diff options
author | Chris Zankel <czankel@tensilica.com> | 2005-06-23 22:01:16 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-24 00:05:21 -0700 |
commit | 5a0015d62668e64c8b6e02e360fbbea121bfd5e6 (patch) | |
tree | ed879f8cbe0efee21ad861f38c4024bdcf25df9b /arch/xtensa/kernel/align.S | |
parent | 4bedea94545165364618d403d03b61d797acba0b (diff) |
[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 3
The attached patches provides part 3 of an architecture implementation for the
Tensilica Xtensa CPU series.
Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/xtensa/kernel/align.S')
-rw-r--r-- | arch/xtensa/kernel/align.S | 459 |
1 files changed, 459 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/align.S b/arch/xtensa/kernel/align.S new file mode 100644 index 000000000000..74b1e90ef08c --- /dev/null +++ b/arch/xtensa/kernel/align.S @@ -0,0 +1,459 @@ +/* + * arch/xtensa/kernel/align.S + * + * Handle unalignment exceptions in kernel space. + * + * 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) 2001 - 2005 Tensilica, Inc. + * + * Rewritten by Chris Zankel <chris@zankel.net> + * + * Based on work from Joe Taylor <joe@tensilica.com, joetylr@yahoo.com> + * and Marc Gauthier <marc@tensilica.com, marc@alimni.uwaterloo.ca> + */ + +#include <linux/linkage.h> +#include <asm/ptrace.h> +#include <asm/ptrace.h> +#include <asm/current.h> +#include <asm/offsets.h> +#include <asm/pgtable.h> +#include <asm/processor.h> +#include <asm/page.h> +#include <asm/thread_info.h> + +#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION + +/* First-level exception handler for unaligned exceptions. + * + * Note: This handler works only for kernel exceptions. Unaligned user + * access should get a seg fault. + */ + +/* Big and little endian 16-bit values are located in + * different halves of a register. HWORD_START helps to + * abstract the notion of extracting a 16-bit value from a + * register. + * We also have to define new shifting instructions because + * lsb and msb are on 'opposite' ends in a register for + * different endian machines. + * + * Assume a memory region in ascending address: + * 0 1 2 3|4 5 6 7 + * + * When loading one word into a register, the content of that register is: + * LE 3 2 1 0, 7 6 5 4 + * BE 0 1 2 3, 4 5 6 7 + * + * Masking the bits of the higher/lower address means: + * LE X X 0 0, 0 0 X X + * BE 0 0 X X, X X 0 0 + * + * Shifting to higher/lower addresses, means: + * LE shift left / shift right + * BE shift right / shift left + * + * Extracting 16 bits from a 32 bit reg. value to higher/lower address means: + * LE mask 0 0 X X / shift left + * BE shift left / mask 0 0 X X + */ + +#define UNALIGNED_USER_EXCEPTION + +#if XCHAL_HAVE_BE + +#define HWORD_START 16 +#define INSN_OP0 28 +#define INSN_T 24 +#define INSN_OP1 16 + +.macro __src_b r, w0, w1; src \r, \w0, \w1; .endm +.macro __ssa8 r; ssa8b \r; .endm +.macro __ssa8r r; ssa8l \r; .endm +.macro __sh r, s; srl \r, \s; .endm +.macro __sl r, s; sll \r, \s; .endm +.macro __exth r, s; extui \r, \s, 0, 16; .endm +.macro __extl r, s; slli \r, \s, 16; .endm + +#else + +#define HWORD_START 