1 files changed, 60 insertions, 37 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 4bf899fb451b..37b95dff0b07 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -42,7 +42,20 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 
-static const char *fault_name(unsigned int esr);
+struct fault_info {
+	int	(*fn)(unsigned long addr, unsigned int esr,
+		      struct pt_regs *regs);
+	int	sig;
+	int	code;
+	const char *name;
+};
+
+static const struct fault_info fault_info[];
+
+static inline const struct fault_info *esr_to_fault_info(unsigned int esr)
+{
+	return fault_info + (esr & 63);
+}
 
 #ifdef CONFIG_KPROBES
 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
@@ -161,12 +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.
@@ -178,9 +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);
@@ -197,10 +242,12 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
 			    struct pt_regs *regs)
 {
 	struct siginfo si;
+	const struct fault_info *inf;
 
 	if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
+		inf = esr_to_fault_info(esr);
 		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
-			tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
+			tsk->comm, task_pid_nr(tsk), inf->name, sig,
 			addr, esr);
 		show_pte(tsk->mm, addr);
 		show_regs(regs);
@@ -219,14 +266,16 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
 {
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->active_mm;
+	const struct fault_info *inf;
 
 	/*
 	 * If we are in kernel mode at this point, we have no context to
 	 * handle this fault with.
 	 */
-	if (user_mode(regs))
-		__do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
-	else
+	if (user_mode(regs)) {
+		inf = esr_to_fault_info(esr);
+		__do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs);
+	} else
 		__do_kernel_fault(mm, addr, esr, regs);
 }
 
@@ -270,21 +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;
@@ -322,7 +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);
@@ -488,12 +522,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 	return 1;
 }
 
-static const struct fault_info {
-	int	(*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
-	int	sig;
-	int	code;
-	const char *name;
-} fault_info[] = {
+static const struct fault_info fault_info[] = {
 	{ do_bad,		SIGBUS,  0,		"ttbr address size fault"	},
 	{ do_bad,		SIGBUS,  0,		"level 1 address size fault"	},
 	{ do_bad,		SIGBUS,  0,		"level 2 address size fault"	},
@@ -560,19 +589,13 @@ static const struct fault_info {
 	{ do_bad,		SIGBUS,  0,		"unknown 63"			},
 };
 
-static const char *fault_name(unsigned int esr)
-{
-	const struct fault_info *inf = fault_info + (esr & 63);
-	return inf->name;
-}
-
 /*
  * Dispatch a data abort to the relevant handler.
  */
 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
 					 struct pt_regs *regs)
 {
-	const struct fault_info *inf = fault_info + (esr & 63);
+	const struct fault_info *inf = esr_to_fault_info(esr);
 	struct siginfo info;
 
 	if (!inf->fn(addr, esr, regs))