| /* |
| * 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 |
| * |
| * Mnemonic names for arguments to memcpy/__copy_user |
| */ |
| #include <linux/config.h> |
| #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 |
| .set noat |
| |
| /* |
| * 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(memcpy) /* a0=dst a1=src a2=len */ |
| move v0, dst /* return value */ |
| __memcpy: |
| FEXPORT(__copy_user) |
| /* |
| * 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, copy_bytes_checklen |
| and t0, src, ADDRMASK |
| PREF( 0, 2*32(src) ) |
| PREF( 1, 2*32(dst) ) |
| bnez t1, dst_unaligned |
| nop |
| bnez t0, src_unaligned_dst_aligned |
| /* |
| * use delay slot for fall-through |
| * src and dst are aligned; need to compute rem |
| */ |
| both_aligned: |
| SRL t0, len, LOG_NBYTES+3 # +3 for 8 units/iter |
| beqz t0, cleanup_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), l_exc) |
| EXC( LOAD t1, UNIT(1)(src), l_exc_copy) |
| EXC( LOAD t2, UNIT(2)(src), l_exc_copy) |
| EXC( LOAD t3, UNIT(3)(src), l_exc_copy) |
| SUB len, len, 8*NBYTES |
| EXC( LOAD t4, UNIT(4)(src), l_exc_copy) |
| EXC( LOAD t7, UNIT(5)(src), l_exc_copy) |
| EXC( STORE t0, UNIT(0)(dst), s_exc_p8u) |
| EXC( STORE t1, UNIT(1)(dst), s_exc_p7u) |
| EXC( LOAD t0, UNIT(6)(src), l_exc_copy) |
| EXC( LOAD t1, UNIT(7)(src), l_exc_copy) |
| ADD src, src, 8*NBYTES |
| ADD dst, dst, 8*NBYTES |
| EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u) |
| EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u) |
| EXC( STORE t4, UNIT(-4)(dst), s_exc_p4u) |
| EXC( STORE t7, UNIT(-3)(dst), s_exc_p3u) |
| EXC( STORE t0, UNIT(-2)(dst), s_exc_p2u) |
| EXC( STORE t1, UNIT(-1)(dst), s_exc_p1u) |
| 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 |
| */ |
| cleanup_both_aligned: |
| beqz len, done |
| sltu t0, len, 4*NBYTES |
| bnez t0, less_than_4units |
| and rem, len, (NBYTES-1) # rem = len % NBYTES |
| /* |
| * len >= 4*NBYTES |
| */ |
| EXC( LOAD t0, UNIT(0)(src), l_exc) |
| EXC( LOAD t1, UNIT(1)(src), l_exc_copy) |
| EXC( LOAD t2, UNIT(2)(src), l_exc_copy) |
| EXC( LOAD t3, UNIT(3)(src), l_exc_copy) |
| SUB len, len, 4*NBYTES |
| ADD src, src, 4*NBYTES |
| EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) |
| EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) |
| EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) |
| EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) |
| beqz len, done |
| ADD dst, dst, 4*NBYTES |
| less_than_4units: |
| /* |
| * rem = len % NBYTES |
| */ |
| beq rem, len, copy_bytes |
| nop |
| 1: |
| EXC( LOAD t0, 0(src), l_exc) |
| ADD src, src, NBYTES |
| SUB len, len, NBYTES |
| EXC( STORE t0, 0(dst), s_exc_p1u) |
| bne rem, len, 1b |
| ADD dst, dst, NBYTES |
| |
| /* |
| * 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, done |
| 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), l_exc) |
| SUB bits, bits, rem # bits = number of bits to discard |
| SHIFT_DISCARD t0, t0, bits |
| EXC( STREST t0, -1(t1), s_exc) |
| jr ra |
| move len, zero |
| dst_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), l_exc) |
| ADD t2, zero, NBYTES |
| EXC( LDREST t3, REST(0)(src), l_exc_copy) |
| SUB t2, t2, t1 # t2 = number of bytes copied |
| xor match, t0, t1 |
| EXC( STFIRST t3, FIRST(0)(dst), s_exc) |
| beq len, t2, done |
| SUB len, len, t2 |
| ADD dst, dst, t2 |
| beqz match, both_aligned |
| ADD src, src, t2 |
| |
| src_unaligned_dst_aligned: |
| SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter |
| PREF( 0, 3*32(src) ) |
| beqz t0, cleanup_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), l_exc) |
| EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy) |
| SUB len, len, 4*NBYTES |
| EXC( LDREST t0, REST(0)(src), l_exc_copy) |
| EXC( LDREST t1, REST(1)(src), l_exc_copy) |
| EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy) |
| EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy) |
| EXC( LDREST t2, REST(2)(src), l_exc_copy) |
| EXC( LDREST t3, REST(3)(src), l_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 |
| EXC( STORE t0, UNIT(0)(dst), s_exc_p4u) |
| EXC( STORE t1, UNIT(1)(dst), s_exc_p3u) |
| EXC( STORE t2, UNIT(2)(dst), s_exc_p2u) |
| EXC( STORE t3, UNIT(3)(dst), s_exc_p1u) |
| PREF( 1, 9*32(dst) ) # 1 is PREF_STORE (not streamed) |
| bne len, rem, 1b |
| ADD dst, dst, 4*NBYTES |
| |
| cleanup_src_unaligned: |
| beqz len, done |
| and rem, len, NBYTES-1 # rem = len % NBYTES |
| beq rem, len, copy_bytes |
| nop |
| 1: |
| EXC( LDFIRST t0, FIRST(0)(src), l_exc) |
| EXC( LDREST t0, REST(0)(src), l_exc_copy) |
| ADD src, src, NBYTES |
| SUB len, len, NBYTES |
| EXC( STORE t0, 0(dst), s_exc_p1u) |
| bne len, rem, 1b |
| ADD dst, dst, NBYTES |
| |
| copy_bytes_checklen: |
| beqz len, done |
| nop |
| copy_bytes: |
| /* 0 < len < NBYTES */ |
| #define COPY_BYTE(N) \ |
| EXC( lb t0, N(src), l_exc); \ |
| SUB len, len, 1; \ |
| beqz len, done; \ |
| EXC( sb t0, N(dst), s_exc_p1) |
| |
| 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), l_exc) |
| SUB len, len, 1 |
| jr ra |
| EXC( sb t0, NBYTES-2(dst), s_exc_p1) |
| done: |
| jr ra |
| nop |
| END(memcpy) |
| |
| 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 |
| /* |
| * Here's where we rely on src and dst being incremented in tandem, |
| * See (3) above. |
| * dst += (fault addr - src) to put dst at first byte to clear |
| */ |
| ADD dst, t0 # compute start address in a1 |
| SUB dst, src |
| /* |
| * Clear len bytes starting at dst. Can't call __bzero because it |
| * might modify len. An inefficient loop for these rare times... |
| */ |
| beqz len, done |
| SUB src, len, 1 |
| 1: sb zero, 0(dst) |
| ADD dst, dst, 1 |
| bnez src, 1b |
| SUB src, src, 1 |
| jr ra |
| nop |
| |
| |
| #define SEXC(n) \ |
| s_exc_p ## n ## u: \ |
| jr ra; \ |
| ADD len, len, n*NBYTES |
| |
| SEXC(8) |
| SEXC(7) |
| SEXC(6) |
| SEXC(5) |
| SEXC(4) |
| SEXC(3) |
| SEXC(2) |
| SEXC(1) |
| |
| s_exc_p1: |
| jr ra |
| ADD len, len, 1 |
| s_exc: |
| jr ra |
| nop |
| |
| .align 5 |
| LEAF(memmove) |
| ADD t0, a0, a2 |
| ADD t1, a1, a2 |
| sltu t0, a1, t0 # dst + len <= src -> memcpy |
| sltu t1, a0, t1 # dst >= src + len -> memcpy |
| and t0, t1 |
| beqz t0, __memcpy |
| move v0, a0 /* return value */ |
| beqz a2, r_out |
| END(memmove) |
| |
| /* fall through to __rmemcpy */ |
| LEAF(__rmemcpy) /* a0=dst a1=src a2=len */ |
| sltu t0, a1, a0 |
| beqz t0, r_end_bytes_up # src >= dst |
| nop |
| ADD a0, a2 # dst = dst + len |
| ADD a1, a2 # src = src + len |
| |
| r_end_bytes: |
| lb t0, -1(a1) |
| SUB a2, a2, 0x1 |
| sb t0, -1(a0) |
| SUB a1, a1, 0x1 |
| bnez a2, r_end_bytes |
| SUB a0, a0, 0x1 |
| |
| r_out: |
| jr ra |
| move a2, zero |
| |
| r_end_bytes_up: |
| lb t0, (a1) |
| SUB a2, a2, 0x1 |
| sb t0, (a0) |
| ADD a1, a1, 0x1 |
| bnez a2, r_end_bytes_up |
| ADD a0, a0, 0x1 |
| |
| jr ra |
| move a2, zero |
| END(__rmemcpy) |