0 +#define INSN_OP0 0 +#define INSN_T 4 +#define INSN_OP1 12 + +.macro __src_b r, w0, w1; src \r, \w1, \w0; .endm +.macro __ssa8 r; ssa8l \r; .endm +.macro __ssa8r r; ssa8b \r; .endm +.macro __sh r, s; sll \r, \s; .endm +.macro __sl r, s; srl \r, \s; .endm +.macro __exth r, s; slli \r, \s, 16; .endm +.macro __extl r, s; extui \r, \s, 0, 16; .endm + +#endif + +/* + * xxxx xxxx = imm8 field + * yyyy = imm4 field + * ssss = s field + * tttt = t field + * + * 16 0 + * ------------------- + * L32I.N yyyy ssss tttt 1000 + * S32I.N yyyy ssss tttt 1001 + * + * 23 0 + * ----------------------------- + * res 0000 0010 + * L16UI xxxx xxxx 0001 ssss tttt 0010 + * L32I xxxx xxxx 0010 ssss tttt 0010 + * XXX 0011 ssss tttt 0010 + * XXX 0100 ssss tttt 0010 + * S16I xxxx xxxx 0101 ssss tttt 0010 + * S32I xxxx xxxx 0110 ssss tttt 0010 + * XXX 0111 ssss tttt 0010 + * XXX 1000 ssss tttt 0010 + * L16SI xxxx xxxx 1001 ssss tttt 0010 + * XXX 1010 0010 + * **L32AI xxxx xxxx 1011 ssss tttt 0010 unsupported + * XXX 1100 0010 + * XXX 1101 0010 + * XXX 1110 0010 + * **S32RI xxxx xxxx 1111 ssss tttt 0010 unsupported + * ----------------------------- + * ^ ^ ^ + * sub-opcode (NIBBLE_R) -+ | | + * t field (NIBBLE_T) -----------+ | + * major opcode (NIBBLE_OP0) --------------+ + */ + +#define OP0_L32I_N 0x8 /* load immediate narrow */ +#define OP0_S32I_N 0x9 /* store immediate narrow */ +#define OP1_SI_MASK 0x4 /* OP1 bit set for stores */ +#define OP1_SI_BIT 2 /* OP1 bit number for stores */ + +#define OP1_L32I 0x2 +#define OP1_L16UI 0x1 +#define OP1_L16SI 0x9 +#define OP1_L32AI 0xb + +#define OP1_S32I 0x6 +#define OP1_S16I 0x5 +#define OP1_S32RI 0xf + +/* + * Entry condition: + * + * a0: trashed, original value saved on stack (PT_AREG0) + * a1: a1 + * a2: new stack pointer, original in DEPC + * a3: dispatch table + * depc: a2, original value saved on stack (PT_DEPC) + * excsave_1: a3 + * + * PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC + * < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception + */ + + +ENTRY(fast_unaligned) + + /* Note: We don't expect the address to be aligned on a word + * boundary. After all, the processor generated that exception + * and it would be a hardware fault. + */ + + /* Save some working register */ + + s32i a4, a2, PT_AREG4 + s32i a5, a2, PT_AREG5 + s32i a6, a2, PT_AREG6 + s32i a7, a2, PT_AREG7 + s32i a8, a2, PT_AREG8 + + rsr a0, DEPC + xsr a3, EXCSAVE_1 + s32i a0, a2, PT_AREG2 + s32i a3, a2, PT_AREG3 + + /* Keep value of SAR in a0 */ + + rsr a0, SAR + rsr a8, EXCVADDR # load unaligned memory address + + /* Now, identify one of the following load/store instructions. + * + * The only possible danger of a double exception on the + * following l32i instructions is kernel code in vmalloc + * memory. The processor was just executing at the EPC_1 + * address, and indeed, already fetched the instruction. That + * guarantees a TLB mapping, which hasn't been replaced by + * this unaligned exception handler that uses only static TLB + * mappings. However, high-level interrupt handlers might + * modify TLB entries, so for the generic case, we register