Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1052 insertions, 0 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
new file mode 100644
index 000000000..bcefe3f51
--- /dev/null
+++ b/arch/arm/mm/alignment.c
@@ -0,0 +1,1052 @@
+// 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 <asm/cp15.h>
+#include <asm/system_info.h>
+#include <asm/unaligned.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 (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 (!(current_thread_info()->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, 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);