/* * linux/arch/arm/mm/alignment.c * * Copyright (C) 1995 Linus Torvalds * Modifications for ARM processor (c) 1995-2001 Russell King * Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc. * - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation. * Copyright (C) 1996, Cygnus Software Technologies Ltd. * * 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. */ #include <linux/compiler.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/proc_fs.h> #include <linux/init.h> #include <asm/uaccess.h> #include <asm/unaligned.h> #include "fault.h" /* * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998 * /proc/sys/debug/alignment, modified and integrated into * Linux 2.1 by Russell King * * Speed optimisations and better fault handling by Russell King. * * *** NOTE *** * This code is not portable to processors with late data abort handling. */ #define CODING_BITS(i) (i & 0x0e000000) #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */ #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */ #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */ #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */ #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */ #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0) #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */ #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */ #define RN_BITS(i) ((i >> 16) & 15) /* Rn */ #define RD_BITS(i) ((i >> 12) & 15) /* Rd */ #define RM_BITS(i) (i & 15) /* Rm */ #define REGMASK_BITS(i) (i & 0xffff) #define OFFSET_BITS(i) (i & 0x0fff) #define IS_SHIFT(i) (i & 0x0ff0) #define SHIFT_BITS(i) ((i >> 7) & 0x1f) #define SHIFT_TYPE(i) (i & 0x60) #define SHIFT_LSL 0x00 #define SHIFT_LSR 0x20 #define SHIFT_ASR 0x40 #define SHIFT_RORRRX 0x60 static unsigned long ai_user; static unsigned long ai_sys; static unsigned long ai_skipped; static unsigned long ai_half; static unsigned long ai_word; static unsigned long ai_dword; static unsigned long ai_multi; static int ai_usermode; #ifdef CONFIG_PROC_FS static const char *usermode_action[] = { "ignored", "warn", "fixup", "fixup+warn", "signal", "signal+warn" }; static int proc_alignment_read(char *page, char **start, off_t off, int count, int *eof, void *data) { char *p = page; int len; p += sprintf(p, "User:\t\t%lu\n", ai_user); p += sprintf(p, "System:\t\t%lu\n", ai_sys); p += sprintf(p, "Skipped:\t%lu\n", ai_skipped); p += sprintf(p, "Half:\t\t%lu\n", ai_half); p += sprintf(p, "Word:\t\t%lu\n", ai_word); if (cpu_architecture() >= CPU_ARCH_ARMv5TE) p += sprintf(p, "DWord:\t\t%lu\n", ai_dword); p += sprintf(p, "Multi:\t\t%lu\n", ai_multi); p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode, usermode_action[ai_usermode]); len = (p - page) - off; if (len < 0) len = 0; *eof = (len <= count) ? 1 : 0; *start = page + off; return len; } static int proc_alignment_write(struct file *file, const char __user *buffer, unsigned long count, void *data) { char mode; if (count > 0) { if (get_user(mode, buffer)) return -EFAULT; if (mode >= '0' && mode <= '5') ai_usermode = mode - '0'; } return count; } #endif /* CONFIG_PROC_FS */ union offset_union { unsigned long un; signed long sn; }; #define TYPE_ERROR 0 #define TYPE_FAULT 1 #define TYPE_LDST 2 #define TYPE_DONE 3 #ifdef __ARMEB__ #define BE 1 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n" #define FIRST_BYTE_32 "mov %1, %1, ror #24\n" #define NEXT_BYTE "ror #24" #else #define BE 0 #define FIRST_BYTE_16 #define FIRST_BYTE_32 #define NEXT_BYTE "lsr #8" #endif #define __get8_unaligned_check(ins,val,addr,err) \ __asm__( \ "1: "ins" %1, [%2], #1\n" \ "2:\n" \ " .section .fixup,\"ax\"\n" \ " .align 2\n" \ "3: mov %0, #1\n" \ " b 2b\n" \ " .previous\n" \ " .section __ex_table,\"a\"\n" \ " .align 3\n" \ " .long 1b, 3b\n" \ " .previous\n" \ : "=r" (err), "=&r" (val), "=r" (addr) \ : "0" (err), "2" (addr)) #define __get16_unaligned_check(ins,val,addr) \ do { \ unsigned int err = 0, v, a = addr; \ __get8_unaligned_check(ins,v,a,err); \ val = v << ((BE) ? 