patch-2.3.43 linux/arch/ia64/lib/copy_user.S

• Lines: 72
• Date: Sun Feb 6 18:42:40 2000
• Orig file: v2.3.42/linux/arch/ia64/lib/copy_user.S
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.42/linux/arch/ia64/lib/copy_user.S linux/arch/ia64/lib/copy_user.S
@@ -0,0 +1,71 @@
+/*
+ * This routine copies a linear memory buffer across the user/kernel boundary.  When
+ * reading a byte from the source causes a fault, the remainder of the destination
+ * buffer is zeroed out.  Note that this can happen only when copying from user
+ * to kernel memory and we do this to absolutely guarantee that the
+ * kernel doesn't operate on random data.
+ *
+ * This file is derived from arch/alpha/lib/copy_user.S.
+ *
+ * Inputs:
+ *	in0:	address of destination buffer
+ *	in1:	address of source buffer
+ *	in2:	length of buffer in bytes
+ * Outputs:
+ *	r8:	number of bytes that didn't get copied due to a fault
+ * 
+ * Copyright (C) 1999 Hewlett-Packard Co
+ * Copyright (C) 1998, 1999 David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+
+#define EXI(x...)				\
+99:	x;					\
+	.section __ex_table,"a";		\
+	data4 @gprel(99b);			\
+	data4 .Lexit_in-99b;			\
+	.previous
+
+#define EXO(x...)				\
+99:	x;					\
+	.section __ex_table,"a";		\
+	data4 @gprel(99b);			\
+	data4 .Lexit_out-99b;			\
+	.previous
+
+	.text
+	.psr abi64
+	.psr lsb
+	.lsb
+
+	.align 32
+	.global __copy_user
+	.proc __copy_user
+__copy_user:
+	alloc r10=ar.pfs,3,0,0,0
+	mov r9=ar.lc		// save ar.lc
+	mov ar.lc=in2		// set ar.lc to length of buffer
+	br.sptk.few .Lentr
+
+	// XXX braindead copy loop---this needs to be optimized
+.Loop1:
+	EXI(ld1 r8=[in1],1)
+	;;
+	EXO(st1 [in0]=r8,1)
+.Lentr:	br.cloop.dptk.few .Loop1	// repeat unless ar.lc--==0
+	;;			// avoid RAW on ar.lc
+.Lexit_out:
+	mov r8=ar.lc		// return how many bytes we _didn't_ copy
+	mov ar.lc=r9
+	br.ret.sptk.few rp
+
+.Lexit_in:
+	// clear the remainder of the buffer:
+	mov r8=ar.lc	// return how many bytes we _didn't_ copy
+.Loop2:
+	st1 [in0]=r0,1	// this cannot fault because we get here only on user->kernel copies
+	br.cloop.dptk.few .Loop2
+	;;				// avoid RAW on ar.lc
+	mov ar.lc=r9
+	br.ret.sptk.few rp
+
+	.endp __copy_user