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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=ouPoIbaznwUvpvUZ+d9Lmd0+7ZlkFrw9Vubc0luuMm4=; b=X6oTwWMiZa/9lbhmVywut3hgb/m9KZJgfGqqaDLaCOca0PdKHn9M5CjXsn3nAkx6uO lC5hXqv39ELltVkF/cXUbgcpAQkrvWMTU8aybbQG+D38XLUrEbtMlytFebk18oYiUBgT Ty23qWWBbO51yB979nxy79NUzuu5NLqPtqgtkKdnXiBHDYmlqjzJ1EL96DP9MAVmDbgp 86sy9Foqw451jlY6mKuDCrJpEaDMGd6R1bnrG9VyfMY/xRwYmZkRp/PoaHY4V9yFnC1r krpzteMC8/Jwf7znFstgPRu9zSlwNAP4E2q+rVOube88iesd7f25DdJIg3/aJS0WiSx3 xKbw== X-Gm-Message-State: AOAM5331hJ7pWp5tVF3K/6t//7U3jw3NdNyqrKec186fpX3nKGZqWv15 VG6/jqMvlsWq6LsKTsIkUBYuaRutMbXAz+9t/0z86g== X-Google-Smtp-Source: ABdhPJxAkNoEdvBMsNoiwT/xtC3KzAJM3mngqfnMyotl0K4+5QQM9nsSc91iJTIh6/lQ8mnSCUp3b+j2mW212gFA81Q= X-Received: by 2002:a17:906:6959:: with SMTP id c25mr9393908ejs.375.1595008082575; Fri, 17 Jul 2020 10:48:02 -0700 (PDT) MIME-Version: 1.0 References: <20200624203200.78870-1-samitolvanen@google.com> <20200624203200.78870-5-samitolvanen@google.com> <20200624212737.GV4817@hirez.programming.kicks-ass.net> <20200624214530.GA120457@google.com> <20200625074530.GW4817@hirez.programming.kicks-ass.net> <20200625161503.GB173089@google.com> <20200625200235.GQ4781@hirez.programming.kicks-ass.net> <20200625224042.GA169781@google.com> <20200626112931.GF4817@hirez.programming.kicks-ass.net> <20200717133645.7816c0b6@oasis.local.home> In-Reply-To: <20200717133645.7816c0b6@oasis.local.home> From: Sami Tolvanen Date: Fri, 17 Jul 2020 10:47:51 -0700 Message-ID: Subject: Re: [RFC][PATCH] objtool,x86_64: Replace recordmcount with objtool To: Steven Rostedt X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200717_134804_105842_0CBD9966 X-CRM114-Status: GOOD ( 22.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch , X86 ML , Kees Cook , "Paul E. McKenney" , Kernel Hardening , Peter Zijlstra , Greg Kroah-Hartman , Masahiro Yamada , linux-kbuild , Nick Desaulniers , LKML , clang-built-linux , Josh Poimboeuf , linux-pci@vger.kernel.org, Will Deacon , linux-arm-kernel , Matt Helsley Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 17, 2020 at 10:36 AM Steven Rostedt wrote: > > On Fri, 17 Jul 2020 10:28:13 -0700 > Sami Tolvanen wrote: > > > On Fri, Jun 26, 2020 at 4:29 AM Peter Zijlstra wrote: > > > > > > On Thu, Jun 25, 2020 at 03:40:42PM -0700, Sami Tolvanen wrote: > > > > > > > > Not boot tested, but it generates the required sections and they look > > > > > more or less as expected, ymmv. > > > > > > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > > > > index a291823f3f26..189575c12434 100644 > > > > > --- a/arch/x86/Kconfig > > > > > +++ b/arch/x86/Kconfig > > > > > @@ -174,7 +174,6 @@ config X86 > > > > > select HAVE_EXIT_THREAD > > > > > select HAVE_FAST_GUP > > > > > select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE > > > > > - select HAVE_FTRACE_MCOUNT_RECORD > > > > > select HAVE_FUNCTION_GRAPH_TRACER > > > > > select HAVE_FUNCTION_TRACER > > > > > select HAVE_GCC_PLUGINS > > > > > > > > This breaks DYNAMIC_FTRACE according to kernel/trace/ftrace.c: > > > > > > > > #ifndef CONFIG_FTRACE_MCOUNT_RECORD > > > > # error Dynamic ftrace depends on MCOUNT_RECORD > > > > #endif > > > > > > > > And the build errors after that seem to confirm this. It looks like we might > > > > need another flag to skip recordmcount. > > > > > > Hurm, Steve, how you want to do that? > > > > Steven, did you have any thoughts about this? Moving recordmcount to > > an objtool pass that knows about call sites feels like a much cleaner > > solution than annotating kernel code to avoid unwanted relocations. > > > > Bah, I started to reply to this then went to look for details, got > distracted, forgot about it, my laptop crashed (due to a zoom call), > and I lost the email I was writing (haven't looked in the drafts > folder, but my idea about this has changed since anyway). > > So the problem is that we process mcount references in other areas and > that confuses the ftrace modification portion? Correct. > Someone just submitted a patch for arm64 for this: > > https://lore.kernel.org/r/20200717143338.19302-1-gregory.herrero@oracle.com > > Is that what you want? That looks like the same issue, but we need to fix this on x86 instead. Sami _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel