patch-2.4.19 linux-2.4.19/arch/arm/mm/alignment.c

• Lines: 610
• Date: Fri Aug 2 17:39:42 2002
• Orig file: linux-2.4.18/arch/arm/mm/alignment.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.18/arch/arm/mm/alignment.c linux-2.4.19/arch/arm/mm/alignment.c
@@ -0,0 +1,609 @@
+/*
+ *  linux/arch/arm/mm/alignment.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Modifications for ARM processor (c) 1995-2001 Russell King
+ *
+ * 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.
+ */
+#include <linux/config.h>
+#include <linux/compiler.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/proc_fs.h>
+#include <linux/bitops.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/unaligned.h>
+
+extern void
+do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr,
+	    int error_code, struct pt_regs *regs);
+
+/*
+ * 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 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 LDSTH_I_BIT(i)	(i & (1 << 22))		/* 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
+
+static unsigned long ai_user;
+static unsigned long ai_sys;
+static unsigned long ai_skipped;
+static unsigned long ai_half;
+static unsigned long ai_word;
+static unsigned long ai_multi;
+static int ai_usermode;
+
+#ifdef CONFIG_PROC_FS
+static const char *usermode_action[] = {
+	"ignored",
+	"warn",
+	"fixup",
+	"fixup+warn",
+	"signal",
+	"signal+warn"
+};
+
+static int
+proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
+		    void *data)
+{
+	char *p = page;
+	int len;
+
+	p += sprintf(p, "User:\t\t%lu\n", ai_user);
+	p += sprintf(p, "System:\t\t%lu\n", ai_sys);
+	p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
+	p += sprintf(p, "Half:\t\t%lu\n", ai_half);
+	p += sprintf(p, "Word:\t\t%lu\n", ai_word);
+	p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
+	p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
+			usermode_action[ai_usermode]);
+
+	len = (p - page) - off;
+	if (len < 0)
+		len = 0;
+
+	*eof = (len <= count) ? 1 : 0;
+	*start = page + off;
+
+	return len;
+}
+
+static int proc_alignment_write(struct file *file, const char *buffer,
+			       unsigned long count, void *data)
+{
+	int mode;
+
+	if (count > 0) {
+		if (get_user(mode, buffer))
+			return -EFAULT;
+		if (mode >= '0' && mode <= '5')
+			   ai_usermode = mode - '0';
+	}
+	return count;
+}
+
+/*
+ * 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)
+{
+	struct proc_dir_entry *res;
+
+	res = proc_mkdir("cpu", NULL);
+	if (!res)
+		return -ENOMEM;
+
+	res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
+	if (!res)
+		return -ENOMEM;
+
+	res->read_proc = proc_alignment_read;
+	res->write_proc = proc_alignment_write;
+
+	return 0;
+}
+
+__initcall(alignment_init);
+#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
+
+#define __get8_unaligned_check(ins,val,addr,err)	\
+	__asm__(					\
+	"1:	"ins"	%1, [%2], #1\n"			\
+	"2:\n"						\
+	"	.section .fixup,\"ax\"\n"		\
+	"	.align	2\n"				\
+	"3:	mov	%0, #1\n"			\
+	"	b	2b\n"				\
+	"	.previous\n"				\
+	"	.section __ex_table,\"a\"\n"		\
+	"	.align	3\n"				\
+	"	.long	1b, 3b\n"			\
+	"	.previous\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,val,a,err);		\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << 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,val,a,err);		\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << 8;					\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << 16;					\
+		__get8_unaligned_check(ins,v,a,err);		\
+		val |= v << 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__(					\
+		"1:	"ins"	%1, [%2], #1\n"			\
+		"	mov	%1, %1, lsr #8\n"		\
+		"2:	"ins"	%1, [%2]\n"			\
+		"3:\n"						\
+		"	.section .fixup,\"ax\"\n"		\
+		"	.align	2\n"				\
+		"4:	mov	%0, #1\n"			\
+		"	b	3b\n"				\
+		"	.previous\n"				\
+		"	.section __ex_table,\"a\"\n"		\
+		"	.align	3\n"				\
+		"	.long	1b, 4b\n"			\
+		"	.long	2b, 4b\n"			\
+		"	.previous\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__(					\
+		"1:	"ins"	%1, [%2], #1\n"			\
+		"	mov	%1, %1, lsr #8\n"		\
+		"2:	"ins"	%1, [%2], #1\n"			\
+		"	mov	%1, %1, lsr #8\n"		\
+		"3:	"ins"	%1, [%2], #1\n"			\
