From c2860d43f5dfab599fc1308ab61b1d3e30801ceb Mon Sep 17 00:00:00 2001 From: "George G. Davis" Date: Thu, 4 Jun 2009 17:16:04 +0100 Subject: [ARM] 5540/1: 32-bit Thumb-2 {ld,st}{m,rd} alignment fault fixup support From: Min Zhang Add alignment fault fixup support for 32-bit Thumb-2 LDM, LDRD, POP, PUSH, STM and STRD instructions. Alignment fault fixup support for the remaining 32-bit Thumb-2 load/store instruction cases is not included since ARMv6 and later processors include hardware support for loads and stores of unaligned words and halfwords. Signed-off-by: Min Zhang Signed-off-by: George G. Davis Signed-off-by: Russell King --- arch/arm/mm/alignment.c | 139 +++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 119 insertions(+), 20 deletions(-) (limited to 'arch/arm') diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c index 3a398befed4..03cd27d917b 100644 --- a/arch/arm/mm/alignment.c +++ b/arch/arm/mm/alignment.c @@ -62,6 +62,12 @@ #define SHIFT_ASR 0x40 #define SHIFT_RORRRX 0x60 +#define BAD_INSTR 0xdeadc0de + +/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */ +#define IS_T32(hi16) \ + (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800)) + static unsigned long ai_user; static unsigned long ai_sys; static unsigned long ai_skipped; @@ -332,38 +338,48 @@ 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)) + unsigned int rd2; + int load; + + if ((instr & 0xfe000000) == 0xe8000000) { + /* ARMv7 Thumb-2 32-bit LDRD/STRD */ + rd2 = (instr >> 8) & 0xf; + load = !!(LDST_L_BIT(instr)); + } else if (((rd & 1) == 1) || (rd == 14)) goto bad; + else { + load = ((instr & 0xf0) == 0xd0); + rd2 = rd + 1; + } ai_dword += 1; if (user_mode(regs)) goto user; - if ((instr & 0xf0) == 0xd0) { + if (load) { unsigned long val; get32_unaligned_check(val, addr); regs->uregs[rd] = val; get32_unaligned_check(val, addr + 4); - regs->uregs[rd + 1] = val; + regs->uregs[rd2] = val; } else { put32_unaligned_check(regs->uregs[rd], addr); - put32_unaligned_check(regs->uregs[rd + 1], addr + 4); + put32_unaligned_check(regs->uregs[rd2], addr + 4); } return TYPE_LDST; user: - if ((instr & 0xf0) == 0xd0) { + if (load) { unsigned long val; get32t_unaligned_check(val, addr); regs->uregs[rd] = val; get32t_unaligned_check(val, addr + 4); - regs->uregs[rd + 1] = val; + regs->uregs[rd2] = val; } else { put32t_unaligned_check(regs->uregs[rd], addr); - put32t_unaligned_check(regs->uregs[rd + 1], addr + 4); + put32t_unaligned_check(regs->uregs[rd2], addr + 4); } return TYPE_LDST; @@ -616,8 +632,72 @@ thumb2arm(u16 tinstr) /* Else fall through for illegal instruction case */ default: - return 0xdeadc0de; + return BAD_INSTR; + } +} + +/* + * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction + * handlable by ARM alignment handler, also find the corresponding handler, + * so that we can reuse ARM userland alignment fault fixups for Thumb. + * + * @pinstr: original Thumb-2 instruction; returns new handlable instruction + * @regs: register context. + * @poffset: return offset from faulted addr for later writeback + * + * NOTES: + * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections. + * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt) + */ +static void * +do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs, + union offset_union *poffset) +{ + unsigned long instr = *pinstr; + u16 tinst1 = (instr >> 16) & 0xffff; + u16 tinst2 = instr & 0xffff; + poffset->un = 0; + + switch (tinst1 & 0xffe0) { + /* A6.3.5 Load/Store multiple */ + case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */ + case 0xe8a0: /* ...above writeback version */ + case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */ + case 0xe920: /* ...above writeback version */ + /* no need offset decision since handler calculates it */ + return do_alignment_ldmstm; + + case 0xf840: /* POP/PUSH T3 (single register) */ + if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) { + u32 L = !!(LDST_L_BIT(instr)); + const u32 subset[2] = { + 0xe92d0000, /* STMDB sp!,{registers} */ + 0xe8bd0000, /* LDMIA sp!,{registers} */ + }; + *pinstr = subset[L] | (1<un = (tinst2 & 0xff) << 2; + case 0xe940: + case 0xe9c0: + return do_alignment_ldrdstrd; + + /* + * No need to handle load/store instructions up to word size + * since ARMv6 and later CPUs can perform unaligned accesses. + */ + default: + break; } + return NULL; } static int @@ -630,6 +710,8 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) mm_segment_t fs; unsigned int fault; u16 tinstr = 0; + int isize = 4; + int thumb2_32b = 0; instrptr = instruction_pointer(regs); @@ -637,8 +719,19 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) set_fs(KERNEL_DS); if (thumb_mode(regs)) { fault = __get_user(tinstr, (u16 *)(instrptr & ~1)); - if (!(fault)) - instr = thumb2arm(tinstr); + if (!fault) { + if (cpu_architecture() >= CPU_ARCH_ARMv7 && + IS_T32(tinstr)) { + /* Thumb-2 32-bit */ + u16 tinst2 = 0; + fault = __get_user(tinst2, (u16 *)(instrptr+2)); + instr = (tinstr << 16) | tinst2; + thumb2_32b = 1; + } else { + isize = 2; + instr = thumb2arm(tinstr); + } + } } else fault = __get_user(instr, (u32 *)instrptr); set_fs(fs); @@ -655,7 +748,7 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) fixup: - regs->ARM_pc += thumb_mode(regs) ? 2 : 4; + regs->ARM_pc += isize; switch (CODING_BITS(instr)) { case 0x00000000: /* 3.13.4 load/store instruction extensions */ @@ -714,18 +807,25 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) handler = do_alignment_ldrstr; break; - case 0x08000000: /* ldm or stm */ - handler = do_alignment_ldmstm; + case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */ + if (thumb2_32b) + handler = do_alignment_t32_to_handler(&instr, regs, &offset); + else + handler = do_alignment_ldmstm; break; default: goto bad; } + if (!handler) + goto bad; type = handler(addr, instr, regs); - if (type == TYPE_ERROR || type == TYPE_FAULT) + if (type == TYPE_ERROR || type == TYPE_FAULT) { + regs->ARM_pc -= isize; goto bad_or_fault; + } if (type == TYPE_LDST) do_alignment_finish_ldst(addr, instr, regs, offset); @@ -735,7 +835,6 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 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. */ @@ -751,8 +850,8 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) */ printk(KERN_ERR "Alignment trap: not handling instruction " "%0*lx at [<%08lx>]\n", - thumb_mode(regs) ? 4 : 8, - thumb_mode(regs) ? tinstr : instr, instrptr); + isize << 1, + isize == 2 ? tinstr : instr, instrptr); ai_skipped += 1; return 1; @@ -763,8 +862,8 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx " "Address=0x%08lx FSR 0x%03x\n", current->comm, task_pid_nr(current), instrptr, - thumb_mode(regs) ? 4 : 8, - thumb_mode(regs) ? tinstr : instr, + isize << 1, + isize == 2 ? tinstr : instr, addr, fsr); if (ai_usermode & UM_FIXUP) -- cgit v1.2.3