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linux/arch/powerpc/kernel/align.c

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/* align.c - handle alignment exceptions for the Power PC.
*
* Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
* Copyright (c) 1998-1999 TiVo, Inc.
* PowerPC 403GCX modifications.
* Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
* PowerPC 403GCX/405GP modifications.
* Copyright (c) 2001-2002 PPC64 team, IBM Corp
* 64-bit and Power4 support
* Copyright (c) 2005 Benjamin Herrenschmidt, IBM Corp
* <benh@kernel.crashing.org>
* Merge ppc32 and ppc64 implementations
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/cache.h>
#include <asm/cputable.h>
struct aligninfo {
unsigned char len;
unsigned char flags;
};
#define IS_XFORM(inst) (((inst) >> 26) == 31)
#define IS_DSFORM(inst) (((inst) >> 26) >= 56)
#define INVALID { 0, 0 }
#define LD 1 /* load */
#define ST 2 /* store */
#define SE 4 /* sign-extend value */
#define F 8 /* to/from fp regs */
#define U 0x10 /* update index register */
#define M 0x20 /* multiple load/store */
#define SW 0x40 /* byte swap int or ... */
#define S 0x40 /* ... single-precision fp */
#define SX 0x40 /* byte count in XER */
#define HARD 0x80 /* string, stwcx. */
#define DCBZ 0x5f /* 8xx/82xx dcbz faults when cache not enabled */
#define SWAP(a, b) (t = (a), (a) = (b), (b) = t)
/*
* The PowerPC stores certain bits of the instruction that caused the
* alignment exception in the DSISR register. This array maps those
* bits to information about the operand length and what the
* instruction would do.
*/
static struct aligninfo aligninfo[128] = {
{ 4, LD }, /* 00 0 0000: lwz / lwarx */
INVALID, /* 00 0 0001 */
{ 4, ST }, /* 00 0 0010: stw */
INVALID, /* 00 0 0011 */
{ 2, LD }, /* 00 0 0100: lhz */
{ 2, LD+SE }, /* 00 0 0101: lha */
{ 2, ST }, /* 00 0 0110: sth */
{ 4, LD+M }, /* 00 0 0111: lmw */
{ 4, LD+F+S }, /* 00 0 1000: lfs */
{ 8, LD+F }, /* 00 0 1001: lfd */
{ 4, ST+F+S }, /* 00 0 1010: stfs */
{ 8, ST+F }, /* 00 0 1011: stfd */
INVALID, /* 00 0 1100 */
{ 8, LD }, /* 00 0 1101: ld/ldu/lwa */
INVALID, /* 00 0 1110 */
{ 8, ST }, /* 00 0 1111: std/stdu */
{ 4, LD+U }, /* 00 1 0000: lwzu */
INVALID, /* 00 1 0001 */
{ 4, ST+U }, /* 00 1 0010: stwu */
INVALID, /* 00 1 0011 */
{ 2, LD+U }, /* 00 1 0100: lhzu */
{ 2, LD+SE+U }, /* 00 1 0101: lhau */
{ 2, ST+U }, /* 00 1 0110: sthu */
{ 4, ST+M }, /* 00 1 0111: stmw */
{ 4, LD+F+S+U }, /* 00 1 1000: lfsu */
{ 8, LD+F+U }, /* 00 1 1001: lfdu */
{ 4, ST+F+S+U }, /* 00 1 1010: stfsu */
{ 8, ST+F+U }, /* 00 1 1011: stfdu */
INVALID, /* 00 1 1100 */
INVALID, /* 00 1 1101 */
INVALID, /* 00 1 1110 */
INVALID, /* 00 1 1111 */
{ 8, LD }, /* 01 0 0000: ldx */
INVALID, /* 01 0 0001 */
{ 8, ST }, /* 01 0 0010: stdx */
INVALID, /* 01 0 0011 */
INVALID, /* 01 0 0100 */
{ 4, LD+SE }, /* 01 0 0101: lwax */
INVALID, /* 01 0 0110 */
INVALID, /* 01 0 0111 */
{ 4, LD+M+HARD+SX }, /* 01 0 1000: lswx */
{ 4, LD+M+HARD }, /* 01 0 1001: lswi */
{ 4, ST+M+HARD+SX }, /* 01 0 1010: stswx */
{ 4, ST+M+HARD }, /* 01 0 1011: stswi */
INVALID, /* 01 0 1100 */
{ 8, LD+U }, /* 01 0 1101: ldu */
INVALID, /* 01 0 1110 */
{ 8, ST+U }, /* 01 0 1111: stdu */
