[PATCH] Kprobes: prevent possible race conditions ppc64 changes

This patch contains the ppc64 architecture specific changes to prevent the
possible race conditions.

Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/kprobes.c

@@ -44,7 +44,7 @@ static struct kprobe *kprobe_prev;
 static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
 static struct pt_regs jprobe_saved_regs;
 
-int arch_prepare_kprobe(struct kprobe *p)
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
 	int ret = 0;
 	kprobe_opcode_t insn = *p->addr;
@@ -68,27 +68,27 @@ int arch_prepare_kprobe(struct kprobe *p)
 	return ret;
 }
 
-void arch_copy_kprobe(struct kprobe *p)
+void __kprobes arch_copy_kprobe(struct kprobe *p)
 {
 	memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
 	p->opcode = *p->addr;
 }
 
-void arch_arm_kprobe(struct kprobe *p)
+void __kprobes arch_arm_kprobe(struct kprobe *p)
 {
 	*p->addr = BREAKPOINT_INSTRUCTION;
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }
 
-void arch_disarm_kprobe(struct kprobe *p)
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
 {
 	*p->addr = p->opcode;
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }
 
-void arch_remove_kprobe(struct kprobe *p)
+void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
 	up(&kprobe_mutex);
 	free_insn_slot(p->ainsn.insn);
@@ -122,7 +122,8 @@ static inline void restore_previous_kprobe(void)
 	kprobe_saved_msr = kprobe_saved_msr_prev;
 }
 
-void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
+void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
+				      struct pt_regs *regs)
 {
 	struct kretprobe_instance *ri;
 
@@ -244,7 +245,7 @@ void kretprobe_trampoline_holder(void)
 /*
  * Called when the probe at kretprobe trampoline is hit
  */
-int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct kretprobe_instance *ri = NULL;
         struct hlist_head *head;
@@ -308,7 +309,7 @@ int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
  * single-stepped a copy of the instruction.  The address of this
  * copy is p->ainsn.insn.
  */
-static void resume_execution(struct kprobe *p, struct pt_regs *regs)
+static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 {
 	int ret;
 	unsigned int insn = *p->ainsn.insn;
@@ -373,8 +374,8 @@ static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 /*
  * Wrapper routine to for handling exceptions.
  */
-int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
-			     void *data)
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+				       unsigned long val, void *data)
 {
 	struct die_args *args = (struct die_args *)data;
 	int ret = NOTIFY_DONE;
@@ -406,7 +407,7 @@ int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
 	return ret;
 }
 
-int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 {
 	struct jprobe *jp = container_of(p, struct jprobe, kp);
 
@@ -419,16 +420,16 @@ int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 	return 1;
 }
 
-void jprobe_return(void)
+void __kprobes jprobe_return(void)
 {
 	asm volatile("trap" ::: "memory");
 }
 
-void jprobe_return_end(void)
+void __kprobes jprobe_return_end(void)
 {
 };
 
-int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
 	/*
 	 * FIXME - we should ideally be validating that we got here 'cos

arch/ppc64/kernel/misc.S

@@ -183,7 +183,7 @@ PPC64_CACHES:
  *   flush all bytes from start through stop-1 inclusive
  */
 
-_GLOBAL(__flush_icache_range)
+_KPROBE(__flush_icache_range)
 
 /*
  * Flush the data cache to memory 
@@ -223,7 +223,7 @@ _GLOBAL(__flush_icache_range)
 	bdnz	2b
 	isync
 	blr
-	
+	.previous .text
 /*
  * Like above, but only do the D-cache.
  *

arch/ppc64/kernel/traps.c

@@ -30,6 +30,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/delay.h>
+#include <linux/kprobes.h>
 #include <asm/kdebug.h>
 
 #include <asm/pgtable.h>
@@ -220,7 +221,7 @@ void instruction_breakpoint_exception(struct pt_regs *regs)
 	_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
 }
 
-void single_step_exception(struct pt_regs *regs)
+void __kprobes single_step_exception(struct pt_regs *regs)
 {
 	regs->msr &= ~MSR_SE;  /* Turn off 'trace' bit */
 
@@ -398,7 +399,7 @@ check_bug_trap(struct pt_regs *regs)
 	return 0;
 }
 
-void program_check_exception(struct pt_regs *regs)
+void __kprobes program_check_exception(struct pt_regs *regs)
 {
 	if (debugger_fault_handler(regs))
 		return;

arch/ppc64/kernel/vmlinux.lds.S

@@ -15,6 +15,7 @@ SECTIONS
 	*(.text .text.*)
 	SCHED_TEXT
 	LOCK_TEXT
+	KPROBES_TEXT
 	*(.fixup)
 	. = ALIGN(4096);
 	_etext = .;

arch/ppc64/mm/fault.c

@@ -29,6 +29,7 @@
 #include <linux/interrupt.h>
 #include <linux/smp_lock.h>
 #include <linux/module.h>
+#include <linux/kprobes.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -84,8 +85,8 @@ static int store_updates_sp(struct pt_regs *regs)
  * The return value is 0 if the fault was handled, or the signal
  * number if this is a kernel fault that can't be handled here.
  */
-int do_page_fault(struct pt_regs *regs, unsigned long address,
-		  unsigned long error_code)
+int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
+			    unsigned long error_code)
 {
 	struct vm_area_struct * vma;
 	struct mm_struct *mm = current->mm;

include/asm-ppc64/processor.h

@@ -311,6 +311,20 @@ name: \
 	.type GLUE(.,name),@function; \
 GLUE(.,name):
 
+#define _KPROBE(name) \
+	.section ".kprobes.text","a"; \
+	.align 2 ; \
+	.globl name; \
+	.globl GLUE(.,name); \
+	.section ".opd","aw"; \
+name: \
+	.quad GLUE(.,name); \
+	.quad .TOC.@tocbase; \
+	.quad 0; \
+	.previous; \
+	.type GLUE(.,name),@function; \
+GLUE(.,name):
+
 #define _STATIC(name) \
 	.section ".text"; \
 	.align 2 ; \