| /* |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file "COPYING" in the main directory of this archive |
| * for more details. |
| * |
| * Unified implementation of memcpy, memmove and the __copy_user backend. |
| * |
| * Copyright (C) 1998, 99, 2000, 01, 2002 Ralf Baechle (ralf@gnu.org) |
| * Copyright (C) 1999, 2000, 01, 2002 Silicon Graphics, Inc. |
| * Copyright (C) 2002 Broadcom, Inc. |
| * memcpy/copy_user author: Mark Vandevoorde |
| * Copyright (C) 2007 Maciej W. Rozycki |
| * |
| * Mnemonic names for arguments to memcpy/__copy_user |
| */ |
| |
| /* |
| * Hack to resolve longstanding prefetch issue |
| * |
| * Prefetching may be fatal on some systems if we're prefetching beyond the |
| * end of memory on some systems. It's also a seriously bad idea on non |
| * dma-coherent systems. |
| */ |
| #if !defined(CONFIG_DMA_COHERENT) || !defined(CONFIG_DMA_IP27) |
| #undef CONFIG_CPU_HAS_PREFETCH |
| #endif |
| #ifdef CONFIG_MIPS_MALTA |
| #undef CONFIG_CPU_HAS_PREFETCH |
| #endif |
| |
| #include <asm/asm.h> |
| #include <asm/asm-offsets.h> |
| #include <asm/regdef.h> |
| |
| #define dst a0 |
| #define src a1 |
| #define len a2 |
| |
| /* |
| * Spec |
| * |
| * memcpy copies len bytes from src to dst and sets v0 to dst. |
| * It assumes that |
| * - src and dst don't overlap |
| * - src is readable |
| * - dst is writable |
| * memcpy uses the standard calling convention |
| * |
| * __copy_user copies up to len bytes from src to dst and sets a2 (len) to |
| * the number of uncopied bytes due to an exception caused by a read or write. |
| * __copy_user assumes that src and dst don't overlap, and that the call is |
| * implementing one of the following: |
| * copy_to_user |
| * - src is readable (no exceptions when reading src) |
| * copy_from_user |
| * - dst is writable (no exceptions when writing dst) |
| * __copy_user uses a non-standard calling convention; see |
| * include/asm-mips/uaccess.h |
| * |
| * When an exception happens on a load, the handler must |
| # ensure that all of the destination buffer is overwritten to prevent |
| * leaking information to user mode programs. |
| */ |
| |
| /* |
| * Implementation |
| */ |
| |
| /* |
| * The exception handler for loads requires that: |
| * 1- AT contain the address of the byte just past the end of the source |
| * of the copy, |
| * 2- src_entry <= src < AT, and |
| * 3- (dst - src) == (dst_entry - src_entry), |
| * The _entry suffix denotes values when __copy_user was called. |
| * |
| * (1) is set up up by uaccess.h and maintained by not writing AT in copy_user |
| * (2) is met by incrementing src by the number of bytes copied |
| * (3) is met by not doing loads between a pair of increments of dst and src |
| * |
| * The exception handlers for stores adjust len (if necessary) and return. |
| * These handlers do not need to overwrite any data. |
| * |
| * For __rmemcpy and memmove an exception is always a kernel bug, therefore |
| * they're not protected. |
| */ |
| |
| #define EXC(inst_reg,addr,handler) \ |
| 9: inst_reg, addr; \ |
| .section __ex_table,"a"; \ |
| PTR 9b, handler; \ |
| .previous |
| |
| /* |
| * Only on the 64-bit kernel we can made use of 64-bit registers. |
| */ |
| #ifdef CONFIG_64BIT |
| #define USE_DOUBLE |
| #endif |
| |
| #ifdef USE_DOUBLE |
| |
| #define LOAD ld |
| #define LOADL ldl |
| #define LOADR ldr |
| #define STOREL sdl |
| #define STORER sdr |
| #define STORE sd |
| #define ADD daddu |
| #define SUB dsubu |
| #define SRL dsrl |
| #define SRA dsra |
| #define SLL dsll |
| #define SLLV dsllv |
| #define SRLV dsrlv |
| #define NBYTES 8 |
| #define LOG_NBYTES 3 |
| |
| /* |
| * As we are sharing code base with the mips32 tree (which use the o32 ABI |
| * register definitions). We need to redefine the register definitions from |
| * the n64 ABI register naming to the o32 ABI register naming. |
| */ |
| #undef t0 |
| #undef t1 |
| #undef t2 |
| #undef t3 |
| #define t0 $8 |
| #define t1 $9 |
| #define t2 $10 |
| #define t3 $11 |
| #define t4 $12 |
| #define t5 $13 |
| #define t6 $14 |
| #define t7 $15 |
| |
| #else |
| |
| #define LOAD lw |
| #define LOADL lwl |
| #define LOADR lwr |
| #define STOREL swl |
| #define STORER swr |
| #define STORE sw |
| #define ADD addu |
| #define SUB subu |
| #define SRL srl |
| #define SLL sll |
| #define SRA sra |
| #define SLLV sllv |
| #define SRLV srlv |
| #define NBYTES 4 |
| #define LOG_NBYTES 2 |
| |
| #endif /* USE_DOUBLE */ |
| |
| #ifdef CONFIG_CPU_LITTLE_ENDIAN |
| #define LDFIRST LOADR |
| #define LDREST LOADL |
| #define STFIRST STORER |
| #define STREST STOREL |
| #define SHIFT_DISCARD SLLV |
| #else |
| #define LDFIRST LOADL |
| #define LDREST LOADR |
| #define STFIRST STOREL |
| #define STREST STORER |
| #define SHIFT_DISCARD SRLV |
| #endif |
| |
| #define FIRST(unit) ((unit)*NBYTES) |
| #define REST(unit) (FIRST(unit)+NBYTES-1) |
| #define UNIT(unit) FIRST(unit) |
| |
| #define ADDRMASK (NBYTES-1) |
| |
| .text |
| .set noreorder |
| #ifndef CONFIG_CPU_DADDI_WORKAROUNDS |
| .set noat |
| #else |
| .set at=v1 |
| #endif |
| |
| /* |
| * A combined memcpy/__copy_user |
| * __copy_user sets len to 0 for success; else to an upper bound of |
| * the number of uncopied bytes. |
| * memcpy sets v0 to dst. |
| */ |
| .align 5 |
| LEAF(__copy_user_inatomic) |
| /* |
| * Note: dst & src may be unaligned, len may be 0 |
| * Temps |
| */ |
| #define rem t8 |
| |
| /* |
| * The "issue break"s below are very approximate. |
| * Issue delays for dcache fills will perturb the schedule, as will |
| * load queue full replay traps, etc. |
| * |
| * If len < NBYTES use byte operations. |
| */ |
| PREF( 0, 0(src) ) |
| PREF( 1, 0(dst) ) |
| sltu t2, len, NBYTES |
| and t1, dst, ADDRMASK |
| PREF( 0, 1*32(src) ) |
| PREF( 1, 1*32(dst) ) |
| bnez t2, .Lcopy_bytes_checklen |
| and t0, src, ADDRMASK |
| PREF( 0, 2*32(src) ) |
| PREF( 1, 2*32(dst) ) |
| bnez t1, .Ldst_unaligned |
| nop |
| bnez t0, .Lsrc_unaligned_dst_aligned |
| /* |
| * use delay slot for fall-through |
| * src and dst are aligned; need to compute rem |
| */ |
| .Lboth_aligned: |
