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linux-stable/arch/parisc/kernel/unaligned.c
Helge Deller 7ae1f5508d parisc: Fix exception handler for fldw and fstw instructions 
The exception handler is broken for unaligned memory acceses with fldw
and fstw instructions, because it trashes or uses randomly some other
floating point register than the one specified in the instruction word
on loads and stores.

The instruction "fldw 0(addr),%fr22L" (and the other fldw/fstw
instructions) encode the target register (%fr22) in the rightmost 5 bits
of the instruction word. The 7th rightmost bit of the instruction word
defines if the left or right half of %fr22 should be used.

While processing unaligned address accesses, the FR3() define is used to
extract the offset into the local floating-point register set.  But the
calculation in FR3() was buggy, so that for example instead of %fr22,
register %fr12 [((22 * 2) & 0x1f) = 12] was used.

This bug has been since forever in the parisc kernel and I wonder why it
wasn't detected earlier. Interestingly I noticed this bug just because
the libime debian package failed to build on *native* hardware, while it
successfully built in qemu.

This patch corrects the bitshift and masking calculation in FR3().

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org>
2022-08-21 08:43:09 +02:00

673 lines
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Unaligned memory access handler
*
* Copyright (C) 2001 Randolph Chung <tausq@debian.org>
* Copyright (C) 2022 Helge Deller <deller@gmx.de>
* Significantly tweaked by LaMont Jones <lamont@debian.org>
*/
#include <linux/sched/signal.h>
#include <linux/signal.h>
#include <linux/ratelimit.h>
#include <linux/uaccess.h>
#include <asm/hardirq.h>
#include <asm/traps.h>
/* #define DEBUG_UNALIGNED 1 */
#ifdef DEBUG_UNALIGNED
#define DPRINTF(fmt, args...) do { printk(KERN_DEBUG "%s:%d:%s ", __FILE__, __LINE__, __func__ ); printk(KERN_DEBUG fmt, ##args ); } while (0)
#else
#define DPRINTF(fmt, args...)
#endif
#define RFMT "%#08lx"
/* 1111 1100 0000 0000 0001 0011 1100 0000 */
#define OPCODE1(a,b,c) ((a)<<26|(b)<<12|(c)<<6)
#define OPCODE2(a,b) ((a)<<26|(b)<<1)
#define OPCODE3(a,b) ((a)<<26|(b)<<2)
#define OPCODE4(a) ((a)<<26)
#define OPCODE1_MASK OPCODE1(0x3f,1,0xf)
#define OPCODE2_MASK OPCODE2(0x3f,1)
#define OPCODE3_MASK OPCODE3(0x3f,1)
#define OPCODE4_MASK OPCODE4(0x3f)
/* skip LDB - never unaligned (index) */
#define OPCODE_LDH_I OPCODE1(0x03,0,0x1)
#define OPCODE_LDW_I OPCODE1(0x03,0,0x2)
#define OPCODE_LDD_I OPCODE1(0x03,0,0x3)
#define OPCODE_LDDA_I OPCODE1(0x03,0,0x4)
#define OPCODE_LDCD_I OPCODE1(0x03,0,0x5)
#define OPCODE_LDWA_I OPCODE1(0x03,0,0x6)
#define OPCODE_LDCW_I OPCODE1(0x03,0,0x7)
/* skip LDB - never unaligned (short) */
#define OPCODE_LDH_S OPCODE1(0x03,1,0x1)