8 : 0); \ __get8_unaligned_check(ins,v,a,err); \ val |= v << ((BE) ? 0 : 8); \ if (err) \ goto fault; \ } while (0) #define get16_unaligned_check(val,addr) \ __get16_unaligned_check("ldrb",val,addr) #define get16t_unaligned_check(val,addr) \ __get16_unaligned_check("ldrbt",val,addr) #define __get32_unaligned_check(ins,val,addr) \ do { \ unsigned int err = 0, v, a = addr; \ __get8_unaligned_check(ins,v,a,err); \ val = v << ((BE) ? 24 : 0); \ __get8_unaligned_check(ins,v,a,err); \ val |= v << ((BE) ? 16 : 8); \ __get8_unaligned_check(ins,v,a,err); \ val |= v << ((BE) ? 8 : 16); \ __get8_unaligned_check(ins,v,a,err); \ val |= v << ((BE) ? 0 : 24); \ if (err) \ goto fault; \ } while (0) #define get32_unaligned_check(val,addr) \ __get32_unaligned_check("ldrb",val,addr) #define get32t_unaligned_check(val,addr) \ __get32_unaligned_check("ldrbt",val,addr) #define __put16_unaligned_check(ins,val,addr) \ do { \ unsigned int err = 0, v = val, a = addr; \ __asm__( FIRST_BYTE_16 \ "1: "ins" %1, [%2], #1\n" \ " mov %1, %1, "NEXT_BYTE"\n" \ "2: "ins" %1, [%2]\n" \ "3:\n" \ " .section .fixup,\"ax\"\n" \ " .align 2\n" \ "4: mov %0, #1\n" \ " b 3b\n" \ " .previous\n" \ " .section __ex_table,\"a\"\n" \ " .align 3\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 put16_unaligned_check(val,addr) \ __put16_unaligned_check("strb",val,addr) #define put16t_unaligned_check(val,addr) \ __put16_unaligned_check("strbt",val,addr) #define __put32_unaligned_check(ins,val,addr) \ do { \ unsigned int err = 0, v = val, a = addr; \ __asm__( FIRST_BYTE_32 \ "1: "ins" %1, [%2], #1\n" \ " mov %1, %1, "NEXT_BYTE"\n" \ "2: "ins" %1, [%2], #1\n" \ " mov %1, %1, "NEXT_BYTE"\n" \ "3: "ins" %1, [%2], #1\n" \ " mov %1, %1, "NEXT_BYTE"\n" \ "4: "ins" %1, [%2]\n" \ "5:\n" \ " .section .fixup,\"ax\"\n" \ " .align 2\n" \ "6: mov %0, #1\n" \ " b 5b\n" \ " .previous\n" \ " .section __ex_table,\"a\"\n" \ " .align 3\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) #define put32_unaligned_check(val,addr) \ __put32_unaligned_check("strb", val, addr) #define put32t_unaligned_check(val,addr) \ __put32_unaligned_check("strbt", val, addr) static void do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset) { if (!LDST_U_BIT(instr)) offset.un = -offset.un; if (!LDST_P_BIT(instr)) addr += offset.un; if (!LDST_P_BIT(instr) || LDST_W_BIT(instr)) regs->uregs[RN_BITS(instr)] = addr; } static int do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs) { unsigned int rd = RD_BITS(instr); ai_half += 1; if (user_mode(regs)) goto user; if (LDST_L_BIT(instr)) { unsigned long val; get16_unaligned_check(val, addr); /* signed half-word? */ if (instr & 0x40) val = (signed long)((signed short) val); regs->uregs[rd] = val; } else put16_unaligned_check(regs->uregs[rd], addr); return TYPE_LDST; user: if (LDST_L_BIT(instr)) { unsigned long val; get16t_unaligned_check(val, addr); /* signed half-word? */ if (instr & 0x40) val = (signed long)((signed short) val); regs->uregs[rd] = val; } else put16t_unaligned_check(regs->uregs[rd], addr); return TYPE_LDST; fault: return TYPE_FAULT; } static int do_alignment_ldrdstrd(unsigned long addr, unsigned long instr, struct pt_regs *regs) { unsigned int rd = RD_BITS(instr); if (((rd & 1) == 1) || (rd == 14)) goto bad; ai_dword += 1; if (user_mode(regs)) goto user; if ((instr & 0xf0) == 0xd0) { unsigned long val; get32_unaligned_check(val, addr); regs->uregs[rd] = val; get32_unaligned_check(val, addr + 4); regs->uregs[rd + 1] = val; } else { put32_unaligned_check(regs->uregs[rd], addr); put32_unaligned_check(regs->uregs[rd + 1], addr + 4); } return TYPE_LDST; user: if ((instr & 0xf0) == 0xd0) { unsigned long val; get32t_unaligned_check(val, addr); regs->uregs[rd] = val; get32t_unaligned_check(val, addr + 4); regs->uregs[rd + 1] = val; } else { put32t_unaligned_check(regs->uregs[rd], addr); put32t_unaligned_check(regs->uregs[rd + 1], addr + 4); } return TYPE_LDST; bad: return TYPE_ERROR; fault: return TYPE_FAULT; } static int do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs) { unsigned int rd = RD_BITS(instr); ai_word += 1; if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs)) goto trans; if (LDST_L_BIT(instr)) { unsigned int val; get32_unaligned_check(val, addr); regs->uregs[rd] = val; } else put32_unaligned_check(regs->uregs[rd], addr); return TYPE_LDST; trans: if (LDST_L_BIT(instr)) { unsigned int val; get32t_unaligned_check(val, addr); regs->uregs[rd] = val; } else put32t_unaligned_check(regs->uregs[rd], addr); return TYPE_LDST; fault: return TYPE_FAULT; } /* * LDM/STM alignment handler. * * There are 4 variants of this instruction: * * B = rn pointer before instruction, A = rn pointer after instruction * ------ increasing address -----> * | | r0 | r1 | ... | rx | | * PU = 01 B A * PU = 11 B A * PU = 00 A B * PU = 10 A B */ static int do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs) { unsigned int rd, rn, correction, nr_regs, regbits; unsigned long eaddr, newaddr; if (LDM_S_BIT(instr)) goto bad; correction = 4; /* processor implementation defined */ regs->ARM_pc += correction; ai_multi += 1; /* count the number of registers in the mask to be transferred */ nr_regs = hweight16(REGMASK_BITS(instr)) * 4; rn = RN_BITS(instr); newaddr = eaddr = regs->uregs[rn]; if (!LDST_U_BIT(instr)) nr_regs = -nr_regs; newaddr += nr_regs; if (!LDST_U_BIT(instr)) eaddr = newaddr; if (LDST_P_EQ_U(instr)) /* U = P */ eaddr += 4; /* * For alignment faults on the ARM922T/ARM920T the MMU makes * the FSR (and hence addr) equal to the updated base address * of the multiple access rather than the restored value. * Switch this message off if we've got a ARM92[02], otherwise * [ls]dm alignment faults are noisy! */ #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T) /* * This is a "hint" - we already have eaddr worked out by the * processor for us. */ if (addr != eaddr) { printk(KERN_ERR "LDMSTM: PC = %08lx, instr = %08lx, " "addr = %08lx, eaddr = %08lx\n", instruction_pointer(regs), instr, addr, eaddr); show_regs(regs); } #endif if (user_mode(regs)) { for (regbits = REGMASK_BITS(instr), rd = 0; regbits; regbits >>= 1, rd += 1) if (regbits & 1) { if (LDST_L_BIT(instr)) { unsigned int val; get32t_unaligned_check(val, eaddr); regs->uregs[rd] = val; } else put32t_unaligned_check(regs->uregs[rd], eaddr); eaddr += 4; } } else { for (regbits = REGMASK_BITS(instr), rd = 0; regbits; regbits >>= 1, rd += 1) if (regbits & 1) { if (LDST_L_BIT(instr)) { unsigned int val; get32_unaligned_check(val, eaddr); regs->uregs[rd] = val; } else put32_unaligned_check(regs->uregs[rd], eaddr); eaddr += 4; } } if (LDST_W_BIT(instr)) regs->uregs[rn] = newaddr; if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15))) regs->ARM_pc -= correction; return TYPE_DONE; fault: regs->ARM_pc -= correction; return TYPE_FAULT; bad: printk(KERN_ERR "Alignment trap: not handling ldm