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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/alpha/lib/copy_user.S
downloadlinux-sh-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/alpha/lib/copy_user.S')
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diff --git a/arch/alpha/lib/copy_user.S b/arch/alpha/lib/copy_user.S
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+/*
+ * arch/alpha/lib/copy_user.S
+ *
+ * Copy to/from user space, handling exceptions as we go.. This
+ * isn't exactly pretty.
+ *
+ * This is essentially the same as "memcpy()", but with a few twists.
+ * Notably, we have to make sure that $0 is always up-to-date and
+ * contains the right "bytes left to copy" value (and that it is updated
+ * only _after_ a successful copy). There is also some rather minor
+ * exception setup stuff..
+ *
+ * NOTE! This is not directly C-callable, because the calling semantics are
+ * different:
+ *
+ * Inputs:
+ * length in $0
+ * destination address in $6
+ * source address in $7
+ * return address in $28
+ *
+ * Outputs:
+ * bytes left to copy in $0
+ *
+ * Clobbers:
+ * $1,$2,$3,$4,$5,$6,$7
+ */
+
+/* Allow an exception for an insn; exit if we get one. */
+#define EXI(x,y...) \
+ 99: x,##y; \
+ .section __ex_table,"a"; \
+ .long 99b - .; \
+ lda $31, $exitin-99b($31); \
+ .previous
+
+#define EXO(x,y...) \
+ 99: x,##y; \
+ .section __ex_table,"a"; \
+ .long 99b - .; \
+ lda $31, $exitout-99b($31); \
+ .previous
+
+ .set noat
+ .align 4
+ .globl __copy_user
+ .ent __copy_user
+__copy_user:
+ .prologue 0
+ and $6,7,$3
+ beq $0,$35
+ beq $3,$36
+ subq $3,8,$3
+ .align 4
+$37:
+ EXI( ldq_u $1,0($7) )
+ EXO( ldq_u $2,0($6) )
+ extbl $1,$7,$1
+ mskbl $2,$6,$2
+ insbl $1,$6,$1
+ addq $3,1,$3
+ bis $1,$2,$1
+ EXO( stq_u $1,0($6) )
+ subq $0,1,$0
+ addq $6,1,$6
+ addq $7,1,$7
+ beq $0,$41
+ bne $3,$37
+$36:
+ and $7,7,$1
+ bic $0,7,$4
+ beq $1,$43
+ beq $4,$48
+ EXI( ldq_u $3,0($7) )
+ .align 4
+$50:
+ EXI( ldq_u $2,8($7) )
+ subq $4,8,$4
+ extql $3,$7,$3
+ extqh $2,$7,$1
+ bis $3,$1,$1
+ EXO( stq $1,0($6) )
+ addq $7,8,$7
+ subq $0,8,$0
+ addq $6,8,$6
+ bis $2,$2,$3
+ bne $4,$50
+$48:
+ beq $0,$41
+ .align 4
+$57:
+ EXI( ldq_u $1,0($7) )
+ EXO( ldq_u $2,0($6) )
+ extbl $1,$7,$1
+ mskbl $2,$6,$2
+ insbl $1,$6,$1
+ bis $1,$2,$1
+ EXO( stq_u $1,0($6) )
+ subq $0,1,$0
+ addq $6,1,$6
+ addq $7,1,$7
+ bne $0,$57
+ br $31,$41
+ .align 4
+$43:
+ beq $4,$65
+ .align 4
+$66:
+ EXI( ldq $1,0($7) )
+ subq $4,8,$4
+ EXO( stq $1,0($6) )
+ addq $7,8,$7
+ subq $0,8,$0
+ addq $6,8,$6
+ bne $4,$66
+$65:
+ beq $0,$41
+ EXI( ldq $2,0($7) )
+ EXO( ldq $1,0($6) )
+ mskql $2,$0,$2
+ mskqh $1,$0,$1
+ bis $2,$1,$2
+ EXO( stq $2,0($6) )
+ bis $31,$31,$0
+$41:
+$35:
+$exitout:
+ ret $31,($28),1
+
+$exitin:
+ /* A stupid byte-by-byte zeroing of the rest of the output
+ buffer. This cures security holes by never leaving
+ random kernel data around to be copied elsewhere. */
+
+ mov $0,$1
+$101:
+ EXO ( ldq_u $2,0($6) )
+ subq $1,1,$1
+ mskbl $2,$6,$2
+ EXO ( stq_u $2,0($6) )
+ addq $6,1,$6
+ bgt $1,$101
+ ret $31,($28),1
+
+ .end __copy_user