From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DC115D528 for ; Mon, 14 Aug 2023 21:09:30 +0000 (UTC) Received: by mail-pl1-f175.google.com with SMTP id d9443c01a7336-1bdf7086ae5so2346705ad.0 for ; Mon, 14 Aug 2023 14:09:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1692047370; x=1692652170; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=4PuvQpJrJqrNy7astmt5IVebXoF5w/a9tG+pRmbryqo=; b=kxnjP4K14WJSvLPejXWZrEY2njof9Zmsz4pFZ+tWjEdwYQPwfyIy1Mbf1S1FDVBq9l 9MWRs8VsKnOSdrE1QbDjEkJezJ9LJ2HWu8lANe7NqKHvNsNkhjfFXFiphBgOObgoJjGR Gfg8K0Q8n07N+ZzpKj9/KJ0ZLGM2DIevYNjic= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692047370; x=1692652170; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=4PuvQpJrJqrNy7astmt5IVebXoF5w/a9tG+pRmbryqo=; b=VV4+6QGRWbRMonWduntJ6dZf1LtsdbO1TpwKlbpv91qsULuONxXCLKhSUjg8DlNEST J8YEh4KDHvs/4TKycNFW+T2cocmcuIj/igwvCKukdA2bLecqV6j4MGp6Lk7k3R4KVkWi 7/BetpKIeaW7NfQkvfTQM1xhrdvxx6EWdWa+S6Sx8c6GfH/zUYK4al4yI2UqwfwhtSBy d0v4oAj9c3Y0NwHRih9rUUZu5odfjZ4iA/i1AUTiJ8eUG/yLPmVbaKDqRsTqLY84FhJI /zNi57f7kLhGMjnSGflpQVQePGh+VluuByMlZvDxYHU1rlFab4GyjJMuPwR+qN5pNVTN nC0Q== X-Gm-Message-State: AOJu0YyxsfntQvKTM3SLmfaWOCAyBGSvoKKweUOAfZl4AcdbOAhRb0+F dM3vULn5ItQ9np0g08R7Rc/q5Q== X-Google-Smtp-Source: AGHT+IFYeDWP5PYNKsk0YR+BiKLZK4N4Rwa0P0VjZkZ6hsNlrW8rO0WgiTO5nntV4saLBRmYH2B/dg== X-Received: by 2002:a17:902:ee44:b0:1b0:6038:2982 with SMTP id 4-20020a170902ee4400b001b060382982mr10965327plo.41.1692047370203; Mon, 14 Aug 2023 14:09:30 -0700 (PDT) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id iw3-20020a170903044300b001b857352285sm9941444plb.247.2023.08.14.14.09.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Aug 2023 14:09:29 -0700 (PDT) Date: Mon, 14 Aug 2023 14:09:29 -0700 From: Kees Cook To: Sami Tolvanen Cc: Nathan Chancellor , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , Deepak Gupta , Nick Desaulniers , Fangrui Song , linux-riscv@lists.infradead.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5] riscv: SCS support Message-ID: <202308141409.76B8A274BF@keescook> References: <20230811233556.97161-7-samitolvanen@google.com> <20230814175928.GA1028706@dev-arch.thelio-3990X> <202308141131.6B90A4205@keescook> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Aug 14, 2023 at 01:18:30PM -0700, Sami Tolvanen wrote: > On Mon, Aug 14, 2023 at 11:57 AM Sami Tolvanen wrote: > > Looks like __builtin_frame_address behaves differently on RISC-V. > > After staring at the disassembly a bit, using > > __builtin_frame_address(0) - 1 instead of + 1 seems to yield correct > > results. > > Elliott was kind enough to point out to me off-list that this behavior > has been documented here: > > https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc#frame-pointer-convention > > I'll include a patch to fix the test on RISC-V in the next version. Perfect! Thanks for figuring out the offset. :) -- Kees Cook