with s-bit set\n"); return TYPE_ERROR; } /* * Convert Thumb ld/st instruction forms to equivalent ARM instructions so * we can reuse ARM userland alignment fault fixups for Thumb. * * This implementation was initially based on the algorithm found in * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same * to convert only Thumb ld/st instruction forms to equivalent ARM forms. * * NOTES: * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections. * 2. If for some reason we're passed an non-ld/st Thumb instruction to * decode, we return 0xdeadc0de. This should never happen under normal * circumstances but if it does, we've got other problems to deal with * elsewhere and we obviously can't fix those problems here. */ static unsigned long thumb2arm(u16 tinstr) { u32 L = (tinstr & (1<<11)) >> 11; switch ((tinstr & 0xf800) >> 11) { /* 6.5.1 Format 1: */ case 0x6000 >> 11: /* 7.1.52 STR(1) */ case 0x6800 >> 11: /* 7.1.26 LDR(1) */ case 0x7000 >> 11: /* 7.1.55 STRB(1) */ case 0x7800 >> 11: /* 7.1.30 LDRB(1) */ return 0xe5800000 | ((tinstr & (1<<12)) << (22-12)) | /* fixup */ (L<<20) | /* L==1? */ ((tinstr & (7<<0)) << (12-0)) | /* Rd */ ((tinstr & (7<<3)) << (16-3)) | /* Rn */ ((tinstr & (31<<6)) >> /* immed_5 */ (6 - ((tinstr & (1<<12)) ? 0 : 2))); case 0x8000 >> 11: /* 7.1.57 STRH(1) */ case 0x8800 >> 11: /* 7.1.32 LDRH(1) */ return 0xe1c000b0 | (L<<20) | /* L==1? */ ((tinstr & (7<<0)) << (12-0)) | /* Rd */ ((tinstr & (7<<3)) << (16-3)) | /* Rn */ ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */ ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */ /* 6.5.1 Format 2: */ case 0x5000 >> 11: case 0x5800 >> 11: { static const u32 subset[8] = { 0xe7800000, /* 7.1.53 STR(2) */ 0xe18000b0, /* 7.1.58 STRH(2) */ 0xe7c00000, /* 7.1.56 STRB(2) */ 0xe19000d0, /* 7.1.34 LDRSB */ 0xe7900000, /* 7.1.27 LDR(2) */ 0xe19000b0, /* 7.1.33 LDRH(2) */ 0xe7d00000, /* 7.1.31 LDRB(2) */ 0xe19000f0 /* 7.1.35 LDRSH */ }; return subset[(tinstr & (7<<9)) >> 9] | ((tinstr & (7<<0)) << (12-0)) | /* Rd */ ((tinstr & (7<<3)) << (16-3)) | /* Rn */ ((tinstr & (7<<6)) >> (6-0)); /* Rm */ } /* 6.5.1 Format 3: */ case 0x4800 >> 11: /* 7.1.28 LDR(3) */ /* NOTE: This case is not technically possible. We're * loading 32-bit memory data via PC relative * addressing mode. So we can and should eliminate * this case. But I'll leave it here for now. */ return 0xe59f0000 | ((tinstr & (7<<8)) << (12-8)) | /* Rd */ ((tinstr & 255) << (2-0)); /* immed_8 */ /* 6.5.1 Format 4: */ case 0x9000 >> 11: /* 7.1.54 STR(3) */ case 0x9800 >> 11: /* 7.1.29 LDR(4) */ return 0xe58d0000 | (L<<20) | /* L==1? */ ((tinstr & (7<<8)) << (12-8)) | /* Rd */ ((tinstr & 255) << 2); /* immed_8 */ /* 6.6.1 Format 1: */ case 0xc000 >> 11: /* 7.1.51 STMIA */ case 0xc800 >> 11: /* 7.1.25 LDMIA */ { u32 Rn = (tinstr & (7<<8)) >> 8; u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21; return 0xe8800000 | W | (L<<20) | (Rn<<16) | (tinstr&255); } /* 6.6.1 Format 2: */ case 0xb000 >> 11: /* 7.1.48 PUSH */ case 0xb800 >> 11: /* 7.1.47 POP */ if ((tinstr & (3 << 9)) == 0x0400) { static const u32 subset[4] = { 0xe92d0000, /* STMDB sp!,{registers} */ 0xe92d4000, /* STMDB sp!,{registers,lr} */ 0xe8bd0000, /* LDMIA sp!,{registers} */ 0xe8bd8000 /* LDMIA sp!,{registers,pc} */ }; return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] | (tinstr & 255); /* register_list */ } /* Else fall through for illegal instruction case */ default: return 0xdeadc0de; } } static int do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { union offset_union offset; unsigned long instr = 0, instrptr; int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); unsigned int type; mm_segment_t fs; unsigned int fault; u16 tinstr = 0; instrptr = instruction_pointer(regs); fs = get_fs(); set_fs(KERNEL_DS); if (thumb_mode(regs)) { fault = __get_user(tinstr, (u16 *)(instrptr & ~1)); if (!