a + * TABLE_FIXUP handler here, too. + */ + + /* a3...a6 saved on stack, a2 = SP */ + + /* Extract the instruction that caused the unaligned access. */ + + rsr a7, EPC_1 # load exception address + movi a3, ~3 + and a3, a3, a7 # mask lower bits + + l32i a4, a3, 0 # load 2 words + l32i a5, a3, 4 + + __ssa8 a7 + __src_b a4, a4, a5 # a4 has the instruction + + /* Analyze the instruction (load or store?). */ + + extui a5, a4, INSN_OP0, 4 # get insn.op0 nibble + +#if XCHAL_HAVE_NARROW + _beqi a5, OP0_L32I_N, .Lload # L32I.N, jump + addi a6, a5, -OP0_S32I_N + _beqz a6, .Lstore # S32I.N, do a store +#endif + /* 'store indicator bit' not set, jump */ + _bbci.l a4, OP1_SI_BIT + INSN_OP1, .Lload + + /* Store: Jump to table entry to get the value in the source register.*/ + +.Lstore:movi a5, .Lstore_table # table + extui a6, a4, INSN_T, 4 # get source register + addx8 a5, a6, a5 + jx a5 # jump into table + + /* Invalid instruction, CRITICAL! */ +.Linvalid_instruction_load: + j .Linvalid_instruction + + /* Load: Load memory address. */ + +.Lload: movi a3, ~3 + and a3, a3, a8 # align memory address + + __ssa8 a8 +#ifdef UNALIGNED_USER_EXCEPTION + addi a3, a3, 8 + l32e a5, a3, -8 + l32e a6, a3, -4 +#else + l32i a5, a3, 0 + l32i a6, a3, 4 +#endif + __src_b a3, a5, a6 # a3 has the data word + +#if XCHAL_HAVE_NARROW + addi a7, a7, 2 # increment PC (assume 16-bit insn) + + extui a5, a4, INSN_OP0, 4 + _beqi a5, OP0_L32I_N, 1f # l32i.n: jump + + addi a7, a7, 1 +#else + addi a7, a7, 3 +#endif + + extui a5, a4, INSN_OP1, 4 + _beqi a5, OP1_L32I, 1f # l32i: jump + + extui a3, a3, 0, 16 # extract lower 16 bits + _beqi a5, OP1_L16UI, 1f + addi a5, a5, -OP1_L16SI + _bnez a5, .Linvalid_instruction_load + + /* sign extend value */ + + slli a3, a3, 16 + srai a3, a3, 16 + + /* Set target register. */ + +1: + +#if XCHAL_HAVE_LOOP + rsr a3, LEND # check if we reached LEND + bne a7, a3, 1f + rsr a3, LCOUNT # and LCOUNT != 0 + beqz a3, 1f + addi a3, a3, -1 # decrement LCOUNT and set + rsr a7, LBEG # set PC to LBEGIN + wsr a3, LCOUNT +#endif + +1: wsr a7, EPC_1 # skip load instruction + extui a4, a4, INSN_T, 4 # extract target register + movi a5, .Lload_table + addx8 a4, a4, a5 + jx a4 # jump to entry for target register + + .align 8 +.Lload_table: + s32i a3, a2, PT_AREG0; _j .Lexit; .align 8 + mov a1, a3; _j .Lexit; .align 8 # fishy?? + s32i a3, a2, PT_AREG2; _j .Lexit; .align 8 + s32i a3, a2, PT_AREG3; _j .Lexit; .align 8 + s32i a3, a2, PT_AREG4; _j .Lexit; .align 8 + s32i a3, a2, PT_AREG5; _j .Lexit; .align 8 + s32i a3, a2, PT_AREG6; _j .Lexit; .align 8 + s32i a3, a2, PT_AREG7; _j .Lexit; .align 8 + s32i a3, a2, PT_AREG8; _j .Lexit; .align 8 + mov a9, a3 ; _j .Lexit; .align 8 + mov a10, a3 ; _j .Lexit; .align 8 + mov a11, a3 ; _j .Lexit; .align 8 + mov a12, a3 ; _j .Lexit; .align 8 + mov a13, a3 ; _j .Lexit; .align 8 + mov a14, a3 ; _j .Lexit; .align 8 + mov a15, a3 ; _j .Lexit; .align 8 + +.Lstore_table: + l32i a3, a2, PT_AREG0; _j 1f; .align 8 + mov a3, a1; _j 1f; .align 8 # fishy?? + l32i a3, a2, PT_AREG2; _j 1f; .align 8 + l32i a3, a2, PT_AREG3; _j 1f; .align 8 + l32i a3, a2, PT_AREG4; _j 