#define OPCODE_LDW_S OPCODE1(0x03,1,0x2)
#define OPCODE_LDD_S OPCODE1(0x03,1,0x3)
#define OPCODE_LDDA_S OPCODE1(0x03,1,0x4)
#define OPCODE_LDCD_S OPCODE1(0x03,1,0x5)
#define OPCODE_LDWA_S OPCODE1(0x03,1,0x6)
#define OPCODE_LDCW_S OPCODE1(0x03,1,0x7)
/* skip STB - never unaligned */
#define OPCODE_STH OPCODE1(0x03,1,0x9)
#define OPCODE_STW OPCODE1(0x03,1,0xa)
#define OPCODE_STD OPCODE1(0x03,1,0xb)
/* skip STBY - never unaligned */
/* skip STDBY - never unaligned */
#define OPCODE_STWA OPCODE1(0x03,1,0xe)
#define OPCODE_STDA OPCODE1(0x03,1,0xf)
#define OPCODE_FLDWX OPCODE1(0x09,0,0x0)
#define OPCODE_FLDWXR OPCODE1(0x09,0,0x1)
#define OPCODE_FSTWX OPCODE1(0x09,0,0x8)
#define OPCODE_FSTWXR OPCODE1(0x09,0,0x9)
#define OPCODE_FLDWS OPCODE1(0x09,1,0x0)
#define OPCODE_FLDWSR OPCODE1(0x09,1,0x1)
#define OPCODE_FSTWS OPCODE1(0x09,1,0x8)
#define OPCODE_FSTWSR OPCODE1(0x09,1,0x9)
#define OPCODE_FLDDX OPCODE1(0x0b,0,0x0)
#define OPCODE_FSTDX OPCODE1(0x0b,0,0x8)
#define OPCODE_FLDDS OPCODE1(0x0b,1,0x0)
#define OPCODE_FSTDS OPCODE1(0x0b,1,0x8)
#define OPCODE_LDD_L OPCODE2(0x14,0)
#define OPCODE_FLDD_L OPCODE2(0x14,1)
#define OPCODE_STD_L OPCODE2(0x1c,0)
#define OPCODE_FSTD_L OPCODE2(0x1c,1)
#define OPCODE_LDW_M OPCODE3(0x17,1)
#define OPCODE_FLDW_L OPCODE3(0x17,0)
#define OPCODE_FSTW_L OPCODE3(0x1f,0)
#define OPCODE_STW_M OPCODE3(0x1f,1)
#define OPCODE_LDH_L OPCODE4(0x11)
#define OPCODE_LDW_L OPCODE4(0x12)
#define OPCODE_LDWM OPCODE4(0x13)
#define OPCODE_STH_L OPCODE4(0x19)
#define OPCODE_STW_L OPCODE4(0x1A)
#define OPCODE_STWM OPCODE4(0x1B)
#define MAJOR_OP(i) (((i)>>26)&0x3f)
#define R1(i) (((i)>>21)&0x1f)
#define R2(i) (((i)>>16)&0x1f)
#define R3(i) ((i)&0x1f)
#define FR3(i) ((((i)&0x1f)<<1)|(((i)>>6)&1))
#define IM(i,n) (((i)>>1&((1<<(n-1))-1))|((i)&1?((0-1L)<<(n-1)):0))
#define IM5_2(i) IM((i)>>16,5)
#define IM5_3(i) IM((i),5)
#define IM14(i) IM((i),14)
#define ERR_NOTHANDLED -1
int unaligned_enabled __read_mostly = 1;
static int emulate_ldh(struct pt_regs *regs, int toreg)
{
unsigned long saddr = regs->ior;
unsigned long val = 0, temp1;
ASM_EXCEPTIONTABLE_VAR(ret);
DPRINTF("load " RFMT ":" RFMT " to r%d for 2 bytes\n",
regs->isr, regs->ior, toreg);
__asm__ __volatile__ (
" mtsp %4, %%sr1\n"
"1: ldbs 0(%%sr1,%3), %2\n"
"2: ldbs 1(%%sr1,%3), %0\n"
" depw %2, 23, 24, %0\n"
"3: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 3b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 3b)
: "+r" (val), "+r" (ret), "=&r" (temp1)
: "r" (saddr), "r" (regs->isr) );
DPRINTF("val = " RFMT "\n", val);
if (toreg)
regs->gr[toreg] = val;
return ret;
}
static int emulate_ldw(struct pt_regs *regs, int toreg, int flop)
{
unsigned long saddr = regs->ior;
unsigned long val = 0, temp1, temp2;
ASM_EXCEPTIONTABLE_VAR(ret);
DPRINTF("load " RFMT ":" RFMT " to r%d for 4 bytes\n",
regs->isr, regs->ior, toreg);