{ 8, LD+U }, /* 01 1 0000: ldux */
INVALID, /* 01 1 0001 */
{ 8, ST+U }, /* 01 1 0010: stdux */
INVALID, /* 01 1 0011 */
INVALID, /* 01 1 0100 */
{ 4, LD+SE+U }, /* 01 1 0101: lwaux */
INVALID, /* 01 1 0110 */
INVALID, /* 01 1 0111 */
INVALID, /* 01 1 1000 */
INVALID, /* 01 1 1001 */
INVALID, /* 01 1 1010 */
INVALID, /* 01 1 1011 */
INVALID, /* 01 1 1100 */
INVALID, /* 01 1 1101 */
INVALID, /* 01 1 1110 */
INVALID, /* 01 1 1111 */
INVALID, /* 10 0 0000 */
INVALID, /* 10 0 0001 */
INVALID, /* 10 0 0010: stwcx. */
INVALID, /* 10 0 0011 */
INVALID, /* 10 0 0100 */
INVALID, /* 10 0 0101 */
INVALID, /* 10 0 0110 */
INVALID, /* 10 0 0111 */
{ 4, LD+SW }, /* 10 0 1000: lwbrx */
INVALID, /* 10 0 1001 */
{ 4, ST+SW }, /* 10 0 1010: stwbrx */
INVALID, /* 10 0 1011 */
{ 2, LD+SW }, /* 10 0 1100: lhbrx */
{ 4, LD+SE }, /* 10 0 1101 lwa */
{ 2, ST+SW }, /* 10 0 1110: sthbrx */
INVALID, /* 10 0 1111 */
INVALID, /* 10 1 0000 */
INVALID, /* 10 1 0001 */
INVALID, /* 10 1 0010 */
INVALID, /* 10 1 0011 */
INVALID, /* 10 1 0100 */
INVALID, /* 10 1 0101 */
INVALID, /* 10 1 0110 */
INVALID, /* 10 1 0111 */
INVALID, /* 10 1 1000 */
INVALID, /* 10 1 1001 */
INVALID, /* 10 1 1010 */
INVALID, /* 10 1 1011 */
INVALID, /* 10 1 1100 */
INVALID, /* 10 1 1101 */
INVALID, /* 10 1 1110 */
{ 0, ST+HARD }, /* 10 1 1111: dcbz */
{ 4, LD }, /* 11 0 0000: lwzx */
INVALID, /* 11 0 0001 */
{ 4, ST }, /* 11 0 0010: stwx */
INVALID, /* 11 0 0011 */
{ 2, LD }, /* 11 0 0100: lhzx */
{ 2, LD+SE }, /* 11 0 0101: lhax */
{ 2, ST }, /* 11 0 0110: sthx */
INVALID, /* 11 0 0111 */
{ 4, LD+F+S }, /* 11 0 1000: lfsx */
{ 8, LD+F }, /* 11 0 1001: lfdx */
{ 4, ST+F+S }, /* 11 0 1010: stfsx */
{ 8, ST+F }, /* 11 0 1011: stfdx */
INVALID, /* 11 0 1100 */
{ 8, LD+M }, /* 11 0 1101: lmd */
INVALID, /* 11 0 1110 */
{ 8, ST+M }, /* 11 0 1111: stmd */
{ 4, LD+U }, /* 11 1 0000: lwzux */
INVALID, /* 11 1 0001 */
{ 4, ST+U }, /* 11 1 0010: stwux */
INVALID, /* 11 1 0011 */
{ 2, LD+U }, /* 11 1 0100: lhzux */
{ 2, LD+SE+U }, /* 11 1 0101: lhaux */
{ 2, ST+U }, /* 11 1 0110: sthux */
INVALID, /* 11 1 0111 */
{ 4, LD+F+S+U }, /* 11 1 1000: lfsux */
{ 8, LD+F+U }, /* 11 1 1001: lfdux */
{ 4, ST+F+S+U }, /* 11 1 1010: stfsux */
{ 8, ST+F+U }, /* 11 1 1011: stfdux */
INVALID, /* 11 1 1100 */
INVALID, /* 11 1 1101 */
INVALID, /* 11 1 1110 */
INVALID, /* 11 1 1111 */
};
/*
* Create a DSISR value from the instruction
*/
static inline unsigned make_dsisr(unsigned instr)
{
unsigned dsisr;
/* bits 6:15 --> 22:31 */
dsisr = (instr & 0x03ff0000) >> 16;
if (IS_XFORM(instr)) {
/* bits 29:30 --> 15:16 */
dsisr |= (instr & 0x00000006) << 14;
/* bit 25 --> 17 */
dsisr |= (instr & 0x00000040) << 8;
/* bits 21:24 --> 18:21 */
dsisr |= (instr & 0x00000780) << 3;
} else {
/* bit 5 --> 17 */
dsisr |= (instr & 0x04000000) >> 12;
/* bits 1: 4 --> 18:21 */
dsisr |= (instr & 0x78000000) >> 17;
/* bits 30:31 --> 12:13 */
if (IS_DSFORM(instr))
dsisr |= (instr & 0x00000003) << 18;
}
return dsisr;
}
/*
* The dcbz (data cache block zero) instruction
* gives an alignment fault if used on non-cacheable
* memory. We handle the fault mainly for the
* case when we are running with the cache disabled
* for debugging.
