From mboxrd@z Thu Jan 1 00:00:00 1970 From: mingo@kernel.org (Ingo Molnar) Date: Wed, 27 Nov 2013 18:54:42 +0100 Subject: [PATCH v2] use -fstack-protector-strong In-Reply-To: References: <20131126203727.GA352@www.outflux.net> <20131127112731.GA10435@gmail.com> Message-ID: <20131127175442.GA28088@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Kees Cook wrote: > On Wed, Nov 27, 2013 at 3:27 AM, Ingo Molnar wrote: > > > > * Kees Cook wrote: > > > >> On a defconfig x86_64 build (with CONFIG_CC_STACKPROTECTOR enabled), the > >> delta in size is just under 9% larger: > >> > >> -rwxrwxr-x 1 kees kees 22134340 Nov 26 10:28 vmlinux.gcc-4.8 > >> -rwxrwxr-x 1 kees kees 22123870 Nov 26 10:40 vmlinux.gcc-4.9 > >> -rwxrwxr-x 1 kees kees 24225118 Nov 26 10:42 vmlinux.gcc-4.9+strong > > > > Please run it through 'size' so that we know the real text size > > increases. > > text data bss dec hex filename > 11407474 1453792 1191936 14053202 d66f52 vmlinux.gcc-4.8 > 11458837 1457504 1191936 14108277 d74675 vmlinux.gcc-4.9 > 11682929 1457504 1191936 14332369 dab1d1 vmlinux.gcc-4.9+strong > > Looks to be 2% for defconfig. That's way better. Shall I send a v3? Well, it's better than 9%, but still almost an order of magnitude higher than the cost is today, and a lot of distros have CONFIG_CC_STACKPROTECTOR=y. So it would be nice to measure how much the instruction count goes up in some realistic system-bound test. How much does something like kernel/built-in.o increase, as per 'size' output? Thanks, Ingo