From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Fri, 11 Feb 2022 16:45:24 +0100 > On Wed, Feb 09, 2022 at 07:57:42PM +0100, Alexander Lobakin wrote: > > Address places which need special care and enable > > CONFIG_ARCH_SUPPORTS_ASM_FUNCTION_SECTIONS. > > > > Notably: > > - propagate `--sectname-subst` to KBUILD_AFLAGS in > > x86/boot/Makefile and x86/boot/compressed/Makefile as both > > override them; > > - symbols starting with a dot (like ".Lrelocated") should be > > handled manually with SYM_*_START_SECT(.Lrelocated, relocated) > > as "two dots" is a special (and CPP doesn't want to concatenate > > two dots in general); > > - some symbols explicitly need to reside in one section (like > > kexec control code, hibernation page etc.); > > - macros creating aliases for functions (like __memcpy() for > > memcpy() etc.) should go after the main declaration (as > > aliases should be declared in the same section and they > > don't have SYM_PUSH_SECTION() inside); > > - things like ".org", ".align" should be manually pushed to > > the same section the next symbol goes to; > > - expand indirect_thunk wildcards in vmlinux.lds.S to catch > > symbols back into the "main" section; > > - inline ASM functions like __raw_callee*() should be pushed > > manually as well. > > > > With these changes and `-ffunction-sections` enabled, "plain" > > ".text" section is empty which means that everything works > > right as expected. > > > > Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx> > > --- > > arch/x86/Kconfig | 1 + > > arch/x86/boot/Makefile | 1 + > > arch/x86/boot/compressed/Makefile | 1 + > > arch/x86/boot/compressed/head_32.S | 2 +- > > arch/x86/boot/compressed/head_64.S | 32 ++++++++++++------- > > arch/x86/boot/pmjump.S | 2 +- > > arch/x86/crypto/aesni-intel_asm.S | 4 +-- > > arch/x86/crypto/poly1305-x86_64-cryptogams.pl | 4 +++ > > arch/x86/include/asm/paravirt.h | 2 ++ > > arch/x86/include/asm/qspinlock_paravirt.h | 2 ++ > > arch/x86/kernel/head_32.S | 4 +-- > > arch/x86/kernel/head_64.S | 4 +-- > > arch/x86/kernel/kprobes/core.c | 2 ++ > > arch/x86/kernel/kvm.c | 2 ++ > > arch/x86/kernel/relocate_kernel_32.S | 10 +++--- > > arch/x86/kernel/relocate_kernel_64.S | 12 ++++--- > > arch/x86/kernel/vmlinux.lds.S | 2 +- > > arch/x86/kvm/emulate.c | 7 +++- > > arch/x86/lib/copy_user_64.S | 2 +- > > arch/x86/lib/error-inject.c | 2 ++ > > arch/x86/lib/getuser.S | 5 ++- > > arch/x86/lib/memcpy_64.S | 4 +-- > > arch/x86/lib/memmove_64.S | 5 ++- > > arch/x86/lib/memset_64.S | 5 +-- > > arch/x86/lib/putuser.S | 2 +- > > arch/x86/power/hibernate_asm_32.S | 10 +++--- > > arch/x86/power/hibernate_asm_64.S | 10 +++--- > > 27 files changed, 89 insertions(+), 50 deletions(-) > > Urgh, how much of that can you avoid by (ab)using __DISABLE_EXPORTS > like: > > https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?h=x86/wip.ibt&id=ab74f54f2b1f6cfeaf2b3ba6999bde7cabada9ca Oh, never thought on that, looks like at least 3 of 27 files and 35 of 139 lines, nice! I'll redo this one in the meantime whilst waiting for more comments here. Thanks! Al