*/
static int emulate_dcbz(struct pt_regs *regs, unsigned char __user *addr)
{
long __user *p;
int i, size;
#ifdef __powerpc64__
size = ppc64_caches.dline_size;
#else
size = L1_CACHE_BYTES;
#endif
p = (long __user *) (regs->dar & -size);
if (user_mode(regs) && !access_ok(VERIFY_WRITE, p, size))
return -EFAULT;
for (i = 0; i < size / sizeof(long); ++i)
if (__put_user(0, p+i))
return -EFAULT;
return 1;
}
/*
* Emulate load & store multiple instructions
* On 64-bit machines, these instructions only affect/use the
* bottom 4 bytes of each register, and the loads clear the
* top 4 bytes of the affected register.
*/
#ifdef CONFIG_PPC64
#define REG_BYTE(rp, i) *((u8 *)((rp) + ((i) >> 2)) + ((i) & 3) + 4)
#else
#define REG_BYTE(rp, i) *((u8 *)(rp) + (i))
#endif
static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr,
unsigned int reg, unsigned int nb,
unsigned int flags, unsigned int instr)
{
unsigned long *rptr;
unsigned int nb0, i;
/*
* We do not try to emulate 8 bytes multiple as they aren't really
* available in our operating environments and we don't try to
* emulate multiples operations in kernel land as they should never
* be used/generated there at least not on unaligned boundaries
*/
if (unlikely((nb > 4) || !user_mode(regs)))
return 0;
/* lmw, stmw, lswi/x, stswi/x */
nb0 = 0;
if (flags & HARD) {
if (flags & SX) {
nb = regs->xer & 127;
if (nb == 0)
return 1;
} else {
if (__get_user(instr,
(unsigned int __user *)regs->nip))
return -EFAULT;
nb = (instr >> 11) & 0x1f;
if (nb == 0)
nb = 32;
}
if (nb + reg * 4 > 128) {
nb0 = nb + reg * 4 - 128;
nb = 128 - reg * 4;
}
} else {
/* lwm, stmw */
nb = (32 - reg) * 4;
}
if (!access_ok((flags & ST ? VERIFY_WRITE: VERIFY_READ), addr, nb+nb0))
return -EFAULT; /* bad address */
rptr = &regs->gpr[reg];
if (flags & LD) {
/*
* This zeroes the top 4 bytes of the affected registers
* in 64-bit mode, and also zeroes out any remaining
* bytes of the last register for lsw*.
*/
memset(rptr, 0, ((nb + 3) / 4) * sizeof(unsigned long));
if (nb0 > 0)
memset(&regs->gpr[0], 0,
((nb0 + 3) / 4) * sizeof(unsigned long));
for (i = 0; i < nb; ++i)
if (__get_user(REG_BYTE(rptr, i), addr + i))
return -EFAULT;
if (nb0 > 0) {
rptr = &regs->gpr[0];
addr += nb;
for (i = 0; i < nb0; ++i)
if (__get_user(REG_BYTE(rptr, i), addr + i))
return -EFAULT;
}
} else {
for (i = 0; i < nb; ++i)
if (__put_user(REG_BYTE(rptr, i), addr + i))
return -EFAULT;
if (nb0 > 0) {
rptr = &regs->gpr[0];
addr += nb;
for (i = 0; i < nb0; ++i)
if (__put_user(REG_BYTE(rptr, i), addr + i))
return -EFAULT;
}
}
return 1;
}
/*
* Called on alignment exception. Attempts to fixup
*
* Return 1 on success
* Return 0 if unable to handle the interrupt
* Return -EFAULT if data address is bad
*/
int fix_alignment(struct pt_regs *regs)
{
unsigned int instr, nb, flags;
unsigned int reg, areg;
unsigned int dsisr;
unsigned char __user *addr;
unsigned char __user *p;
int ret, t;
union {
u64 ll;
double dd;
unsigned char v[8];
struct {
unsigned hi32;
int low32;
} x32;
struct {
unsigned char hi48[6];
short low16;
} x16;
} data;
/*
* We require a complete register set, if not, then our assembly
* is broken
*/
CHECK_FULL_REGS(regs);
dsisr = regs->dsisr;
/* Some processors don't provide us with a DSISR we can use here,
* let's make one up from the instruction
*/
if (cpu_has_feature(CPU_FTR_NODSISRALIGN)) {
