[RFC PATCH 04/11] x86: kprobes: introduce early kprobes related code area.

From: Wang Nan
Date: Wed Jan 07 2015 - 02:42:44 EST


This patch introduces EARLY_KPROBES_CODES_AREA in x86 vmlinux for early
kprobes.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
arch/x86/include/asm/insn.h | 7 ++++---
arch/x86/include/asm/kprobes.h | 45 ++++++++++++++++++++++++++++++++++--------
arch/x86/kernel/vmlinux.lds.S | 2 ++
3 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h
index 47f29b1..ea6f318 100644
--- a/arch/x86/include/asm/insn.h
+++ b/arch/x86/include/asm/insn.h
@@ -20,6 +20,9 @@
* Copyright (C) IBM Corporation, 2009
*/

+#define MAX_INSN_SIZE 16
+
+#ifndef __ASSEMBLY__
/* insn_attr_t is defined in inat.h */
#include <asm/inat.h>

@@ -69,8 +72,6 @@ struct insn {
const insn_byte_t *next_byte;
};

-#define MAX_INSN_SIZE 16
-
#define X86_MODRM_MOD(modrm) (((modrm) & 0xc0) >> 6)
#define X86_MODRM_REG(modrm) (((modrm) & 0x38) >> 3)
#define X86_MODRM_RM(modrm) ((modrm) & 0x07)
@@ -197,5 +198,5 @@ static inline int insn_offset_immediate(struct insn *insn)
{
return insn_offset_displacement(insn) + insn->displacement.nbytes;
}
-
+#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_INSN_H */
diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h
index 4421b5d..017f4bb 100644
--- a/arch/x86/include/asm/kprobes.h
+++ b/arch/x86/include/asm/kprobes.h
@@ -21,23 +21,52 @@
*
* See arch/x86/kernel/kprobes.c for x86 kprobes history.
*/
-#include <linux/types.h>
-#include <linux/ptrace.h>
-#include <linux/percpu.h>
-#include <asm/insn.h>

#define __ARCH_WANT_KPROBES_INSN_SLOT

-struct pt_regs;
-struct kprobe;
+#include <linux/types.h>
+#include <asm/insn.h>

-typedef u8 kprobe_opcode_t;
#define BREAKPOINT_INSTRUCTION 0xcc
#define RELATIVEJUMP_OPCODE 0xe9
#define RELATIVEJUMP_SIZE 5
#define RELATIVECALL_OPCODE 0xe8
#define RELATIVE_ADDR_SIZE 4
#define MAX_STACK_SIZE 64
+#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + RELATIVE_ADDR_SIZE)
+
+#ifdef __ASSEMBLY__
+
+#define KPROBE_OPCODE_SIZE 1
+#define MAX_OPTINSN_SIZE ((optprobe_template_end - optprobe_template_entry) + \
+ MAX_OPTIMIZED_LENGTH + RELATIVEJUMP_SIZE)
+
+#ifdef CONFIG_EARLY_KPROBES
+# define EARLY_KPROBES_CODES_AREA \
+ . = ALIGN(8); \
+ VMLINUX_SYMBOL(__early_kprobes_code_area_start) = .; \
+ . = . + MAX_OPTINSN_SIZE * CONFIG_NR_EARLY_KPROBES_SLOTS; \
+ VMLINUX_SYMBOL(__early_kprobes_code_area_end) = .; \
+ . = ALIGN(8); \
+ VMLINUX_SYMBOL(__early_kprobes_insn_slot_start) = .; \
+ . = . + MAX_INSN_SIZE * KPROBE_OPCODE_SIZE * \
+ CONFIG_NR_EARLY_KPROBES_SLOTS; \
+ VMLINUX_SYMBOL(__early_kprobes_insn_slot_end) = .;
+#else
+# define EARLY_KPROBES_CODES_AREA
+#endif
+
+#else
+
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+
+
+struct pt_regs;
+struct kprobe;
+
+typedef u8 kprobe_opcode_t;
+#define KPROBE_OPCODE_SIZE sizeof(kprobe_opcode_t)
#define MIN_STACK_SIZE(ADDR) \
(((MAX_STACK_SIZE) < (((unsigned long)current_thread_info()) + \
THREAD_SIZE - (unsigned long)(ADDR))) \
@@ -52,7 +81,6 @@ extern __visible kprobe_opcode_t optprobe_template_entry;
extern __visible kprobe_opcode_t optprobe_template_val;
extern __visible kprobe_opcode_t optprobe_template_call;
extern __visible kprobe_opcode_t optprobe_template_end;
-#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + RELATIVE_ADDR_SIZE)
#define MAX_OPTINSN_SIZE \
(((unsigned long)&optprobe_template_end - \
(unsigned long)&optprobe_template_entry) + \
@@ -117,4 +145,5 @@ extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
extern int kprobe_int3_handler(struct pt_regs *regs);
extern int kprobe_debug_handler(struct pt_regs *regs);
+#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_KPROBES_H */
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 00bf300..69f3f0e 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -26,6 +26,7 @@
#include <asm/page_types.h>
#include <asm/cache.h>
#include <asm/boot.h>
+#include <asm/kprobes.h>

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

@@ -100,6 +101,7 @@ SECTIONS
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
+ EARLY_KPROBES_CODES_AREA
ENTRY_TEXT
IRQENTRY_TEXT
*(.fixup)
--
1.8.4

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