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Diffstat (limited to 'arch/tile/lib/memcpy_user_64.c')
-rw-r--r--arch/tile/lib/memcpy_user_64.c94
1 files changed, 94 insertions, 0 deletions
diff --git a/arch/tile/lib/memcpy_user_64.c b/arch/tile/lib/memcpy_user_64.c
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+++ b/arch/tile/lib/memcpy_user_64.c
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+/*
+ * Copyright 2011 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * 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, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ *
+ * Do memcpy(), but trap and return "n" when a load or store faults.
+ *
+ * Note: this idiom only works when memcpy() compiles to a leaf function.
+ * Here leaf function not only means it does not have calls, but also
+ * requires no stack operations (sp, stack frame pointer) and no
+ * use of callee-saved registers, else "jrp lr" will be incorrect since
+ * unwinding stack frame is bypassed. Since memcpy() is not complex so
+ * these conditions are satisfied here, but we need to be careful when
+ * modifying this file. This is not a clean solution but is the best
+ * one so far.
+ *
+ * Also note that we are capturing "n" from the containing scope here.
+ */
+
+#define _ST(p, inst, v) \
+ ({ \
+ asm("1: " #inst " %0, %1;" \
+ ".pushsection .coldtext.memcpy,\"ax\";" \
+ "2: { move r0, %2; jrp lr };" \
+ ".section __ex_table,\"a\";" \
+ ".align 8;" \
+ ".quad 1b, 2b;" \
+ ".popsection" \
+ : "=m" (*(p)) : "r" (v), "r" (n)); \
+ })
+
+#define _LD(p, inst) \
+ ({ \
+ unsigned long __v; \
+ asm("1: " #inst " %0, %1;" \
+ ".pushsection .coldtext.memcpy,\"ax\";" \
+ "2: { move r0, %2; jrp lr };" \
+ ".section __ex_table,\"a\";" \
+ ".align 8;" \
+ ".quad 1b, 2b;" \
+ ".popsection" \
+ : "=r" (__v) : "m" (*(p)), "r" (n)); \
+ __v; \
+ })
+
+#define USERCOPY_FUNC __copy_to_user_inatomic
+#define ST1(p, v) _ST((p), st1, (v))
+#define ST2(p, v) _ST((p), st2, (v))
+#define ST4(p, v) _ST((p), st4, (v))
+#define ST8(p, v) _ST((p), st, (v))
+#define LD1 LD
+#define LD2 LD
+#define LD4 LD
+#define LD8 LD
+#include "memcpy_64.c"
+
+#define USERCOPY_FUNC __copy_from_user_inatomic
+#define ST1 ST
+#define ST2 ST
+#define ST4 ST
+#define ST8 ST
+#define LD1(p) _LD((p), ld1u)
+#define LD2(p) _LD((p), ld2u)
+#define LD4(p) _LD((p), ld4u)
+#define LD8(p) _LD((p), ld)
+#include "memcpy_64.c"
+
+#define USERCOPY_FUNC __copy_in_user_inatomic
+#define ST1(p, v) _ST((p), st1, (v))
+#define ST2(p, v) _ST((p), st2, (v))
+#define ST4(p, v) _ST((p), st4, (v))
+#define ST8(p, v) _ST((p), st, (v))
+#define LD1(p) _LD((p), ld1u)
+#define LD2(p) _LD((p), ld2u)
+#define LD4(p) _LD((p), ld4u)
+#define LD8(p) _LD((p), ld)
+#include "memcpy_64.c"
+
+unsigned long __copy_from_user_zeroing(void *to, const void __user *from,
+ unsigned long n)
+{
+ unsigned long rc = __copy_from_user_inatomic(to, from, n);
+ if (unlikely(rc))
+ memset(to + n - rc, 0, rc);
+ return rc;
+}