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Diffstat (limited to 'arch/mips/lib/csum_partial.S')
| -rw-r--r-- | arch/mips/lib/csum_partial.S | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S index 9db357294be1..c0a77fe038be 100644 --- a/arch/mips/lib/csum_partial.S +++ b/arch/mips/lib/csum_partial.S @@ -8,7 +8,9 @@ * Copyright (C) 1998, 1999 Ralf Baechle * Copyright (C) 1999 Silicon Graphics, Inc. */ +#include <linux/errno.h> #include <asm/asm.h> +#include <asm/asm-offsets.h> #include <asm/regdef.h> #ifdef CONFIG_64BIT @@ -271,3 +273,443 @@ small_csumcpy: jr ra .set noreorder END(csum_partial) + + +/* + * checksum and copy routines based on memcpy.S + * + * csum_partial_copy_nocheck(src, dst, len, sum) + * __csum_partial_copy_user(src, dst, len, sum, errp) + * + * See "Spec" in memcpy.S for details. Unlike __copy_user, all + * function in this file use the standard calling convention. + */ + +#define src a0 +#define dst a1 +#define len a2 +#define psum a3 +#define sum v0 +#define odd t8 +#define errptr t9 + +/* + * 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 __csum_partial_copy_from_user and maintained by + * not writing AT in __csum_partial_copy + * (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 stores -EFAULT to errptr and return. + * These handlers do not need to overwrite any data. + */ + +#define EXC(inst_reg,addr,handler) \ +9: inst_reg, addr; \ + .section __ex_table,"a"; \ + PTR 9b, handler; \ + .previous + +#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 SLL dsll +#define SLLV dsllv +#define SRLV dsrlv +#define NBYTES 8 +#define LOG_NBYTES 3 + +#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 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 +#define SHIFT_DISCARD_REVERT SRLV +#else +#define LDFIRST LOADL +#define LDREST LOADR +#define STFIRST STOREL +#define STREST STORER +#define SHIFT_DISCARD SRLV +#define SHIFT_DISCARD_REVERT SLLV +#endif + +#define FIRST(unit) ((unit)*NBYTES) +#define REST(unit) (FIRST(unit)+NBYTES-1) + +#define ADDRMASK (NBYTES-1) + + .set noat + +LEAF(__csum_partial_copy_user) + PTR_ADDU AT, src, len /* See (1) above. */ +#ifdef CONFIG_64BIT + move errptr, a4 +#else + lw errptr, 16(sp) +#endif +FEXPORT(csum_partial_copy_nocheck) + move sum, zero + move odd, zero + /* + * Note: dst & src may be unaligned, len may be 0 + * Temps + */ + /* + * 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. + */ + sltu t2, len, NBYTES + and t1, dst, ADDRMASK + bnez t2, copy_bytes_checklen + and t0, src, ADDRMASK + andi odd, dst, 0x1 /* odd buffer? */ + 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 + nop + SUB len, 8*NBYTES # subtract here for bgez loop + .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) +EXC( LOAD t4, UNIT(4)(src), l_exc_copy) +EXC( LOAD t5, UNIT(5)(src), l_exc_copy) +EXC( LOAD t6, UNIT(6)(src), l_exc_copy) +EXC( LOAD t7, UNIT(7)(src), l_exc_copy) + SUB len, len, 8*NBYTES + ADD src, src, 8*NBYTES +EXC( STORE t0, UNIT(0)(dst), s_exc) + ADDC(sum, t0) +EXC( STORE t1, UNIT(1)(dst), s_exc) + ADDC(sum, t1) +EXC( STORE t2, UNIT(2)(dst), s_exc) + ADDC(sum, t2) +EXC( STORE t3, UNIT(3)(dst), s_exc) + ADDC(sum, t3) +EXC( STORE t4, UNIT(4)(dst), s_exc) + ADDC(sum, t4) +EXC( STORE t5, UNIT(5)(dst), s_exc) + ADDC(sum, t5) +EXC( STORE