unaligned.c
/*
* Copyright (C) 2011-2012 Synopsys (www.synopsys.com)
*
* 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.
*
* vineetg : May 2011
* -Adapted (from .26 to .35)
* -original contribution by Tim.yao@amlogic.com
*
*/
#include <linux/types.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>
#include <asm/disasm.h>
#ifdef CONFIG_CPU_BIG_ENDIAN
#define BE 1
#define FIRST_BYTE_16 "swap %1, %1\n swape %1, %1\n"
#define FIRST_BYTE_32 "swape %1, %1\n"
#else
#define BE 0
#define FIRST_BYTE_16
#define FIRST_BYTE_32
#endif
#define __get8_unaligned_check(val, addr, err) \
__asm__( \
"1: ldb.ab %1, [%2, 1]\n" \
"2:\n" \
" .section .fixup,\"ax\"\n" \
" .align 4\n" \
"3: mov %0, 1\n" \
" j 2b\n" \
" .previous\n" \
" .section __ex_table,\"a\"\n" \
" .align 4\n" \
" .long 1b, 3b\n" \
" .previous\n" \
: "=r" (err), "=&r" (val), "=r" (addr) \
: "0" (err), "2" (addr))
#define get16_unaligned_check(val, addr) \
do { \
unsigned int err = 0, v, a = addr; \
__get8_unaligned_check(v, a, err); \
val = v << ((BE) ? 8 : 0); \
__get8_unaligned_check(v, a, err); \
val |= v << ((BE) ? 0 : 8); \
if (err) \
goto fault; \
} while (0)
#define get32_unaligned_check(val, addr) \
do { \
unsigned int err = 0, v, a = addr; \
__get8_unaligned_check(v, a, err); \
val = v << ((BE) ? 24 : 0); \
__get8_unaligned_check(v, a, err); \
val |= v << ((BE) ? 16 : 8); \
__get8_unaligned_check(v, a, err); \
val |= v << ((BE) ? 8 : 16); \
__get8_unaligned_check(v, a, err); \
val |= v << ((BE) ? 0 : 24); \
if (err) \
goto fault; \
} while (0)
#define put16_unaligned_check(val, addr) \
do { \
unsigned int err = 0, v = val, a = addr;\
\
__asm__( \
FIRST_BYTE_16 \
"1: stb.ab %1, [%2, 1]\n" \
" lsr %1, %1, 8\n" \
"2: stb %1, [%2]\n" \
"3:\n" \
" .section .fixup,\"ax\"\n" \
" .align 4\n" \
"4: mov %0, 1\n" \
" j 3b\n" \
" .previous\n" \
" .section __ex_table,\"a\"\n" \
" .align 4\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 put32_unaligned_check(val, addr) \
do { \
unsigned int err = 0, v = val, a = addr;\
\
__asm__( \
FIRST_BYTE_32 \
"1: stb.ab %1, [%2, 1]\n" \
" lsr %1, %1, 8\n" \
"2: stb.ab %1, [%2, 1]\n" \
" lsr %1, %1, 8\n" \
"3: stb.ab %1, [%2, 1]\n" \
" lsr %1, %1, 8\n" \
"4: stb %1, [%2]\n" \
"5:\n" \
" .section .fixup,\"ax\"\n" \
" .align 4\n" \
"6: mov %0, 1\n" \
" j 5b\n" \
" .previous\n" \
" .section __ex_table,\"a\"\n" \
" .align 4\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)
/* sysctl hooks */
int unaligned_enabled __read_mostly = 1; /* Enabled by default */
int no_unaligned_warning __read_mostly = 1; /* Only 1 warning by default */
static void fixup_load(struct disasm_state *state, struct pt_regs *regs,
struct callee_regs *cregs)
{
int val;
/* register write back */
if ((state->aa == 1) || (state->aa == 2)) {
set_reg(state->wb_reg, state->src1 + state->src2, regs, cregs);
if (state->aa == 2)
state->src2 = 0;
}
if (state->zz == 0) {
get32_unaligned_check(val, state->src1 + state->src2);
} else {
get16_unaligned_check(val, state->src1 + state->src2);
if (state->x)
val = (val << 16) >> 16;
}
if (state->pref == 0)
set_reg(state->dest, val, regs, cregs);
return;
fault: state->fault = 1;
}
static void fixup_store(struct disasm_state *state, struct pt_regs *regs,
struct callee_regs *cregs)
{
/* register write back */
if ((state->aa == 1) || (state->aa == 2)) {
set_reg(state->wb_reg, state->src2 + state->src3, regs, cregs);
if (state->aa == 3)
state->src3 = 0;
} else if (state->aa == 3) {
if (state->zz == 2) {
set_reg(state->wb_reg, state->src2 + (state->src3 << 1),
regs, cregs);
} else if (!state->zz) {
set_reg(state->wb_reg, state->src2 + (state->src3 << 2),
regs, cregs);
} else {
goto fault;
}
}
/* write fix-up */
if (!state->zz)
put32_unaligned_check(state->src1, state->src2 + state->src3);
else
put16_unaligned_check(state->src1, state->src2 + state->src3);
return;
fault: state->fault = 1;
}
/*
* Handle an unaligned access
* Returns 0 if successfully handled, 1 if some error happened
*/
int misaligned_fixup(unsigned long address, struct pt_regs *regs,
struct callee_regs *cregs)
{
struct disasm_state state;
char buf[TASK_COMM_LEN];
/* handle user mode only and only if enabled by sysadmin */
if (!user_mode(regs) || !unaligned_enabled)
return 1;
if (no_unaligned_warning) {
pr_warn_once("%s(%d) made unaligned access which was emulated"
" by kernel assist\n. This can degrade application"
" performance significantly\n. To enable further"
" logging of such instances, please \n"
" echo 0 > /proc/sys/kernel/ignore-unaligned-usertrap\n",
get_task_comm(buf, current), task_pid_nr(current));
} else {
/* Add rate limiting if it gets down to it */
pr_warn("%s(%d): unaligned access to/from 0x%lx by PC: 0x%lx\n",
get_task_comm(buf, current), task_pid_nr(current),
address, regs->ret);
}
disasm_instr(regs->ret, &state, 1, regs, cregs);
if (state.fault)
goto fault;
/* ldb/stb should not have unaligned exception */
if ((state.zz == 1) || (state.di))
goto fault;
if (!state.write)
fixup_load(&state, regs, cregs);
else
fixup_store(&state, regs, cregs);
if (state.fault)
goto fault;
/* clear any remanants of delay slot */
if (delay_mode(regs)) {
regs->ret = regs->bta & ~1U;
regs->status32 &= ~STATUS_DE_MASK;
} else {
regs->ret += state.instr_len;
/* handle zero-overhead-loop */
if ((regs->ret == regs->lp_end) && (regs->lp_count)) {
regs->ret = regs->lp_start;
regs->lp_count--;
}
}
perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, address);
return 0;
fault:
pr_err("Alignment trap: fault in fix-up %08lx at [<%08lx>]\n",
state.words[0], address);
return 1;
}