+		"	mov	%1, %1, lsr #8\n"		\
+		"4:	"ins"	%1, [%2]\n"			\
+		"5:\n"						\
+		"	.section .fixup,\"ax\"\n"		\
+		"	.align	2\n"				\
+		"6:	mov	%0, #1\n"			\
+		"	b	5b\n"				\
+		"	.previous\n"				\
+		"	.section __ex_table,\"a\"\n"		\
+		"	.align	3\n"				\
+		"	.long	1b, 6b\n"			\
+		"	.long	2b, 6b\n"			\
+		"	.long	3b, 6b\n"			\
+		"	.long	4b, 6b\n"			\
+		"	.previous\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, unsigned long 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, unsigned long instr, struct pt_regs *regs)
+{
+	unsigned int rd = RD_BITS(instr);
+
+	if ((instr & 0x01f00ff0) == 0x01000090)
+		goto swp;
+
+	if ((instr & 0x90) != 0x90 || (instr & 0x60) == 0)
+		goto bad;
+
+	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;
+ 		get16t_unaligned_check(val, addr);
+
+ 		/* signed half-word? */
+ 		if (instr & 0x40)
+ 			val = (signed long)((signed short) val);
+
+ 		regs->uregs[rd] = val;
+ 	} else
+ 		put16t_unaligned_check(regs->uregs[rd], addr);
+
+ 	return TYPE_LDST;
+
+ swp:
+	printk(KERN_ERR "Alignment trap: not handling swp instruction\n");
+ bad:
+	return TYPE_ERROR;
+
+ fault:
+	return TYPE_FAULT;
+}
+
+static int
+do_alignment_ldrstr(unsigned long addr, unsigned long 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;
+		get32t_unaligned_check(val, addr);
+		regs->uregs[rd] = val;
+	} else
+		put32t_unaligned_check(regs->uregs[rd], addr);
+	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, unsigned long 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 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 messsage off if we've got a ARM922, otherwise
+	 * [ls]dm alignment faults are noisy!
+	 */
+#if !(defined CONFIG_CPU_ARM922T)  
+	/*
+	 * This is a "hint" - we already have eaddr worked out by the
+	 * processor for us.
+	 */
+	if (addr != eaddr) {
+		printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, "
+			"addr = %08lx, eaddr = %08lx\n",
+			 instruction_pointer(regs), instr, addr, eaddr);
+		show_regs(regs);
+	}
+#endif
+
+	if (user_mode(regs)) {
+		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;
+			}
+	} 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:
+	printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n");
+	return TYPE_ERROR;
+}
+
+int do_alignment(unsigned long addr, int error_code, struct pt_regs *regs)
+{
+	union offset_union offset;
+	unsigned long instr, instrptr;
+	int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
+	unsigned int type;
+
+	instrptr = instruction_pointer(regs);
+	instr = *(unsigned long *)instrptr;
+
+	if (user_mode(regs))
+		goto user;
+
+	ai_sys += 1;
+
+ fixup:
+
+	regs->ARM_pc += 4;
+
+	switch (CODING_BITS(instr)) {
+	case 0x00000000:	/* ldrh or strh */
+		if (LDSTH_I_BIT(instr))
+			offset.un = (instr & 0xf00) >> 4 | (instr & 15);
+		else
+			offset.un = regs->uregs[RM_BITS(instr)];
+		handler = do_alignment_ldrhstrh;
+		break;
+
+	case 0x04000000:	/* ldr or str immediate */
+		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 & CC_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 */
+		handler = do_alignment_ldmstm;
+		break;
+
+	default:
+		goto bad;
+	}
+
+	type = handler(addr, instr, regs);
+
+	if (type == TYPE_ERROR || type == TYPE_FAULT)
+		goto bad_or_fault;
+
+	if (type == TYPE_LDST)
+		do_alignment_finish_ldst(addr, instr, regs, offset);
+
+	return 0;
+
+ bad_or_fault:
+	if (type == TYPE_ERROR)
+		goto bad;
+	regs->ARM_pc -= 4;
+	/*
+	 * We got a fault - fix it up, or die.
+	 */
+	do_bad_area(current, current->mm, addr, error_code, regs);
+	return 0;
+
+ bad:
+	/*
+	 * Oops, we didn't handle the instruction.
+	 */
+	printk(KERN_ERR "Alignment trap: not handling instruction "
+		"%08lx at [<%08lx>]\n", instr, instrptr);
+	ai_skipped += 1;
+	return 1;
+
+ user:
+	ai_user += 1;
+
+	if (ai_usermode & 1)
+		printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%08lx "
+		       "Address=0x%08lx Code 0x%02x\n", current->comm,
+			current->pid, instrptr, instr, addr, error_code);
+
+	if (ai_usermode & 2)
+		goto fixup;
+
+	if (ai_usermode & 4)
+		force_sig(SIGBUS, current);
+	else
+		set_cr(cr_no_alignment);
+
+	return 0;
+}