| SRL t0, len, LOG_NBYTES+3 # +3 for 8 units/iter |
| beqz t0, .Lcleanup_both_aligned # len < 8*NBYTES |
| and rem, len, (8*NBYTES-1) # rem = len % (8*NBYTES) |
| PREF( 0, 3*32(src) ) |
| PREF( 1, 3*32(dst) ) |
| .align 4 |
| 1: |
| EXC( LOAD t0, UNIT(0)(src), .Ll_exc) |
| EXC( LOAD t1, UNIT(1)(src), .Ll_exc_copy) |
| EXC( LOAD t2, UNIT(2)(src), .Ll_exc_copy) |
| EXC( LOAD t3, UNIT(3)(src), .Ll_exc_copy) |
| SUB len, len, 8*NBYTES |
| EXC( LOAD t4, UNIT(4)(src), .Ll_exc_copy) |
| EXC( LOAD t7, UNIT(5)(src), .Ll_exc_copy) |
| STORE t0, UNIT(0)(dst) |
| STORE t1, UNIT(1)(dst) |
| EXC( LOAD t0, UNIT(6)(src), .Ll_exc_copy) |
| EXC( LOAD t1, UNIT(7)(src), .Ll_exc_copy) |
| ADD src, src, 8*NBYTES |
| ADD dst, dst, 8*NBYTES |
| STORE t2, UNIT(-6)(dst) |
| STORE t3, UNIT(-5)(dst) |
| STORE t4, UNIT(-4)(dst) |
| STORE t7, UNIT(-3)(dst) |
| STORE t0, UNIT(-2)(dst) |
| STORE t1, UNIT(-1)(dst) |
| PREF( 0, 8*32(src) ) |
| PREF( 1, 8*32(dst) ) |
| bne len, rem, 1b |
| nop |
| |
| /* |
| * len == rem == the number of bytes left to copy < 8*NBYTES |
| */ |
| .Lcleanup_both_aligned: |
| beqz len, .Ldone |
| sltu t0, len, 4*NBYTES |
| bnez t0, .Lless_than_4units |
| and rem, len, (NBYTES-1) # rem = len % NBYTES |
| /* |
| * len >= 4*NBYTES |
| */ |
| EXC( LOAD t0, UNIT(0)(src), .Ll_exc) |
| EXC( LOAD t1, UNIT(1)(src), .Ll_exc_copy) |
| EXC( LOAD t2, UNIT(2)(src), .Ll_exc_copy) |
| EXC( LOAD t3, UNIT(3)(src), .Ll_exc_copy) |
| SUB len, len, 4*NBYTES |
| ADD src, src, 4*NBYTES |
| STORE t0, UNIT(0)(dst) |
| STORE t1, UNIT(1)(dst) |
| STORE t2, UNIT(2)(dst) |
| STORE t3, UNIT(3)(dst) |
| .set reorder /* DADDI_WAR */ |
| ADD dst, dst, 4*NBYTES |
| beqz len, .Ldone |
| .set noreorder |
| .Lless_than_4units: |
| /* |
| * rem = len % NBYTES |
| */ |
| beq rem, len, .Lcopy_bytes |
| nop |
| 1: |
| EXC( LOAD t0, 0(src), .Ll_exc) |
| ADD src, src, NBYTES |
| SUB len, len, NBYTES |
| STORE t0, 0(dst) |
| .set reorder /* DADDI_WAR */ |
| ADD dst, dst, NBYTES |
| bne rem, len, 1b |
| .set noreorder |
| |
| /* |
| * src and dst are aligned, need to copy rem bytes (rem < NBYTES) |
| * A loop would do only a byte at a time with possible branch |
| * mispredicts. Can't do an explicit LOAD dst,mask,or,STORE |
| * because can't assume read-access to dst. Instead, use |
| * STREST dst, which doesn't require read access to dst. |
| * |
| * This code should perform better than a simple loop on modern, |
| * wide-issue mips processors because the code has fewer branches and |
| * more instruction-level parallelism. |
| */ |
| #define bits t2 |
| beqz len, .Ldone |
| ADD t1, dst, len # t1 is just past last byte of dst |
| li bits, 8*NBYTES |
| SLL rem, len, 3 # rem = number of bits to keep |
| EXC( LOAD t0, 0(src), .Ll_exc) |
| SUB bits, bits, rem # bits = number of bits to discard |
| SHIFT_DISCARD t0, t0, bits |
| STREST t0, -1(t1) |
| jr ra |
| move len, zero |
| .Ldst_unaligned: |
| /* |
| * dst is unaligned |
| * t0 = src & ADDRMASK |
| * t1 = dst & ADDRMASK; T1 > 0 |
| * len >= NBYTES |
| * |
| * Copy enough bytes to align dst |
