1 files changed, 53 insertions, 158 deletions

diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index f5c8bce70db2..dc39f5b3fb83 100644
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  *  Kernel Probes (KProbes)
  *  arch/mips/kernel/kprobes.c
@@ -8,21 +9,10 @@
  *  Some portions copied from the powerpc version.
  *
  *   Copyright (C) IBM Corporation, 2002, 2004
- *
- *  This program is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; version 2 of the License.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#define pr_fmt(fmt) "kprobes: " fmt
+
 #include <linux/kprobes.h>
 #include <linux/preempt.h>
 #include <linux/uaccess.h>
@@ -54,19 +44,20 @@ static const union mips_instruction breakpoint2_insn = {
 DEFINE_PER_CPU(struct kprobe *, current_kprobe);
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
-static int __kprobes insn_has_delayslot(union mips_instruction insn)
+static int insn_has_delayslot(union mips_instruction insn)
 {
 	return __insn_has_delay_slot(insn);
 }
+NOKPROBE_SYMBOL(insn_has_delayslot);
 
 /*
  * insn_has_ll_or_sc function checks whether instruction is ll or sc
  * one; putting breakpoint on top of atomic ll/sc pair is bad idea;
  * so we need to prevent it and refuse kprobes insertion for such
  * instructions; cannot do much about breakpoint in the middle of
- * ll/sc pair; it is upto user to avoid those places
+ * ll/sc pair; it is up to user to avoid those places
  */
-static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
+static int insn_has_ll_or_sc(union mips_instruction insn)
 {
 	int ret = 0;
 
@@ -82,8 +73,9 @@ static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
 	}
 	return ret;
 }
+NOKPROBE_SYMBOL(insn_has_ll_or_sc);
 
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
+int arch_prepare_kprobe(struct kprobe *p)
 {
 	union mips_instruction insn;
 	union mips_instruction prev_insn;
@@ -92,15 +84,14 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 	insn = p->addr[0];
 
 	if (insn_has_ll_or_sc(insn)) {
-		pr_notice("Kprobes for ll and sc instructions are not"
-			  "supported\n");
+		pr_notice("Kprobes for ll and sc instructions are not supported\n");
 		ret = -EINVAL;
 		goto out;
 	}
 
-	if ((probe_kernel_read(&prev_insn, p->addr - 1,
-				sizeof(mips_instruction)) == 0) &&
-				insn_has_delayslot(prev_insn)) {
+	if (copy_from_kernel_nofault(&prev_insn, p->addr - 1,
+			sizeof(mips_instruction)) == 0 &&
+	    insn_has_delayslot(prev_insn)) {
 		pr_notice("Kprobes for branch delayslot are not supported\n");
 		ret = -EINVAL;
 		goto out;
@@ -143,26 +134,30 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 out:
 	return ret;
 }
+NOKPROBE_SYMBOL(arch_prepare_kprobe);
 
-void __kprobes arch_arm_kprobe(struct kprobe *p)
+void arch_arm_kprobe(struct kprobe *p)
 {
 	*p->addr = breakpoint_insn;
 	flush_insn_slot(p);
 }
+NOKPROBE_SYMBOL(arch_arm_kprobe);
 
-void __kprobes arch_disarm_kprobe(struct kprobe *p)
+void arch_disarm_kprobe(struct kprobe *p)
 {
 	*p->addr = p->opcode;
 	flush_insn_slot(p);
 }
+NOKPROBE_SYMBOL(arch_disarm_kprobe);
 
-void __kprobes arch_remove_kprobe(struct kprobe *p)
+void arch_remove_kprobe(struct kprobe *p)
 {
 	if (p->ainsn.insn) {
 		free_insn_slot(p->ainsn.insn, 0);
 		p->ainsn.insn = NULL;
 	}
 }
+NOKPROBE_SYMBOL(arch_remove_kprobe);
 
 static void save_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
@@ -231,8 +226,8 @@ static int evaluate_branch_instruction(struct kprobe *p, struct pt_regs *regs,
 	return 0;
 
 unaligned:
-	pr_notice("%s: unaligned epc - sending SIGBUS.\n", current->comm);
-	force_sig(SIGBUS, current);
+	pr_notice("Failed to emulate branch instruction because of unaligned epc - sending SIGBUS to %s.\n", current->comm);
+	force_sig(SIGBUS);
 	return -EFAULT;
 
