/*
* Handle unaligned accesses by emulation.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996, 1998, 1999, 2002 by Ralf Baechle
* Copyright (C) 1999 Silicon Graphics, Inc.
* Copyright (C) 2014 Imagination Technologies Ltd.
*
* This file contains exception handler for address error exception with the
* special capability to execute faulting instructions in software. The
* handler does not try to handle the case when the program counter points
* to an address not aligned to a word boundary.
*
* Putting data to unaligned addresses is a bad practice even on Intel where
* only the performance is affected. Much worse is that such code is non-
* portable. Due to several programs that die on MIPS due to alignment
* problems I decided to implement this handler anyway though I originally
* didn't intend to do this at all for user code.
*
* For now I enable fixing of address errors by default to make life easier.
* I however intend to disable this somewhen in the future when the alignment
* problems with user programs have been fixed. For programmers this is the
* right way to go.
*
* Fixing address errors is a per process option. The option is inherited
* across fork(2) and execve(2) calls. If you really want to use the
* option in your user programs - I discourage the use of the software
* emulation strongly - use the following code in your userland stuff:
*
* #include <sys/sysmips.h>
*
* ...
* sysmips(MIPS_FIXADE, x);
* ...
*
* The argument x is 0 for disabling software emulation, enabled otherwise.
*
* Below a little program to play around with this feature.
*
* #include <stdio.h>
* #include <sys/sysmips.h>
*
* struct foo {
* unsigned char bar[8];
* };
*
* main(int argc, char *argv[])
* {
* struct foo x = {0, 1, 2, 3, 4, 5, 6, 7};
* unsigned int *p = (unsigned int *) (x.bar + 3);
* int i;
*
* if (argc > 1)
* sysmips(MIPS_FIXADE, atoi(argv[1]));
*
* printf("*p = %08lx\n", *p);
*
* *p = 0xdeadface;
*
* for(i = 0; i <= 7; i++)
* printf("%02x ", x.bar[i]);
* printf("\n");
* }
*
* Coprocessor loads are not supported; I think this case is unimportant
* in the practice.
*
* TODO: Handle ndc (attempted store to doubleword in uncached memory)
* exception for the R6000.
* A store crossing a page boundary might be executed only partially.
* Undo the partial store in this case.
*/
#include <linux/context_tracking.h>
#include <linux/mm.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/debugfs.h>
#include <linux/perf_event.h>
#include <asm/asm.h>
#include <asm/branch.h>
#include <asm/byteorder.h>
#include <asm/cop2.h>
#include <asm/fpu.h>
#include <asm/fpu_emulator.h>
#include <asm/inst.h>
#include <asm/uaccess.h>
#define STR(x) __STR(x)
#define __STR(x) #x
enum {
UNALIGNED_ACTION_QUIET,
UNALIGNED_ACTION_SIGNAL,
UNALIGNED_ACTION_SHOW,
};
#ifdef CONFIG_DEBUG_FS
static u32 unaligned_instructions;
static u32 unaligned_action;
#else
#define unaligned_action UNALIGNED_ACTION_QUIET
#endif
extern void show_registers(struct pt_regs *regs);
#ifdef __BIG_ENDIAN
#define _LoadHW(addr, value, res, type) \
do { \
__asm__ __volatile__ (".set\tnoat\n" \
"1:\t"type##_lb("%0", "0(%2)")"\n" \
"2:\t"type##_lbu("$1", "1(%2)")"\n\t"\
"sll\t%0, 0x8\n\t" \
"or\t%0, $1\n\t" \
"li\t%1, 0\n" \
"3:\t.set\tat\n\t" \
".insn\n\t" \
".section\t.fixup,\"ax\"\n\t" \
"4:\tli\t%1, %3\n\t" \
"j\t3b\n\t" \
".previous\n\t" \
".section\t__ex_table,\"a\"\n\t" \
STR(PTR)"\t1b, 4b\n\t" \
STR(PTR)"\t2b, 4b\n\t" \
".previous" \
: "=&r" (value), "=r" (res) \
: "r" (addr), "i" (-EFAULT)); \
} while(0)
#ifndef CONFIG_CPU_MIPSR6
#define _LoadW(addr, value, res, type) \
do { \
__asm__ __volatile__ ( \
"1:\t"type##_lwl("%0", "(%2)")"\n" \
"2:\t"type##_lwr("%0", "3(%2)")"\n\t"\
"li\t%1, 0\n" \
"3:\n\t" \
".insn\n\t" \
".section\t.fixup,\"ax\"\n\t" \
"4:\tli\t%1, %3\n\t" \
"j\t3b\n\t" \
".previous\n\t" \
".section\t__ex_table,\"a\"\n\t" \
STR(PTR)"\t1b, 4b\n\t" \
STR(PTR)"\t2b, 4b\n\t" \
".previous" \
: "=&r" (value), "=r" (res) \
: "r" (addr), "i" (-EFAULT)); \
} while(0)
#else
/* MIPSR6 has no lwl instruction */
#define _LoadW(addr, value, res, type) \
do { \
__asm__ __volatile__ ( \
".set\tpush\n" \
".set\tnoat\n\t" \
"1:"type##_lb("%0", "0(%2)")"\n\t" \
"2:"type##_lbu("$1", "1(%2)")"\n\t" \
"sll\t%0, 0x8\n\t" \
"or\t%0, $1\n\t" \
"3:"type##_lbu("$1", "2(%2)")"\n\t" \
"sll\t%0, 0x8\n\t" \
"or\t%0, $1\n\t" \
"4:"type##_lbu("$1", "3(%2)")"\n\t" \
"sll\t%0, 0x8\n\t" \
"or\t%0, $1\n\t" \
"li\t%1, 0\n" \
".set\tpop\n" \
"10:\n\t" \
".insn\n\t" \
".section\t.fixup,\"ax\"\n\t" \
"11:\tli\t%1, %3\n\t" \
"j\t10b\n\t" \
".previous\n\t" \
".section\t__ex_table,\"a\"\n\t" \
STR(PTR)"\t1b, 11b\n\t" \
STR(PTR)"\t2b, 11b\n\t" \
STR(PTR)"\t3b, 11b\n\t" \
STR(PTR)"\t4b, 11b\n\t" \
".previous" \
: "=&r" (value), "=r" (res) \
: "r" (addr), "i" (-EFAULT)); \
} while(0)
#endif /* CONFIG_CPU_MIPSR6 */
#define _LoadHWU(addr, value, res, type) \
do { \
__asm__ __volatile__ ( \
".set\tnoat\n" \
"1:\t"type##_lbu("%0", "0(%2)")"\n" \
"2:\t"type##_lbu("$1", "1(%2)")"\n\t"\
"sll\t%0, 0x8\n\t" \
"or\t%0, $1\n\t" \
"li\t%1, 0\n" \
"3:\n\t" \
".insn\n\t" \
".set\tat\n\t" \
".section\t.fixup,\"ax\"\n\t" \
"4:\tli\t%1, %3\n\t" \
"j\t3b\n\t" \
".previous\n\t" \
".section\t__ex_table,\"a\"\n\t" \
STR(PTR)"\t1b, 4b\n\t" \
STR(PTR)"\t2b, 4b\n\t" \
".previous" \
: "=&r" (value), "=r" (res) \
: "r" (addr), "i" (-EFAULT)); \
} while(0)
#ifndef CONFIG_CPU_MIPSR6
#define _LoadWU(addr, value, res, type) \
do { \
__asm__ __volatile__ ( \
"1:\t"type##_lwl("%0", "(%2)")"\n" \
"2:\t"type##_lwr("%0", "3(%2)")"\n\t"\
"dsll\t%0, %0, 32\n\t" \
"dsrl\t%0, %0, 32\n\t" \
"li\t%1, 0\n" \
"3:\n\t" \
".insn\n\t" \
"\t.section\t.fixup,\"ax\"\n\t" \
"4:\tli\t%1, %3\n\t" \
"j\t3b\n\t" \
".previous\n\t" \
".section\t__ex_table,\"a\"\n\t" \
STR(PTR)"\t1b, 4b\n\t" \
STR(PTR)"\t2b, 4b\n\t" \
".previous" \
: "=&r" (value), "=r" (res) \
: "r" (addr), "i" (-EFAULT)); \
} while(0)
#define _LoadDW(addr, value, res) \
do {
