From d9f5ab7b1c0a520867af389bab5d5fcdbd0e407e Mon Sep 17 00:00:00 2001 From: Jason Baron Date: Fri, 17 Sep 2010 11:09:22 -0400 Subject: [PATCH] jump label: x86 support add x86 support for jump label. I'm keeping this patch separate so its clear to arch maintainers what was required for x86 support this new feature. Hopefully, it wouldn't be too painful for other archs. Signed-off-by: Jason Baron LKML-Reference: [ cleaned up some formatting ] Signed-off-by: Steven Rostedt --- arch/x86/Kconfig | 1 + arch/x86/include/asm/jump_label.h | 47 ++++++++++++++++++++++++++++++++++++ arch/x86/kernel/Makefile | 2 +- arch/x86/kernel/jump_label.c | 50 +++++++++++++++++++++++++++++++++++++++ arch/x86/kernel/module.c | 3 +++ 5 files changed, 102 insertions(+), 1 deletion(-) create mode 100644 arch/x86/include/asm/jump_label.h create mode 100644 arch/x86/kernel/jump_label.c diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index cea0cd9..afcd663 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -59,6 +59,7 @@ config X86 select ANON_INODES select HAVE_ARCH_KMEMCHECK select HAVE_USER_RETURN_NOTIFIER + select HAVE_ARCH_JUMP_LABEL if !CC_OPTIMIZE_FOR_SIZE config INSTRUCTION_DECODER def_bool (KPROBES || PERF_EVENTS) diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h new file mode 100644 index 0000000..b4a2cb4 --- /dev/null +++ b/arch/x86/include/asm/jump_label.h @@ -0,0 +1,47 @@ +#ifndef _ASM_X86_JUMP_LABEL_H +#define _ASM_X86_JUMP_LABEL_H + +#ifdef __KERNEL__ + +#include +#include + +#define JUMP_LABEL_NOP_SIZE 5 + +# define JUMP_LABEL_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t" + +# define JUMP_LABEL(key, label) \ + do { \ + asm goto("1:" \ + JUMP_LABEL_INITIAL_NOP \ + ".pushsection __jump_table, \"a\" \n\t"\ + _ASM_PTR "1b, %l[" #label "], %c0 \n\t" \ + ".popsection \n\t" \ + : : "i" (key) : : label); \ + } while (0) + +#endif /* __KERNEL__ */ + +#ifdef CONFIG_X86_64 + +typedef u64 jump_label_t; + +struct jump_entry { + jump_label_t code; + jump_label_t target; + jump_label_t key; +}; + +#else + +typedef u32 jump_label_t; + +struct jump_entry { + jump_label_t code; + jump_label_t target; + jump_label_t key; +}; + +#endif + +#endif diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 0925676..24fa171 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -32,7 +32,7 @@ GCOV_PROFILE_paravirt.o := n obj-y := process_$(BITS).o signal.o entry_$(BITS).o obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o obj-y += time.o ioport.o ldt.o dumpstack.o -obj-y += setup.o x86_init.o i8259.o irqinit.o +obj-y += setup.o x86_init.o i8259.o irqinit.o jump_label.o obj-$(CONFIG_X86_VISWS) += visws_quirks.o obj-$(CONFIG_X86_32) += probe_roms_32.o obj-$(CONFIG_X86_32) += sys_i386_32.o i386_ksyms_32.o diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c new file mode 100644 index 0000000..961b6b3 --- /dev/null +++ b/arch/x86/kernel/jump_label.c @@ -0,0 +1,50 @@ +/* + * jump label x86 support + * + * Copyright (C) 2009 Jason Baron + * + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifdef HAVE_JUMP_LABEL + +union jump_code_union { + char code[JUMP_LABEL_NOP_SIZE]; + struct { + char jump; + int offset; + } __attribute__((packed)); +}; + +void arch_jump_label_transform(struct jump_entry *entry, + enum jump_label_type type) +{ + union jump_code_union code; + + if (type == JUMP_LABEL_ENABLE) { + code.jump = 0xe9; + code.offset = entry->target - + (entry->code + JUMP_LABEL_NOP_SIZE); + } else + memcpy(&code, ideal_nop5, JUMP_LABEL_NOP_SIZE); + get_online_cpus(); + mutex_lock(&text_mutex); + text_poke_smp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE); + mutex_unlock(&text_mutex); + put_online_cpus(); +} + +void arch_jump_label_text_poke_early(jump_label_t addr) +{ + text_poke_early((void *)addr, ideal_nop5, JUMP_LABEL_NOP_SIZE); +} + +#endif diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index e0bc186..5399f58 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -239,6 +239,9 @@ int module_finalize(const Elf_Ehdr *hdr, apply_paravirt(pseg, pseg + para->sh_size); } + /* make jump label nops */ + jump_label_apply_nops(me); + return module_bug_finalize(hdr, sechdrs, me); } -- 2.7.4