__asm__ __volatile__ (
" zdep %4,28,2,%2\n" /* r19=(ofs&3)*8 */
" mtsp %5, %%sr1\n"
" depw %%r0,31,2,%4\n"
"1: ldw 0(%%sr1,%4),%0\n"
"2: ldw 4(%%sr1,%4),%3\n"
" subi 32,%2,%2\n"
" mtctl %2,11\n"
" vshd %0,%3,%0\n"
"3: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 3b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 3b)
: "+r" (val), "+r" (ret), "=&r" (temp1), "=&r" (temp2)
: "r" (saddr), "r" (regs->isr) );
DPRINTF("val = " RFMT "\n", val);
if (flop)
((__u32*)(regs->fr))[toreg] = val;
else if (toreg)
regs->gr[toreg] = val;
return ret;
}
static int emulate_ldd(struct pt_regs *regs, int toreg, int flop)
{
unsigned long saddr = regs->ior;
__u64 val = 0;
ASM_EXCEPTIONTABLE_VAR(ret);
DPRINTF("load " RFMT ":" RFMT " to r%d for 8 bytes\n",
regs->isr, regs->ior, toreg);
if (!IS_ENABLED(CONFIG_64BIT) && !flop)
return ERR_NOTHANDLED;
#ifdef CONFIG_64BIT
__asm__ __volatile__ (
" depd,z %3,60,3,%%r19\n" /* r19=(ofs&7)*8 */
" mtsp %4, %%sr1\n"
" depd %%r0,63,3,%3\n"
"1: ldd 0(%%sr1,%3),%0\n"
"2: ldd 8(%%sr1,%3),%%r20\n"
" subi 64,%%r19,%%r19\n"
" mtsar %%r19\n"
" shrpd %0,%%r20,%%sar,%0\n"
"3: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 3b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 3b)
: "=r" (val), "+r" (ret)
: "0" (val), "r" (saddr), "r" (regs->isr)
: "r19", "r20" );
#else
{
unsigned long shift, temp1;
__asm__ __volatile__ (
" zdep %2,29,2,%3\n" /* r19=(ofs&3)*8 */
" mtsp %5, %%sr1\n"
" dep %%r0,31,2,%2\n"
"1: ldw 0(%%sr1,%2),%0\n"
"2: ldw 4(%%sr1,%2),%R0\n"
"3: ldw 8(%%sr1,%2),%4\n"
" subi 32,%3,%3\n"
" mtsar %3\n"
" vshd %0,%R0,%0\n"
" vshd %R0,%4,%R0\n"
"4: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 4b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 4b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(3b, 4b)
: "+r" (val), "+r" (ret), "+r" (saddr), "=&r" (shift), "=&r" (temp1)
: "r" (regs->isr) );
}
#endif
DPRINTF("val = 0x%llx\n", val);
if (flop)
regs->fr[toreg] = val;
else if (toreg)
regs->gr[toreg] = val;
return ret;
}
static int emulate_sth(struct pt_regs *regs, int frreg)
{
unsigned long val = regs->gr[frreg], temp1;
ASM_EXCEPTIONTABLE_VAR(ret);
if (!frreg)
val = 0;
DPRINTF("store r%d (" RFMT ") to " RFMT ":" RFMT " for 2 bytes\n", frreg,
val, regs->isr, regs->ior);
__asm__ __volatile__ (
" mtsp %4, %%sr1\n"
" extrw,u %2, 23, 8, %1\n"
"1: stb %1, 0(%%sr1, %3)\n"
"2: stb %2, 1(%%sr1, %3)\n"
"3: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 3b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 3b)
: "+r" (ret), "=&r" (temp1)
: "r" (val), "r" (regs->ior), "r" (regs->isr) );
return ret;
}
static int emulate_stw(struct pt_regs *regs, int frreg, int flop)
{
unsigned long val;
ASM_EXCEPTIONTABLE_VAR(ret);
if (flop)
val = ((__u32*)(regs->fr))[frreg];
else if (frreg)
val = regs->gr[frreg];
else
val = 0;
