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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=SpNwJfSJO9MidRCrn2p9uupIwuhjvEPSgYuh9TBYZuw=; b=nemoOrjuqmts+chzdp0hfyOqmYOMLnWKxLVcExiImslnyxxyIcmEMpKdw9s3vDm3Uv SzgvY7kn/l9CeED3Qvr+mQ/qnwwqFYSyV9DZW+1iPADMEEbOSFkEvj+fEtWzwMqsPT2L 5AEOziSlq01ay9gjzqdFICUZSG4V8lu4ooxrfYdqtRPO3+mSkvvxGUmjbt1yQMbVbZRA eYmokh8+xltWNuqog6iUbV1oDawA2DePcqN0txASR4rSfmwrFNjBOPwgzvU5+lzYPIqb oGux/BeHzL0xVqDym9OE8Ba9ZbAYit7DkCkZj20YBzPPWZF589dwqnW1jw9ZoS7QWBX2 h0sg== X-Gm-Message-State: APjAAAX2EOcHq6uT0pcxnpiikUXnCIF0Y/RjbuUMJJBl+x7GmJJr9OqM NwK9OMd8VDflzE3aiwwUP+YskPBEV5++W94YFt24og== X-Google-Smtp-Source: APXvYqwMrHXnmCbhr/Nl5pMJrYHuxKP6Lu2UQKV7ItSK55vLCW1x6A4Use4SMcLe4G85I9Dvt99c2soxGNjz4r8rNRQ= X-Received: by 2002:ab0:4587:: with SMTP id u7mr3850575uau.67.1572911090684; Mon, 04 Nov 2019 15:44:50 -0800 (PST) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191101221150.116536-1-samitolvanen@google.com> <20191101221150.116536-12-samitolvanen@google.com> <20191104171132.GB2024@lakrids.cambridge.arm.com> In-Reply-To: <20191104171132.GB2024@lakrids.cambridge.arm.com> From: Sami Tolvanen Date: Mon, 4 Nov 2019 15:44:39 -0800 Message-ID: Subject: Re: [PATCH v4 11/17] arm64: disable function graph tracing with SCS To: Mark Rutland X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191104_154452_504258_587B0092 X-CRM114-Status: GOOD ( 11.53 ) 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: Kees Cook , Ard Biesheuvel , Masahiro Yamada , Catalin Marinas , Jann Horn , Nick Desaulniers , LKML , Steven Rostedt , Miguel Ojeda , clang-built-linux , Masami Hiramatsu , Marc Zyngier , Kernel Hardening , Laura Abbott , Will Deacon , Dave Martin , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Nov 4, 2019 at 9:11 AM Mark Rutland wrote: > Can you please elaborate on _how_ this is incompatible in the commit > message? > > For example, it's not clear to me if you mean that's functionally > incompatible, or if you're trying to remove return-altering gadgets. > > If there's a functional incompatibility, please spell that out a bit > more clearly. Likewise if this is about minimizing the set of places > that can mess with control-flow outside of usual function conventions. Sure, I'll add a better description in v5. In this case, the return address is modified in the kernel stack, which means the changes are ignored with SCS. Sami _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel