Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1056 insertions, 0 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
new file mode 100644
index 000000000..812380f30
--- /dev/null
+++ b/arch/arm/mm/alignment.c
@@ -0,0 +1,1056 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/mm/alignment.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Modifications for ARM processor (c) 1995-2001 Russell King
+ *  Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc.
+ *  - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation.
+ *    Copyright (C) 1996, Cygnus Software Technologies Ltd.
+ */
+#include <linux/moduleparam.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/sched/debug.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/sched/signal.h>
+#include <linux/uaccess.h>
+#include <linux/unaligned.h>
+
+#include <asm/cp15.h>
+#include <asm/system_info.h>
+#include <asm/system_misc.h>
+#include <asm/opcodes.h>
+
+#include "fault.h"
+#include "mm.h"
+
+/*
+ * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
+ * /proc/sys/debug/alignment, modified and integrated into
+ * Linux 2.1 by Russell King
+ *
+ * Speed optimisations and better fault handling by Russell King.
+ *
+ * *** NOTE ***
+ * This code is not portable to processors with late data abort handling.
+ */
+#define CODING_BITS(i)	(i & 0x0e000000)
+#define COND_BITS(i)	(i & 0xf0000000)
+
+#define LDST_I_BIT(i)	(i & (1 << 26))		/* Immediate constant	*/
+#define LDST_P_BIT(i)	(i & (1 << 24))		/* Preindex		*/
+#define LDST_U_BIT(i)	(i & (1 << 23))		/* Add offset		*/
+#define LDST_W_BIT(i)	(i & (1 << 21))		/* Writeback		*/
+#define LDST_L_BIT(i)	(i & (1 << 20))		/* Load			*/
+
+#define LDST_P_EQ_U(i)	((((i) ^ ((i) >> 1)) & (1 << 23)) == 0)
+
+#define LDSTHD_I_BIT(i)	(i & (1 << 22))		/* double/half-word immed */
+#define LDM_S_BIT(i)	(i & (1 << 22))		/* write CPSR from SPSR	*/
+
+#define RN_BITS(i)	((i >> 16) & 15)	/* Rn			*/
+#define RD_BITS(i)	((i >> 12) & 15)	/* Rd			*/
+#define RM_BITS(i)	(i & 15)		/* Rm			*/
+
+#define REGMASK_BITS(i)	(i & 0xffff)
+#define OFFSET_BITS(i)	(i & 0x0fff)
+
+#define IS_SHIFT(i)	(i & 0x0ff0)
+#define SHIFT_BITS(i)	((i >> 7) & 0x1f)
+#define SHIFT_TYPE(i)	(i & 0x60)
+#define SHIFT_LSL	0x00
+#define SHIFT_LSR	0x20
+#define SHIFT_ASR	0x40
+#define SHIFT_RORRRX	0x60
+
+#define BAD_INSTR 	0xdeadc0de
+
+/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */
+#define IS_T32(hi16) \
+	(((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800))
+
+static unsigned long ai_user;
+static unsigned long ai_sys;
+static void *ai_sys_last_pc;
+static unsigned long ai_skipped;
+static unsigned long ai_half;
+static unsigned long ai_word;
+static unsigned long ai_dword;
+static unsigned long ai_multi;
+static int ai_usermode;
+static unsigned long cr_no_alignment;
+
+core_param(alignment, ai_usermode, int, 0600);
+
+#define UM_WARN		(1 << 0)
+#define UM_FIXUP	(1 << 1)
+#define UM_SIGNAL	(1 << 2)
+
+/* Return true if and only if the ARMv6 unaligned access model is in use. */
+static bool cpu_is_v6_unaligned(void)
+{
+	return cpu_architecture() >= CPU_ARCH_ARMv6 && get_cr() & CR_U;
+}
+
+static int safe_usermode(int new_usermode, bool warn)
+{
+	/*
+	 * ARMv6 and later CPUs can perform unaligned accesses for
+	 * most single load and store instructions up to word size.
+	 * LDM, STM, LDRD and STRD still need to be handled.
+	 *
+	 * Ignoring the alignment fault is not an option on these
+	 * CPUs since we spin re-faulting the instruction without
+	 * making any progress.