1f; .align 8 + l32i a3, a2, PT_AREG5; _j 1f; .align 8 + l32i a3, a2, PT_AREG6; _j 1f; .align 8 + l32i a3, a2, PT_AREG7; _j 1f; .align 8 + l32i a3, a2, PT_AREG8; _j 1f; .align 8 + mov a3, a9 ; _j 1f; .align 8 + mov a3, a10 ; _j 1f; .align 8 + mov a3, a11 ; _j 1f; .align 8 + mov a3, a12 ; _j 1f; .align 8 + mov a3, a13 ; _j 1f; .align 8 + mov a3, a14 ; _j 1f; .align 8 + mov a3, a15 ; _j 1f; .align 8 + +1: # a7: instruction pointer, a4: instruction, a3: value + + movi a6, 0 # mask: ffffffff:00000000 + +#if XCHAL_HAVE_NARROW + addi a7, a7, 2 # incr. PC,assume 16-bit instruction + + extui a5, a4, INSN_OP0, 4 # extract OP0 + addi a5, a5, -OP0_S32I_N + _beqz a5, 1f # s32i.n: jump + + addi a7, a7, 1 # increment PC, 32-bit instruction +#else + addi a7, a7, 3 # increment PC, 32-bit instruction +#endif + + extui a5, a4, INSN_OP1, 4 # extract OP1 + _beqi a5, OP1_S32I, 1f # jump if 32 bit store + _bnei a5, OP1_S16I, .Linvalid_instruction_store + + movi a5, -1 + __extl a3, a3 # get 16-bit value + __exth a6, a5 # get 16-bit mask ffffffff:ffff0000 + + /* Get memory address */ + +1: +#if XCHAL_HAVE_LOOP + rsr a3, LEND # check if we reached LEND + bne a7, a3, 1f + rsr a3, LCOUNT # and LCOUNT != 0 + beqz a3, 1f + addi a3, a3, -1 # decrement LCOUNT and set + rsr a7, LBEG # set PC to LBEGIN + wsr a3, LCOUNT +#endif + +1: wsr a7, EPC_1 # skip store instruction + movi a4, ~3 + and a4, a4, a8 # align memory address + + /* Insert value into memory */ + + movi a5, -1 # mask: ffffffff:XXXX0000 +#ifdef UNALIGNED_USER_EXCEPTION + addi a4, a4, 8 +#endif + + __ssa8r a8 + __src_b a7, a5, a6 # lo-mask F..F0..0 (BE) 0..0F..F (LE) + __src_b a6, a6, a5 # hi-mask 0..0F..F (BE) F..F0..0 (LE) +#ifdef UNALIGNED_USER_EXCEPTION + l32e a5, a4, -8 +#else + l32i a5, a4, 0 # load lower address word +#endif + and a5, a5, a7 # mask + __sh a7, a3 # shift value + or a5, a5, a7 # or with original value +#ifdef UNALIGNED_USER_EXCEPTION + s32e a5, a4, -8 + l32e a7, a4, -4 +#else + s32i a5, a4, 0 # store + l32i a7, a4, 4 # same for upper address word +#endif + __sl a5, a3 + and a6, a7, a6 + or a6, a6, a5 +#ifdef UNALIGNED_USER_EXCEPTION + s32e a6, a4, -4 +#else + s32i a6, a4, 4 +#endif + + /* Done. restore stack and return */ + +.Lexit: + movi a4, 0 + rsr a3, EXCSAVE_1 + s32i a4, a3, EXC_TABLE_FIXUP + + /* Restore working register */ + + l32i a7, a2, PT_AREG7 + l32i a6, a2, PT_AREG6 + l32i a5, a2, PT_AREG5 + l32i a4, a2, PT_AREG4 + l32i a3, a2, PT_AREG3 + + /* restore SAR and return */ + + wsr a0, SAR + l32i a0, a2, PT_AREG0 + l32i a2, a2, PT_AREG2 + rfe + + /* We cannot handle this exception. */ + + .extern _kernel_exception +.Linvalid_instruction_store: +.Linvalid_instruction: + + /* Restore a4...a8 and SAR, set SP, and jump to default exception. */ + + l32i a8, a2, PT_AREG8 + l32i a7, a2, PT_AREG7 + l32i a6, a2, PT_AREG6 + l32i a5, a2, PT_AREG5 + l32i a4, a2, PT_AREG4 + wsr a0, SAR + mov a1, a2 + + rsr a0, PS + bbsi.l a2, PS_UM_SHIFT, 1f # jump if user mode + + movi a0, _kernel_exception + jx a0 + +1: movi a0, _user_exception + jx a0 + + +#endif /* XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION */ + |