/*
* 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/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/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>
#include "fault.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 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;
}
#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/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) {
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;
}
static int
do_alignment(unsigned long addr, unsigned int fsr, 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 & 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 */
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, fsr, 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 FSR 0x%03x\n", current->comm,
current->pid, instrptr, instr, addr, fsr);
if (ai_usermode & 2)
goto fixup;
if (ai_usermode & 4)
force_sig(SIGBUS, current);
else
set_cr(cr_no_alignment);
return 0;
}
/*
* 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_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;
#endif
hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
return 0;
}
fs_initcall(alignment_init);
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