/*- * Copyright (c) 2018 The FreeBSD Foundation * * This software was developed by Mateusz Guzik * under sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include /* * Note: this routine was written with kernel use in mind (read: no simd), * it is only present in userspace as a temporary measure until something * better gets imported. */ #define ALIGN_TEXT .p2align 4,0x90 /* 16-byte alignment, nop filled */ #ifdef BCMP ENTRY(bcmp) #else ENTRY(memcmp) #endif xorl %eax,%eax 10: cmpq $16,%rdx ja 101632f cmpb $8,%dl jg 100816f cmpb $4,%dl jg 100408f cmpb $2,%dl jge 100204f cmpb $1,%dl jl 100000f movzbl (%rdi),%eax movzbl (%rsi),%r8d subl %r8d,%eax 100000: ret ALIGN_TEXT 100816: movq (%rdi),%r8 movq (%rsi),%r9 cmpq %r8,%r9 jne 80f movq -8(%rdi,%rdx),%r8 movq -8(%rsi,%rdx),%r9 cmpq %r8,%r9 jne 10081608f ret ALIGN_TEXT 100408: movl (%rdi),%r8d movl (%rsi),%r9d cmpl %r8d,%r9d jne 80f movl -4(%rdi,%rdx),%r8d movl -4(%rsi,%rdx),%r9d cmpl %r8d,%r9d jne 10040804f ret ALIGN_TEXT 100204: movzwl (%rdi),%r8d movzwl (%rsi),%r9d cmpl %r8d,%r9d jne 1f movzwl -2(%rdi,%rdx),%r8d movzwl -2(%rsi,%rdx),%r9d cmpl %r8d,%r9d jne 1f ret ALIGN_TEXT 101632: cmpq $32,%rdx ja 103200f movq (%rdi),%r8 movq (%rsi),%r9 cmpq %r8,%r9 jne 80f movq 8(%rdi),%r8 movq 8(%rsi),%r9 cmpq %r8,%r9 jne 10163208f movq -16(%rdi,%rdx),%r8 movq -16(%rsi,%rdx),%r9 cmpq %r8,%r9 jne 10163216f movq -8(%rdi,%rdx),%r8 movq -8(%rsi,%rdx),%r9 cmpq %r8,%r9 jne 10163224f ret ALIGN_TEXT 103200: movq (%rdi),%r8 movq 8(%rdi),%r9 subq (%rsi),%r8 subq 8(%rsi),%r9 orq %r8,%r9 jnz 10320000f movq 16(%rdi),%r8 movq 24(%rdi),%r9 subq 16(%rsi),%r8 subq 24(%rsi),%r9 orq %r8,%r9 jnz 10320016f leaq 32(%rdi),%rdi leaq 32(%rsi),%rsi subq $32,%rdx cmpq $32,%rdx jae 103200b cmpb $0,%dl jne 10b ret /* * Mismatch was found. */ #ifdef BCMP ALIGN_TEXT 10320016: 10320000: 10081608: 10163224: 10163216: 10163208: 10040804: 80: 1: leal 1(%eax),%eax ret END(bcmp) #else /* * We need to compute the difference between strings. * Start with narrowing the range down (16 -> 8 -> 4 bytes). */ ALIGN_TEXT 10320016: leaq 16(%rdi),%rdi leaq 16(%rsi),%rsi 10320000: movq (%rdi),%r8 movq (%rsi),%r9 cmpq %r8,%r9 jne 80f leaq 8(%rdi),%rdi leaq 8(%rsi),%rsi jmp 80f ALIGN_TEXT 10081608: 10163224: leaq -8(%rdi,%rdx),%rdi leaq -8(%rsi,%rdx),%rsi jmp 80f ALIGN_TEXT 10163216: leaq -16(%rdi,%rdx),%rdi leaq -16(%rsi,%rdx),%rsi jmp 80f ALIGN_TEXT 10163208: leaq 8(%rdi),%rdi leaq 8(%rsi),%rsi jmp 80f ALIGN_TEXT 10040804: leaq -4(%rdi,%rdx),%rdi leaq -4(%rsi,%rdx),%rsi jmp 1f ALIGN_TEXT 80: movl (%rdi),%r8d movl (%rsi),%r9d cmpl %r8d,%r9d jne 1f leaq 4(%rdi),%rdi leaq 4(%rsi),%rsi /* * We have up to 4 bytes to inspect. */ 1: movzbl (%rdi),%eax movzbl (%rsi),%r8d cmpb %r8b,%al jne 2f movzbl 1(%rdi),%eax movzbl 1(%rsi),%r8d cmpb %r8b,%al jne 2f movzbl 2(%rdi),%eax movzbl 2(%rsi),%r8d cmpb %r8b,%al jne 2f movzbl 3(%rdi),%eax movzbl 3(%rsi),%r8d 2: subl %r8d,%eax ret END(memcmp) #endif .section .note.GNU-stack,"",%progbits