diff options
Diffstat (limited to 'arch/arc/kernel/unaligned.c')
| -rw-r--r-- | arch/arc/kernel/unaligned.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c new file mode 100644 index 00000000000..4cd81633feb --- /dev/null +++ b/arch/arc/kernel/unaligned.c @@ -0,0 +1,245 @@ +/* + * 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/ptrace.h> +#include <linux/uaccess.h> +#include <asm/disasm.h> + +#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" \ + " b 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 ; \ + __get8_unaligned_check(v, a, err); \ + val |= v << 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 << 0; \ + __get8_unaligned_check(v, a, err); \ + val |= v << 8; \ + __get8_unaligned_check(v, a, err); \ + val |= v << 16; \ + __get8_unaligned_check(v, a, err); \ + val |= v << 24; \ + if (err) \ + goto fault; \ + } while (0) + +#define put16_unaligned_check(val, addr) \ + do { \ + unsigned int err = 0, v = val, a = addr;\ + \ + __asm__( \ + "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" \ + " b 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__( \ + \ + "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" \ + " b 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, + unsigned long cause, 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; + + if (delay_mode(regs)) { + regs->ret = regs->bta; + regs->status32 &= ~STATUS_DE_MASK; + } else { + regs->ret += state.instr_len; + } + + return 0; + +fault: + pr_err("Alignment trap: fault in fix-up %08lx at [<%08lx>]\n", + state.words[0], address); + + return 1; +} |