DPRINTF("store r%d (" RFMT ") to " RFMT ":" RFMT " for 4 bytes\n", frreg,
val, regs->isr, regs->ior);
__asm__ __volatile__ (
" mtsp %3, %%sr1\n"
" zdep %2, 28, 2, %%r19\n"
" dep %%r0, 31, 2, %2\n"
" mtsar %%r19\n"
" depwi,z -2, %%sar, 32, %%r19\n"
"1: ldw 0(%%sr1,%2),%%r20\n"
"2: ldw 4(%%sr1,%2),%%r21\n"
" vshd %%r0, %1, %%r22\n"
" vshd %1, %%r0, %%r1\n"
" and %%r20, %%r19, %%r20\n"
" andcm %%r21, %%r19, %%r21\n"
" or %%r22, %%r20, %%r20\n"
" or %%r1, %%r21, %%r21\n"
" stw %%r20,0(%%sr1,%2)\n"
" stw %%r21,4(%%sr1,%2)\n"
"3: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 3b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 3b)
: "+r" (ret)
: "r" (val), "r" (regs->ior), "r" (regs->isr)
: "r19", "r20", "r21", "r22", "r1" );
return ret;
}
static int emulate_std(struct pt_regs *regs, int frreg, int flop)
{
__u64 val;
ASM_EXCEPTIONTABLE_VAR(ret);
if (flop)
val = regs->fr[frreg];
else if (frreg)
val = regs->gr[frreg];
else
val = 0;
DPRINTF("store r%d (0x%016llx) to " RFMT ":" RFMT " for 8 bytes\n", frreg,
val, regs->isr, regs->ior);
if (!IS_ENABLED(CONFIG_64BIT) && !flop)
return ERR_NOTHANDLED;
#ifdef CONFIG_64BIT
__asm__ __volatile__ (
" mtsp %3, %%sr1\n"
" depd,z %2, 60, 3, %%r19\n"
" depd %%r0, 63, 3, %2\n"
" mtsar %%r19\n"
" depdi,z -2, %%sar, 64, %%r19\n"
"1: ldd 0(%%sr1,%2),%%r20\n"
"2: ldd 8(%%sr1,%2),%%r21\n"
" shrpd %%r0, %1, %%sar, %%r22\n"
" shrpd %1, %%r0, %%sar, %%r1\n"
" and %%r20, %%r19, %%r20\n"
" andcm %%r21, %%r19, %%r21\n"
" or %%r22, %%r20, %%r20\n"
" or %%r1, %%r21, %%r21\n"
"3: std %%r20,0(%%sr1,%2)\n"
"4: std %%r21,8(%%sr1,%2)\n"
"5: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 5b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 5b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(3b, 5b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(4b, 5b)
: "+r" (ret)
: "r" (val), "r" (regs->ior), "r" (regs->isr)
: "r19", "r20", "r21", "r22", "r1" );
#else
{
unsigned long valh=(val>>32),vall=(val&0xffffffffl);
__asm__ __volatile__ (
" mtsp %4, %%sr1\n"
" zdep %2, 29, 2, %%r19\n"
" dep %%r0, 31, 2, %3\n"
" mtsar %%r19\n"
" zvdepi -2, 32, %%r19\n"
"1: ldw 0(%%sr1,%3),%%r20\n"
"2: ldw 8(%%sr1,%3),%%r21\n"
" vshd %1, %2, %%r1\n"
" vshd %%r0, %1, %1\n"
" vshd %2, %%r0, %2\n"
" and %%r20, %%r19, %%r20\n"
" andcm %%r21, %%r19, %%r21\n"
" or %1, %%r20, %1\n"
" or %2, %%r21, %2\n"
"3: stw %1,0(%%sr1,%3)\n"
"4: stw %%r1,4(%%sr1,%3)\n"
"5: stw %2,8(%%sr1,%3)\n"
"6: \n"
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 6b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 6b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(3b, 6b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(4b, 6b)
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(5b, 6b)
: "+r" (ret)
: "r" (valh), "r" (vall), "r" (regs->ior), "r" (regs->isr)