| * Set match = (src and dst have same alignment) |
| */ |
| #define match rem |
| EXC( LDFIRST t3, FIRST(0)(src), .Ll_exc) |
| ADD t2, zero, NBYTES |
| EXC( LDREST t3, REST(0)(src), .Ll_exc_copy) |
| SUB t2, t2, t1 # t2 = number of bytes copied |
| xor match, t0, t1 |
| STFIRST t3, FIRST(0)(dst) |
| beq len, t2, .Ldone |
| SUB len, len, t2 |
| ADD dst, dst, t2 |
| beqz match, .Lboth_aligned |
| ADD src, src, t2 |
| |
| .Lsrc_unaligned_dst_aligned: |
| SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter |
| PREF( 0, 3*32(src) ) |
| beqz t0, .Lcleanup_src_unaligned |
| and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES |
| PREF( 1, 3*32(dst) ) |
| 1: |
| /* |
| * Avoid consecutive LD*'s to the same register since some mips |
| * implementations can't issue them in the same cycle. |
| * It's OK to load FIRST(N+1) before REST(N) because the two addresses |
| * are to the same unit (unless src is aligned, but it's not). |
| */ |
| EXC( LDFIRST t0, FIRST(0)(src), .Ll_exc) |
| EXC( LDFIRST t1, FIRST(1)(src), .Ll_exc_copy) |
| SUB len, len, 4*NBYTES |
| EXC( LDREST t0, REST(0)(src), .Ll_exc_copy) |
| EXC( LDREST t1, REST(1)(src), .Ll_exc_copy) |
| EXC( LDFIRST t2, FIRST(2)(src), .Ll_exc_copy) |
| EXC( LDFIRST t3, FIRST(3)(src), .Ll_exc_copy) |
| EXC( LDREST t2, REST(2)(src), .Ll_exc_copy) |
| EXC( LDREST t3, REST(3)(src), .Ll_exc_copy) |
| PREF( 0, 9*32(src) ) # 0 is PREF_LOAD (not streamed) |
| ADD src, src, 4*NBYTES |
| #ifdef CONFIG_CPU_SB1 |
| nop # improves slotting |
| #endif |
| STORE t0, UNIT(0)(dst) |
| STORE t1, UNIT(1)(dst) |
| STORE t2, UNIT(2)(dst) |
| STORE t3, UNIT(3)(dst) |
| PREF( 1, 9*32(dst) ) # 1 is PREF_STORE (not streamed) |
| .set reorder /* DADDI_WAR */ |
| ADD dst, dst, 4*NBYTES |
| bne len, rem, 1b |
| .set noreorder |
| |
| .Lcleanup_src_unaligned: |
| beqz len, .Ldone |
| and rem, len, NBYTES-1 # rem = len % NBYTES |
| beq rem, len, .Lcopy_bytes |
| nop |
| 1: |
| EXC( LDFIRST t0, FIRST(0)(src), .Ll_exc) |
| EXC( LDREST t0, REST(0)(src), .Ll_exc_copy) |
| ADD src, src, NBYTES |
| SUB len, len, NBYTES |
| STORE t0, 0(dst) |
| .set reorder /* DADDI_WAR */ |
| ADD dst, dst, NBYTES |
| bne len, rem, 1b |
| .set noreorder |
| |
| .Lcopy_bytes_checklen: |
| beqz len, .Ldone |
| nop |
| .Lcopy_bytes: |
| /* 0 < len < NBYTES */ |
| #define COPY_BYTE(N) \ |
| EXC( lb t0, N(src), .Ll_exc); \ |
| SUB len, len, 1; \ |
| beqz len, .Ldone; \ |
| sb t0, N(dst) |
| |
| COPY_BYTE(0) |
| COPY_BYTE(1) |
| #ifdef USE_DOUBLE |
| COPY_BYTE(2) |
| COPY_BYTE(3) |
| COPY_BYTE(4) |
| COPY_BYTE(5) |
| #endif |
| EXC( lb t0, NBYTES-2(src), .Ll_exc) |
| SUB len, len, 1 |
| jr ra |
| sb t0, NBYTES-2(dst) |
| .Ldone: |
| jr ra |
| nop |
| END(__copy_user_inatomic) |
| |
| .Ll_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), .Ll_exc) |
| ADD src, src, 1 |
| sb t1, 0(dst) # can't fault -- we're copy_from_user |
| .set reorder /* DADDI_WAR */ |
| ADD dst, dst, 1 |
| bne src, t0, 1b |
| .set noreorder |
| .Ll_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 |
