diff options
Diffstat (limited to 'arch/alpha/lib/clear_user.S')
-rw-r--r-- | arch/alpha/lib/clear_user.S | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/arch/alpha/lib/clear_user.S b/arch/alpha/lib/clear_user.S new file mode 100644 index 0000000000..848eb60a00 --- /dev/null +++ b/arch/alpha/lib/clear_user.S @@ -0,0 +1,102 @@ +/* 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 <linux/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) |