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146 lines
2.5 KiB
146 lines
2.5 KiB
20 years ago
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/*
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* arch/alpha/lib/copy_user.S
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*
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* Copy to/from user space, handling exceptions as we go.. This
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* isn't exactly pretty.
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*
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* This is essentially the same as "memcpy()", but with a few twists.
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* Notably, we have to make sure that $0 is always up-to-date and
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* contains the right "bytes left to copy" value (and that it is updated
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* only _after_ a successful copy). There is also some rather minor
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* exception setup stuff..
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*
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* NOTE! This is not directly C-callable, because the calling semantics are
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* different:
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*
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* Inputs:
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* length in $0
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* destination address in $6
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* source address in $7
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* return address in $28
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*
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* Outputs:
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* bytes left to copy in $0
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*
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* Clobbers:
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* $1,$2,$3,$4,$5,$6,$7
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*/
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/* Allow an exception for an insn; exit if we get one. */
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#define EXI(x,y...) \
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99: x,##y; \
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.section __ex_table,"a"; \
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.long 99b - .; \
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lda $31, $exitin-99b($31); \
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.previous
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#define EXO(x,y...) \
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99: x,##y; \
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.section __ex_table,"a"; \
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.long 99b - .; \
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lda $31, $exitout-99b($31); \
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.previous
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.set noat
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.align 4
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.globl __copy_user
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.ent __copy_user
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__copy_user:
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.prologue 0
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and $6,7,$3
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beq $0,$35
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beq $3,$36
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subq $3,8,$3
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.align 4
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$37:
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EXI( ldq_u $1,0($7) )
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EXO( ldq_u $2,0($6) )
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extbl $1,$7,$1
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mskbl $2,$6,$2
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insbl $1,$6,$1
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addq $3,1,$3
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bis $1,$2,$1
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EXO( stq_u $1,0($6) )
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subq $0,1,$0
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addq $6,1,$6
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addq $7,1,$7
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beq $0,$41
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bne $3,$37
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$36:
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and $7,7,$1
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bic $0,7,$4
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beq $1,$43
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beq $4,$48
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EXI( ldq_u $3,0($7) )
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.align 4
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$50:
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EXI( ldq_u $2,8($7) )
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subq $4,8,$4
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extql $3,$7,$3
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extqh $2,$7,$1
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bis $3,$1,$1
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EXO( stq $1,0($6) )
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addq $7,8,$7
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subq $0,8,$0
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addq $6,8,$6
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bis $2,$2,$3
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bne $4,$50
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$48:
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beq $0,$41
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.align 4
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$57:
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EXI( ldq_u $1,0($7) )
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EXO( ldq_u $2,0($6) )
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extbl $1,$7,$1
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mskbl $2,$6,$2
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insbl $1,$6,$1
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bis $1,$2,$1
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EXO( stq_u $1,0($6) )
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subq $0,1,$0
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addq $6,1,$6
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addq $7,1,$7
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bne $0,$57
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br $31,$41
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.align 4
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$43:
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beq $4,$65
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.align 4
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$66:
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EXI( ldq $1,0($7) )
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subq $4,8,$4
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EXO( stq $1,0($6) )
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addq $7,8,$7
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subq $0,8,$0
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addq $6,8,$6
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bne $4,$66
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$65:
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beq $0,$41
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EXI( ldq $2,0($7) )
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EXO( ldq $1,0($6) )
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mskql $2,$0,$2
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mskqh $1,$0,$1
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bis $2,$1,$2
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EXO( stq $2,0($6) )
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bis $31,$31,$0
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$41:
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$35:
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$exitout:
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ret $31,($28),1
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$exitin:
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/* A stupid byte-by-byte zeroing of the rest of the output
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buffer. This cures security holes by never leaving
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random kernel data around to be copied elsewhere. */
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mov $0,$1
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$101:
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EXO ( ldq_u $2,0($6) )
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subq $1,1,$1
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mskbl $2,$6,$2
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EXO ( stq_u $2,0($6) )
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addq $6,1,$6
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bgt $1,$101
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ret $31,($28),1
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.end __copy_user
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