1 files changed, 371 insertions, 260 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index cab094c234ee..afbd2ebe5c39 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -1,13 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  *  linux/arch/arm/kernel/traps.c
  *
  *  Copyright (C) 1995-2009 Russell King
  *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
  *  'traps.c' handles hardware exceptions after we have saved some state in
  *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
  *  kill the offending process.
@@ -19,25 +16,39 @@
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
 #include <linux/kdebug.h>
+#include <linux/kprobes.h>
 #include <linux/module.h>
 #include <linux/kexec.h>
 #include <linux/bug.h>
 #include <linux/delay.h>
 #include <linux/init.h>
-#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/irq.h>
+#include <linux/vmalloc.h>
 
 #include <linux/atomic.h>
 #include <asm/cacheflush.h>
 #include <asm/exception.h>
+#include <asm/spectre.h>
 #include <asm/unistd.h>
 #include <asm/traps.h>
+#include <asm/ptrace.h>
 #include <asm/unwind.h>
 #include <asm/tls.h>
+#include <asm/stacktrace.h>
 #include <asm/system_misc.h>
+#include <asm/opcodes.h>
 
-#include "signal.h"
 
-static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
+static const char *handler[]= {
+	"prefetch abort",
+	"data abort",
+	"address exception",
+	"interrupt",
+	"undefined instruction",
+};
 
 void *vectors_page;
 
@@ -52,18 +63,56 @@ static int __init user_debug_setup(char *str)
 __setup("user_debug=", user_debug_setup);
 #endif
 
-static void dump_mem(const char *, const char *, unsigned long, unsigned long);
+void dump_backtrace_entry(unsigned long where, unsigned long from,
+			  unsigned long frame, const char *loglvl)
+{
+	unsigned long end = frame + 4 + sizeof(struct pt_regs);
+
+	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
+	    IS_ENABLED(CONFIG_CC_IS_GCC) &&
+	    end > ALIGN(frame, THREAD_SIZE)) {
+		/*
+		 * If we are walking past the end of the stack, it may be due
+		 * to the fact that we are on an IRQ or overflow stack. In this
+		 * case, we can load the address of the other stack from the
+		 * frame record.
+		 */
+		frame = ((unsigned long *)frame)[-2] - 4;
+		end = frame + 4 + sizeof(struct pt_regs);
+	}
 
-void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
-{
-#ifdef CONFIG_KALLSYMS
-	printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
+#ifndef CONFIG_KALLSYMS
+	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
+		loglvl, where, from);
+#elif defined CONFIG_BACKTRACE_VERBOSE
+	printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
+		loglvl, where, (void *)where, from, (void *)from);
 #else
-	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
+	printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
 #endif
 
-	if (in_exception_text(where))
-		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
+	if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
+		dump_mem(loglvl, "Exception stack", frame + 4, end);
+}
+
+void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
+{
+	char str[80], *p;
+	unsigned int x;
+	int reg;
+
+	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
+		if (instruction & BIT(reg)) {
+			p += sprintf(p, " r%d:%08x", reg, *stack--);
+			if (++x == 6) {
+				x = 0;
+				p = str;
+				printk("%s%s\n", loglvl, str);
+			}
+		}
+	}
+	if (p != str)
+		printk("%s%s\n", loglvl, str);
 }
 
 #ifndef CONFIG_ARM_UNWIND
@@ -75,7 +124,8 @@ void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long
 static int verify_stack(unsigned long sp)
 {
 	if (sp < PAGE_OFFSET ||
-	    (sp > (unsigned long)high_memory && high_memory != NULL))
+	    (!IS_ENABLED(CONFIG_VMAP_STACK) &&
+	     sp > (unsigned long)high_memory && high_memory != NULL))
 		return -EFAULT;
 
 	return 0;
@@ -85,21 +135,12 @@ static int verify_stack(unsigned long sp)
 /*
  * Dump out the contents of some memory nicely...
  */
-static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
-		     unsigned long top)
+void dump_mem(const char *lvl, const char *str, unsigned long bottom,
+	      unsigned long top)
 {
 	unsigned long first;
-	mm_segment_t fs;
 	int i;
 