t6, UNIT(6)(dst), s_exc) + ADDC(sum, t6) +EXC( STORE t7, UNIT(7)(dst), s_exc) + ADDC(sum, t7) + bgez len, 1b + ADD dst, dst, 8*NBYTES + ADD len, 8*NBYTES # revert len (see above) + + /* + * len == the number of bytes left to copy < 8*NBYTES + */ +cleanup_both_aligned: +#define rem t7 + 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) + ADDC(sum, t0) +EXC( STORE t1, UNIT(1)(dst), s_exc) + ADDC(sum, t1) +EXC( STORE t2, UNIT(2)(dst), s_exc) + ADDC(sum, t2) +EXC( STORE t3, UNIT(3)(dst), s_exc) + ADDC(sum, t3) + 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) + ADDC(sum, t0) + 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) + SHIFT_DISCARD_REVERT t0, t0, bits + .set reorder + ADDC(sum, t0) + b done + .set noreorder +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) + SLL t4, t1, 3 # t4 = number of bits to discard + SHIFT_DISCARD t3, t3, t4 + /* no SHIFT_DISCARD_REVERT to handle odd buffer properly */ + ADDC(sum, t3) + 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 + beqz t0, cleanup_src_unaligned + and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES +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) + ADD src, src, 4*NBYTES +#ifdef CONFIG_CPU_SB1 + nop # improves slotting +#endif +EXC( STORE t0, UNIT(0)(dst), s_exc) + ADDC(sum, t0) +EXC( STORE t1, UNIT(1)(dst), s_exc) + ADDC(sum, t1) +EXC( STORE t2, UNIT(2)(dst), s_exc) + ADDC(sum, t2) +EXC( STORE t3, UNIT(3)(dst), s_exc) + ADDC(sum, t3) + 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) + ADDC(sum, t0) + bne len, rem, 1b + ADD dst, dst, NBYTES + +copy_bytes_checklen: + beqz len, done + nop +copy_bytes: + /* 0 < len < NBYTES */ +#ifdef CONFIG_CPU_LITTLE_ENDIAN +#define SHIFT_START 0 +#define SHIFT_INC 8 +#else +#define SHIFT_START 8*(NBYTES-1) +#define SHIFT_INC -8 +#endif + move t2, zero # partial word + li t3, SHIFT_START # shift +/* use l_exc_copy here to return correct sum on fault */ +#define COPY_BYTE(N) \ +EXC( lbu t0, N(src), l_exc_copy); \ + SUB len, len, 1; \ +EXC( sb t0, N(dst), s_exc); \ + SLLV t0, t0, t3; \ + addu t3, SHIFT_INC; \ + beqz len, copy_bytes_done; \ + or t2, t0 + + COPY_BYTE(0) + COPY_BYTE(1) +#ifdef USE_DOUBLE + COPY_BYTE(2) + COPY_BYTE(3) + COPY_BYTE(4) + COPY_BYTE(5) +#endif +EXC( lbu t0, NBYTES-2(src), l_exc_copy) + SUB len, len, 1 +EXC( sb t0, NBYTES-2(dst), s_exc) + SLLV t0, t0, t3 + or t2, t0 +copy_bytes_done: + ADDC(sum, t2) +done: + /* fold checksum */ +#ifdef USE_DOUBLE + dsll32 v1, sum, 0 + daddu sum, v1 + sltu v1, sum, v1 + dsra32 sum, sum, 0 + addu sum, v1 +#endif + sll v1, sum, 16 + addu sum, v1 + sltu v1, sum, v1 + srl sum, sum, 16 + addu sum, v1 + + /* odd buffer alignment? */ + beqz odd, 1f + nop + sll v1, sum, 8 + srl sum, sum, 8 + or sum, v1 + andi sum, 0xffff +1: + .set reorder + ADDC(sum, psum) + jr ra + .set noreorder + +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) + li t2, SHIFT_START + LOAD t0, THREAD_BUADDR(t0) +1: +EXC( lbu t1, 0(src), l_exc) + ADD src, src, 1 + sb t1, 0(dst) # can't fault -- we're copy_from_user + SLLV t1, t1, t2 + addu t2, SHIFT_INC + ADDC(sum, t1) + 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 + li v1, -EFAULT + b done + sw v1, (errptr) + +s_exc: + li v0, -1 /* invalid checksum */ + li v1, -EFAULT + jr ra + sw v1, (errptr) + END(__csum_partial_copy_user) |