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Subject[PATCH 10/12] jump label v10: 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 arches.

Signed-off-by: Jason Baron <jbaron@redhat.com>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/jump_label.h | 47 +++++++++++++++++++++++++++++++++++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/jump_label.c | 49 +++++++++++++++++++++++++++++++++++++
arch/x86/kernel/module.c | 3 ++
5 files changed, 101 insertions(+), 1 deletions(-)
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 3069a6d..089ef9f 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 <linux/types.h>
+#include <asm/nops.h>
+
+#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..b3c0f37
--- /dev/null
+++ b/arch/x86/kernel/jump_label.c
@@ -0,0 +1,49 @@
+/*
+ * jump label x86 support
+ *
+ * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
+ *
+ */
+#include <linux/jump_label.h>
+#include <linux/memory.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/cpu.h>
+#include <asm/kprobes.h>
+#include <asm/alternative.h>
+
+#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);
}

--
1.7.1


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