-	/*
-	 * We need to switch to kernel mode so that we can use __get_user
-	 * to safely read from kernel space.  Note that we now dump the
-	 * code first, just in case the backtrace kills us.
-	 */
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-
 	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
 
 	for (first = bottom & ~31; first < top; first += 32) {
@@ -112,7 +153,7 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
 		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
 			if (p >= bottom && p < top) {
 				unsigned long val;
-				if (__get_user(val, (unsigned long *)p) == 0)
+				if (!get_kernel_nofault(val, (unsigned long *)p))
 					sprintf(str + i * 9, " %08lx", val);
 				else
 					sprintf(str + i * 9, " ????????");
@@ -120,8 +161,6 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
 		}
 		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
 	}
-
-	set_fs(fs);
 }
 
 static void dump_instr(const char *lvl, struct pt_regs *regs)
@@ -129,25 +168,34 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
 	unsigned long addr = instruction_pointer(regs);
 	const int thumb = thumb_mode(regs);
 	const int width = thumb ? 4 : 8;
-	mm_segment_t fs;
 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 	int i;
 
 	/*
-	 * We need to switch to kernel mode so that we can use __get_user
-	 * to safely read from kernel space.  Note that we now dump the
-	 * code first, just in case the backtrace kills us.
+	 * Note that we now dump the code first, just in case the backtrace
+	 * kills us.
 	 */
-	fs = get_fs();
-	set_fs(KERNEL_DS);
 
 	for (i = -4; i < 1 + !!thumb; i++) {
 		unsigned int val, bad;
 
-		if (thumb)
-			bad = __get_user(val, &((u16 *)addr)[i]);
-		else
-			bad = __get_user(val, &((u32 *)addr)[i]);
+		if (thumb) {
+			u16 tmp;
+
+			if (user_mode(regs))
+				bad = get_user(tmp, &((u16 __user *)addr)[i]);
+			else
+				bad = get_kernel_nofault(tmp, &((u16 *)addr)[i]);
+
+			val = __mem_to_opcode_thumb16(tmp);
+		} else {
+			if (user_mode(regs))
+				bad = get_user(val, &((u32 __user *)addr)[i]);
+			else
+				bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
+
+			val = __mem_to_opcode_arm(val);
+		}
 
 		if (!bad)
 			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
@@ -158,28 +206,28 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
 		}
 	}
 	printk("%sCode: %s\n", lvl, str);
-
-	set_fs(fs);
 }
 
 #ifdef CONFIG_ARM_UNWIND
-static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
+		    const char *loglvl)
 {
-	unwind_backtrace(regs, tsk);
+	unwind_backtrace(regs, tsk, loglvl);
 }
 #else
-static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
+		    const char *loglvl)
 {
 	unsigned int fp, mode;
 	int ok = 1;
 
-	printk("Backtrace: ");
+	printk("%sCall trace: ", loglvl);
 
 	if (!tsk)
 		tsk = current;
 
 	if (regs) {
-		fp = regs->ARM_fp;
+		fp = frame_pointer(regs);
 		mode = processor_mode(regs);
 	} else if (tsk != current) {
 		fp = thread_saved_fp(tsk);
@@ -190,31 +238,26 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 	}
 
 	if (!fp) {
-		printk("no frame pointer");
+		pr_cont("no frame pointer");
 		ok = 0;
 	} else if (verify_stack(fp)) {
-		printk("invalid frame pointer 0x%08x", fp);
+		pr_cont("invalid frame pointer 0x%08x", fp);
 		ok = 0;
 	} else if (fp < (unsigned long)end_of_stack(tsk))
-		printk("frame pointer underflow");
-	printk("\n");
+		pr_cont("frame pointer underflow");
+	pr_cont("\n");
 
 	if (ok)
-		c_backtrace(fp, mode);
+		c_backtrace(fp, mode, loglvl);
 }
 #endif
 
-void show_stack(struct task_struct *tsk, unsigned long *sp)
+void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
 {
-	dump_backtrace(NULL, tsk);
+	dump_backtrace(NULL, tsk, loglvl);
 	barrier();
 }
 
