From: Amit Pundir <amit.pundir@linaro.org>
Date: Mon, 16 Jan 2017 09:12:00 +0000 (+0530)
Subject: Revert "FROMLIST: arm64: Handle faults caused by inadvertent user access with PAN... 
X-Git-Tag: firefly_0821_release~176^2~27
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=23640f22070a47ad93b76a5227163587265258ad;p=firefly-linux-kernel-4.4.55.git

Revert "FROMLIST: arm64: Handle faults caused by inadvertent user access with PAN enabled"

This reverts commit 0a75f2be2d16a271d64b20f9dc7de3e2629652a1.
---

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 380e02941691..66af8d9479bc 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -270,19 +270,13 @@ out:
 	return fault;
 }
 
-static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs)
+static inline bool is_permission_fault(unsigned int esr)
 {
 	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;
+	return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM) ||
+	       (ec == ESR_ELx_EC_IABT_CUR && fsc_type == ESR_ELx_FSC_PERM);
 }
 
 static bool is_el0_instruction_abort(unsigned int esr)
@@ -326,7 +320,7 @@ 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 (is_permission_fault(esr) && (addr < USER_DS)) {
 		if (get_fs() == KERNEL_DS)
 			die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
 
@@ -510,10 +504,10 @@ static const struct fault_info {
 	{ do_bad,		SIGBUS,  0,		"unknown 17"			},
 	{ do_bad,		SIGBUS,  0,		"unknown 18"			},
 	{ do_bad,		SIGBUS,  0,		"unknown 19"			},
-	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
-	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
-	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
-	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
+	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
+	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
+	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
+	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
 	{ do_bad,		SIGBUS,  0,		"synchronous parity error"	},
 	{ do_bad,		SIGBUS,  0,		"unknown 25"			},
 	{ do_bad,		SIGBUS,  0,		"unknown 26"			},