+	 */
+	if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) {
+		new_usermode |= UM_FIXUP;
+
+		if (warn)
+			pr_warn("alignment: ignoring faults is unsafe on this CPU.  Defaulting to fixup mode.\n");
+	}
+
+	return new_usermode;
+}
+
+#ifdef CONFIG_PROC_FS
+static const char *usermode_action[] = {
+	"ignored",
+	"warn",
+	"fixup",
+	"fixup+warn",
+	"signal",
+	"signal+warn"
+};
+
+static int alignment_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "User:\t\t%lu\n", ai_user);
+	seq_printf(m, "System:\t\t%lu (%pS)\n", ai_sys, ai_sys_last_pc);
+	seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
+	seq_printf(m, "Half:\t\t%lu\n", ai_half);
+	seq_printf(m, "Word:\t\t%lu\n", ai_word);
+	if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
+		seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
+	seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
+	seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
+			usermode_action[ai_usermode]);
+
+	return 0;
+}
+
+static int alignment_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, alignment_proc_show, NULL);
+}
+
+static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
+				    size_t count, loff_t *pos)
+{
+	char mode;
+
+	if (count > 0) {
+		if (get_user(mode, buffer))
+			return -EFAULT;
+		if (mode >= '0' && mode <= '5')
+			ai_usermode = safe_usermode(mode - '0', true);
+	}
+	return count;
+}
+
+static const struct proc_ops alignment_proc_ops = {
+	.proc_open	= alignment_proc_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
+	.proc_write	= alignment_proc_write,
+};
+#endif /* CONFIG_PROC_FS */
+
+union offset_union {
+	unsigned long un;
+	  signed long sn;
+};
+
+#define TYPE_ERROR	0
+#define TYPE_FAULT	1
+#define TYPE_LDST	2
+#define TYPE_DONE	3
+
+#ifdef __ARMEB__
+#define BE		1
+#define FIRST_BYTE_16	"mov	%1, %1, ror #8\n"
+#define FIRST_BYTE_32	"mov	%1, %1, ror #24\n"
+#define NEXT_BYTE	"ror #24"
+#else
+#define BE		0
+#define FIRST_BYTE_16
+#define FIRST_BYTE_32
+#define NEXT_BYTE	"lsr #8"
+#endif
+
+#define __get8_unaligned_check(ins,val,addr,err)	\
+	__asm__(					\
+ ARM(	"1:	"ins"	%1, [%2], #1\n"	)		\
+ THUMB(	"1:	"ins"	%1, [%2]\n"	)		\
+ THUMB(	"	add	%2, %2, #1\n"	)		\
+	"2:\n"						\
+	"	.pushsection .text.fixup,\"ax\"\n"	\
+	"	.align	2\n"				\
+	"3:	mov	%0, #1\n"			\
+	"	b	2b\n"				\
+	"	.popsection\n"				\
+	"	.pushsection __ex_table,\"a\"\n"	\
+	"	.align	3\n"				\
+	"	.long	1b, 3b\n"			\
+	"	.popsection\n"				\
+	: "=r" (err), "=&r" (val), "=r" (addr)		\
+	: "0" (err), "2" (addr))
+
+#define __get16_unaligned_check(ins,val,addr)			\
+	do {							\
+		unsigned int err = 0, v, a = addr;		\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val =  v << ((BE) ? 8 : 0);			\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << ((BE) ? 0 : 8);			\
+		if (err)					\
+			goto fault;				\
+	} while (0)
+
+#define get16_unaligned_check(val,addr) \
+	__get16_unaligned_check("ldrb",val,addr)
+
+#define get16t_unaligned_check(val,addr) \
+	__get16_unaligned_check("ldrbt",val,addr)
+
+#define __get32_unaligned_check(ins,val,addr)			\
+	do {							\
+		unsigned int err = 0, v, a = addr;		\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val =  v << ((BE) ? 24 :  0);			\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << ((BE) ? 16 :  8);			\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << ((BE) ?  8 : 16);			\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << ((BE) ?  0 : 24);			\
+		if (err)					\
+			goto fault;				\
+	} while (0)
+
+#define get32_unaligned_check(val,addr) \