-#ifdef CONFIG_PREEMPT
-#define S_PREEMPT " PREEMPT"
-#else
-#define S_PREEMPT ""
-#endif
 #ifdef CONFIG_SMP
 #define S_SMP " SMP"
 #else
@@ -232,8 +275,8 @@ static int __die(const char *str, int err, struct pt_regs *regs)
 	static int die_counter;
 	int ret;
 
-	printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
-	       S_ISA "\n", str, err, ++die_counter);
+	pr_emerg("Internal error: %s: %x [#%d]" S_SMP S_ISA "\n",
+		 str, err, ++die_counter);
 
 	/* trap and error numbers are mostly meaningless on ARM */
 	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
@@ -242,13 +285,15 @@ static int __die(const char *str, int err, struct pt_regs *regs)
 
 	print_modules();
 	__show_regs(regs);
-	printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
-		TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
+	__show_regs_alloc_free(regs);
+	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
+		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
 
 	if (!user_mode(regs) || in_interrupt()) {
 		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
-			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
-		dump_backtrace(regs, tsk);
+			 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
+			 + THREAD_SIZE);
+		dump_backtrace(regs, tsk, KERN_EMERG);
 		dump_instr(KERN_EMERG, regs);
 	}
 
@@ -302,7 +347,7 @@ static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 	if (panic_on_oops)
 		panic("Fatal exception");
 	if (signr)
-		do_exit(signr);
+		make_task_dead(signr);
 }
 
 /*
@@ -326,13 +371,14 @@ void die(const char *str, struct pt_regs *regs, int err)
 }
 
 void arm_notify_die(const char *str, struct pt_regs *regs,
-		struct siginfo *info, unsigned long err, unsigned long trap)
+		int signo, int si_code, void __user *addr,
+		unsigned long err, unsigned long trap)
 {
 	if (user_mode(regs)) {
 		current->thread.error_code = err;
 		current->thread.trap_no = trap;
 
-		force_sig_info(info->si_signo, info, current);
+		force_sig_fault(signo, si_code, addr);
 	} else {
 		die(str, regs, err);
 	}
@@ -343,15 +389,17 @@ void arm_notify_die(const char *str, struct pt_regs *regs,
 int is_valid_bugaddr(unsigned long pc)
 {
 #ifdef CONFIG_THUMB2_KERNEL
-	unsigned short bkpt;
+	u16 bkpt;
+	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
 #else
-	unsigned long bkpt;
+	u32 bkpt;
+	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
 #endif
 
-	if (probe_kernel_address((unsigned *)pc, bkpt))
+	if (get_kernel_nofault(bkpt, (void *)pc))
 		return 0;
 
-	return bkpt == BUG_INSTR_VALUE;
+	return bkpt == insn;
 }
 
 #endif
@@ -377,7 +425,8 @@ void unregister_undef_hook(struct undef_hook *hook)
 	raw_spin_unlock_irqrestore(&undef_lock, flags);
 }
 
-static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
+static nokprobe_inline
+int call_undef_hook(struct pt_regs *regs, unsigned int instr)
 {
 	struct undef_hook *hook;
 	unsigned long flags;
@@ -393,10 +442,9 @@ static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
 	return fn ? fn(regs, instr) : 1;
 }
 
-asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
+asmlinkage void do_undefinstr(struct pt_regs *regs)
 {
 	unsigned int instr;
-	siginfo_t info;
 	void __user *pc;
 
 	pc = (void __user *)instruction_pointer(regs);
@@ -404,26 +452,30 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 	if (processor_mode(regs) == SVC_MODE) {
 #ifdef CONFIG_THUMB2_KERNEL
 		if (thumb_mode(regs)) {
-			instr = ((u16 *)pc)[0];
+			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
 			if (is_wide_instruction(instr)) {
-				instr <<= 16;
-				instr |= ((u16 *)pc)[1];
+				u16 inst2;
+				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
+				instr = __opcode_thumb32_compose(instr, inst2);
 			}
 		} else
 #endif
-			instr = *(u32 *) pc;
+			instr = __mem_to_opcode_arm(*(u32 *) pc);
 	} else if (thumb_mode(regs)) {
 		if (get_user(instr, (u16 __user *)pc))
 			goto die_sig;
+		instr = __mem_to_opcode_thumb16(instr);
 		if (is_wide_instruction(instr)) {
 			unsigned int instr2;
 			if (get_user(instr2, (u16 __user *)pc+1))
 				goto die_sig;
-			instr <<= 16;
-			instr |= instr2;
+			instr2 = __mem_to_opcode_thumb16(instr2);
+			instr = __opcode_thumb32_compose(instr, instr2);
 		}
-	} else if (get_user(instr, (u32 __user *)pc)) {
-		goto die_sig;
+	} else {
+		if (get_user(instr, (u32 __user *)pc))
+			goto die_sig;
+		instr = __mem_to_opcode_arm(instr);
 	}
 
 	if (call_undef_hook(regs, instr) == 0)
@@ -432,24 +484,40 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 die_sig:
 #ifdef CONFIG_DEBUG_USER
 	if (user_debug & UDBG_UNDEFINED) {
-		printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
+		pr_info("%s (%d): undefined instruction: pc=%px\n",
 			current->comm, task_pid_nr(current), pc);
+		__show_regs(regs);
 		dump_instr(KERN_INFO, regs);
 	}
 #endif
-
-	info.si_signo = SIGILL;
-	info.si_errno = 0;
-	info.si_code  = ILL_ILLOPC;
-	info.si_addr  = pc;
-
-	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
+	arm_notify_die("Oops - undefined instruction", regs,
+		       SIGILL, ILL_ILLOPC, pc, 0, 6);
 }
+NOKPROBE_SYMBOL(do_undefinstr)
 
-asmlinkage void do_unexp_fiq (struct pt_regs *regs)
+/*
+ * Handle FIQ similarly to NMI on x86 systems.
+ *
+ * The runtime environment for NMIs is extremely restrictive
+ * (NMIs can pre-empt critical sections meaning almost all locking is
+ * forbidden) meaning this default FIQ handling must only be used in
+ * circumstances where non-maskability improves robustness, such as
+ * watchdog or debug logic.
+ *
+ * This handler is not appropriate for general purpose use in drivers
+ * platform code and can be overrideen using set_fiq_handler.
+ */
+asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
 {
-	printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
-	printk("You may have a hardware problem...\n");
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	nmi_enter();
+
+	/* nop. FIQ handlers for special arch/arm features can be added here. */
+
+	nmi_exit();
+
+	set_irq_regs(old_regs);
 }
 
 /*
@@ -462,7 +530,7 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason)
 {
 	console_verbose();
 
-	printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
+	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
 
 	die("Oops - bad mode", regs, 0);
 	local_irq_disable();
@@ -471,56 +539,62 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason)
 
 static int bad_syscall(int n, struct pt_regs *regs)
 {
-	struct thread_info *thread = current_thread_info();
-	siginfo_t info;
-
-	if ((current->personality & PER_MASK) != PER_LINUX &&
-	    thread->exec_domain->handler) {
-		thread->exec_domain->handler(n, regs);
+	if ((current->personality & PER_MASK) != PER_LINUX) {
+		send_sig(SIGSEGV, current, 1);
 		return regs->ARM_r0;
 	}
 
