489 lines
12 KiB
ArmAsm
Executable File
489 lines
12 KiB
ArmAsm
Executable File
/*
|
|
* 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.
|
|
* Copyright (C) 2014 Cadence Design Systems 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/current.h>
|
|
#include <asm/asm-offsets.h>
|
|
#include <asm/processor.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: a3
|
|
* depc: a2, original value saved on stack (PT_DEPC)
|
|
* excsave_1: dispatch table
|
|
*
|
|
* 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
|
|
s32i a0, a2, PT_AREG2
|
|
s32i a3, a2, PT_AREG3
|
|
|
|
rsr a3, excsave1
|
|
movi a4, fast_unaligned_fixup
|
|
s32i a4, a3, EXC_TABLE_FIXUP
|
|
|
|
/* 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, epc1 # 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_DENSITY
|
|
_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
|
|
|
|
/* 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_DENSITY
|
|
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:
|
|
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
|
|
|
|
/* We cannot handle this exception. */
|
|
|
|
.extern _kernel_exception
|
|
.Linvalid_instruction_load:
|
|
.Linvalid_instruction_store:
|
|
|
|
movi a4, 0
|
|
rsr a3, excsave1
|
|
s32i a4, a3, EXC_TABLE_FIXUP
|
|
|
|
/* 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 a0, PS_UM_BIT, 2f # jump if user mode
|
|
|
|
movi a0, _kernel_exception
|
|
jx a0
|
|
|
|
2: movi a0, _user_exception
|
|
jx a0
|
|
|
|
1: # a7: instruction pointer, a4: instruction, a3: value
|
|
|
|
movi a6, 0 # mask: ffffffff:00000000
|
|
|
|
#if XCHAL_HAVE_DENSITY
|
|
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:
|
|
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 a8, 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, a8 # mask
|
|
__sh a8, a3 # shift value
|
|
or a5, a5, a8 # or with original value
|
|
#ifdef UNALIGNED_USER_EXCEPTION
|
|
s32e a5, a4, -8
|
|
l32e a8, a4, -4
|
|
#else
|
|
s32i a5, a4, 0 # store
|
|
l32i a8, a4, 4 # same for upper address word
|
|
#endif
|
|
__sl a5, a3
|
|
and a6, a8, a6
|
|
or a6, a6, a5
|
|
#ifdef UNALIGNED_USER_EXCEPTION
|
|
s32e a6, a4, -4
|
|
#else
|
|
s32i a6, a4, 4
|
|
#endif
|
|
|
|
.Lexit:
|
|
#if XCHAL_HAVE_LOOPS
|
|
rsr a4, lend # check if we reached LEND
|
|
bne a7, a4, 1f
|
|
rsr a4, lcount # and LCOUNT != 0
|
|
beqz a4, 1f
|
|
addi a4, a4, -1 # decrement LCOUNT and set
|
|
rsr a7, lbeg # set PC to LBEGIN
|
|
wsr a4, lcount
|
|
#endif
|
|
|
|
1: wsr a7, epc1 # skip emulated instruction
|
|
|
|
/* Update icount if we're single-stepping in userspace. */
|
|
rsr a4, icountlevel
|
|
beqz a4, 1f
|
|
bgeui a4, LOCKLEVEL + 1, 1f
|
|
rsr a4, icount
|
|
addi a4, a4, 1
|
|
wsr a4, icount
|
|
1:
|
|
movi a4, 0
|
|
rsr a3, excsave1
|
|
s32i a4, a3, EXC_TABLE_FIXUP
|
|
|
|
/* Restore working register */
|
|
|
|
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
|
|
l32i a3, a2, PT_AREG3
|
|
|
|
/* restore SAR and return */
|
|
|
|
wsr a0, sar
|
|
l32i a0, a2, PT_AREG0
|
|
l32i a2, a2, PT_AREG2
|
|
rfe
|
|
|
|
ENDPROC(fast_unaligned)
|
|
|
|
ENTRY(fast_unaligned_fixup)
|
|
|
|
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
|
|
wsr a3, excsave1
|
|
|
|
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
|
|
l32i a0, a2, PT_AREG2
|
|
xsr a0, depc # restore depc and a0
|
|
wsr a0, sar
|
|
|
|
rsr a0, exccause
|
|
s32i a0, a2, PT_DEPC # mark as a regular exception
|
|
|
|
rsr a0, ps
|
|
bbsi.l a0, PS_UM_BIT, 1f # jump if user mode
|
|
|
|
rsr a0, exccause
|
|
addx4 a0, a0, a3 # find entry in table
|
|
l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler
|
|
l32i a3, a2, PT_AREG3
|
|
jx a0
|
|
1:
|
|
rsr a0, exccause
|
|
addx4 a0, a0, a3 # find entry in table
|
|
l32i a0, a0, EXC_TABLE_FAST_USER # load handler
|
|
l32i a3, a2, PT_AREG3
|
|
jx a0
|
|
|
|
ENDPROC(fast_unaligned_fixup)
|
|
|
|
#endif /* XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION */
|