+	__get32_unaligned_check("ldrb",val,addr)
+
+#define get32t_unaligned_check(val,addr) \
+	__get32_unaligned_check("ldrbt",val,addr)
+
+#define __put16_unaligned_check(ins,val,addr)			\
+	do {							\
+		unsigned int err = 0, v = val, a = addr;	\
+		__asm__( FIRST_BYTE_16				\
+	 ARM(	"1:	"ins"	%1, [%2], #1\n"	)		\
+	 THUMB(	"1:	"ins"	%1, [%2]\n"	)		\
+	 THUMB(	"	add	%2, %2, #1\n"	)		\
+		"	mov	%1, %1, "NEXT_BYTE"\n"		\
+		"2:	"ins"	%1, [%2]\n"			\
+		"3:\n"						\
+		"	.pushsection .text.fixup,\"ax\"\n"	\
+		"	.align	2\n"				\
+		"4:	mov	%0, #1\n"			\
+		"	b	3b\n"				\
+		"	.popsection\n"				\
+		"	.pushsection __ex_table,\"a\"\n"	\
+		"	.align	3\n"				\
+		"	.long	1b, 4b\n"			\
+		"	.long	2b, 4b\n"			\
+		"	.popsection\n"				\
+		: "=r" (err), "=&r" (v), "=&r" (a)		\
+		: "0" (err), "1" (v), "2" (a));			\
+		if (err)					\
+			goto fault;				\
+	} while (0)
+
+#define put16_unaligned_check(val,addr)  \
+	__put16_unaligned_check("strb",val,addr)
+
+#define put16t_unaligned_check(val,addr) \
+	__put16_unaligned_check("strbt",val,addr)
+
+#define __put32_unaligned_check(ins,val,addr)			\
+	do {							\
+		unsigned int err = 0, v = val, a = addr;	\
+		__asm__( FIRST_BYTE_32				\
+	 ARM(	"1:	"ins"	%1, [%2], #1\n"	)		\
+	 THUMB(	"1:	"ins"	%1, [%2]\n"	)		\
+	 THUMB(	"	add	%2, %2, #1\n"	)		\
+		"	mov	%1, %1, "NEXT_BYTE"\n"		\
+	 ARM(	"2:	"ins"	%1, [%2], #1\n"	)		\
+	 THUMB(	"2:	"ins"	%1, [%2]\n"	)		\
+	 THUMB(	"	add	%2, %2, #1\n"	)		\
+		"	mov	%1, %1, "NEXT_BYTE"\n"		\
+	 ARM(	"3:	"ins"	%1, [%2], #1\n"	)		\
+	 THUMB(	"3:	"ins"	%1, [%2]\n"	)		\
+	 THUMB(	"	add	%2, %2, #1\n"	)		\
+		"	mov	%1, %1, "NEXT_BYTE"\n"		\
+		"4:	"ins"	%1, [%2]\n"			\
+		"5:\n"						\
+		"	.pushsection .text.fixup,\"ax\"\n"	\
+		"	.align	2\n"				\
+		"6:	mov	%0, #1\n"			\
+		"	b	5b\n"				\
+		"	.popsection\n"				\
+		"	.pushsection __ex_table,\"a\"\n"	\
+		"	.align	3\n"				\
+		"	.long	1b, 6b\n"			\
+		"	.long	2b, 6b\n"			\
+		"	.long	3b, 6b\n"			\
+		"	.long	4b, 6b\n"			\
+		"	.popsection\n"				\
+		: "=r" (err), "=&r" (v), "=&r" (a)		\
+		: "0" (err), "1" (v), "2" (a));			\
+		if (err)					\
+			goto fault;				\
+	} while (0)
+
+#define put32_unaligned_check(val,addr) \
+	__put32_unaligned_check("strb", val, addr)
+
+#define put32t_unaligned_check(val,addr) \
+	__put32_unaligned_check("strbt", val, addr)
+
+static void
+do_alignment_finish_ldst(unsigned long addr, u32 instr, struct pt_regs *regs, union offset_union offset)
+{
+	if (!LDST_U_BIT(instr))
+		offset.un = -offset.un;
+
+	if (!LDST_P_BIT(instr))
+		addr += offset.un;
+
+	if (!LDST_P_BIT(instr) || LDST_W_BIT(instr))
+		regs->uregs[RN_BITS(instr)] = addr;
+}
+
+static int
+do_alignment_ldrhstrh(unsigned long addr, u32 instr, struct pt_regs *regs)
+{
+	unsigned int rd = RD_BITS(instr);
+
+	ai_half += 1;
+
+	if (user_mode(regs))
+		goto user;
+
+	if (LDST_L_BIT(instr)) {
+		unsigned long val;
+		get16_unaligned_check(val, addr);
+
+		/* signed half-word? */
+		if (instr & 0x40)
+			val = (signed long)((signed short) val);
+
+		regs->uregs[rd] = val;
+	} else
+		put16_unaligned_check(regs->uregs[rd], addr);
+
+	return TYPE_LDST;
+
+ user:
+	if (LDST_L_BIT(instr)) {
+		unsigned long val;
+		unsigned int __ua_flags = uaccess_save_and_enable();
+
+		get16t_unaligned_check(val, addr);
+		uaccess_restore(__ua_flags);
+
+		/* signed half-word? */
+		if (instr & 0x40)
+			val = (signed long)((signed short) val);
+
+		regs->uregs[rd] = val;
+	} else {
+		unsigned int __ua_flags = uaccess_save_and_enable();
+		put16t_unaligned_check(regs->uregs[rd], addr);
+		uaccess_restore(__ua_flags);
+	}
+
