Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / arm64 / lib / copy_from_user.S

diff --git a/kernel/arch/arm64/lib/copy_from_user.S b/kernel/arch/arm64/lib/copy_from_user.S
new file mode 100644 (file)
index 0000000..5e27add
--- /dev/null
+++ b/kernel/arch/arm64/lib/copy_from_user.S
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+/*
+ * Copy from user space to a kernel buffer (alignment handled by the hardware)
+ *
+ * Parameters:
+ *     x0 - to
+ *     x1 - from
+ *     x2 - n
+ * Returns:
+ *     x0 - bytes not copied
+ */
+ENTRY(__copy_from_user)
+       add     x4, x1, x2                      // upper user buffer boundary
+       subs    x2, x2, #8
+       b.mi    2f
+1:
+USER(9f, ldr   x3, [x1], #8    )
+       subs    x2, x2, #8
+       str     x3, [x0], #8
+       b.pl    1b
+2:     adds    x2, x2, #4
+       b.mi    3f
+USER(9f, ldr   w3, [x1], #4    )
+       sub     x2, x2, #4
+       str     w3, [x0], #4
+3:     adds    x2, x2, #2
+       b.mi    4f
+USER(9f, ldrh  w3, [x1], #2    )
+       sub     x2, x2, #2
+       strh    w3, [x0], #2
+4:     adds    x2, x2, #1
+       b.mi    5f
+USER(9f, ldrb  w3, [x1]        )
+       strb    w3, [x0]
+5:     mov     x0, #0
+       ret
+ENDPROC(__copy_from_user)
+
+       .section .fixup,"ax"
+       .align  2
+9:     sub     x2, x4, x1
+       mov     x3, x2
+10:    strb    wzr, [x0], #1                   // zero remaining buffer space
+       subs    x3, x3, #1
+       b.ne    10b
+       mov     x0, x2                          // bytes not copied
+       ret
+       .previous