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@@ -0,0 +1,436 @@
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+/*
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+ * This file is subject to the terms and conditions of the GNU General Public
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+ * License. See the file "COPYING" in the main directory of this archive
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+ * for more details.
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+ *
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+ * Unified implementation of memcpy, memmove and the __copy_user backend.
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+ *
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+ * Copyright (C) 1998, 99, 2000, 01, 2002 Ralf Baechle (ralf@gnu.org)
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+ * Copyright (C) 1999, 2000, 01, 2002 Silicon Graphics, Inc.
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+ * Copyright (C) 2002 Broadcom, Inc.
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+ * memcpy/copy_user author: Mark Vandevoorde
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+ *
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+ * Mnemonic names for arguments to memcpy/__copy_user
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+ */
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+
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+/*
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+ * Hack to resolve longstanding prefetch issue
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+ *
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+ * Prefetching may be fatal on some systems if we're prefetching beyond the
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+ * end of memory on some systems. It's also a seriously bad idea on non
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+ * dma-coherent systems.
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+ */
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+#if !defined(CONFIG_DMA_COHERENT) || !defined(CONFIG_DMA_IP27)
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+#undef CONFIG_CPU_HAS_PREFETCH
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+#endif
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+#ifdef CONFIG_MIPS_MALTA
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+#undef CONFIG_CPU_HAS_PREFETCH
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+#endif
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+
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+#include <asm/asm.h>
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+#include <asm/asm-offsets.h>
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+#include <asm/regdef.h>
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+
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+#define dst a0
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+#define src a1
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+#define len a2
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+
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+/*
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+ * Spec
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+ *
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+ * memcpy copies len bytes from src to dst and sets v0 to dst.
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+ * It assumes that
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+ * - src and dst don't overlap
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+ * - src is readable
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+ * - dst is writable
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+ * memcpy uses the standard calling convention
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+ *
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+ * __copy_user copies up to len bytes from src to dst and sets a2 (len) to
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+ * the number of uncopied bytes due to an exception caused by a read or write.
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+ * __copy_user assumes that src and dst don't overlap, and that the call is
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+ * implementing one of the following:
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+ * copy_to_user
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+ * - src is readable (no exceptions when reading src)
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+ * copy_from_user
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+ * - dst is writable (no exceptions when writing dst)
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+ * __copy_user uses a non-standard calling convention; see
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+ * include/asm-mips/uaccess.h
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+ *
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+ * When an exception happens on a load, the handler must
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+ # ensure that all of the destination buffer is overwritten to prevent
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+ * leaking information to user mode programs.
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+ */
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+
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+/*
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+ * Implementation
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+ */
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+
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+/*
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+ * The exception handler for loads requires that:
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+ * 1- AT contain the address of the byte just past the end of the source
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+ * of the copy,
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+ * 2- src_entry <= src < AT, and
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+ * 3- (dst - src) == (dst_entry - src_entry),
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+ * The _entry suffix denotes values when __copy_user was called.
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+ *
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+ * (1) is set up up by uaccess.h and maintained by not writing AT in copy_user
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+ * (2) is met by incrementing src by the number of bytes copied
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+ * (3) is met by not doing loads between a pair of increments of dst and src
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+ *
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+ * The exception handlers for stores adjust len (if necessary) and return.
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+ * These handlers do not need to overwrite any data.
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+ *
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+ * For __rmemcpy and memmove an exception is always a kernel bug, therefore
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+ * they're not protected.
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+ */
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+
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+#define EXC(inst_reg,addr,handler) \
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+9: inst_reg, addr; \
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+ .section __ex_table,"a"; \
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+ PTR 9b, handler; \
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+ .previous
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+
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+/*
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+ * Only on the 64-bit kernel we can made use of 64-bit registers.
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+ */
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+#ifdef CONFIG_64BIT
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+#define USE_DOUBLE
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+#endif
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+
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+#ifdef USE_DOUBLE
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+
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+#define LOAD ld
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+#define LOADL ldl
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+#define LOADR ldr
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+#define STOREL sdl
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+#define STORER sdr
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+#define STORE sd
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+#define ADD daddu
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+#define SUB dsubu
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+#define SRL dsrl
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+#define SRA dsra
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+#define SLL dsll
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+#define SLLV dsllv
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+#define SRLV dsrlv
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+#define NBYTES 8
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+#define LOG_NBYTES 3
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+
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+/*
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+ * As we are sharing code base with the mips32 tree (which use the o32 ABI
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+ * register definitions). We need to redefine the register definitions from
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+ * the n64 ABI register naming to the o32 ABI register naming.