 #ifdef CONFIG_DEBUG_USER
 	if (user_debug & UDBG_SYSCALL) {
-		printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
+		pr_err("[%d] %s: obsolete system call %08x.\n",
 			task_pid_nr(current), current->comm, n);
 		dump_instr(KERN_ERR, regs);
 	}
 #endif
 
-	info.si_signo = SIGILL;
-	info.si_errno = 0;
-	info.si_code  = ILL_ILLTRP;
-	info.si_addr  = (void __user *)instruction_pointer(regs) -
-			 (thumb_mode(regs) ? 2 : 4);
-
-	arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
+	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
+		       (void __user *)instruction_pointer(regs) -
+			 (thumb_mode(regs) ? 2 : 4),
+		       n, 0);
 
 	return regs->ARM_r0;
 }
 
 static inline int
-do_cache_op(unsigned long start, unsigned long end, int flags)
+__do_cache_op(unsigned long start, unsigned long end)
 {
-	struct mm_struct *mm = current->active_mm;
-	struct vm_area_struct *vma;
+	unsigned int ua_flags;
+	int ret;
+
+	do {
+		unsigned long chunk = min(PAGE_SIZE, end - start);
+
+		if (fatal_signal_pending(current))
+			return 0;
+
+		ua_flags = uaccess_save_and_enable();
+		ret = flush_icache_user_range(start, start + chunk);
+		uaccess_restore(ua_flags);
+		if (ret)
+			return ret;
+
+		cond_resched();
+		start += chunk;
+	} while (start < end);
+
+	return 0;
+}
 
+static inline int
+do_cache_op(unsigned long start, unsigned long end, int flags)
+{
 	if (end < start || flags)
 		return -EINVAL;
 
-	down_read(&mm->mmap_sem);
-	vma = find_vma(mm, start);
-	if (vma && vma->vm_start < end) {
-		if (start < vma->vm_start)
-			start = vma->vm_start;
-		if (end > vma->vm_end)
-			end = vma->vm_end;
+	if (!access_ok((void __user *)start, end - start))
+		return -EFAULT;
 
-		up_read(&mm->mmap_sem);
-		return flush_cache_user_range(start, end);
-	}
-	up_read(&mm->mmap_sem);
-	return -EINVAL;
+	return __do_cache_op(start, end);
 }
 
 /*
@@ -530,25 +604,18 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 {
-	struct thread_info *thread = current_thread_info();
-	siginfo_t info;
-
 	if ((no >> 16) != (__ARM_NR_BASE>> 16))
 		return bad_syscall(no, regs);
 
 	switch (no & 0xffff) {
 	case 0: /* branch through 0 */
-		info.si_signo = SIGSEGV;
-		info.si_errno = 0;
-		info.si_code  = SEGV_MAPERR;
-		info.si_addr  = NULL;
-
-		arm_notify_die("branch through zero", regs, &info, 0, 0);
+		arm_notify_die("branch through zero", regs,
+			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
 		return 0;
 
 	case NR(breakpoint): /* SWI BREAK_POINT */
 		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
-		ptrace_break(current, regs);
+		ptrace_break(regs);
 		return regs->ARM_r0;
 
 	/*
@@ -581,74 +648,11 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 		return regs->ARM_r0;
 
 	case NR(set_tls):
-		thread->tp_value[0] = regs->ARM_r0;
-		if (tls_emu)
-			return 0;
-		if (has_tls_reg) {
-			asm ("mcr p15, 0, %0, c13, c0, 3"
-				: : "r" (regs->ARM_r0));
-		} else {
-			/*
-			 * User space must never try to access this directly.
-			 * Expect your app to break eventually if you do so.
-			 * The user helper at 0xffff0fe0 must be used instead.
-			 * (see entry-armv.S for details)
-			 */
-			*((unsigned int *)0xffff0ff0) = regs->ARM_r0;
-		}
+		set_tls(regs->ARM_r0);
 		return 0;
 
