From: Larry Woodman <lwoodman@redhat.com>
Date: Tue, 8 Dec 2009 15:06:10 -0500
Subject: [mm] add kernel pagefault tracepoint for x86 & x86_64
Message-id: <1260284770.3221.42.camel@dhcp-100-19-198.bos.redhat.com>
Patchwork-id: 21744
O-Subject: Re: [RHEL5.5 PATCH] re-post: Add kernel pagefault tracepoint for
	x86 & x86_64.
Bugzilla: 517133
RH-Acked-by: Rik van Riel <riel@redhat.com>
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>

On Tue, 2009-12-08 at 00:31 -0500, Don Zickus wrote:
> On Mon, Dec 07, 2009 at 03:39:48PM -0500, Larry Woodman wrote:
> > This is a repost of a corrected patch that I self-NAK'd last week
> > because Hitachi said it didnt meet their requirements.
> >
> > >>>
> > mm, unfortunately, I think our original request is not achieved by this
> > patch, because the information your tracepoint traced is easily found in
> > kernel vmcore image or oops message. And also, right after your
> > tracepoint is hit, the kernel goes to crash.
> > >>>
> >
> > +	if (!user_mode_vm())
> > +		trace_mm_kernel_pagefault(current, address, regs->eip);
>
> This fails to compile complaining about user_mode_vm() doesn't have enough
> args.
>
> Cheers,
> Don
>

Sorry, accidentally posted an earlier patch :(

This is the correct one:

Signed-off-by: Don Zickus <dzickus@redhat.com>

diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index dd6cef4..c88708a 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -22,6 +22,7 @@
 #include <linux/highmem.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
+#include <trace/mm.h>
 
 #include <asm/system.h>
 #include <asm/uaccess.h>
@@ -318,31 +319,16 @@ static inline int vmalloc_fault(unsigned long address)
 	return 0;
 }
 
-/*
- * This routine handles page faults.  It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
- *
- * error_code:
- *	bit 0 == 0 means no page found, 1 means protection fault
- *	bit 1 == 0 means read, 1 means write
- *	bit 2 == 0 means kernel, 1 means user-mode
- *	bit 3 == 1 means use of reserved bit detected
- *	bit 4 == 1 means fault was an instruction fetch
- */
-fastcall void __kprobes do_page_fault(struct pt_regs *regs,
+static inline void __do_page_fault(struct pt_regs *regs,
+				      unsigned long address,
 				      unsigned long error_code)
 {
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
-	unsigned long address;
 	unsigned long page;
 	int write, si_code;
 
-	/* get the address */
-        address = read_cr2();
-
 	tsk = current;
 
 	si_code = SEGV_MAPERR;
@@ -548,7 +534,6 @@ no_context:
  * Oops. The kernel tried to access some bad page. We'll have to
  * terminate things with extreme prejudice.
  */
-
 	bust_spinlocks(1);
 
 	if (oops_may_print()) {
@@ -630,6 +615,32 @@ do_sigbus:
 	force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
 }
 
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * error_code:
+ *	bit 0 == 0 means no page found, 1 means protection fault
+ *	bit 1 == 0 means read, 1 means write
+ *	bit 2 == 0 means kernel, 1 means user-mode
+ *	bit 3 == 1 means use of reserved bit detected
+ *	bit 4 == 1 means fault was an instruction fetch
+ */
+fastcall void __kprobes do_page_fault(struct pt_regs *regs,
+				      unsigned long error_code)
+{
+	unsigned long address;
+
+	/* get the address */
+	address = read_cr2();
+
+	__do_page_fault(regs, address, error_code);
+
+	if (!user_mode_vm(regs))
+		trace_mm_kernel_pagefault(current, address, regs->eip);
+}
+
 #ifndef CONFIG_X86_PAE
 void vmalloc_sync_all(void)
 {
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index 5a0c483..6dd6a22 100644
--- a/arch/x86_64/mm/fault.c
+++ b/arch/x86_64/mm/fault.c
@@ -23,6 +23,7 @@
 #include <linux/compiler.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
+#include <trace/mm.h>
 
 #include <asm/system.h>
 #include <asm/uaccess.h>
@@ -335,18 +336,13 @@ static int vmalloc_fault(unsigned long address)
 int page_fault_trace = 0;
 int exception_trace = 1;
 
-/*
- * This routine handles page faults.  It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
- */
-asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+static inline void __do_page_fault(struct pt_regs *regs,
+					unsigned long address,
 					unsigned long error_code)
 {
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
-	unsigned long address;
 	const struct exception_table_entry *fixup;
 	int write;
 	unsigned long flags;
@@ -356,9 +352,6 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 	mm = tsk->mm;
 	prefetchw(&mm->mmap_sem);
 
-	/* get the address */
-	__asm__("movq %%cr2,%0":"=r" (address));
-
 	info.si_code = SEGV_MAPERR;
 
 
@@ -572,7 +565,6 @@ no_context:
  * Oops. The kernel tried to access some bad page. We'll have to
  * terminate things with extreme prejudice.
  */
-
 	flags = oops_begin();
 
 	if (address < PAGE_SIZE)
@@ -624,6 +616,25 @@ do_sigbus:
 	return;
 }
 
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+					unsigned long error_code)
+{
+	unsigned long address;
+
+	/* get the address */
+	__asm__("movq %%cr2,%0":"=r" (address));
+
+	__do_page_fault(regs, address, error_code);
+
+	if (!user_mode_vm(regs))
+		trace_mm_kernel_pagefault(current, address, regs->rip);
+}
+	
 DEFINE_SPINLOCK(pgd_lock);
 struct page *pgd_list;
 
diff --git a/include/trace/mm.h b/include/trace/mm.h
index 7b949bc..df6392c 100644
--- a/include/trace/mm.h
+++ b/include/trace/mm.h
@@ -7,6 +7,10 @@
 #include <linux/tracepoint.h>
 #include <linux/mm.h>
 
+DEFINE_TRACE(mm_kernel_pagefault,
+	TPPROTO(struct task_struct *task, unsigned long address, unsigned long ip),
+	TPARGS(task, address, ip));
+
 DEFINE_TRACE(mm_anon_fault,
 	TPPROTO(struct mm_struct *mm, unsigned long address, struct page *page),
 	TPARGS(mm, address, page));