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+ */
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+#undef t0
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+#undef t1
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+#undef t2
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+#undef t3
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+#define t0 $8
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+#define t1 $9
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+#define t2 $10
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+#define t3 $11
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+#define t4 $12
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+#define t5 $13
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+#define t6 $14
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+#define t7 $15
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+
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+#else
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+
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+#define LOAD lw
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+#define LOADL lwl
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+#define LOADR lwr
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+#define STOREL swl
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+#define STORER swr
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+#define STORE sw
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+#define ADD addu
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+#define SUB subu
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+#define SRL srl
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+#define SLL sll
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+#define SRA sra
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+#define SLLV sllv
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+#define SRLV srlv
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+#define NBYTES 4
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+#define LOG_NBYTES 2
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+
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+#endif /* USE_DOUBLE */
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+
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+#ifdef CONFIG_CPU_LITTLE_ENDIAN
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+#define LDFIRST LOADR
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+#define LDREST LOADL
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+#define STFIRST STORER
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+#define STREST STOREL
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+#define SHIFT_DISCARD SLLV
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+#else
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+#define LDFIRST LOADL
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+#define LDREST LOADR
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+#define STFIRST STOREL
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+#define STREST STORER
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+#define SHIFT_DISCARD SRLV
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+#endif
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+
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+#define FIRST(unit) ((unit)*NBYTES)
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+#define REST(unit) (FIRST(unit)+NBYTES-1)
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+#define UNIT(unit) FIRST(unit)
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+
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+#define ADDRMASK (NBYTES-1)
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+
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+ .text
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+ .set noreorder
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+ .set noat
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+
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+/*
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+ * A combined memcpy/__copy_user
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+ * __copy_user sets len to 0 for success; else to an upper bound of
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+ * the number of uncopied bytes.
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+ * memcpy sets v0 to dst.
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+ */
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+ .align 5
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+LEAF(__copy_user_inatomic)
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+ /*
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+ * Note: dst & src may be unaligned, len may be 0
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+ * Temps
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+ */
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+#define rem t8
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+
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+ /*
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+ * The "issue break"s below are very approximate.
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+ * Issue delays for dcache fills will perturb the schedule, as will
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+ * load queue full replay traps, etc.
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+ *
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+ * If len < NBYTES use byte operations.
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+ */
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+ PREF( 0, 0(src) )
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+ PREF( 1, 0(dst) )
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+ sltu t2, len, NBYTES
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+ and t1, dst, ADDRMASK
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+ PREF( 0, 1*32(src) )
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+ PREF( 1, 1*32(dst) )
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+ bnez t2, copy_bytes_checklen
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+ and t0, src, ADDRMASK
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+ PREF( 0, 2*32(src) )
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+ PREF( 1, 2*32(dst) )
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+ bnez t1, dst_unaligned
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+ nop
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+ bnez t0, src_unaligned_dst_aligned
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+ /*
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+ * use delay slot for fall-through
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+ * src and dst are aligned; need to compute rem
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+ */
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+both_aligned:
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+ SRL t0, len, LOG_NBYTES+3 # +3 for 8 units/iter
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+ beqz t0, cleanup_both_aligned # len < 8*NBYTES
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+ and rem, len, (8*NBYTES-1) # rem = len % (8*NBYTES)
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+ PREF( 0, 3*32(src) )
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+ PREF( 1, 3*32(dst) )
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+ .align 4
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+1:
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+EXC( LOAD t0, UNIT(0)(src), l_exc)
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+EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
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+EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
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+EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
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+ SUB len, len, 8*NBYTES
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+EXC( LOAD t4, UNIT(4)(src), l_exc_copy)
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+EXC( LOAD t7, UNIT(5)(src), l_exc_copy)
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+ STORE t0, UNIT(0)(dst)
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+ STORE t1, UNIT(1)(dst)
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+EXC( LOAD t0, UNIT(6)(src), l_exc_copy)