 }
@@ -250,10 +245,8 @@ static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
 		regs->cp0_epc = (unsigned long)p->addr;
 	else if (insn_has_delayslot(p->opcode)) {
 		ret = evaluate_branch_instruction(p, regs, kcb);
-		if (ret < 0) {
-			pr_notice("Kprobes: Error in evaluating branch\n");
+		if (ret < 0)
 			return;
-		}
 	}
 	regs->cp0_epc = (unsigned long)&p->ainsn.insn[0];
 }
@@ -270,7 +263,7 @@ static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
  * breakpoint trap. In case of branch instructions, the target
  * epc to be restored.
  */
-static void __kprobes resume_execution(struct kprobe *p,
+static void resume_execution(struct kprobe *p,
 				       struct pt_regs *regs,
 				       struct kprobe_ctlblk *kcb)
 {
@@ -281,8 +274,9 @@ static void __kprobes resume_execution(struct kprobe *p,
 		regs->cp0_epc = orig_epc + 4;
 	}
 }
+NOKPROBE_SYMBOL(resume_execution);
 
-static int __kprobes kprobe_handler(struct pt_regs *regs)
+static int kprobe_handler(struct pt_regs *regs)
 {
 	struct kprobe *p;
 	int ret = 0;
@@ -326,19 +320,13 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 				preempt_enable_no_resched();
 			}
 			return 1;
-		} else {
-			if (addr->word != breakpoint_insn.word) {
-				/*
-				 * The breakpoint instruction was removed by
-				 * another cpu right after we hit, no further
-				 * handling of this interrupt is appropriate
-				 */
-				ret = 1;
-				goto no_kprobe;
-			}
-			p = __this_cpu_read(current_kprobe);
-			if (p->break_handler && p->break_handler(p, regs))
-				goto ss_probe;
+		} else if (addr->word != breakpoint_insn.word) {
+			/*
+			 * The breakpoint instruction was removed by
+			 * another cpu right after we hit, no further
+			 * handling of this interrupt is appropriate
+			 */
+			ret = 1;
 		}
 		goto no_kprobe;
 	}
@@ -364,10 +352,11 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 
 	if (p->pre_handler && p->pre_handler(p, regs)) {
 		/* handler has already set things up, so skip ss setup */
+		reset_current_kprobe();
+		preempt_enable_no_resched();
 		return 1;
 	}
 
-ss_probe:
 	prepare_singlestep(p, regs, kcb);
 	if (kcb->flags & SKIP_DELAYSLOT) {
 		kcb->kprobe_status = KPROBE_HIT_SSDONE;
@@ -385,6 +374,7 @@ no_kprobe:
 	return ret;
 
 }
+NOKPROBE_SYMBOL(kprobe_handler);
 
 static inline int post_kprobe_handler(struct pt_regs *regs)
 {
@@ -415,14 +405,11 @@ out:
 	return 1;
 }
 
-static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	struct kprobe *cur = kprobe_running();
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 
-	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
-		return 1;
-
 	if (kcb->kprobe_status & KPROBE_HIT_SS) {
 		resume_execution(cur, regs, kcb);
 		regs->cp0_status |= kcb->kprobe_old_SR;
@@ -436,7 +423,7 @@ static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 /*
  * Wrapper routine for handling exceptions.
  */
-int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+int kprobe_exceptions_notify(struct notifier_block *self,
 				       unsigned long val, void *data)
 {
 
