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* [Patch] kprobes exception notifier fix 2.6.9-rc2
@ 2004-09-23  5:30 Prasanna S Panchamukhi
  2004-09-23  8:06 ` Andi Kleen
  0 siblings, 1 reply; 5+ messages in thread
From: Prasanna S Panchamukhi @ 2004-09-23  5:30 UTC (permalink / raw)
  To: linux-kernel
  Cc: torvalds, Andrew Morton, ak, suparna, Tom Rini, kgdb-bugreport

[-- Attachment #1: Type: text/plain, Size: 387 bytes --]

In order to make other debuggers use exception notifiers, kprobes 
notifier return values are required to be modified. This patch modifies the
return values of kprobes notifier return values in a clean way.

Please let me know your comments.

Thanks
Prasanna
-- 

Prasanna S Panchamukhi
Linux Technology Center
India Software Labs, IBM Bangalore
Ph: 91-80-25044636
<prasanna@in.ibm.com>

[-- Attachment #2: kprobes-exceptions-notifier-fix.patch --]
[-- Type: text/plain, Size: 7302 bytes --]


This patch modifies the return value of kprobes exceptions notify handler.
The kprobes exception notifier returns NOTIFY_STOP on handling notification.
This patch helps other debuggers to co-exists with the Kprobes. Other debuggers 
registered for exceptions notification must return NOTIFY_STOP on handling 
the notification.

Signed-off by : Prasanna S Panchamukhi <prasanna@in.ibm.com>


---

 linux-2.6.9-rc2-prasanna/arch/i386/kernel/kprobes.c |   10 +++++-----
 linux-2.6.9-rc2-prasanna/arch/i386/kernel/traps.c   |   18 +++++++++---------
 linux-2.6.9-rc2-prasanna/arch/i386/mm/fault.c       |    2 +-
 linux-2.6.9-rc2-prasanna/include/linux/notifier.h   |    4 ++++
 linux-2.6.9-rc2-prasanna/kernel/kprobes.c           |    3 +++
 5 files changed, 22 insertions(+), 15 deletions(-)

diff -puN arch/i386/kernel/kprobes.c~kprobes-exceptions-nofitier-fix arch/i386/kernel/kprobes.c
--- linux-2.6.9-rc2/arch/i386/kernel/kprobes.c~kprobes-exceptions-nofitier-fix	2004-09-21 15:06:22.000000000 +0530
+++ linux-2.6.9-rc2-prasanna/arch/i386/kernel/kprobes.c	2004-09-21 15:06:22.000000000 +0530
@@ -267,26 +267,26 @@ int kprobe_exceptions_notify(struct noti
 	switch (val) {
 	case DIE_INT3:
 		if (kprobe_handler(args->regs))
-			return NOTIFY_OK;
+			return NOTIFY_STOP;
 		break;
 	case DIE_DEBUG:
 		if (post_kprobe_handler(args->regs))
-			return NOTIFY_OK;
+			return NOTIFY_STOP;
 		break;
 	case DIE_GPF:
 		if (kprobe_running() &&
 		    kprobe_fault_handler(args->regs, args->trapnr))
-			return NOTIFY_OK;
+			return NOTIFY_STOP;
 		break;
 	case DIE_PAGE_FAULT:
 		if (kprobe_running() &&
 		    kprobe_fault_handler(args->regs, args->trapnr))
-			return NOTIFY_OK;
+			return NOTIFY_STOP;
 		break;
 	default:
 		break;
 	}
-	return NOTIFY_BAD;
+	return NOTIFY_DONE;
 }
 
 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
diff -puN arch/i386/kernel/traps.c~kprobes-exceptions-nofitier-fix arch/i386/kernel/traps.c
--- linux-2.6.9-rc2/arch/i386/kernel/traps.c~kprobes-exceptions-nofitier-fix	2004-09-21 15:06:22.000000000 +0530
+++ linux-2.6.9-rc2-prasanna/arch/i386/kernel/traps.c	2004-09-21 15:06:22.000000000 +0530
@@ -422,7 +422,7 @@ static inline void do_trap(int trapnr, i
 asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
 { \
 	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
-						== NOTIFY_OK) \
+						== NOTIFY_STOP) \
 		return; \
 	do_trap(trapnr, signr, str, 0, regs, error_code, NULL); \
 }
@@ -436,7 +436,7 @@ asmlinkage void do_##name(struct pt_regs
 	info.si_code = sicode; \
 	info.si_addr = (void __user *)siaddr; \
 	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
-						== NOTIFY_BAD) \
+						== NOTIFY_STOP) \
 		return; \
 	do_trap(trapnr, signr, str, 0, regs, error_code, &info); \
 }
@@ -445,7 +445,7 @@ asmlinkage void do_##name(struct pt_regs
 asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
 { \
 	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
-						== NOTIFY_OK) \
+						== NOTIFY_STOP) \
 		return; \
 	do_trap(trapnr, signr, str, 1, regs, error_code, NULL); \
 }
@@ -459,7 +459,7 @@ asmlinkage void do_##name(struct pt_regs
 	info.si_code = sicode; \
 	info.si_addr = (void __user *)siaddr; \
 	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
-						== NOTIFY_OK) \
+						== NOTIFY_STOP) \
 		return; \
 	do_trap(trapnr, signr, str, 1, regs, error_code, &info); \
 }
@@ -498,7 +498,7 @@ gp_in_vm86:
 gp_in_kernel:
 	if (!fixup_exception(regs)) {
 		if (notify_die(DIE_GPF, "general protection fault", regs,
-				error_code, 13, SIGSEGV) == NOTIFY_OK);
+				error_code, 13, SIGSEGV) == NOTIFY_STOP);
 			return;
 		die("general protection fault", regs, error_code);
 	}
@@ -572,7 +572,7 @@ static void default_do_nmi(struct pt_reg
  
 	if (!(reason & 0xc0)) {
 		if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 0, SIGINT)
-							== NOTIFY_BAD)
+							== NOTIFY_STOP)
 			return;
 #ifdef CONFIG_X86_LOCAL_APIC
 		/*
@@ -587,7 +587,7 @@ static void default_do_nmi(struct pt_reg
 		unknown_nmi_error(reason, regs);
 		return;
 	}
-	if (notify_die(DIE_NMI, "nmi", regs, reason, 0, SIGINT) == NOTIFY_BAD)
+	if (notify_die(DIE_NMI, "nmi", regs, reason, 0, SIGINT) == NOTIFY_STOP)
 		return;
 	if (reason & 0x80)
 		mem_parity_error(reason, regs);
@@ -636,7 +636,7 @@ void unset_nmi_callback(void)
 asmlinkage int do_int3(struct pt_regs *regs, long error_code)
 {
 	if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
-			== NOTIFY_OK)
+			== NOTIFY_STOP)
 		return 1;
 	/* This is an interrupt gate, because kprobes wants interrupts
 	disabled.  Normal trap handlers don't. */
@@ -677,7 +677,7 @@ asmlinkage void do_debug(struct pt_regs 
 	__asm__ __volatile__("movl %%db6,%0" : "=r" (condition));
 
 	if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
-					SIGTRAP) == NOTIFY_OK)
+					SIGTRAP) == NOTIFY_STOP)
 		return;
 	/* It's safe to allow irq's after DR6 has been saved */
 	if (regs->eflags & X86_EFLAGS_IF)
diff -puN arch/i386/mm/fault.c~kprobes-exceptions-nofitier-fix arch/i386/mm/fault.c
--- linux-2.6.9-rc2/arch/i386/mm/fault.c~kprobes-exceptions-nofitier-fix	2004-09-21 15:06:22.000000000 +0530
+++ linux-2.6.9-rc2-prasanna/arch/i386/mm/fault.c	2004-09-21 15:06:22.000000000 +0530
@@ -227,7 +227,7 @@ asmlinkage void do_page_fault(struct pt_
 	__asm__("movl %%cr2,%0":"=r" (address));
 
 	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
-					SIGSEGV) == NOTIFY_OK)
+					SIGSEGV) == NOTIFY_STOP)
 		return;
 	/* It's safe to allow irq's after cr2 has been saved */
 	if (regs->eflags & (X86_EFLAGS_IF|VM_MASK))
diff -puN kernel/kprobes.c~kprobes-exceptions-nofitier-fix kernel/kprobes.c
--- linux-2.6.9-rc2/kernel/kprobes.c~kprobes-exceptions-nofitier-fix	2004-09-21 15:06:22.000000000 +0530
+++ linux-2.6.9-rc2-prasanna/kernel/kprobes.c	2004-09-21 15:06:22.000000000 +0530
@@ -25,6 +25,8 @@
  *		hlists and exceptions notifier as suggested by Andi Kleen.
  * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
  *		interface to access function arguments.
+ * 2004-Sep	Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
+ *		exceptions notifier to be first on the priority list.
  */
 #include <linux/kprobes.h>
 #include <linux/spinlock.h>
@@ -108,6 +110,7 @@ void unregister_kprobe(struct kprobe *p)
 
 static struct notifier_block kprobe_exceptions_nb = {
 	.notifier_call = kprobe_exceptions_notify,
+	.priority = 0x7fffffff /* we need to notified first */
 };
 
 int register_jprobe(struct jprobe *jp)
diff -puN include/linux/notifier.h~kprobes-exceptions-nofitier-fix include/linux/notifier.h
--- linux-2.6.9-rc2/include/linux/notifier.h~kprobes-exceptions-nofitier-fix	2004-09-21 15:06:22.000000000 +0530
+++ linux-2.6.9-rc2-prasanna/include/linux/notifier.h	2004-09-21 15:07:21.000000000 +0530
@@ -29,6 +29,10 @@ extern int notifier_call_chain(struct no
 #define NOTIFY_OK		0x0001		/* Suits me */
 #define NOTIFY_STOP_MASK	0x8000		/* Don't call further */
 #define NOTIFY_BAD		(NOTIFY_STOP_MASK|0x0002)	/* Bad/Veto action	*/
+/*
+ * Clean way to return from the notifier and stop further calls.
+ */
+#define NOTIFY_STOP		(NOTIFY_OK|NOTIFY_STOP_MASK)
 
 /*
  *	Declared notifiers so far. I can imagine quite a few more chains

_

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2004-09-27 12:10 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-09-23  5:30 [Patch] kprobes exception notifier fix 2.6.9-rc2 Prasanna S Panchamukhi
2004-09-23  8:06 ` Andi Kleen
2004-09-23  8:45   ` Prasanna S Panchamukhi
2004-09-23 19:32   ` David S. Miller
2004-09-27 12:10     ` Prasanna S Panchamukhi

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