(fault)) instr = thumb2arm(tinstr); } else fault = __get_user(instr, (u32 *)instrptr); set_fs(fs); if (fault) { type = TYPE_FAULT; goto bad_or_fault; } if (user_mode(regs)) goto user; ai_sys += 1; fixup: regs->ARM_pc += thumb_mode(regs) ? 2 : 4; switch (CODING_BITS(instr)) { case 0x00000000: /* 3.13.4 load/store instruction extensions */ if (LDSTHD_I_BIT(instr)) offset.un = (instr & 0xf00) >> 4 | (instr & 15); else offset.un = regs->uregs[RM_BITS(instr)]; if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */ (instr & 0x001000f0) == 0x001000f0) /* LDRSH */ handler = do_alignment_ldrhstrh; else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */ (instr & 0x001000f0) == 0x000000f0) /* STRD */ handler = do_alignment_ldrdstrd; else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */ goto swp; else goto bad; break; case 0x04000000: /* ldr or str immediate */ offset.un = OFFSET_BITS(instr); handler = do_alignment_ldrstr; break; case 0x06000000: /* ldr or str register */ offset.un = regs->uregs[RM_BITS(instr)]; if (IS_SHIFT(instr)) { unsigned int shiftval = SHIFT_BITS(instr); switch(SHIFT_TYPE(instr)) { case SHIFT_LSL: offset.un <<= shiftval; break; case SHIFT_LSR: offset.un >>= shiftval; break; case SHIFT_ASR: offset.sn >>= shiftval; break; case SHIFT_RORRRX: if (shiftval == 0) { offset.un >>= 1; if (regs->ARM_cpsr & PSR_C_BIT) offset.un |= 1 << 31; } else offset.un = offset.un >> shiftval | offset.un << (32 - shiftval); break; } } handler = do_alignment_ldrstr; break; case 0x08000000: /* ldm or stm */ handler = do_alignment_ldmstm; break; default: goto bad; } type = handler(addr, instr, regs); if (type == TYPE_ERROR || type == TYPE_FAULT) goto bad_or_fault; if (type == TYPE_LDST) do_alignment_finish_ldst(addr, instr, regs, offset); return 0; bad_or_fault: if (type == TYPE_ERROR) goto bad; regs->ARM_pc -= thumb_mode(regs) ? 2 : 4; /* * We got a fault - fix it up, or die. */ do_bad_area(addr, fsr, regs); return 0; swp: printk(KERN_ERR "Alignment trap: not handling swp instruction\n"); bad: /* * Oops, we didn't handle the instruction. */ printk(KERN_ERR "Alignment trap: not handling instruction " "%0*lx at [<%08lx>]\n", thumb_mode(regs) ? 4 : 8, thumb_mode(regs) ? tinstr : instr, instrptr); ai_skipped += 1; return 1; user: ai_user += 1; if (ai_usermode & 1) printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx " "Address=0x%08lx FSR 0x%03x\n", current->comm, current->pid, instrptr, thumb_mode(regs) ? 4 : 8, thumb_mode(regs) ? tinstr : instr, addr, fsr); if (ai_usermode & 2) goto fixup; if (ai_usermode & 4) force_sig(SIGBUS, current); else set_cr(cr_no_alignment); return 0; } /* * This needs to be done after sysctl_init, otherwise sys/ will be * overwritten. Actually, this shouldn't be in sys/ at all since * it isn't a sysctl, and it doesn't contain sysctl information. * We now locate it in /proc/cpu/alignment instead. */ static int __init alignment_init(void) { #ifdef CONFIG_PROC_FS struct proc_dir_entry *res; res = proc_mkdir("cpu", NULL); if (!res) return -ENOMEM; res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res); if (!res) return -ENOMEM; res->read_proc = proc_alignment_read; res->write_proc = proc_alignment_write; #endif hook_fault_code(1, do_alignment, SIGILL, "alignment exception"); hook_fault_code(3, do_alignment, SIGILL, "alignment exception"); return 0; } fs_initcall(alignment_init);