@@ -467,51 +454,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 	}
 	return ret;
 }
-
-int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
-{
-	struct jprobe *jp = container_of(p, struct jprobe, kp);
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	kcb->jprobe_saved_regs = *regs;
-	kcb->jprobe_saved_sp = regs->regs[29];
-
-	memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
-	       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
-
-	regs->cp0_epc = (unsigned long)(jp->entry);
-
-	return 1;
-}
-
-/* Defined in the inline asm below. */
-void jprobe_return_end(void);
-
-void __kprobes jprobe_return(void)
-{
-	/* Assembler quirk necessitates this '0,code' business.	 */
-	asm volatile(
-		"break 0,%0\n\t"
-		".globl jprobe_return_end\n"
-		"jprobe_return_end:\n"
-		: : "n" (BRK_KPROBE_BP) : "memory");
-}
-
-int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
-{
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	if (regs->cp0_epc >= (unsigned long)jprobe_return &&
-	    regs->cp0_epc <= (unsigned long)jprobe_return_end) {
-		*regs = kcb->jprobe_saved_regs;
-		memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
-		       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
-		preempt_enable_no_resched();
-
-		return 1;
-	}
-	return 0;
-}
+NOKPROBE_SYMBOL(kprobe_exceptions_notify);
 
 /*
  * Function return probe trampoline:
@@ -526,83 +469,33 @@ static void __used kretprobe_trampoline_holder(void)
 		/* Keep the assembler from reordering and placing JR here. */
 		".set noreorder\n\t"
 		"nop\n\t"
-		".global kretprobe_trampoline\n"
-		"kretprobe_trampoline:\n\t"
+		".global __kretprobe_trampoline\n"
+		"__kretprobe_trampoline:\n\t"
 		"nop\n\t"
 		".set pop"
 		: : : "memory");
 }
 
-void kretprobe_trampoline(void);
+void __kretprobe_trampoline(void);
 
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				      struct pt_regs *regs)
 {
 	ri->ret_addr = (kprobe_opcode_t *) regs->regs[31];
+	ri->fp = NULL;
 
 	/* Replace the return addr with trampoline addr */
-	regs->regs[31] = (unsigned long)kretprobe_trampoline;
+	regs->regs[31] = (unsigned long)__kretprobe_trampoline;
 }
+NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 
 /*
  * Called when the probe at kretprobe trampoline is hit
  */
-static int __kprobes trampoline_probe_handler(struct kprobe *p,
+static int trampoline_probe_handler(struct kprobe *p,
 						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;
-
-	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 an multiple functions in the call path
-	 * have a return probe installed on them, and/or more than one return
-	 * 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;
-
-		if (ri->rp && ri->rp->handler)
-			ri->rp->handler(ri, regs);
-
-		orig_ret_address = (unsigned long)ri->ret_addr;
-		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_assert(ri, orig_ret_address, trampoline_address);
-	instruction_pointer(regs) = orig_ret_address;
-
-	reset_current_kprobe();
-	kretprobe_hash_unlock(current, &flags);
-	preempt_enable_no_resched();
-
-	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
-		hlist_del(&ri->hlist);
-		kfree(ri);
-	}
+	instruction_pointer(regs) = __kretprobe_trampoline_handler(regs, NULL);
 	/*
 	 * By returning a non-zero value, we are telling
 	 * kprobe_handler() that we don't want the post_handler
@@ -610,17 +503,19 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
 	 */
 	return 1;
 }
+NOKPROBE_SYMBOL(trampoline_probe_handler);
 
-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+int arch_trampoline_kprobe(struct kprobe *p)
 {
-	if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
+	if (p->addr == (kprobe_opcode_t *)__kretprobe_trampoline)
 		return 1;
 
 	return 0;
 }
+NOKPROBE_SYMBOL(arch_trampoline_kprobe);
 
 static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *)kretprobe_trampoline,
+	.addr = (kprobe_opcode_t *)__kretprobe_trampoline,
 	.pre_handler = trampoline_probe_handler
 };