mips/lib/memcpy.S

21  * Prefetching may be fatal on some systems if we're prefetching beyond the
22  * end of memory on some systems.  It's also a seriously bad idea on non
23  * dma-coherent systems.
37 #include <asm/asm-offsets.h>
49  *   - src and dst don't overlap
50  *   - src is readable
51  *   - dst is writable
59  *     - src is readable  (no exceptions when reading src)
61  *     - dst is writable  (no exceptions when writing dst)
62  * __copy_user uses a non-standard calling convention; see
63  * include/asm-mips/uaccess.h
76  *  1- AT contain the address of the byte just past the end of the source
78  *  2- src_entry <= src < AT, and
79  *  3- (dst - src) == (dst_entry - src_entry),
140  * Only on the 64-bit kernel we can made use of 64-bit registers.
156 #define SUB    dsubu  macro
193 #define SUB    subu  macro
250 #define REST(unit)  (FIRST(unit)+NBYTES-1)
253 #define ADDRMASK (NBYTES-1)
313 	 * use delay slot for fall-through
319 	 and	rem, len, (8*NBYTES-1)	 # rem = len % (8*NBYTES)
329 	SUB	len, len, 8*NBYTES
338 	STORE(t2, UNIT(-6)(dst), .Ls_exc_p6u\@)
339 	STORE(t3, UNIT(-5)(dst), .Ls_exc_p5u\@)
340 	STORE(t4, UNIT(-4)(dst), .Ls_exc_p4u\@)
341 	STORE(t7, UNIT(-3)(dst), .Ls_exc_p3u\@)
342 	STORE(t0, UNIT(-2)(dst), .Ls_exc_p2u\@)
343 	STORE(t1, UNIT(-1)(dst), .Ls_exc_p1u\@)
356 	 and	rem, len, (NBYTES-1)	# rem = len % NBYTES
364 	SUB	len, len, 4*NBYTES
385 	SUB	len, len, NBYTES
397 	 * because can't assume read-access to dst.  Instead, use
401 	 * wide-issue mips processors because the code has fewer branches and
402 	 * more instruction-level parallelism.
410 	SUB	bits, bits, rem # bits = number of bits to discard
412 	STREST(t0, -1(t1), .Ls_exc\@)
429 	SUB	t2, t2, t1	# t2 = number of bytes copied
434 	 SUB	len, len, t2
443 	 and	rem, len, (4*NBYTES-1)	 # rem = len % 4*NBYTES
455 	SUB	len, len, 4*NBYTES
479 	 and	rem, len, NBYTES-1  # rem = len % NBYTES
487 	SUB	len, len, NBYTES
503 	SUB	len, len, 1;		\
515 	LOADB(t0, NBYTES-2(src), .Ll_exc\@)
516 	SUB	len, len, 1
518 	STOREB(t0, NBYTES-2(dst), .Ls_exc_p1\@)
561 	sb	t1, 0(dst)	# can't fault -- we're copy_from_user
571 	SUB	len, AT, t0		# len number of uncopied bytes
607 	sltu	t0, a1, t0			# dst + len <= src -> memcpy
608 	sltu	t1, a0, t1			# dst >= src + len -> memcpy
625 	lb	t0, -1(a1)
626 	SUB	a2, a2, 0x1
627 	sb	t0, -1(a0)
628 	SUB	a1, a1, 0x1
630 	SUB	a0, a0, 0x1
641 	SUB	a2, a2, 0x1
670 	/* Legacy Mode, user <-> user */
680  * virtual <-> physical translation when a virtual address is actually in user