On Wed, Jan 20, 2016 at 1:05 AM, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > This enables the newly introduced text-relative kallsyms support when > building 64-bit targets. This cuts the size of the kallsyms address > table in half, reducing the memory footprint of the kernel .rodata > section by about 400 KB for a KALLSYMS_ALL build, and about 100 KB > reduction in compressed size. (with CONFIG_RELOCATABLE=y) > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Tested-by: Kees Cook <keescook@xxxxxxxxxxxx> -Kees > --- > I tested this with my Ubuntu Wily box's config-4.2.0-23-generic, and > got the following results: > > BEFORE: > ======= > $ size vmlinux > text data bss dec hex filename > 12972949 2213240 1482752 16668941 fe590d vmlinux > > $ readelf -S .tmp_kallsyms2.o |less > There are 9 section headers, starting at offset 0x3e0788: > > Section Headers: > [Nr] Name Type Address Offset > Size EntSize Flags Link Info Align > ... > [ 4] .rodata PROGBITS 0000000000000000 00000040 > 00000000001c7738 0000000000000000 A 0 0 8 > [ 5] .rela.rodata RELA 0000000000000000 001c7950 > 0000000000218e38 0000000000000018 I 7 4 8 > [ 6] .shstrtab STRTAB 0000000000000000 001c7778 > 0000000000000039 0000000000000000 0 0 1 > > $ ls -l arch/x86/boot/bzImage > -rw-rw-r-- 1 ard ard 6893168 Jan 20 09:36 arch/x86/boot/bzImage > > AFTER: > ====== > $ size vmlinux > text data bss dec hex filename > 12604501 2213240 1482752 16300493 f8b9cd vmlinux > > $ readelf -S .tmp_kallsyms2.o |less > There are 8 section headers, starting at offset 0x16dd10: > > Section Headers: > [Nr] Name Type Address Offset > Size EntSize Flags Link Info Align > ... > [ 4] .rodata PROGBITS 0000000000000000 00000040 > 000000000016db20 0000000000000000 A 0 0 8 > [ 5] .shstrtab STRTAB 0000000000000000 0016db60 > 0000000000000034 0000000000000000 0 0 1 > ... > > $ ls -l arch/x86/boot/bzImage > -rw-rw-r-- 1 ard ard 6790224 Jan 19 22:24 arch/x86/boot/bzImage > --- > arch/x86/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 4a10ba9e95da..180a94bda8d4 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -142,6 +142,7 @@ config X86 > select HAVE_UNSTABLE_SCHED_CLOCK > select HAVE_USER_RETURN_NOTIFIER > select IRQ_FORCED_THREADING > + select KALLSYMS_TEXT_RELATIVE if X86_64 > select MODULES_USE_ELF_RELA if X86_64 > select MODULES_USE_ELF_REL if X86_32 > select OLD_SIGACTION if X86_32 > -- > 2.5.0 > -- Kees Cook Chrome OS & Brillo Security -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
