1 files changed, 36 insertions, 19 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 1b35b8bddbfb..37b95dff0b07 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -174,12 +174,33 @@ static bool is_el1_instruction_abort(unsigned int esr)
 	return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
 }
 
+static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs,
+				       unsigned long addr)
+{
+	unsigned int ec       = ESR_ELx_EC(esr);
+	unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
+
+	if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
+		return false;
+
+	if (fsc_type == ESR_ELx_FSC_PERM)
+		return true;
+
+	if (addr < USER_DS && system_uses_ttbr0_pan())
+		return fsc_type == ESR_ELx_FSC_FAULT &&
+			(regs->pstate & PSR_PAN_BIT);
+
+	return false;
+}
+
 /*
  * The kernel tried to access some page that wasn't present.
  */
 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
 			      unsigned int esr, struct pt_regs *regs)
 {
+	const char *msg;
+
 	/*
 	 * Are we prepared to handle this kernel fault?
 	 * We are almost certainly not prepared to handle instruction faults.
@@ -191,9 +212,20 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
 	 * No handler, we'll have to terminate things with extreme prejudice.
 	 */
 	bust_spinlocks(1);
-	pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
-		 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
-		 "paging request", addr);
+
+	if (is_permission_fault(esr, regs, addr)) {
+		if (esr & ESR_ELx_WNR)
+			msg = "write to read-only memory";
+		else
+			msg = "read from unreadable memory";
+	} else if (addr < PAGE_SIZE) {
+		msg = "NULL pointer dereference";
+	} else {
+		msg = "paging request";
+	}
+
+	pr_alert("Unable to handle kernel %s at virtual address %08lx\n", msg,
+		 addr);
 
 	show_pte(mm, addr);
 	die("Oops", regs, esr);
@@ -287,21 +319,6 @@ out:
 	return fault;
 }
 
-static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs)
-{
-	unsigned int ec       = ESR_ELx_EC(esr);
-	unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
-
-	if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
-		return false;
-
-	if (system_uses_ttbr0_pan())
-		return fsc_type == ESR_ELx_FSC_FAULT &&
-			(regs->pstate & PSR_PAN_BIT);
-	else
-		return fsc_type == ESR_ELx_FSC_PERM;
-}
-
 static bool is_el0_instruction_abort(unsigned int esr)
 {
 	return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
@@ -339,7 +356,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 		mm_flags |= FAULT_FLAG_WRITE;
 	}
 
-	if (addr < USER_DS && is_permission_fault(esr, regs)) {
+	if (addr < USER_DS && is_permission_fault(esr, regs, addr)) {
 		/* regs->orig_addr_limit may be 0 if we entered from EL0 */
 		if (regs->orig_addr_limit == KERNEL_DS)
 			die("Accessing user space memory with fs=KERNEL_DS", regs, esr);