1 /* 2 * BSD LICENSE 3 * 4 * Copyright (C) Cavium, Inc. 2017. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * * Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * * Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in 14 * the documentation and/or other materials provided with the 15 * distribution. 16 * * Neither the name of Cavium, Inc nor the names of its 17 * contributors may be used to endorse or promote products derived 18 * from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #ifndef STACK_H 34 #define STACK_H 35 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 #include "lthread_int.h" 41 42 /* 43 * Sets up the initial stack for the lthread. 44 */ 45 static inline void 46 arch_set_stack(struct lthread *lt, void *func) 47 { 48 void **stack_top = (void *)((char *)(lt->stack) + lt->stack_size); 49 50 /* 51 * Align stack_top to 16 bytes. Arm64 has the constraint that the 52 * stack pointer must always be quad-word aligned. 53 */ 54 stack_top = (void **)(((unsigned long)(stack_top)) & ~0xfUL); 55 56 /* 57 * First Stack Frame 58 */ 59 stack_top[0] = NULL; 60 stack_top[-1] = NULL; 61 62 /* 63 * Initialize the context 64 */ 65 lt->ctx.fp = &stack_top[-1]; 66 lt->ctx.sp = &stack_top[-2]; 67 68 /* 69 * Here only the address of _lthread_exec is saved as the link 70 * register value. The argument to _lthread_exec i.e the address of 71 * the lthread struct is not saved. This is because the first 72 * argument to ctx_switch is the address of the new context, 73 * which also happens to be the address of required lthread struct. 74 * So while returning from ctx_switch into _thread_exec, parameter 75 * register x0 will always contain the required value. 76 */ 77 lt->ctx.lr = func; 78 } 79 80 #ifdef __cplusplus 81 } 82 #endif 83 84 #endif /* STACK_H_ */ 85