/*
* linux/arch/arm/mm/alignment.c
*
* Copyright (C) 1995 Linus Torvalds
* Modifications for ARM processor (c) 1995-2001 Russell King
* Thumb aligment fault fixups (c) 2004 MontaVista Software, Inc.
* - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation.
* Copyright (C) 1996, Cygnus Software Technologies Ltd.
*
* 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/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <asm/uaccess.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 __user *buffer,
unsigned long count, void *data)
{
char 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
#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__( \
"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,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 \
"1: "ins" %1, [%2], #1\n" \
" mov %1, %1, "NEXT_BYTE"\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__( FIRST_BYTE_32 \
"1: "ins" %1, [%2], #1\n" \
" mov %1, %1, "NEXT_BYTE"\n" \
"2: "ins" %1, [%2], #1\n" \
" mov %1, %1, "NEXT_BYTE"\n" \
"3: "ins" %1, [%2], #1\n" \
" mov %1, %1, "NEXT_BYTE"\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;
}
/*
* 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 */
}
/* Else fall through for illegal instruction case */
default:
return 0xdeadc0de;
}
}
static int
do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
union offset_union offset;
unsigned long instr = 0, instrptr;
int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs);
unsigned int type;
mm_segment_t fs;
unsigned int fault;
u16 tinstr = 0;
instrptr = instruction_pointer(regs);
fs = get_fs();
set_fs(KERNEL_DS);
if thumb_mode(regs) {
fault = __get_user(tinstr, (u16 *)(instrptr & ~1));
if (!(fault))
instr = thumb2arm(tinstr);
} else
fault = __get_user(instr, (u32 *)instrptr);
set_fs(fs);
if (fault) {
type = TYPE_FAULT;
goto bad_or_fault;
}
if (user_mode(regs))
goto user;
ai_sys += 1;
fixup:
regs->ARM_pc += thumb_mode(regs) ? 2 : 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 -= thumb_mode(regs) ? 2 : 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 "
"%0*lx at [<%08lx>]\n",
thumb_mode(regs) ? 4 : 8,
thumb_mode(regs) ? tinstr : 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%0*lx "
"Address=0x%08lx FSR 0x%03x\n", current->comm,
current->pid, instrptr,
thumb_mode(regs) ? 4 : 8,
thumb_mode(regs) ? tinstr : 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);