+	return TYPE_LDST;
+
+ fault:
+	return TYPE_FAULT;
+}
+
+static int
+do_alignment_ldrdstrd(unsigned long addr, u32 instr, struct pt_regs *regs)
+{
+	unsigned int rd = RD_BITS(instr);
+	unsigned int rd2;
+	int load;
+
+	if ((instr & 0xfe000000) == 0xe8000000) {
+		/* ARMv7 Thumb-2 32-bit LDRD/STRD */
+		rd2 = (instr >> 8) & 0xf;
+		load = !!(LDST_L_BIT(instr));
+	} else if (((rd & 1) == 1) || (rd == 14))
+		goto bad;
+	else {
+		load = ((instr & 0xf0) == 0xd0);
+		rd2 = rd + 1;
+	}
+
+	ai_dword += 1;
+
+	if (user_mode(regs))
+		goto user;
+
+	if (load) {
+		unsigned long val;
+		get32_unaligned_check(val, addr);
+		regs->uregs[rd] = val;
+		get32_unaligned_check(val, addr + 4);
+		regs->uregs[rd2] = val;
+	} else {
+		put32_unaligned_check(regs->uregs[rd], addr);
+		put32_unaligned_check(regs->uregs[rd2], addr + 4);
+	}
+
+	return TYPE_LDST;
+
+ user:
+	if (load) {
+		unsigned long val, val2;
+		unsigned int __ua_flags = uaccess_save_and_enable();
+
+		get32t_unaligned_check(val, addr);
+		get32t_unaligned_check(val2, addr + 4);
+
+		uaccess_restore(__ua_flags);
+
+		regs->uregs[rd] = val;
+		regs->uregs[rd2] = val2;
+	} else {
+		unsigned int __ua_flags = uaccess_save_and_enable();
+		put32t_unaligned_check(regs->uregs[rd], addr);
+		put32t_unaligned_check(regs->uregs[rd2], addr + 4);
+		uaccess_restore(__ua_flags);
+	}
+
+	return TYPE_LDST;
+ bad:
+	return TYPE_ERROR;
+ fault:
+	return TYPE_FAULT;
+}
+
+static int
+do_alignment_ldrstr(unsigned long addr, u32 instr, struct pt_regs *regs)
+{
+	unsigned int rd = RD_BITS(instr);
+
+	ai_word += 1;
+
+	if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs))
+		goto trans;
+
+	if (LDST_L_BIT(instr)) {
+		unsigned int val;
+		get32_unaligned_check(val, addr);
+		regs->uregs[rd] = val;
+	} else
+		put32_unaligned_check(regs->uregs[rd], addr);
+	return TYPE_LDST;
+
+ trans:
+	if (LDST_L_BIT(instr)) {
+		unsigned int val;
+		unsigned int __ua_flags = uaccess_save_and_enable();
+		get32t_unaligned_check(val, addr);
+		uaccess_restore(__ua_flags);
+		regs->uregs[rd] = val;
+	} else {
+		unsigned int __ua_flags = uaccess_save_and_enable();
+		put32t_unaligned_check(regs->uregs[rd], addr);
+		uaccess_restore(__ua_flags);
+	}
+	return TYPE_LDST;
+
+ fault:
+	return TYPE_FAULT;
+}
+
+/*
+ * LDM/STM alignment handler.
+ *
+ * There are 4 variants of this instruction:
+ *
+ * B = rn pointer before instruction, A = rn pointer after instruction
+ *              ------ increasing address ----->
+ *	        |    | r0 | r1 | ... | rx |    |
+ * PU = 01             B                    A
+ * PU = 11        B                    A
+ * PU = 00        A                    B
+ * PU = 10             A                    B
+ */
+static int
+do_alignment_ldmstm(unsigned long addr, u32 instr, struct pt_regs *regs)
+{
+	unsigned int rd, rn, correction, nr_regs, regbits;
+	unsigned long eaddr, newaddr;
+
+	if (LDM_S_BIT(instr))
+		goto bad;
+
+	correction = 4; /* processor implementation defined */
+	regs->ARM_pc += correction;
+
+	ai_multi += 1;
+
+	/* count the number of registers in the mask to be transferred */
+	nr_regs = hweight16(REGMASK_BITS(instr)) * 4;
+
+	rn = RN_BITS(instr);
+	newaddr = eaddr = regs->uregs[rn];
+
+	if (!LDST_U_BIT(instr))
+		nr_regs = -nr_regs;
+	newaddr += nr_regs;
+	if (!LDST_U_BIT(instr))
+		eaddr = newaddr;
+
+	if (LDST_P_EQ_U(instr))	/* U = P */
+		eaddr += 4;
+
+	/*
+	 * For alignment faults on the ARM922T/ARM920T the MMU  makes
+	 * the FSR (and hence addr) equal to the updated base address
+	 * of the multiple access rather than the restored value.
