On Wed, Nov 27, 2013 at 3:27 AM, Ingo Molnar <[email protected]> wrote: > > * Kees Cook <[email protected]> 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? > If the cost of -fstack-protector-strong is really +9% in kernel text > size then that's rather significant! > > If this option blows up our performance critical codepaths as well > then this will likely cause a runtime slowdown as well, in addition to > the increase in I$ footprint. That needs to be measured. > > CONFIG_CC_STACKPROTECTOR=y is relatively cheap today. For example on > x86-64 defconfig: > > text data bss dec filename > 11378972 1455056 1191936 14025964 vmlinux # CONFIG_CC_STACKPROTECTOR > is not set > 11420243 1455056 1191936 14067235 vmlinux CONFIG_CC_STACKPROTECTOR=y > > that's a +0.3% cost currently. Yeah -- not a lot of functions have char arrays. :) > > Thanks, > > Ingo -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
