From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Subject: Re: CONFIG_HAVE_ARCH_TRACEHOOK and you Date: Fri, 12 Sep 2008 14:13:51 +0100 Message-ID: <20080912131351.GA31545@flint.arm.linux.org.uk> References: <20080912025733.E55F415420D@magilla.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:41024 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751273AbYILNON (ORCPT ); Fri, 12 Sep 2008 09:14:13 -0400 Content-Disposition: inline In-Reply-To: <20080912025733.E55F415420D@magilla.localdomain> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Roland McGrath Cc: linux-arch@vger.kernel.org, utrace-devel@redhat.com, linux-kernel@vger.kernel.org Okay, let's comment on each bit separately. Regsets ------- These don't appear to be a problem for ARM, and turn out to be relatively clean. The only thing I did do was invent some alternative simpler helper functions rather than using the user_regset_copy* functions (to avoid taking the address of function arguments, which needlessly forces them onto the stack.) However, in looking at other architectures, I notice that sparc does this when initializing its regsets: .n = 38 * sizeof(u32), .size = sizeof(u32), .align = sizeof(u32), and sparc64: .n = 36 * sizeof(u64), .size = sizeof(u64), .align = sizeof(u64), which, given that fs/binfmt_elf.c does this: size_t size = regset->n * regset->size; void *data = kmalloc(size, GFP_KERNEL); if (unlikely(!data)) return 0; means sparc ends up allocating 38 * sizeof(u32) * sizeof(u32), and sparc64 ends up with 36 * sizeof(u64) * sizeof(u64), which must surely be wrong? -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: