* 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.
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.
Thanks,
Ingo
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