+	 * Switch this message off if we've got a ARM92[02], otherwise
+	 * [ls]dm alignment faults are noisy!
+	 */
+#if !(defined CONFIG_CPU_ARM922T)  && !(defined CONFIG_CPU_ARM920T)
+	/*
+	 * This is a "hint" - we already have eaddr worked out by the
+	 * processor for us.
+	 */
+	if (addr != eaddr) {
+		pr_err("LDMSTM: PC = %08lx, instr = %08x, "
+			"addr = %08lx, eaddr = %08lx\n",
+			 instruction_pointer(regs), instr, addr, eaddr);
+		show_regs(regs);
+	}
+#endif
+
+	if (user_mode(regs)) {
+		unsigned int __ua_flags = uaccess_save_and_enable();
+		for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
+		     regbits >>= 1, rd += 1)
+			if (regbits & 1) {
+				if (LDST_L_BIT(instr)) {
+					unsigned int val;
+					get32t_unaligned_check(val, eaddr);
+					regs->uregs[rd] = val;
+				} else
+					put32t_unaligned_check(regs->uregs[rd], eaddr);
+				eaddr += 4;
+			}
+		uaccess_restore(__ua_flags);
+	} else {
+		for (regbits = REGMASK_BITS(instr), rd = 0; regbits;
+		     regbits >>= 1, rd += 1)
+			if (regbits & 1) {
+				if (LDST_L_BIT(instr)) {
+					unsigned int val;
+					get32_unaligned_check(val, eaddr);
+					regs->uregs[rd] = val;
+				} else
+					put32_unaligned_check(regs->uregs[rd], eaddr);
+				eaddr += 4;
+			}
+	}
+
+	if (LDST_W_BIT(instr))
+		regs->uregs[rn] = newaddr;
+	if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15)))
+		regs->ARM_pc -= correction;
+	return TYPE_DONE;
+
+fault:
+	regs->ARM_pc -= correction;
+	return TYPE_FAULT;
+
+bad:
+	pr_err("Alignment trap: not handling ldm with s-bit set\n");
+	return TYPE_ERROR;
+}
+
+/*
+ * Convert Thumb ld/st instruction forms to equivalent ARM instructions so
+ * we can reuse ARM userland alignment fault fixups for Thumb.
+ *
+ * This implementation was initially based on the algorithm found in
+ * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same
+ * to convert only Thumb ld/st instruction forms to equivalent ARM forms.
+ *
+ * NOTES:
+ * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections.
+ * 2. If for some reason we're passed an non-ld/st Thumb instruction to
+ *    decode, we return 0xdeadc0de. This should never happen under normal
+ *    circumstances but if it does, we've got other problems to deal with
+ *    elsewhere and we obviously can't fix those problems here.
+ */
+
+static unsigned long
+thumb2arm(u16 tinstr)
+{
+	u32 L = (tinstr & (1<<11)) >> 11;
+
+	switch ((tinstr & 0xf800) >> 11) {
+	/* 6.5.1 Format 1: */
+	case 0x6000 >> 11:				/* 7.1.52 STR(1) */
+	case 0x6800 >> 11:				/* 7.1.26 LDR(1) */
+	case 0x7000 >> 11:				/* 7.1.55 STRB(1) */
+	case 0x7800 >> 11:				/* 7.1.30 LDRB(1) */
+		return 0xe5800000 |
+			((tinstr & (1<<12)) << (22-12)) |	/* fixup */
+			(L<<20) |				/* L==1? */
+			((tinstr & (7<<0)) << (12-0)) |		/* Rd */
+			((tinstr & (7<<3)) << (16-3)) |		/* Rn */
+			((tinstr & (31<<6)) >>			/* immed_5 */
+				(6 - ((tinstr & (1<<12)) ? 0 : 2)));
+	case 0x8000 >> 11:				/* 7.1.57 STRH(1) */
+	case 0x8800 >> 11:				/* 7.1.32 LDRH(1) */
+		return 0xe1c000b0 |
+			(L<<20) |				/* L==1? */
+			((tinstr & (7<<0)) << (12-0)) |		/* Rd */
+			((tinstr & (7<<3)) << (16-3)) |		/* Rn */
+			((tinstr & (7<<6)) >> (6-1)) |	 /* immed_5[2:0] */
+			((tinstr & (3<<9)) >> (9-8));	 /* immed_5[4:3] */
+
+	/* 6.5.1 Format 2: */
+	case 0x5000 >> 11:
+	case 0x5800 >> 11:
+		{
+			static const u32 subset[8] = {
+				0xe7800000,		/* 7.1.53 STR(2) */
+				0xe18000b0,		/* 7.1.58 STRH(2) */
+				0xe7c00000,		/* 7.1.56 STRB(2) */
+				0xe19000d0,		/* 7.1.34 LDRSB */
+				0xe7900000,		/* 7.1.27 LDR(2) */
+				0xe19000b0,		/* 7.1.33 LDRH(2) */
+				0xe7d00000,		/* 7.1.31 LDRB(2) */
+				0xe19000f0		/* 7.1.35 LDRSH */
+			};
+			return subset[(tinstr & (7<<9)) >> 9] |
+			    ((tinstr & (7<<0)) << (12-0)) |	/* Rd */
+			    ((tinstr & (7<<3)) << (16-3)) |	/* Rn */
+			    ((tinstr & (7<<6)) >> (6-0));	/* Rm */
+		}
+
+	/* 6.5.1 Format 3: */
+	case 0x4800 >> 11:				/* 7.1.28 LDR(3) */
+		/* NOTE: This case is not technically possible. We're
+		 *	 loading 32-bit memory data via PC relative
+		 *	 addressing mode. So we can and should eliminate
+		 *	 this case. But I'll leave it here for now.
