Google-Smtp-Source: APXvYqwitHy/uW9BgFO85xlL31gu4CkfssJm5Y58pk3pu/OFECEhzo8ZcmTg1xeRhUyxbxF5+qEX2qRHXCg/5F+6CB8= X-Received: by 2002:a67:ed8b:: with SMTP id d11mr3107850vsp.104.1572036693631; Fri, 25 Oct 2019 13:51:33 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191024225132.13410-1-samitolvanen@google.com> <20191024225132.13410-6-samitolvanen@google.com> In-Reply-To: From: Sami Tolvanen Date: Fri, 25 Oct 2019 13:51:22 -0700 Message-ID: Subject: Re: [PATCH v2 05/17] add support for Clang's Shadow Call Stack (SCS) To: Nick Desaulniers Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux , Kernel Hardening , Linux ARM , LKML Content-Type: text/plain; charset="UTF-8" On Fri, Oct 25, 2019 at 9:22 AM Nick Desaulniers wrote: > > +static void scs_free(void *s) > > +{ > > + int i; > > + > > + for (i = 0; i < SCS_CACHE_SIZE; i++) { > > + if (this_cpu_cmpxchg(scs_cache[i], 0, s) != 0) > > + continue; > > + > > + return; > > + } > > prefer: > > for ...: > if foo() == 0: > return > > to: > > for ...: > if foo() != 0: > continue > return This was essentially copied from free_thread_stack in kernel/fork.c, but I agree, your way is cleaner. I'll change this in the next version. Thanks! Sami