linux-kernel - [PATCH 07/16] x86, asmlinkage: Make kprobes code visible and fix assembler code

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Date:	Mon,  5 Aug 2013 15:02:41 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	x86@...nel.org
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	ananth@...ibm.com
Subject: [PATCH 07/16] x86, asmlinkage: Make kprobes code visible and fix assembler code

From: Andi Kleen <ak@...ux.intel.com>

- Make all the external assembler template symbols __visible
- Move the templates inline assembler code into a top level
assembler statement, not inside a function. This avoids it being
optimized away or cloned.

Cc: ananth@...ibm.com
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/include/asm/kprobes.h | 10 +++++-----
 arch/x86/kernel/kprobes/core.c |  2 +-
 arch/x86/kernel/kprobes/opt.c  |  5 +----
 3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h
index 5a6d287..9454c16 100644
--- a/arch/x86/include/asm/kprobes.h
+++ b/arch/x86/include/asm/kprobes.h
@@ -49,10 +49,10 @@ typedef u8 kprobe_opcode_t;
 #define flush_insn_slot(p)	do { } while (0)
 
 /* optinsn template addresses */
-extern kprobe_opcode_t optprobe_template_entry;
-extern kprobe_opcode_t optprobe_template_val;
-extern kprobe_opcode_t optprobe_template_call;
-extern kprobe_opcode_t optprobe_template_end;
+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 -	\
@@ -62,7 +62,7 @@ extern kprobe_opcode_t optprobe_template_end;
 extern const int kretprobe_blacklist_size;
 
 void arch_remove_kprobe(struct kprobe *p);
-void kretprobe_trampoline(void);
+asmlinkage void kretprobe_trampoline(void);
 
 /* Architecture specific copy of original instruction*/
 struct arch_specific_insn {
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 211bce4..048852d 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -661,7 +661,7 @@ static void __used __kprobes kretprobe_trampoline_holder(void)
 /*
  * Called from kretprobe_trampoline
  */
-static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
+__visible __used __kprobes void *trampoline_handler(struct pt_regs *regs)
 {
 	struct kretprobe_instance *ri = NULL;
 	struct hlist_head *head, empty_rp;
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 76dc6f0..2c1ac28 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -88,9 +88,7 @@ static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long v
 	*(unsigned long *)addr = val;
 }
 
-static void __used __kprobes kprobes_optinsn_template_holder(void)
-{
-	asm volatile (
+asm (
 			".global optprobe_template_entry\n"
 			"optprobe_template_entry:\n"
 #ifdef CONFIG_X86_64
@@ -129,7 +127,6 @@ static void __used __kprobes kprobes_optinsn_template_holder(void)
 #endif
 			".global optprobe_template_end\n"
 			"optprobe_template_end:\n");
-}
 
 #define TMPL_MOVE_IDX \
 	((long)&optprobe_template_val - (long)&optprobe_template_entry)
-- 
1.8.3.1

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