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Message-Id: <98c4c0b11300ac3b7de3acb2096f8f34184b1457.1253831946.git.jbaron@redhat.com>
Date: Thu, 24 Sep 2009 19:17:53 -0400
From: Jason Baron <jbaron@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...e.hu, mathieu.desnoyers@...ymtl.ca, tglx@...utronix.de,
rostedt@...dmis.org, ak@...e.de, roland@...hat.com, rth@...hat.com,
mhiramat@...hat.com
Subject: [PATCH 2/4] jump label - base patch
Base jump label patch which creates macros for jump patching. This feature is
dependent on gcc version >= 4.5
Signed-off-by: Jason Baron <jbaron@...hat.com>
---
arch/x86/include/asm/jump_label.h | 27 +++++++++++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/jump_label.c | 92 +++++++++++++++++++++++++++++++++++++
include/asm-generic/vmlinux.lds.h | 11 ++++
include/linux/jump_label.h | 53 +++++++++++++++++++++
5 files changed, 184 insertions(+), 1 deletions(-)
create mode 100644 arch/x86/include/asm/jump_label.h
create mode 100644 arch/x86/kernel/jump_label.c
create mode 100644 include/linux/jump_label.h
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
new file mode 100644
index 0000000..21a7b79
--- /dev/null
+++ b/arch/x86/include/asm/jump_label.h
@@ -0,0 +1,27 @@
+#ifndef _ASM_X86_JUMP_LABEL_H
+#define _ASM_X86_JUMP_LABEL_H
+
+#include <asm/nops.h>
+
+#if (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
+#define __HAVE_ARCH_JUMP_LABEL
+#endif
+
+#ifdef __HAVE_ARCH_JUMP_LABEL
+
+#define JUMP_LABEL(tag, label, cond) \
+ do { \
+ static const char __jlstrtab_##tag[] \
+ __used __attribute__((section("__jump_strings"))) = #tag; \
+ asm goto ("1:" \
+ "jmp %l[" #label "] \n\t" \
+ ".pushsection __jump_table, \"a\" \n\t" \
+ _ASM_PTR "1b, %l[" #label "], %c0, 0 \n\t" \
+ ".popsection \n\t" \
+ : : "i" (__jlstrtab_##tag) : : label); \
+ } while (0)
+
+#endif
+
+#endif
+
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 91d4189..b6b3e42 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..207947d
--- /dev/null
+++ b/arch/x86/kernel/jump_label.c
@@ -0,0 +1,92 @@
+#include <linux/jump_label.h>
+#include <linux/memory.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+
+#ifdef __HAVE_ARCH_JUMP_LABEL
+
+extern struct jump_entry __start___jump_table[];
+extern struct jump_entry __stop___jump_table[];
+
+DEFINE_MUTEX(jump_label_mutex);
+
+union jump_code_union {
+ char code[RELATIVEJUMP_SIZE];
+ struct {
+ char jump;
+ int offset;
+ } __attribute__((packed));
+};
+
+void jump_label_transform(struct jump_entry *entry, enum jump_label_type type)
+{
+ union jump_code_union code;
+ long jump_length;
+ unsigned char opcode;
+ size_t opcode_length;
+
+ if (entry->type == UNKOWN_JUMP) {
+ if (probe_kernel_read(&opcode, (void *)entry->code, 1))
+ BUG();
+
+ if (opcode == 0xe9)
+ entry->type = LONG_JUMP;
+ else if (opcode == 0xeb)
+ entry->type = SHORT_JUMP;
+ else
+ BUG();
+ }
+
+ if (entry->type == LONG_JUMP)
+ opcode_length = 5;
+ else
+ opcode_length = 2;
+
+ if (type == JUMP_LABEL_ENABLE) {
+ if (entry->type == SHORT_JUMP) {