+		 */
+		return 0xe59f0000 |
+		    ((tinstr & (7<<8)) << (12-8)) |		/* Rd */
+		    ((tinstr & 255) << (2-0));			/* immed_8 */
+
+	/* 6.5.1 Format 4: */
+	case 0x9000 >> 11:				/* 7.1.54 STR(3) */
+	case 0x9800 >> 11:				/* 7.1.29 LDR(4) */
+		return 0xe58d0000 |
+			(L<<20) |				/* L==1? */
+			((tinstr & (7<<8)) << (12-8)) |		/* Rd */
+			((tinstr & 255) << 2);			/* immed_8 */
+
+	/* 6.6.1 Format 1: */
+	case 0xc000 >> 11:				/* 7.1.51 STMIA */
+	case 0xc800 >> 11:				/* 7.1.25 LDMIA */
+		{
+			u32 Rn = (tinstr & (7<<8)) >> 8;
+			u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21;
+
+			return 0xe8800000 | W | (L<<20) | (Rn<<16) |
+				(tinstr&255);
+		}
+
+	/* 6.6.1 Format 2: */
+	case 0xb000 >> 11:				/* 7.1.48 PUSH */
+	case 0xb800 >> 11:				/* 7.1.47 POP */
+		if ((tinstr & (3 << 9)) == 0x0400) {
+			static const u32 subset[4] = {
+				0xe92d0000,	/* STMDB sp!,{registers} */
+				0xe92d4000,	/* STMDB sp!,{registers,lr} */
+				0xe8bd0000,	/* LDMIA sp!,{registers} */
+				0xe8bd8000	/* LDMIA sp!,{registers,pc} */
+			};
+			return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] |
+			    (tinstr & 255);		/* register_list */
+		}
+		fallthrough;	/* for illegal instruction case */
+
+	default:
+		return BAD_INSTR;
+	}
+}
+
+/*
+ * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction
+ * handlable by ARM alignment handler, also find the corresponding handler,
+ * so that we can reuse ARM userland alignment fault fixups for Thumb.
+ *
+ * @pinstr: original Thumb-2 instruction; returns new handlable instruction
+ * @regs: register context.
+ * @poffset: return offset from faulted addr for later writeback
+ *
+ * NOTES:
+ * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections.
+ * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt)
+ */
+static void *
+do_alignment_t32_to_handler(u32 *pinstr, struct pt_regs *regs,
+			    union offset_union *poffset)
+{
+	u32 instr = *pinstr;
+	u16 tinst1 = (instr >> 16) & 0xffff;
+	u16 tinst2 = instr & 0xffff;
+
+	switch (tinst1 & 0xffe0) {
+	/* A6.3.5 Load/Store multiple */
+	case 0xe880:		/* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */
+	case 0xe8a0:		/* ...above writeback version */
+	case 0xe900:		/* STMDB/STMFD, LDMDB/LDMEA */
+	case 0xe920:		/* ...above writeback version */
+		/* no need offset decision since handler calculates it */
+		return do_alignment_ldmstm;
+
+	case 0xf840:		/* POP/PUSH T3 (single register) */
+		if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) {
+			u32 L = !!(LDST_L_BIT(instr));
+			const u32 subset[2] = {
+				0xe92d0000,	/* STMDB sp!,{registers} */
+				0xe8bd0000,	/* LDMIA sp!,{registers} */
+			};
+			*pinstr = subset[L] | (1<<RD_BITS(instr));
+			return do_alignment_ldmstm;
+		}
+		/* Else fall through for illegal instruction case */
+		break;
+
+	/* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */
+	case 0xe860:
+	case 0xe960:
+	case 0xe8e0:
+	case 0xe9e0:
+		poffset->un = (tinst2 & 0xff) << 2;
+		fallthrough;
+
+	case 0xe940:
+	case 0xe9c0:
+		return do_alignment_ldrdstrd;
+
+	/*
+	 * No need to handle load/store instructions up to word size
+	 * since ARMv6 and later CPUs can perform unaligned accesses.