-#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
-	/*
-	 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
-	 * Return zero in r0 if *MEM was changed or non-zero if no exchange
-	 * happened.  Also set the user C flag accordingly.
-	 * If access permissions have to be fixed up then non-zero is
-	 * returned and the operation has to be re-attempted.
-	 *
-	 * *NOTE*: This is a ghost syscall private to the kernel.  Only the
-	 * __kuser_cmpxchg code in entry-armv.S should be aware of its
-	 * existence.  Don't ever use this from user code.
-	 */
-	case NR(cmpxchg):
-	for (;;) {
-		extern void do_DataAbort(unsigned long addr, unsigned int fsr,
-					 struct pt_regs *regs);
-		unsigned long val;
-		unsigned long addr = regs->ARM_r2;
-		struct mm_struct *mm = current->mm;
-		pgd_t *pgd; pmd_t *pmd; pte_t *pte;
-		spinlock_t *ptl;
-
-		regs->ARM_cpsr &= ~PSR_C_BIT;
-		down_read(&mm->mmap_sem);
-		pgd = pgd_offset(mm, addr);
-		if (!pgd_present(*pgd))
-			goto bad_access;
-		pmd = pmd_offset(pgd, addr);
-		if (!pmd_present(*pmd))
-			goto bad_access;
-		pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
-		if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
-			pte_unmap_unlock(pte, ptl);
-			goto bad_access;
-		}
-		val = *(unsigned long *)addr;
-		val -= regs->ARM_r0;
-		if (val == 0) {
-			*(unsigned long *)addr = regs->ARM_r1;
-			regs->ARM_cpsr |= PSR_C_BIT;
-		}
-		pte_unmap_unlock(pte, ptl);
-		up_read(&mm->mmap_sem);
-		return val;
-
-		bad_access:
-		up_read(&mm->mmap_sem);
-		/* simulate a write access fault */
-		do_DataAbort(addr, 15 + (1 << 11), regs);
-	}
-#endif
+	case NR(get_tls):
+		return current_thread_info()->tp_value[0];
 
 	default:
 		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
@@ -665,22 +669,19 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 	 * something catastrophic has happened
 	 */
 	if (user_debug & UDBG_SYSCALL) {
-		printk("[%d] %s: arm syscall %d\n",
+		pr_err("[%d] %s: arm syscall %d\n",
 		       task_pid_nr(current), current->comm, no);
-		dump_instr("", regs);
+		dump_instr(KERN_ERR, regs);
 		if (user_mode(regs)) {
 			__show_regs(regs);
-			c_backtrace(regs->ARM_fp, processor_mode(regs));
+			c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
 		}
 	}
 #endif
-	info.si_signo = SIGILL;
-	info.si_errno = 0;
-	info.si_code  = ILL_ILLTRP;
-	info.si_addr  = (void __user *)instruction_pointer(regs) -
-			 (thumb_mode(regs) ? 2 : 4);
-
-	arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
+	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
+		       (void __user *)instruction_pointer(regs) -
+			 (thumb_mode(regs) ? 2 : 4),
+		       no, 0);
 	return 0;
 }
 
@@ -722,14 +723,6 @@ late_initcall(arm_mrc_hook_init);
 
 #endif
 
-void __bad_xchg(volatile void *ptr, int size)
-{
-	printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
-		__builtin_return_address(0), ptr, size);
-	BUG();
-}
-EXPORT_SYMBOL(__bad_xchg);
-
 /*
  * A data abort trap was taken, but we did not handle the instruction.
  * Try to abort the user program, or panic if it was the kernel.
@@ -738,50 +731,48 @@ asmlinkage void
 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
 {
 	unsigned long addr = instruction_pointer(regs);
-	siginfo_t info;
 
 #ifdef CONFIG_DEBUG_USER
 	if (user_debug & UDBG_BADABORT) {
-		printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
-			task_pid_nr(current), current->comm, code, instr);
+		pr_err("8<--- cut here ---\n");
+		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
+		       task_pid_nr(current), current->comm, code, instr);
 		dump_instr(KERN_ERR, regs);
-		show_pte(current->mm, addr);
+		show_pte(KERN_ERR, current->mm, addr);
 	}
 #endif
 
