Hi Emese, On Tue, Jun 28, 2016 at 01:34:07PM +0200, Emese Revfy wrote: > I would like to introduce the initify gcc plugin. The kernel already has > a mechanism to free up code and data memory that is only used during kernel > or module initialization. > This plugin will teach the compiler to find more such code and data that > can be freed after initialization. It reduces memory usage. > The initify gcc plugin can be useful for embedded systems. > > It is a CII project supported by the Linux Foundation. > > This plugin is the part of grsecurity/PaX. > > The plugin supports all gcc versions from 4.5 to 6.0. > > I made some changes on top of the PaX version (since March 6.). These are > the important ones: > * move all local strings to init.rodata.str and exit.rodata.str > (not just __func__) > * report all initified strings and functions > (GCC_PLUGIN_INITIFY_VERBOSE config option) > * automatically discover init/exit functions and apply the __init or > __exit attributes on them > > You can find more about the changes here: > https://github.com/ephox-gcc-plugins/initify > > This patch set is based on the "Add support for complex gcc plugins that > don't fit in a single file" patch set (git/kees/linux.git#kspp HEAD: > e5d4798b284cd192c8b). > > Some statistics about the plugin: > > On allyes config (amd64, gcc-6): > * 7731 initified strings > * 231 initified functions > > On allmod config (i386, gcc-6): > * 8846 initified strings > * 252 initified functions > > On allyes config (amd64, gcc-6): > > section vanilla vanilla + initify change > ----------------------------------------------------------------------- > .rodata 39059688 (0x25400e8) 38527210 (0x24be0ea) -532478 > .data 45744128 (0x2ba0000) 45404160 (0x2b4d000) -339968 > .init.data 1361144 (0x14c4f8) 1674200 (0x198bd8) +313056 > .text 77615128 (0x4a05018) 77576664 (0x49fb9d8) -38464 > .init.text 1108455 (0x10e9e7) 1137618 (0x115bd2) +29163 You should probably provide numbers for .init.rodata.str, .exit.rodata.str and .exit.text as well. Otherwise this delta calculation suggests a rather gigantic image size reduction which is probably not the case ;) Also a comparison of the final kernel image size would be nice to see if the string duplication issue mentioned in [1] is actually an issue. [1] http://marc.info/?l=linux-kernel&m=140364632417795&w=2 Thanks, Mathias > > > Emese Revfy (2): > Add the initify gcc plugin > Mark functions with the __nocapture attribute > > --- > arch/Kconfig | 23 + > arch/arm/include/asm/string.h | 10 +- > arch/arm64/include/asm/string.h | 23 +- > arch/powerpc/include/asm/string.h | 19 +- > arch/x86/boot/string.h | 4 +- > arch/x86/include/asm/string_32.h | 21 +- > arch/x86/include/asm/string_64.h | 18 +- > arch/x86/kernel/hpet.c | 2 +- > include/asm-generic/bug.h | 6 +- > include/asm-generic/vmlinux.lds.h | 2 + > include/linux/compiler-gcc.h | 10 +- > include/linux/compiler.h | 4 + > include/linux/fs.h | 5 +- > include/linux/printk.h | 2 +- > include/linux/string.h | 73 +-- > scripts/Makefile.gcc-plugins | 4 + > scripts/gcc-plugins/initify_plugin.c | 1147 ++++++++++++++++++++++++++++++++++ > 17 files changed, 1283 insertions(+), 90 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
