1 files changed, 27 insertions, 86 deletions

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index ec0a337891dd..fcc783e8e9bb 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -53,18 +53,12 @@ struct fault_info {
 };
 
 static const struct fault_info fault_info[];
-static struct fault_info debug_fault_info[];
 
 static inline const struct fault_info *esr_to_fault_info(unsigned long esr)
 {
 	return fault_info + (esr & ESR_ELx_FSC);
 }
 
-static inline const struct fault_info *esr_to_debug_fault_info(unsigned long esr)
-{
-	return debug_fault_info + DBG_ESR_EVT(esr);
-}
-
 static void data_abort_decode(unsigned long esr)
 {
 	unsigned long iss2 = ESR_ELx_ISS2(esr);
@@ -487,17 +481,29 @@ static void do_bad_area(unsigned long far, unsigned long esr,
 	}
 }
 
-static bool fault_from_pkey(unsigned long esr, struct vm_area_struct *vma,
-			unsigned int mm_flags)
+static bool fault_from_pkey(struct vm_area_struct *vma, unsigned int mm_flags)
 {
-	unsigned long iss2 = ESR_ELx_ISS2(esr);
-
 	if (!system_supports_poe())
 		return false;
 
-	if (esr_fsc_is_permission_fault(esr) && (iss2 & ESR_ELx_Overlay))
-		return true;
-
+	/*
+	 * We do not check whether an Overlay fault has occurred because we
+	 * cannot make a decision based solely on its value:
+	 *
+	 * - If Overlay is set, a fault did occur due to POE, but it may be
+	 *   spurious in those cases where we update POR_EL0 without ISB (e.g.
+	 *   on context-switch). We would then need to manually check POR_EL0
+	 *   against vma_pkey(vma), which is exactly what
+	 *   arch_vma_access_permitted() does.
+	 *
+	 * - If Overlay is not set, we may still need to report a pkey fault.
+	 *   This is the case if an access was made within a mapping but with no
+	 *   page mapped, and POR_EL0 forbids the access (according to
+	 *   vma_pkey()). Such access will result in a SIGSEGV regardless
+	 *   because core code checks arch_vma_access_permitted(), but in order
+	 *   to report the correct error code - SEGV_PKUERR - we must handle
+	 *   that case here.
+	 */
 	return !arch_vma_access_permitted(vma,
 			mm_flags & FAULT_FLAG_WRITE,
 			mm_flags & FAULT_FLAG_INSTRUCTION,
@@ -635,7 +641,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 		goto bad_area;
 	}
 
-	if (fault_from_pkey(esr, vma, mm_flags)) {
+	if (fault_from_pkey(vma, mm_flags)) {
 		pkey = vma_pkey(vma);
 		vma_end_read(vma);
 		fault = 0;
@@ -679,7 +685,7 @@ retry:
 		goto bad_area;
 	}
 
-	if (fault_from_pkey(esr, vma, mm_flags)) {
+	if (fault_from_pkey(vma, mm_flags)) {
 		pkey = vma_pkey(vma);
 		mmap_read_unlock(mm);
 		fault = 0;
@@ -826,6 +832,7 @@ static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs)
 		 */
 		siaddr  = untagged_addr(far);
 	}
+	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_STILL_OK);
 	arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr);
 
 	return 0;
@@ -837,9 +844,12 @@ static int do_tag_check_fault(unsigned long far, unsigned long esr,
 	/*
 	 * The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN
 	 * for tag check faults. Set them to corresponding bits in the untagged
-	 * address.
+	 * address if ARM64_MTE_FAR isn't supported.
+	 * Otherwise, bits 63:60 of FAR_EL1 are not UNKNOWN.
 	 */
-	far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK);
+	if (!cpus_have_cap(ARM64_MTE_FAR))
+		far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK);
+
 	do_bad_area(far, esr, regs);
 	return 0;
 }
@@ -939,75 +949,6 @@ void do_sp_pc_abort(unsigned long addr, unsigned long esr, struct pt_regs *regs)
 NOKPROBE_SYMBOL(do_sp_pc_abort);
 
 /*
- * __refdata because early_brk64 is __init, but the reference to it is
- * clobbered at arch_initcall time.
- * See traps.c and debug-monitors.c:debug_traps_init().
- */
-static struct fault_info __refdata debug_fault_info[] = {
-	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware breakpoint"	},
-	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware single-step"	},
-	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware watchpoint"	},
-	{ do_bad,	SIGKILL,	SI_KERNEL,	"unknown 3"		},
-	{ do_bad,	SIGTRAP,	TRAP_BRKPT,	"aarch32 BKPT"		},
-	{ do_bad,	SIGKILL,	SI_KERNEL,	"aarch32 vector catch"	},
-	{ early_brk64,	SIGTRAP,	TRAP_BRKPT,	"aarch64 BRK"		},
-	{ do_bad,	SIGKILL,	SI_KERNEL,	"unknown 7"		},
-};
-
-void __init hook_debug_fault_code(int nr,
-				  int (*fn)(unsigned long, unsigned long, struct pt_regs *),
-				  int sig, int code, const char *name)
-{
-	BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
-
-	debug_fault_info[nr].fn		= fn;
-	debug_fault_info[nr].sig	= sig;
-	debug_fault_info[nr].code	= code;
-	debug_fault_info[nr].name	= name;
-}
-
-/*
- * In debug exception context, we explicitly disable preemption despite
- * having interrupts disabled.
- * This serves two purposes: it makes it much less likely that we would
- * accidentally schedule in exception context and it will force a warning
- * if we somehow manage to schedule by accident.
- */
-static void debug_exception_enter(struct pt_regs *regs)
-{
-	preempt_disable();
-
-	/* This code is a bit fragile.  Test it. */
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work");
-}
-NOKPROBE_SYMBOL(debug_exception_enter);
-
-static void debug_exception_exit(struct pt_regs *regs)
-{
-	preempt_enable_no_resched();
-}
-NOKPROBE_SYMBOL(debug_exception_exit);
-
-void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr,
-			struct pt_regs *regs)
-{
-	const struct fault_info *inf = esr_to_debug_fault_info(esr);
-	unsigned long pc = instruction_pointer(regs);
-
-	debug_exception_enter(regs);
-
-	if (user_mode(regs) && !is_ttbr0_addr(pc))
-		arm64_apply_bp_hardening();
-
-	if (inf->fn(addr_if_watchpoint, esr, regs)) {
-		arm64_notify_die(inf->name, regs, inf->sig, inf->code, pc, esr);
-	}
-
-	debug_exception_exit(regs);
-}
-NOKPROBE_SYMBOL(do_debug_exception);
-
-/*
  * Used during anonymous page fault handling.
  */
 struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,