riscv/lib/uaccess.S

2 #include <asm-generic/export.h>
4 #include <asm/asm-extable.h>
21 	 * Save the terminal address which will be used to compute the number
28 	 * a0 - start of uncopied dst
29 	 * a1 - start of uncopied src
30 	 * a2 - size
31 	 * t0 - end of uncopied dst
43 	 * Copy first bytes until dst is aligned to word boundary.
44 	 * a0 - start of dst
45 	 * t1 - start of aligned dst
47 	addi	t1, a0, SZREG-1
48 	andi	t1, t1, ~(SZREG-1)
49 	/* dst is already aligned, skip */
52 	/* a5 - one byte for copying data */
57 	bltu	a0, t1, 1b	/* t1 - start of aligned dst */
61 	 * Now dst is aligned.
62 	 * Use shift-copy if src is misaligned.
63 	 * Use word-copy if both src and dst are aligned because
64 	 * can not use shift-copy which do not require shifting
66 	/* a1 - start of src */
67 	andi	a3, a1, SZREG-1
72 	 * Both src and dst are aligned, unrolled word copy
74 	 * a0 - start of aligned dst
75 	 * a1 - start of aligned src
76 	 * t0 - end of aligned dst
78 	addi	t0, t0, -(8*SZREG) /* not to over run */
107 	 * For misaligned copy we still perform aligned word copy, but
112 	 * a0 - start of aligned dst
113 	 * a1 - start of src
114 	 * a3 - a1 & mask:(SZREG-1)
115 	 * t0 - end of uncopied dst
116 	 * t1 - end of aligned dst
118 	/* calculating aligned word boundary for dst */
119 	andi	t1, t0, ~(SZREG-1)
120 	/* Converting unaligned src to aligned src */
121 	andi	a1, a1, ~(SZREG-1)
125 	 * t3 - prev shift
126 	 * t4 - current shift
138 	 * a0 - start of aligned dst
139 	 * a1 - start of aligned src
140 	 * t1 - end of aligned dst
160 	 * a0 - start of remaining dst
161 	 * a1 - start of remaining src
162 	 * t0 - end of remaining dst
170 	bltu	a0, t0, 4b	/* t0 - end of dst */
197 	addi t0, a0, SZREG-1
198 	andi t1, a3, ~(SZREG-1)
199 	andi t0, t0, ~(SZREG-1)
201 	 * a3: terminal address of target region
202 	 * t0: lowest doubleword-aligned address in target region
203 	 * t1: highest doubleword-aligned address in target region