+	 */
+	default:
+		break;
+	}
+	return NULL;
+}
+
+static int alignment_get_arm(struct pt_regs *regs, u32 *ip, u32 *inst)
+{
+	u32 instr = 0;
+	int fault;
+
+	if (user_mode(regs))
+		fault = get_user(instr, ip);
+	else
+		fault = get_kernel_nofault(instr, ip);
+
+	*inst = __mem_to_opcode_arm(instr);
+
+	return fault;
+}
+
+static int alignment_get_thumb(struct pt_regs *regs, u16 *ip, u16 *inst)
+{
+	u16 instr = 0;
+	int fault;
+
+	if (user_mode(regs))
+		fault = get_user(instr, ip);
+	else
+		fault = get_kernel_nofault(instr, ip);
+
+	*inst = __mem_to_opcode_thumb16(instr);
+
+	return fault;
+}
+
+static int
+do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+	union offset_union offset;
+	unsigned long instrptr;
+	int (*handler)(unsigned long addr, u32 instr, struct pt_regs *regs);
+	unsigned int type;
+	u32 instr = 0;
+	u16 tinstr = 0;
+	int isize = 4;
+	int thumb2_32b = 0;
+	int fault;
+
+	if (addr >= TASK_SIZE && user_mode(regs))
+		harden_branch_predictor();
+
+	if (interrupts_enabled(regs))
+		local_irq_enable();
+
+	instrptr = instruction_pointer(regs);
+
+	if (thumb_mode(regs)) {
+		u16 *ptr = (u16 *)(instrptr & ~1);
+
+		fault = alignment_get_thumb(regs, ptr, &tinstr);
+		if (!fault) {
+			if (cpu_architecture() >= CPU_ARCH_ARMv7 &&
+			    IS_T32(tinstr)) {
+				/* Thumb-2 32-bit */
+				u16 tinst2;
+				fault = alignment_get_thumb(regs, ptr + 1, &tinst2);
+				instr = __opcode_thumb32_compose(tinstr, tinst2);
+				thumb2_32b = 1;
+			} else {
+				isize = 2;
+				instr = thumb2arm(tinstr);
+			}
+		}
+	} else {
+		fault = alignment_get_arm(regs, (void *)instrptr, &instr);
+	}
+
+	if (fault) {
+		type = TYPE_FAULT;
+		goto bad_or_fault;
+	}
+
+	if (user_mode(regs))
+		goto user;
+
+	ai_sys += 1;
+	ai_sys_last_pc = (void *)instruction_pointer(regs);
+
+ fixup:
+
+	regs->ARM_pc += isize;
+
+	switch (CODING_BITS(instr)) {
+	case 0x00000000:	/* 3.13.4 load/store instruction extensions */
+		if (LDSTHD_I_BIT(instr))
+			offset.un = (instr & 0xf00) >> 4 | (instr & 15);
+		else
+			offset.un = regs->uregs[RM_BITS(instr)];
+
+		if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */
+		    (instr & 0x001000f0) == 0x001000f0)   /* LDRSH */
+			handler = do_alignment_ldrhstrh;
+		else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */
+			 (instr & 0x001000f0) == 0x000000f0)   /* STRD */
+			handler = do_alignment_ldrdstrd;
+		else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */
+			goto swp;
+		else
+			goto bad;
+		break;
+
+	case 0x04000000:	/* ldr or str immediate */
+		if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */
+			goto bad;
+		offset.un = OFFSET_BITS(instr);
+		handler = do_alignment_ldrstr;
+		break;
+
+	case 0x06000000:	/* ldr or str register */
+		offset.un = regs->uregs[RM_BITS(instr)];
+
+		if (IS_SHIFT(instr)) {
+			unsigned int shiftval = SHIFT_BITS(instr);
+
+			switch(SHIFT_TYPE(instr)) {
+			case SHIFT_LSL:
+				offset.un <<= shiftval;
+				break;
+
+			case SHIFT_LSR:
+				offset.un >>= shiftval;
+				break;
+
+			case SHIFT_ASR:
+				offset.sn >>= shiftval;
+				break;
+
+			case SHIFT_RORRRX:
+				if (shiftval == 0) {
+					offset.un >>= 1;
+					if (regs->ARM_cpsr & PSR_C_BIT)
+						offset.un |= 1 << 31;
+				} else
+					offset.un = offset.un >> shiftval |
+							  offset.un << (32 - shiftval);
+				break;
+			}
+		}
+		handler = do_alignment_ldrstr;
+		break;
+
+	case 0x08000000:	/* ldm or stm, or thumb-2 32bit instruction */
+		if (thumb2_32b) {