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+EXC( LOAD t1, UNIT(7)(src), l_exc_copy)
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+ ADD src, src, 8*NBYTES
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+ ADD dst, dst, 8*NBYTES
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+ STORE t2, UNIT(-6)(dst)
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+ STORE t3, UNIT(-5)(dst)
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+ STORE t4, UNIT(-4)(dst)
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+ STORE t7, UNIT(-3)(dst)
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+ STORE t0, UNIT(-2)(dst)
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+ STORE t1, UNIT(-1)(dst)
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+ PREF( 0, 8*32(src) )
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+ PREF( 1, 8*32(dst) )
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+ bne len, rem, 1b
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+ nop
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+
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+ /*
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+ * len == rem == the number of bytes left to copy < 8*NBYTES
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+ */
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+cleanup_both_aligned:
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+ beqz len, done
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+ sltu t0, len, 4*NBYTES
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+ bnez t0, less_than_4units
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+ and rem, len, (NBYTES-1) # rem = len % NBYTES
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+ /*
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+ * len >= 4*NBYTES
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+ */
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+EXC( LOAD t0, UNIT(0)(src), l_exc)
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+EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
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+EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
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+EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
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+ SUB len, len, 4*NBYTES
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+ ADD src, src, 4*NBYTES
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+ STORE t0, UNIT(0)(dst)
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+ STORE t1, UNIT(1)(dst)
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+ STORE t2, UNIT(2)(dst)
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+ STORE t3, UNIT(3)(dst)
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+ beqz len, done
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+ ADD dst, dst, 4*NBYTES
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+less_than_4units:
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+ /*
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+ * rem = len % NBYTES
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+ */
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+ beq rem, len, copy_bytes
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+ nop
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+1:
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+EXC( LOAD t0, 0(src), l_exc)
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+ ADD src, src, NBYTES
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+ SUB len, len, NBYTES
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+ STORE t0, 0(dst)
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+ bne rem, len, 1b
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+ ADD dst, dst, NBYTES
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+
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+ /*
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+ * src and dst are aligned, need to copy rem bytes (rem < NBYTES)
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+ * A loop would do only a byte at a time with possible branch
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+ * mispredicts. Can't do an explicit LOAD dst,mask,or,STORE
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+ * because can't assume read-access to dst. Instead, use
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+ * STREST dst, which doesn't require read access to dst.
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+ *
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+ * This code should perform better than a simple loop on modern,
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+ * wide-issue mips processors because the code has fewer branches and
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+ * more instruction-level parallelism.
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+ */
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+#define bits t2
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+ beqz len, done
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+ ADD t1, dst, len # t1 is just past last byte of dst
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+ li bits, 8*NBYTES
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+ SLL rem, len, 3 # rem = number of bits to keep
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+EXC( LOAD t0, 0(src), l_exc)
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+ SUB bits, bits, rem # bits = number of bits to discard
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+ SHIFT_DISCARD t0, t0, bits
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+ STREST t0, -1(t1)
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+ jr ra
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+ move len, zero
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+dst_unaligned:
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+ /*
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+ * dst is unaligned
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+ * t0 = src & ADDRMASK
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+ * t1 = dst & ADDRMASK; T1 > 0
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+ * len >= NBYTES
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+ *
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+ * Copy enough bytes to align dst
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+ * Set match = (src and dst have same alignment)
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+ */
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+#define match rem
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+EXC( LDFIRST t3, FIRST(0)(src), l_exc)
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+ ADD t2, zero, NBYTES
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+EXC( LDREST t3, REST(0)(src), l_exc_copy)
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+ SUB t2, t2, t1 # t2 = number of bytes copied
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+ xor match, t0, t1
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+ STFIRST t3, FIRST(0)(dst)
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+ beq len, t2, done
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+ SUB len, len, t2
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+ ADD dst, dst, t2
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+ beqz match, both_aligned
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+ ADD src, src, t2
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+
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+src_unaligned_dst_aligned:
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+ SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter
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+ PREF( 0, 3*32(src) )
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+ beqz t0, cleanup_src_unaligned
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+ and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES
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+ PREF( 1, 3*32(dst) )
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+1:
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+/*
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+ * Avoid consecutive LD*'s to the same register since some mips
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+ * implementations can't issue them in the same cycle.