+ code.code[0] = 0xeb;
+ code.code[1] = 0;
+ } else {
+ code.code[0] = 0xe9;
+ code.offset = 0;
+ }
+ } else {
+ jump_length = entry->target - (entry->code + opcode_length);
+ if (entry->type == SHORT_JUMP) {
+ if ((jump_length > 127 || jump_length < -128)) {
+ BUG();
+ }
+ code.code[0] = 0xeb;
+ code.code[1] = (char)jump_length;
+ } else {
+ if ((jump_length > INT_MAX || jump_length < INT_MIN)) {
+ BUG();
+ }
+ code.code[0] = 0xe9;
+ code.offset = jump_length;
+ }
+ }
+
+ mutex_lock(&text_mutex);
+ text_poke_fixup((void *)entry->code, &code,
+ opcode_length, (void *)entry->code + opcode_length);
+ mutex_unlock(&text_mutex);
+}
+
+int jump_label_update(const char *name, enum jump_label_type type)
+{
+ struct jump_entry *iter;
+
+ mutex_lock(&jump_label_mutex);
+ for (iter = __start___jump_table; iter < __stop___jump_table; iter++) {
+ if (!strcmp(name, iter->name)) {
+ if (!(system_state == SYSTEM_RUNNING &&
+ (init_kernel_text(iter->code))))
+ jump_label_transform(iter, type);
+ }
+ }
+ mutex_unlock(&jump_label_mutex);
+ return 0;
+}
+
+#endif
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index e7eae37..d2f38e2 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -213,6 +213,7 @@
*(__vermagic) /* Kernel version magic */ \
*(__markers_strings) /* Markers: strings */ \
*(__tracepoints_strings)/* Tracepoints: strings */ \
+ *(__jump_strings)/* Jump: strings */ \
} \
\
.rodata1 : AT(ADDR(.rodata1) - LOAD_OFFSET) { \
@@ -220,6 +221,8 @@
} \
\
BUG_TABLE \
+ JUMP_TABLE \
+ \
\
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
@@ -564,6 +567,14 @@
#define BUG_TABLE
#endif
+#define JUMP_TABLE \
+ . = ALIGN(8); \
+ __jump_table : AT(ADDR(__jump_table) - LOAD_OFFSET) { \
+ VMLINUX_SYMBOL(__start___jump_table) = .; \
+ *(__jump_table) \
+ VMLINUX_SYMBOL(__stop___jump_table) = .; \
+ }
+
#ifdef CONFIG_PM_TRACE
#define TRACEDATA \
. = ALIGN(4); \
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
new file mode 100644
index 0000000..eb0a4ef
--- /dev/null
+++ b/include/linux/jump_label.h
@@ -0,0 +1,53 @@
+#ifndef _LINUX_JUMP_LABEL_H
+#define _LINUX_JUMP_LABEL_H
+
+#include <asm/jump_label.h>
+
+struct jump_entry {
+ unsigned long code;
+ unsigned long target;
+ char *name;
+ unsigned long type;
+};
+
+enum jump_label_type {
+ JUMP_LABEL_ENABLE,
+ JUMP_LABEL_DISABLE
+};
+
+enum jump_label_instruction {
+ UNKOWN_JUMP,
+ SHORT_JUMP,
+ LONG_JUMP
+};
+
+#ifdef __HAVE_ARCH_JUMP_LABEL
+
+extern int jump_label_update(const char *name, enum jump_label_type type);
+
+#define enable_jump_label(name) \
+ jump_label_update(name, JUMP_LABEL_ENABLE);
+
+#define disable_jump_label(name) \
+ jump_label_update(name, JUMP_LABEL_DISABLE);
+
+#else
+
+#define JUMP_LABEL(tag, label, cond) \
+ if (likely(!cond)) \
+ goto label;
+
+static inline int enable_jump_label(const char *name, enum jump_label_type type)
+{
+ return 0;
+}
+
+static inline int disable_jump_label(const char *name,
+ enum jump_label_type type)
+{
+ return 0;
+}
+
+#endif
+
+#endif
--
1.6.2.5
--
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