+			offset.un = 0;
+			handler = do_alignment_t32_to_handler(&instr, regs, &offset);
+		} else {
+			offset.un = 0;
+			handler = do_alignment_ldmstm;
+		}
+		break;
+
+	default:
+		goto bad;
+	}
+
+	if (!handler)
+		goto bad;
+	type = handler(addr, instr, regs);
+
+	if (type == TYPE_ERROR || type == TYPE_FAULT) {
+		regs->ARM_pc -= isize;
+		goto bad_or_fault;
+	}
+
+	if (type == TYPE_LDST)
+		do_alignment_finish_ldst(addr, instr, regs, offset);
+
+	if (thumb_mode(regs))
+		regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
+
+	return 0;
+
+ bad_or_fault:
+	if (type == TYPE_ERROR)
+		goto bad;
+	/*
+	 * We got a fault - fix it up, or die.
+	 */
+	do_bad_area(addr, fsr, regs);
+	return 0;
+
+ swp:
+	pr_err("Alignment trap: not handling swp instruction\n");
+
+ bad:
+	/*
+	 * Oops, we didn't handle the instruction.
+	 */
+	pr_err("Alignment trap: not handling instruction "
+		"%0*x at [<%08lx>]\n",
+		isize << 1,
+		isize == 2 ? tinstr : instr, instrptr);
+	ai_skipped += 1;
+	return 1;
+
+ user:
+	ai_user += 1;
+
+	if (ai_usermode & UM_WARN)
+		printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*x "
+		       "Address=0x%08lx FSR 0x%03x\n", current->comm,
+			task_pid_nr(current), instrptr,
+			isize << 1,
+			isize == 2 ? tinstr : instr,
+		        addr, fsr);
+
+	if (ai_usermode & UM_FIXUP)
+		goto fixup;
+
+	if (ai_usermode & UM_SIGNAL) {
+		force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr);
+	} else {
+		/*
+		 * We're about to disable the alignment trap and return to
+		 * user space.  But if an interrupt occurs before actually
+		 * reaching user space, then the IRQ vector entry code will
+		 * notice that we were still in kernel space and therefore
+		 * the alignment trap won't be re-enabled in that case as it
+		 * is presumed to be always on from kernel space.
+		 * Let's prevent that race by disabling interrupts here (they
+		 * are disabled on the way back to user space anyway in
+		 * entry-common.S) and disable the alignment trap only if
+		 * there is no work pending for this thread.
+		 */
+		raw_local_irq_disable();
+		if (!(read_thread_flags() & _TIF_WORK_MASK))
+			set_cr(cr_no_alignment);
+	}
+
+	return 0;
+}
+
+static int __init noalign_setup(char *__unused)
+{
+	set_cr(__clear_cr(CR_A));
+	return 1;
+}
+__setup("noalign", noalign_setup);
+
+/*
+ * This needs to be done after sysctl_init_bases(), otherwise sys/ will be
+ * overwritten.  Actually, this shouldn't be in sys/ at all since
+ * it isn't a sysctl, and it doesn't contain sysctl information.
+ * We now locate it in /proc/cpu/alignment instead.
+ */
+static int __init alignment_init(void)
+{
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *res;
+
+	res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
+			  &alignment_proc_ops);
+	if (!res)
+		return -ENOMEM;
+#endif
+
+	if (cpu_is_v6_unaligned()) {
+		set_cr(__clear_cr(CR_A));
+		ai_usermode = safe_usermode(ai_usermode, false);
+	}
+
+	cr_no_alignment = get_cr() & ~CR_A;
+
+	hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
+			"alignment exception");
+
+	/*
+	 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section
+	 * fault, not as alignment error.
+	 *
+	 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is
+	 * needed.
+	 */
+	if (cpu_architecture() <= CPU_ARCH_ARMv6) {
+		hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN,
+				"alignment exception");
+	}
+
+	return 0;
+}
+
+fs_initcall(alignment_init);