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| /* SPDX-License-Identifier: GPL-2.0 */
| /*
| * arch/alpha/lib/clear_user.S
| * Contributed by Richard Henderson <rth@tamu.edu>
| *
| * Zero user space, handling exceptions as we go.
| *
| * We have to make sure that $0 is always up-to-date and contains the
| * right "bytes left to zero" value (and that it is updated only _after_
| * a successful copy). There is also some rather minor exception setup
| * stuff.
| */
| #include <asm/export.h>
|
| /* Allow an exception for an insn; exit if we get one. */
| #define EX(x,y...) \
| 99: x,##y; \
| .section __ex_table,"a"; \
| .long 99b - .; \
| lda $31, $exception-99b($31); \
| .previous
|
| .set noat
| .set noreorder
| .align 4
|
| .globl __clear_user
| .ent __clear_user
| .frame $30, 0, $26
| .prologue 0
|
| $loop:
| and $1, 3, $4 # e0 :
| beq $4, 1f # .. e1 :
|
| 0: EX( stq_u $31, 0($16) ) # e0 : zero one word
| subq $0, 8, $0 # .. e1 :
| subq $4, 1, $4 # e0 :
| addq $16, 8, $16 # .. e1 :
| bne $4, 0b # e1 :
| unop # :
|
| 1: bic $1, 3, $1 # e0 :
| beq $1, $tail # .. e1 :
|
| 2: EX( stq_u $31, 0($16) ) # e0 : zero four words
| subq $0, 8, $0 # .. e1 :
| EX( stq_u $31, 8($16) ) # e0 :
| subq $0, 8, $0 # .. e1 :
| EX( stq_u $31, 16($16) ) # e0 :
| subq $0, 8, $0 # .. e1 :
| EX( stq_u $31, 24($16) ) # e0 :
| subq $0, 8, $0 # .. e1 :
| subq $1, 4, $1 # e0 :
| addq $16, 32, $16 # .. e1 :
| bne $1, 2b # e1 :
|
| $tail:
| bne $2, 1f # e1 : is there a tail to do?
| ret $31, ($26), 1 # .. e1 :
|
| 1: EX( ldq_u $5, 0($16) ) # e0 :
| clr $0 # .. e1 :
| nop # e1 :
| mskqh $5, $0, $5 # e0 :
| EX( stq_u $5, 0($16) ) # e0 :
| ret $31, ($26), 1 # .. e1 :
|
| __clear_user:
| and $17, $17, $0
| and $16, 7, $4 # e0 : find dest misalignment
| beq $0, $zerolength # .. e1 :
| addq $0, $4, $1 # e0 : bias counter
| and $1, 7, $2 # e1 : number of bytes in tail
| srl $1, 3, $1 # e0 :
| beq $4, $loop # .. e1 :
|
| EX( ldq_u $5, 0($16) ) # e0 : load dst word to mask back in
| beq $1, $oneword # .. e1 : sub-word store?
|
| mskql $5, $16, $5 # e0 : take care of misaligned head
| addq $16, 8, $16 # .. e1 :
| EX( stq_u $5, -8($16) ) # e0 :
| addq $0, $4, $0 # .. e1 : bytes left -= 8 - misalignment
| subq $1, 1, $1 # e0 :
| subq $0, 8, $0 # .. e1 :
| br $loop # e1 :
| unop # :
|
| $oneword:
| mskql $5, $16, $4 # e0 :
| mskqh $5, $2, $5 # e0 :
| or $5, $4, $5 # e1 :
| EX( stq_u $5, 0($16) ) # e0 :
| clr $0 # .. e1 :
|
| $zerolength:
| $exception:
| ret $31, ($26), 1 # .. e1 :
|
| .end __clear_user
| EXPORT_SYMBOL(__clear_user)
|
|
