1 files changed, 36 insertions, 108 deletions

diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c
index 90b5bc723c83..9090c3a74dcc 100644
--- a/arch/arm/probes/kprobes/core.c
+++ b/arch/arm/probes/kprobes/core.c
@@ -11,6 +11,8 @@
  * Copyright (C) 2007 Marvell Ltd.
  */
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
 #include <linux/module.h>
@@ -278,9 +280,9 @@ void __kprobes kprobe_handler(struct pt_regs *regs)
 				break;
 			case KPROBE_REENTER:
 				/* A nested probe was hit in FIQ, it is a BUG */
-				pr_warn("Unrecoverable kprobe detected.\n");
+				pr_warn("Failed to recover from reentered kprobes.\n");
 				dump_kprobe(p);
-				/* fall through */
+				fallthrough;
 			default:
 				/* impossible cases */
 				BUG();
@@ -348,29 +350,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
 			reset_current_kprobe();
 		}
 		break;
-
-	case KPROBE_HIT_ACTIVE:
-	case KPROBE_HIT_SSDONE:
-		/*
-		 * We increment the nmissed count for accounting,
-		 * we can also use npre/npostfault count for accounting
-		 * these specific fault cases.
-		 */
-		kprobes_inc_nmissed_count(cur);
-
-		/*
-		 * We come here because instructions in the pre/post
-		 * handler caused the page_fault, this could happen
-		 * if handler tries to access user space by
-		 * copy_from_user(), get_user() etc. Let the
-		 * user-specified handler try to fix it.
-		 */
-		if (cur->fault_handler && cur->fault_handler(cur, regs, fsr))
-			return 1;
-		break;
-
-	default:
-		break;
 	}
 
 	return 0;
@@ -389,19 +368,41 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 /*
  * When a retprobed function returns, trampoline_handler() is called,
  * calling the kretprobe's handler. We construct a struct pt_regs to
- * give a view of registers r0-r11 to the user return-handler.  This is
- * not a complete pt_regs structure, but that should be plenty sufficient
- * for kretprobe handlers which should normally be interested in r0 only
- * anyway.
+ * give a view of registers r0-r11, sp, lr, and pc to the user
+ * return-handler. This is not a complete pt_regs structure, but that
+ * should be enough for stacktrace from the return handler with or
+ * without pt_regs.
  */
-void __naked __kprobes kretprobe_trampoline(void)
+void __naked __kprobes __kretprobe_trampoline(void)
 {
 	__asm__ __volatile__ (
+#ifdef CONFIG_FRAME_POINTER
+		"ldr	lr, =__kretprobe_trampoline	\n\t"
+	/* __kretprobe_trampoline makes a framepointer on pt_regs. */
+#ifdef CONFIG_CC_IS_CLANG
+		"stmdb	sp, {sp, lr, pc}	\n\t"
+		"sub	sp, sp, #12		\n\t"
+		/* In clang case, pt_regs->ip = lr. */
+		"stmdb	sp!, {r0 - r11, lr}	\n\t"
+		/* fp points regs->r11 (fp) */
+		"add	fp, sp,	#44		\n\t"
+#else /* !CONFIG_CC_IS_CLANG */
+		/* In gcc case, pt_regs->ip = fp. */
+		"stmdb	sp, {fp, sp, lr, pc}	\n\t"
+		"sub	sp, sp, #16		\n\t"
 		"stmdb	sp!, {r0 - r11}		\n\t"
+		/* fp points regs->r15 (pc) */
+		"add	fp, sp, #60		\n\t"
+#endif /* CONFIG_CC_IS_CLANG */
+#else /* !CONFIG_FRAME_POINTER */
+		"sub	sp, sp, #16		\n\t"
+		"stmdb	sp!, {r0 - r11}		\n\t"
+#endif /* CONFIG_FRAME_POINTER */
 		"mov	r0, sp			\n\t"
 		"bl	trampoline_handler	\n\t"
 		"mov	lr, r0			\n\t"
 		"ldmia	sp!, {r0 - r11}		\n\t"
+		"add	sp, sp, #16		\n\t"
 #ifdef CONFIG_THUMB2_KERNEL
 		"bx	lr			\n\t"
 #else
@@ -410,93 +411,20 @@ void __naked __kprobes kretprobe_trampoline(void)
 		: : : "memory");
 }
 
-/* Called from kretprobe_trampoline */
+/* Called from __kretprobe_trampoline */
 static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
 {
-	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head, empty_rp;
-	struct hlist_node *tmp;
-	unsigned long flags, orig_ret_address = 0;
-	unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
-	kprobe_opcode_t *correct_ret_addr = NULL;
-
-	INIT_HLIST_HEAD(&empty_rp);
-	kretprobe_hash_lock(current, &head, &flags);
-
-	/*
-	 * It is possible to have multiple instances associated with a given
-	 * task either because multiple functions in the call path have
-	 * a return probe installed on them, and/or more than one return
-	 * probe was registered for a target function.
-	 *
-	 * We can handle this because:
-	 *     - instances are always inserted at the head of the list
-	 *     - when multiple return probes are registered for the same
-	 *       function, the first instance's ret_addr will point to the
-	 *       real return address, and all the rest will point to
-	 *       kretprobe_trampoline
-	 */
-	hlist_for_each_entry_safe(ri, tmp, head, hlist) {
-		if (ri->task != current)
-			/* another task is sharing our hash bucket */
-			continue;
-
-		orig_ret_address = (unsigned long)ri->ret_addr;
-
-		if (orig_ret_address != trampoline_address)
-			/*
-			 * This is the real return address. Any other
-			 * instances associated with this task are for
-			 * other calls deeper on the call stack
-			 */
-			break;
-	}
-
-	kretprobe_assert(ri, orig_ret_address, trampoline_address);
-
-	correct_ret_addr = ri->ret_addr;
-	hlist_for_each_entry_safe(ri, tmp, head, hlist) {
-		if (ri->task != current)
-			/* another task is sharing our hash bucket */
-			continue;
-
-		orig_ret_address = (unsigned long)ri->ret_addr;
-		if (ri->rp && ri->rp->handler) {
-			__this_cpu_write(current_kprobe, &ri->rp->kp);
-			get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
-			ri->ret_addr = correct_ret_addr;
-			ri->rp->handler(ri, regs);
-			__this_cpu_write(current_kprobe, NULL);
-		}
-
-		recycle_rp_inst(ri, &empty_rp);
-
-		if (orig_ret_address != trampoline_address)
-			/*
-			 * This is the real return address. Any other
-			 * instances associated with this task are for
-			 * other calls deeper on the call stack
-			 */
-			break;
-	}
-
-	kretprobe_hash_unlock(current, &flags);
-
-	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
-		hlist_del(&ri->hlist);
-		kfree(ri);
-	}
-
-	return (void *)orig_ret_address;
+	return (void *)kretprobe_trampoline_handler(regs, (void *)regs->ARM_fp);
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				      struct pt_regs *regs)
 {
 	ri->ret_addr = (kprobe_opcode_t *)regs->ARM_lr;
+	ri->fp = (void *)regs->ARM_fp;
 
 	/* Replace the return addr with trampoline addr. */
-	regs->ARM_lr = (unsigned long)&kretprobe_trampoline;
+	regs->ARM_lr = (unsigned long)&__kretprobe_trampoline;
 }
 
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
@@ -534,7 +462,7 @@ static struct undef_hook kprobes_arm_break_hook = {
 
 #endif /* !CONFIG_THUMB2_KERNEL */
 
-int __init arch_init_kprobes()
+int __init arch_init_kprobes(void)
 {
 	arm_probes_decode_init();
 #ifdef CONFIG_THUMB2_KERNEL