-	info.si_signo = SIGILL;
-	info.si_errno = 0;
-	info.si_code  = ILL_ILLOPC;
-	info.si_addr  = (void __user *)addr;
-
-	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
+	arm_notify_die("unknown data abort code", regs,
+		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
 }
 
 void __readwrite_bug(const char *fn)
 {
-	printk("%s called, but not implemented\n", fn);
+	pr_err("%s called, but not implemented\n", fn);
 	BUG();
 }
 EXPORT_SYMBOL(__readwrite_bug);
 
+#ifdef CONFIG_MMU
 void __pte_error(const char *file, int line, pte_t pte)
 {
-	printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
+	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
 }
 
 void __pmd_error(const char *file, int line, pmd_t pmd)
 {
-	printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
+	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
 }
 
 void __pgd_error(const char *file, int line, pgd_t pgd)
 {
-	printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
+	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
 }
+#endif
 
 asmlinkage void __div0(void)
 {
-	printk("Division by zero in kernel.\n");
+	pr_err("Division by zero in kernel.\n");
 	dump_stack();
 }
 EXPORT_SYMBOL(__div0);
@@ -793,62 +784,182 @@ void abort(void)
 	/* if that doesn't kill us, halt */
 	panic("Oops failed to kill thread");
 }
-EXPORT_SYMBOL(abort);
 
-void __init trap_init(void)
+#ifdef CONFIG_KUSER_HELPERS
+static void __init kuser_init(void *vectors)
 {
-	return;
-}
+	extern char __kuser_helper_start[], __kuser_helper_end[];
+	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
+
+	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
 
-static void __init kuser_get_tls_init(unsigned long vectors)
-{
 	/*
 	 * vectors + 0xfe0 = __kuser_get_tls
 	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
 	 */
 	if (tls_emu || has_tls_reg)
-		memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
+		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
 }
+#else
+static inline void __init kuser_init(void *vectors)
+{
+}
+#endif
+
+#ifndef CONFIG_CPU_V7M
+static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
+{
+	memcpy(vma, lma_start, lma_end - lma_start);
+}
+
+static void flush_vectors(void *vma, size_t offset, size_t size)
+{
+	unsigned long start = (unsigned long)vma + offset;
+	unsigned long end = start + size;
+
+	flush_icache_range(start, end);
+}
+
+#ifdef CONFIG_HARDEN_BRANCH_HISTORY
+int spectre_bhb_update_vectors(unsigned int method)
+{
+	extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
+	extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
+	void *vec_start, *vec_end;
+
+	if (system_state >= SYSTEM_FREEING_INITMEM) {
+		pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
+		       smp_processor_id());
+		return SPECTRE_VULNERABLE;
+	}
+
+	switch (method) {
+	case SPECTRE_V2_METHOD_LOOP8:
+		vec_start = __vectors_bhb_loop8_start;
+		vec_end = __vectors_bhb_loop8_end;
+		break;
+
+	case SPECTRE_V2_METHOD_BPIALL:
+		vec_start = __vectors_bhb_bpiall_start;
+		vec_end = __vectors_bhb_bpiall_end;
+		break;
+
+	default:
+		pr_err("CPU%u: unknown Spectre BHB state %d\n",
+		       smp_processor_id(), method);
+		return SPECTRE_VULNERABLE;
+	}
+
+	copy_from_lma(vectors_page, vec_start, vec_end);
+	flush_vectors(vectors_page, 0, vec_end - vec_start);
+
+	return SPECTRE_MITIGATED;
+}
+#endif
 
 void __init early_trap_init(void *vectors_base)
 {
-#ifndef CONFIG_CPU_V7M
-	unsigned long vectors = (unsigned long)vectors_base;
 	extern char __stubs_start[], __stubs_end[];
 	extern char __vectors_start[], __vectors_end[];
-	extern char __kuser_helper_start[], __kuser_helper_end[];
-	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
+	unsigned i;
 
 	vectors_page = vectors_base;
 