: "r19", "r20", "r21", "r1" );
}
#endif
return ret;
}
void handle_unaligned(struct pt_regs *regs)
{
static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 5);
unsigned long newbase = R1(regs->iir)?regs->gr[R1(regs->iir)]:0;
int modify = 0;
int ret = ERR_NOTHANDLED;
__inc_irq_stat(irq_unaligned_count);
/* log a message with pacing */
if (user_mode(regs)) {
if (current->thread.flags & PARISC_UAC_SIGBUS) {
goto force_sigbus;
}
if (!(current->thread.flags & PARISC_UAC_NOPRINT) &&
__ratelimit(&ratelimit)) {
printk(KERN_WARNING "%s(%d): unaligned access to " RFMT
" at ip " RFMT " (iir " RFMT ")\n",
current->comm, task_pid_nr(current), regs->ior,
regs->iaoq[0], regs->iir);
#ifdef DEBUG_UNALIGNED
show_regs(regs);
#endif
}
if (!unaligned_enabled)
goto force_sigbus;
}
/* handle modification - OK, it's ugly, see the instruction manual */
switch (MAJOR_OP(regs->iir))
{
case 0x03:
case 0x09:
case 0x0b:
if (regs->iir&0x20)
{
modify = 1;
if (regs->iir&0x1000) /* short loads */
if (regs->iir&0x200)
newbase += IM5_3(regs->iir);
else
newbase += IM5_2(regs->iir);
else if (regs->iir&0x2000) /* scaled indexed */
{
int shift=0;
switch (regs->iir & OPCODE1_MASK)
{
case OPCODE_LDH_I:
shift= 1; break;
case OPCODE_LDW_I:
shift= 2; break;
case OPCODE_LDD_I:
case OPCODE_LDDA_I:
shift= 3; break;
}
newbase += (R2(regs->iir)?regs->gr[R2(regs->iir)]:0)<<shift;
} else /* simple indexed */
newbase += (R2(regs->iir)?regs->gr[R2(regs->iir)]:0);
}
break;
case 0x13:
case 0x1b:
modify = 1;
newbase += IM14(regs->iir);
break;
case 0x14:
case 0x1c:
if (regs->iir&8)
{
modify = 1;
newbase += IM14(regs->iir&~0xe);
}
break;
case 0x16:
case 0x1e:
modify = 1;
newbase += IM14(regs->iir&6);
break;
case 0x17:
case 0x1f:
if (regs->iir&4)
{
modify = 1;
newbase += IM14(regs->iir&~4);
}
break;
}
/* TODO: make this cleaner... */
switch (regs->iir & OPCODE1_MASK)
{
case OPCODE_LDH_I:
case OPCODE_LDH_S:
ret = emulate_ldh(regs, R3(regs->iir));
break;
case OPCODE_LDW_I:
case OPCODE_LDWA_I:
case OPCODE_LDW_S:
case OPCODE_LDWA_S:
ret = emulate_ldw(regs, R3(regs->iir),0);
break;
case OPCODE_STH:
ret = emulate_sth(regs, R2(regs->iir));
break;
case OPCODE_STW:
case OPCODE_STWA:
ret = emulate_stw(regs, R2(regs->iir),0);
break;
#ifdef CONFIG_64BIT
case OPCODE_LDD_I:
case OPCODE_LDDA_I:
case OPCODE_LDD_S:
case OPCODE_LDDA_S:
ret = emulate_ldd(regs, R3(regs->iir),0);
break;
case OPCODE_STD:
case OPCODE_STDA:
ret = emulate_std(regs, R2(regs->iir),0);
break;
#endif
case OPCODE_FLDWX:
case OPCODE_FLDWS:
case OPCODE_FLDWXR:
case OPCODE_FLDWSR:
ret = emulate_ldw(regs,FR3(regs->iir),1);
break;
case OPCODE_FLDDX:
case OPCODE_FLDDS:
ret = emulate_ldd(regs,R3(regs->iir),1);
break;
case OPCODE_FSTWX:
case OPCODE_FSTWS:
case OPCODE_FSTWXR:
case OPCODE_FSTWSR:
ret = emulate_stw(regs,FR3(regs->iir),1);
break;
case OPCODE_FSTDX:
case OPCODE_FSTDS:
ret = emulate_std(regs,R3(regs->iir),1);
break;
case OPCODE_LDCD_I:
case OPCODE_LDCW_I:
case OPCODE_LDCD_S:
case OPCODE_LDCW_S:
ret = ERR_NOTHANDLED; /* "undefined", but lets kill them. */
break;
}
switch (regs->iir & OPCODE2_MASK)
{
case OPCODE_FLDD_L:
ret = emulate_ldd(regs,R2(regs->iir),1);
break;
case OPCODE_FSTD_L:
ret = emulate_std(regs, R2(regs->iir),1);
break;
#ifdef CONFIG_64BIT
case OPCODE_LDD_L:
ret = emulate_ldd(regs, R2(regs->iir),0);
break;
case OPCODE_STD_L:
ret = emulate_std(regs, R2(regs->iir),0);
break;
#endif
}
switch (regs->iir & OPCODE3_MASK)
{
case OPCODE_FLDW_L:
ret = emulate_ldw(regs, R2(regs->iir), 1);
break;
case OPCODE_LDW_M:
ret = emulate_ldw(regs, R2(regs->iir), 0);
break;
case OPCODE_FSTW_L:
ret = emulate_stw(regs, R2(regs->iir),1);
break;
case OPCODE_STW_M:
ret = emulate_stw(regs, R2(regs->iir),0);
break;
}
switch (regs->iir & OPCODE4_MASK)
{
case OPCODE_LDH_L:
ret = emulate_ldh(regs, R2(regs->iir));
break;
case OPCODE_LDW_L:
case OPCODE_LDWM:
ret = emulate_ldw(regs, R2(regs->iir),0);
break;
case OPCODE_STH_L:
ret = emulate_sth(regs, R2(regs->iir));
break;
case OPCODE_STW_L:
case OPCODE_STWM:
ret = emulate_stw(regs, R2(regs->iir),0);
break;
}
if (ret == 0 && modify && R1(regs->iir))
regs->gr[R1(regs->iir)] = newbase;
if (ret == ERR_NOTHANDLED)
printk(KERN_CRIT "Not-handled unaligned insn 0x%08lx\n", regs->iir);
DPRINTF("ret = %d\n", ret);
if (ret)
{
/*
* The unaligned handler failed.
* If we were called by __get_user() or __put_user() jump
* to it's exception fixup handler instead of crashing.
*/
if (!user_mode(regs) && fixup_exception(regs))
return;
printk(KERN_CRIT "Unaligned handler failed, ret = %d\n", ret);
die_if_kernel("Unaligned data reference", regs, 28);
if (ret == -EFAULT)
{
force_sig_fault(SIGSEGV, SEGV_MAPERR,
(void __user *)regs->ior);
}
else
{
force_sigbus:
/* couldn't handle it ... */
force_sig_fault(SIGBUS, BUS_ADRALN,
(void __user *)regs->ior);
}
return;
}
/* else we handled it, let life go on. */
regs->gr[0]|=PSW_N;
}
/*
* NB: check_unaligned() is only used for PCXS processors right
* now, so we only check for PA1.1 encodings at this point.
*/
int
check_unaligned(struct pt_regs *regs)
{
unsigned long align_mask;
/* Get alignment mask */
align_mask = 0UL;
switch (regs->iir & OPCODE1_MASK) {
case OPCODE_LDH_I:
case OPCODE_LDH_S:
case OPCODE_STH:
align_mask = 1UL;
break;
case OPCODE_LDW_I:
case OPCODE_LDWA_I:
case OPCODE_LDW_S:
case OPCODE_LDWA_S:
case OPCODE_STW:
case OPCODE_STWA:
align_mask = 3UL;
break;
default:
switch (regs->iir & OPCODE4_MASK) {
case OPCODE_LDH_L:
case OPCODE_STH_L:
align_mask = 1UL;
break;
case OPCODE_LDW_L:
case OPCODE_LDWM:
case OPCODE_STW_L:
case OPCODE_STWM:
align_mask = 3UL;
break;
}
break;
}
return (int)(regs->ior & align_mask);
}
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