From 785d3cd286f0bf67d1bf692559b9ae5de12678f5 Mon Sep 17 00:00:00 2001
From: Nicolas Pitre <nico@cam.org>
Date: Mon, 3 Dec 2007 15:27:56 -0500
Subject: [PATCH] ARM kprobes: prevent some functions involved with kprobes
 from being probed

Signed-off-by: Nicolas Pitre <nico@marvell.com>
---
 arch/arm/kernel/entry-armv.S  | 8 +++++++-
 arch/arm/kernel/kprobes.c     | 2 +-
 arch/arm/kernel/traps.c       | 9 ---------
 arch/arm/kernel/vmlinux.lds.S | 1 +
 arch/arm/mm/fault.c           | 4 ++--
 include/asm-arm/traps.h       | 9 +++++++++
 6 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 12ecc817be3f..3727537f5825 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -58,6 +58,12 @@
 
 	.endm
 
+#ifdef CONFIG_KPROBES
+	.section	.kprobes.text,"ax",%progbits
+#else
+	.text
+#endif
+
 /*
  * Invalid mode handlers
  */
@@ -562,7 +568,7 @@ do_fpe:
 	.data
 ENTRY(fp_enter)
 	.word	no_fp
-	.text
+	.previous
 
 no_fp:	mov	pc, lr
 
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index a18a8458e99d..450ee2cbfe17 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -55,7 +55,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 	unsigned long addr = (unsigned long)p->addr;
 	int is;
 
-	if (addr & 0x3)
+	if (addr & 0x3 || in_exception_text(addr))
 		return -EINVAL;
 
 	insn = *p->addr;
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index c34db4e868fa..65bb762b2d80 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -46,15 +46,6 @@ __setup("user_debug=", user_debug_setup);
 
 static void dump_mem(const char *str, unsigned long bottom, unsigned long top);
 
-static inline int in_exception_text(unsigned long ptr)
-{
-	extern char __exception_text_start[];
-	extern char __exception_text_end[];
-
-	return ptr >= (unsigned long)&__exception_text_start &&
-	       ptr < (unsigned long)&__exception_text_end;
-}
-
 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
 {
 #ifdef CONFIG_KALLSYMS
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 5ff5406666b4..30f732c7fdb5 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -94,6 +94,7 @@ SECTIONS
 			TEXT_TEXT
 			SCHED_TEXT
 			LOCK_TEXT
+			KPROBES_TEXT
 #ifdef CONFIG_MMU
 			*(.fixup)
 #endif
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 1e7b1ed304d8..28ad7ab1c0cd 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -239,7 +239,7 @@ out:
 	return fault;
 }
 
-static int
+static int __kprobes
 do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	struct task_struct *tsk;
@@ -338,7 +338,7 @@ no_context:
  * interrupt or a critical region, and should only copy the information
  * from the master page table, nothing more.
  */
-static int
+static int __kprobes
 do_translation_fault(unsigned long addr, unsigned int fsr,
 		     struct pt_regs *regs)
 {
diff --git a/include/asm-arm/traps.h b/include/asm-arm/traps.h
index d4f34dc83eb0..f1541afcf85c 100644
--- a/include/asm-arm/traps.h
+++ b/include/asm-arm/traps.h
@@ -15,4 +15,13 @@ struct undef_hook {
 void register_undef_hook(struct undef_hook *hook);
 void unregister_undef_hook(struct undef_hook *hook);
 
+static inline int in_exception_text(unsigned long ptr)
+{
+	extern char __exception_text_start[];
+	extern char __exception_text_end[];
+
+	return ptr >= (unsigned long)&__exception_text_start &&
+	       ptr < (unsigned long)&__exception_text_end;
+}
+
 #endif
-- 
2.39.5