 	/*
-	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
-	 * into the vector page, mapped at 0xffff0000, and ensure these
-	 * are visible to the instruction stream.
+	 * Poison the vectors page with an undefined instruction.  This
+	 * instruction is chosen to be undefined for both ARM and Thumb
+	 * ISAs.  The Thumb version is an undefined instruction with a
+	 * branch back to the undefined instruction.
 	 */
-	memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
-	memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
-	memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
+	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
+		((u32 *)vectors_base)[i] = 0xe7fddef1;
 
 	/*
-	 * Do processor specific fixups for the kuser helpers
+	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
+	 * into the vector page, mapped at 0xffff0000, and ensure these
+	 * are visible to the instruction stream.
 	 */
-	kuser_get_tls_init(vectors);
+	copy_from_lma(vectors_base, __vectors_start, __vectors_end);
+	copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
 
-	/*
-	 * Copy signal return handlers into the vector page, and
-	 * set sigreturn to be a pointer to these.
-	 */
-	memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
-	       sigreturn_codes, sizeof(sigreturn_codes));
+	kuser_init(vectors_base);
 
-	flush_icache_range(vectors, vectors + PAGE_SIZE);
-	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
+	flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
+}
 #else /* ifndef CONFIG_CPU_V7M */
+void __init early_trap_init(void *vectors_base)
+{
 	/*
 	 * on V7-M there is no need to copy the vector table to a dedicated
 	 * memory area. The address is configurable and so a table in the kernel
 	 * image can be used.
 	 */
+}
+#endif
+
+#ifdef CONFIG_VMAP_STACK
+
+DECLARE_PER_CPU(u8 *, irq_stack_ptr);
+
+asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
+
+static int __init allocate_overflow_stacks(void)
+{
+	u8 *stack;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		stack = (u8 *)__get_free_page(GFP_KERNEL);
+		if (WARN_ON(!stack))
+			return -ENOMEM;
+		per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
+	}
+	return 0;
+}
+early_initcall(allocate_overflow_stacks);
+
+asmlinkage void handle_bad_stack(struct pt_regs *regs)
+{
+	unsigned long tsk_stk = (unsigned long)current->stack;
+#ifdef CONFIG_IRQSTACKS
+	unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
+#endif
+	unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
+
+	console_verbose();
+	pr_emerg("Insufficient stack space to handle exception!");
+
+	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
+		 tsk_stk, tsk_stk + THREAD_SIZE);
+#ifdef CONFIG_IRQSTACKS
+	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
+		 irq_stk - THREAD_SIZE, irq_stk);
 #endif
+	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
+		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
+
+	die("kernel stack overflow", regs, 0);
 }
+
+#ifndef CONFIG_ARM_LPAE
+/*
+ * Normally, we rely on the logic in do_translation_fault() to update stale PMD
+ * entries covering the vmalloc space in a task's page tables when it first
+ * accesses the region in question. Unfortunately, this is not sufficient when
+ * the task stack resides in the vmalloc region, as do_translation_fault() is a
+ * C function that needs a stack to run.
+ *
+ * So we need to ensure that these PMD entries are up to date *before* the MM
+ * switch. As we already have some logic in the MM switch path that takes care
+ * of this, let's trigger it by bumping the counter every time the core vmalloc
+ * code modifies a PMD entry in the vmalloc region. Use release semantics on
+ * the store so that other CPUs observing the counter's new value are
+ * guaranteed to see the updated page table entries as well.
+ */
+void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
+{
+	if (start < VMALLOC_END && end > VMALLOC_START)
+		atomic_inc_return_release(&init_mm.context.vmalloc_seq);
+}
+#endif
+#endif