linux-kernel - [PATCH 47/74] x86, lto: Fix kprobes for LTO

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Date:	Sat, 18 Aug 2012 19:56:43 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	linux-kernel@...r.kernel.org
Cc:	x86@...nel.org, mmarek@...e.cz, linux-kbuild@...r.kernel.org,
	JBeulich@...e.com, akpm@...ux-foundation.org,
	Andi Kleen <ak@...ux.intel.com>, ananth@...ibm.com
Subject: [PATCH 47/74] x86, lto: Fix kprobes for LTO

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 |    8 ++++----
 arch/x86/kernel/kprobes-opt.c  |    5 +----
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h
index a967173..fa2d12e 100644
--- a/arch/x86/include/asm/kprobes.h
+++ b/arch/x86/include/asm/kprobes.h
@@ -48,10 +48,10 @@ 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 -	\
diff --git a/arch/x86/kernel/kprobes-opt.c b/arch/x86/kernel/kprobes-opt.c
index c5e410e..43c34e8 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)
-- 
1.7.7.6

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