Commit f14b5f05 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 build updates from Ingo Molnar:
 "Misc cleanups and a retpoline code generation optimization"

* 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, retpolines: Raise limit for generating indirect calls from switch-case
  x86/build: Use the single-argument OUTPUT_FORMAT() linker script command
  x86/build: Specify elf_i386 linker emulation explicitly for i386 objects
  x86/build: Mark per-CPU symbols as absolute explicitly for LLD
parents 37d18565 ce02ef06

arch/x86/Makefile

+5 −0
Original line number Diff line number Diff line
@@ -217,6 +217,11 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables 
# Avoid indirect branches in kernel to deal with Spectre

ifdef CONFIG_RETPOLINE

  KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)

  # Additionally, avoid generating expensive indirect jumps which

  # are subject to retpolines for small number of switch cases.

  # clang turns off jump table generation by default when under

  # retpoline builds, however, gcc does not for x86.

  KBUILD_CFLAGS += $(call cc-option,--param=case-values-threshold=20)

endif



archscripts: scripts_basic

arch/x86/boot/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE 
AFLAGS_header.o += -I$(objtree)/$(obj)

$(obj)/header.o: $(obj)/zoffset.h



LDFLAGS_setup.elf	:= -T

LDFLAGS_setup.elf	:= -m elf_i386 -T

$(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE

	$(call if_changed,ld)

arch/x86/boot/compressed/vmlinux.lds.S

+1 −1
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#include <asm-generic/vmlinux.lds.h>



OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)

OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT)



#undef i386

arch/x86/boot/setup.ld

+1 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 
 *

 * Linker script for the i386 setup code

 */

OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")

OUTPUT_FORMAT("elf32-i386")

OUTPUT_ARCH(i386)

ENTRY(_start)

arch/x86/kernel/vmlinux.lds.S

+2 −2
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ 


#undef i386     /* in case the preprocessor is a 32bit one */



OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT)

OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT)



#ifdef CONFIG_X86_32

OUTPUT_ARCH(i386)
@@ -401,7 +401,7 @@ SECTIONS 
 * Per-cpu symbols which need to be offset from __per_cpu_load

 * for the boot processor.

 */

#define INIT_PER_CPU(x) init_per_cpu__##x = x + __per_cpu_load

#define INIT_PER_CPU(x) init_per_cpu__##x = ABSOLUTE(x) + __per_cpu_load

INIT_PER_CPU(gdt_page);

INIT_PER_CPU(irq_stack_union);

CRA Git | Maintained and supported by SUSTech CRA and CCSE