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+ * It's OK to load FIRST(N+1) before REST(N) because the two addresses
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+ * are to the same unit (unless src is aligned, but it's not).
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+ */
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+EXC( LDFIRST t0, FIRST(0)(src), l_exc)
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+EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy)
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+ SUB len, len, 4*NBYTES
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+EXC( LDREST t0, REST(0)(src), l_exc_copy)
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+EXC( LDREST t1, REST(1)(src), l_exc_copy)
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+EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy)
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+EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy)
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+EXC( LDREST t2, REST(2)(src), l_exc_copy)
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+EXC( LDREST t3, REST(3)(src), l_exc_copy)
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+ PREF( 0, 9*32(src) ) # 0 is PREF_LOAD (not streamed)
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+ ADD src, src, 4*NBYTES
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+#ifdef CONFIG_CPU_SB1
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+ nop # improves slotting
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+#endif
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+ STORE t0, UNIT(0)(dst)
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+ STORE t1, UNIT(1)(dst)
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+ STORE t2, UNIT(2)(dst)
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+ STORE t3, UNIT(3)(dst)
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+ PREF( 1, 9*32(dst) ) # 1 is PREF_STORE (not streamed)
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+ bne len, rem, 1b
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+ ADD dst, dst, 4*NBYTES
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+
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+cleanup_src_unaligned:
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+ beqz len, done
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+ and rem, len, NBYTES-1 # rem = len % NBYTES
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+ beq rem, len, copy_bytes
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+ nop
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+1:
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+EXC( LDFIRST t0, FIRST(0)(src), l_exc)
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+EXC( LDREST t0, REST(0)(src), l_exc_copy)
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+ ADD src, src, NBYTES
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+ SUB len, len, NBYTES
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+ STORE t0, 0(dst)
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+ bne len, rem, 1b
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+ ADD dst, dst, NBYTES
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+
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+copy_bytes_checklen:
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+ beqz len, done
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+ nop
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+copy_bytes:
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+ /* 0 < len < NBYTES */
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+#define COPY_BYTE(N) \
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+EXC( lb t0, N(src), l_exc); \
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+ SUB len, len, 1; \
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+ beqz len, done; \
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+ sb t0, N(dst)
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+
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+ COPY_BYTE(0)
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+ COPY_BYTE(1)
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+#ifdef USE_DOUBLE
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|
+ COPY_BYTE(2)
|
|
|
+ COPY_BYTE(3)
|
|
|
+ COPY_BYTE(4)
|
|
|
+ COPY_BYTE(5)
|
|
|
+#endif
|
|
|
+EXC( lb t0, NBYTES-2(src), l_exc)
|
|
|
+ SUB len, len, 1
|
|
|
+ jr ra
|
|
|
+ sb t0, NBYTES-2(dst)
|
|
|
+done:
|
|
|
+ jr ra
|
|
|
+ nop
|
|
|
+ END(__copy_user_inatomic)
|
|
|
+
|
|
|
+l_exc_copy:
|
|
|
+ /*
|
|
|
+ * Copy bytes from src until faulting load address (or until a
|
|
|
+ * lb faults)
|
|
|
+ *
|
|
|
+ * When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28)
|
|
|
+ * may be more than a byte beyond the last address.
|
|
|
+ * Hence, the lb below may get an exception.
|
|
|
+ *
|
|
|
+ * Assumes src < THREAD_BUADDR($28)
|
|
|
+ */
|
|
|
+ LOAD t0, TI_TASK($28)
|
|
|
+ nop
|
|
|
+ LOAD t0, THREAD_BUADDR(t0)
|
|
|
+1:
|
|
|
+EXC( lb t1, 0(src), l_exc)
|
|
|
+ ADD src, src, 1
|
|
|
+ sb t1, 0(dst) # can't fault -- we're copy_from_user
|
|
|
+ bne src, t0, 1b
|
|
|
+ ADD dst, dst, 1
|
|
|
+l_exc:
|
|
|
+ LOAD t0, TI_TASK($28)
|
|
|
+ nop
|
|
|
+ LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address
|
|
|
+ nop
|
|
|
+ SUB len, AT, t0 # len number of uncopied bytes
|
|
|
+ jr ra
|
|
|
+ nop
|