unsigned int real_instr;
if (unlikely(__get_user(real_instr,
(unsigned int __user *)regs->nip)))
return -EFAULT;
dsisr = make_dsisr(real_instr);
}
/* extract the operation and registers from the dsisr */
reg = (dsisr >> 5) & 0x1f; /* source/dest register */
areg = dsisr & 0x1f; /* register to update */
instr = (dsisr >> 10) & 0x7f;
instr |= (dsisr >> 13) & 0x60;
/* Lookup the operation in our table */
nb = aligninfo[instr].len;
flags = aligninfo[instr].flags;
/* DAR has the operand effective address */
addr = (unsigned char __user *)regs->dar;
/* A size of 0 indicates an instruction we don't support, with
* the exception of DCBZ which is handled as a special case here
*/
if (instr == DCBZ)
return emulate_dcbz(regs, addr);
if (unlikely(nb == 0))
return 0;
/* Load/Store Multiple instructions are handled in their own
* function
*/
if (flags & M)
return emulate_multiple(regs, addr, reg, nb, flags, instr);
/* Verify the address of the operand */
if (unlikely(user_mode(regs) &&
!access_ok((flags & ST ? VERIFY_WRITE : VERIFY_READ),
addr, nb)))
return -EFAULT;
/* Force the fprs into the save area so we can reference them */
if (flags & F) {
/* userland only */
if (unlikely(!user_mode(regs)))
return 0;
flush_fp_to_thread(current);
}
/* If we are loading, get the data from user space, else
* get it from register values
*/
if (flags & LD) {
data.ll = 0;
ret = 0;
p = addr;
switch (nb) {
case 8:
ret |= __get_user(data.v[0], p++);
ret |= __get_user(data.v[1], p++);
ret |= __get_user(data.v[2], p++);
ret |= __get_user(data.v[3], p++);
case 4:
ret |= __get_user(data.v[4], p++);
ret |= __get_user(data.v[5], p++);
case 2:
ret |= __get_user(data.v[6], p++);
ret |= __get_user(data.v[7], p++);
if (unlikely(ret))
return -EFAULT;
}
} else if (flags & F)
data.dd = current->thread.fpr[reg];
else
data.ll = regs->gpr[reg];
/* Perform other misc operations like sign extension, byteswap,
* or floating point single precision conversion
*/
switch (flags & ~U) {
case LD+SE: /* sign extend */
if ( nb == 2 )
data.ll = data.x16.low16;
else /* nb must be 4 */
data.ll = data.x32.low32;
break;
case LD+S: /* byte-swap */
case ST+S:
if (nb == 2) {
SWAP(data.v[6], data.v[7]);
} else {
SWAP(data.v[4], data.v[7]);
SWAP(data.v[5], data.v[6]);
}
break;
/* Single-precision FP load and store require conversions... */
case LD+F+S:
#ifdef CONFIG_PPC_FPU
preempt_disable();
enable_kernel_fp();
cvt_fd((float *)&data.v[4], &data.dd, &current->thread);
preempt_enable();
#else
return 0;
#endif
break;
case ST+F+S:
#ifdef CONFIG_PPC_FPU
preempt_disable();
enable_kernel_fp();
cvt_df(&data.dd, (float *)&data.v[4], &current->thread);
preempt_enable();
#else
return 0;
#endif
break;
}
/* Store result to memory or update registers */
if (flags & ST) {
ret = 0;
p = addr;
switch (nb) {
case 8:
ret |= __put_user(data.v[0], p++);
ret |= __put_user(data.v[1], p++);
ret |= __put_user(data.v[2], p++);
ret |= __put_user(data.v[3], p++);
case 4:
ret |= __put_user(data.v[4], p++);
ret |= __put_user(data.v[5], p++);
case 2:
ret |= __put_user(data.v[6], p++);
ret |= __put_user(data.v[7], p++);
}
if (unlikely(ret))
return -EFAULT;
} else if (flags & F)
current->thread.fpr[reg] = data.dd;
else
regs->gpr[reg] = data.ll;
/* Update RA as needed */
if (flags & U)
regs->gpr[areg] = regs->dar;
return 1;
}
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