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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
This commit is contained in:
Linus Torvalds 2019-03-07 13:38:27 -08:00
parent 37d18565e4 ce02ef06fc
commit f14b5f05cd
7 changed files with 12 additions and 7 deletions
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5
arch/x86/Makefile
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@ -217,6 +217,11 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
# Avoid indirect branches in kernel to deal with Spectre # Avoid indirect branches in kernel to deal with Spectre
ifdef CONFIG_RETPOLINE ifdef CONFIG_RETPOLINE
KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) 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 endif
archscripts: scripts_basic archscripts: scripts_basic

2
arch/x86/boot/Makefile
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@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE
AFLAGS_header.o += -I$(objtree)/$(obj) AFLAGS_header.o += -I$(objtree)/$(obj)
$(obj)/header.o: $(obj)/zoffset.h $(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 $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
$(call if_changed,ld) $(call if_changed,ld)

2
arch/x86/boot/compressed/vmlinux.lds.S
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@ -1,7 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */ /* SPDX-License-Identifier: GPL-2.0 */
#include <asm-generic/vmlinux.lds.h> #include <asm-generic/vmlinux.lds.h>
OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT, CONFIG_OUTPUT_FORMAT) OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT)
#undef i386 #undef i386

2
arch/x86/boot/setup.ld
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@ -3,7 +3,7 @@
* *
* Linker script for the i386 setup code * Linker script for the i386 setup code
*/ */
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386") OUTPUT_FORMAT("elf32-i386")
OUTPUT_ARCH(i386) OUTPUT_ARCH(i386)
ENTRY(_start) ENTRY(_start)

4
arch/x86/kernel/vmlinux.lds.S
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@ -31,7 +31,7 @@
#undef i386 /* in case the preprocessor is a 32bit one */ #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 #ifdef CONFIG_X86_32
OUTPUT_ARCH(i386) OUTPUT_ARCH(i386)
@ -401,7 +401,7 @@ SECTIONS
* Per-cpu symbols which need to be offset from __per_cpu_load * Per-cpu symbols which need to be offset from __per_cpu_load
* for the boot processor. * 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(gdt_page);
INIT_PER_CPU(irq_stack_union); INIT_PER_CPU(irq_stack_union);

2
arch/x86/realmode/rm/Makefile
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@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE
targets += realmode.lds targets += realmode.lds
$(obj)/realmode.lds: $(obj)/pasyms.h $(obj)/realmode.lds: $(obj)/pasyms.h
LDFLAGS_realmode.elf := --emit-relocs -T LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T
CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj)
targets += realmode.elf targets += realmode.elf

2
arch/x86/realmode/rm/realmode.lds.S
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@ -9,7 +9,7 @@
#undef i386 #undef i386
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386") OUTPUT_FORMAT("elf32-i386")
OUTPUT_ARCH(i386) OUTPUT_ARCH(i386)
SECTIONS SECTIONS