From: David Daney <david.daney@xxxxxxxxxx> We can save the 451 lines of code that comprise memcpy-inatomic.S at the expense of a single instruction in the memcpy prolog. We also use an additional register (t6), so this may cause increased register pressure in some places as well. But I think the reduced maintenance burden, of not having two nearly identical implementations, makes it worth it. Signed-off-by: David Daney <david.daney@xxxxxxxxxx> --- arch/mips/include/asm/uaccess.h | 6 +- arch/mips/lib/Makefile | 2 +- arch/mips/lib/memcpy-inatomic.S | 451 --------------------------------------- arch/mips/lib/memcpy.S | 11 + 4 files changed, 15 insertions(+), 455 deletions(-) delete mode 100644 arch/mips/lib/memcpy-inatomic.S diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h index 653a412..3b92efe 100644 --- a/arch/mips/include/asm/uaccess.h +++ b/arch/mips/include/asm/uaccess.h @@ -687,7 +687,7 @@ extern size_t __copy_user(void *__to, const void *__from, size_t __n); __MODULE_JAL(__copy_user) \ : "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r) \ : \ - : "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31", \ + : "$8", "$9", "$10", "$11", "$12", "$14", "$15", "$24", "$31", \ DADDI_SCRATCH, "memory"); \ __cu_len_r; \ }) @@ -797,7 +797,7 @@ extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n); ".set\treorder" \ : "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r) \ : \ - : "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31", \ + : "$8", "$9", "$10", "$11", "$12", "$14", "$15", "$24", "$31", \ DADDI_SCRATCH, "memory"); \ __cu_len_r; \ }) @@ -820,7 +820,7 @@ extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n); ".set\treorder" \ : "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r) \ : \ - : "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31", \ + : "$8", "$9", "$10", "$11", "$12", "$14", "$15", "$24", "$31", \ DADDI_SCRATCH, "memory"); \ __cu_len_r; \ }) diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile index 2a7c74f..399a50a 100644 --- a/arch/mips/lib/Makefile +++ b/arch/mips/lib/Makefile @@ -2,7 +2,7 @@ # Makefile for MIPS-specific library files.. # -lib-y += csum_partial.o delay.o memcpy.o memcpy-inatomic.o memset.o \ +lib-y += csum_partial.o delay.o memcpy.o memset.o \ strlen_user.o strncpy_user.o strnlen_user.o uncached.o obj-y += iomap.o diff --git a/arch/mips/lib/memcpy-inatomic.S b/arch/mips/lib/memcpy-inatomic.S deleted file mode 100644 index 68853a0..0000000 --- a/arch/mips/lib/memcpy-inatomic.S +++ /dev/null @@ -1,451 +0,0 @@ -/* - * 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@xxxxxxx) - * 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. - */ -#ifdef CONFIG_DMA_NONCOHERENT -#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 diff --git a/arch/mips/lib/memcpy.S b/arch/mips/lib/memcpy.S index 56a1f85..f1feeb9 100644 --- a/arch/mips/lib/memcpy.S +++ b/arch/mips/lib/memcpy.S @@ -183,6 +183,14 @@ #endif /* + * t6 is used as a flag to note inatomic mode. + */ +LEAF(__copy_user_inatomic) + b __copy_user_common + li t6, 1 + END(__copy_user_inatomic) + +/* * A combined memcpy/__copy_user * __copy_user sets len to 0 for success; else to an upper bound of * the number of uncopied bytes. @@ -193,6 +201,8 @@ LEAF(memcpy) /* a0=dst a1=src a2=len */ move v0, dst /* return value */ .L__memcpy: FEXPORT(__copy_user) + li t6, 0 /* not inatomic */ +__copy_user_common: /* * Note: dst & src may be unaligned, len may be 0 * Temps @@ -458,6 +468,7 @@ EXC( lb t1, 0(src), .Ll_exc) LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address nop SUB len, AT, t0 # len number of uncopied bytes + bnez t6, .Ldone /* Skip the zeroing part if inatomic */ /* * Here's where we rely on src and dst being incremented in tandem, * See (3) above. -- 1.7.2.3
