| paul@156 | 1 | /* |
| paul@156 | 2 | * Task handling. |
| paul@156 | 3 | * |
| paul@156 | 4 | * Copyright (C) 2015, 2016 Paul Boddie <paul@boddie.org.uk> |
| paul@156 | 5 | * |
| paul@156 | 6 | * This program is free software: you can redistribute it and/or modify |
| paul@156 | 7 | * it under the terms of the GNU General Public License as published by |
| paul@156 | 8 | * the Free Software Foundation, either version 3 of the License, or |
| paul@156 | 9 | * (at your option) any later version. |
| paul@156 | 10 | * |
| paul@156 | 11 | * This program is distributed in the hope that it will be useful, |
| paul@156 | 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| paul@156 | 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| paul@156 | 14 | * GNU General Public License for more details. |
| paul@156 | 15 | * |
| paul@156 | 16 | * You should have received a copy of the GNU General Public License |
| paul@156 | 17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| paul@156 | 18 | */ |
| paul@156 | 19 | |
| paul@156 | 20 | #include "cpu.h" |
| paul@186 | 21 | #include "cpu_op.h" |
| paul@194 | 22 | #include "memory.h" |
| paul@193 | 23 | #include "mips.h" |
| paul@156 | 24 | #include "paging.h" |
| paul@159 | 25 | #include "tasks.h" |
| paul@156 | 26 | |
| paul@156 | 27 | /* Task tables and data. */ |
| paul@156 | 28 | |
| paul@156 | 29 | static u32 stack_pointers[max_tasks]; |
| paul@156 | 30 | static u32 registers[max_tasks][32]; |
| paul@156 | 31 | |
| paul@156 | 32 | u8 current_task; |
| paul@156 | 33 | u32 *current_stack_pointer; |
| paul@156 | 34 | u32 *current_registers; |
| paul@156 | 35 | |
| paul@179 | 36 | /* A reference to locations for the symbol tables. */ |
| paul@179 | 37 | |
| paul@179 | 38 | extern u32 _got_start, _got_copy_start, _got_copy_end; |
| paul@156 | 39 | |
| paul@189 | 40 | /* A reference to the start of the payload and end of memory locations. */ |
| paul@179 | 41 | |
| paul@189 | 42 | extern u32 _payload_start, _memory_end; |
| paul@156 | 43 | |
| paul@156 | 44 | /* Task management functions. */ |
| paul@156 | 45 | |
| paul@156 | 46 | void init_tasks() |
| paul@156 | 47 | { |
| paul@166 | 48 | current_task = 1; |
| paul@160 | 49 | init_task(); |
| paul@160 | 50 | } |
| paul@160 | 51 | |
| paul@160 | 52 | void init_task() |
| paul@160 | 53 | { |
| paul@156 | 54 | current_stack_pointer = &stack_pointers[current_task]; |
| paul@156 | 55 | current_registers = registers[current_task]; |
| paul@156 | 56 | } |
| paul@156 | 57 | |
| paul@159 | 58 | void start_task(unsigned short task, void (*function)(), u32 args[], u8 nargs) |
| paul@156 | 59 | { |
| paul@179 | 60 | u32 virtual, physical, address; |
| paul@156 | 61 | |
| paul@156 | 62 | /* |
| paul@156 | 63 | Each task employs a stack at a multiple of the given start address in |
| paul@193 | 64 | physical memory, but at the same address in virtual memory. Task zero |
| paul@193 | 65 | is never started. |
| paul@156 | 66 | */ |
| paul@156 | 67 | |
| paul@194 | 68 | virtual = STAGE2_TASK_STACK; |
| paul@194 | 69 | physical = STAGE2_TASK_STACK - STAGE2_TASK_STACK_SIZE * task; |
| paul@156 | 70 | |
| paul@194 | 71 | init_page_table(STAGE2_PAGE_TABLE, virtual - STAGE2_PAGESIZE * 2, physical - STAGE2_PAGESIZE * 2, STAGE2_PAGESIZE, TLB_WRITE, task); |
| paul@156 | 72 | |
| paul@156 | 73 | /* |
| paul@156 | 74 | Subtract from the stack pointer to prevent the called function from |
| paul@156 | 75 | reaching into unmapped memory. |
| paul@156 | 76 | */ |
| paul@156 | 77 | |
| paul@156 | 78 | stack_pointers[task] = virtual - 12; |
| paul@156 | 79 | |
| paul@156 | 80 | /* |
| paul@156 | 81 | Set the registers for the new task, initialising the global pointer and |
| paul@156 | 82 | return address. |
| paul@156 | 83 | */ |
| paul@156 | 84 | |
| paul@173 | 85 | init_registers(registers[task], (u32) &_got_copy_start, function, args, nargs); |
| paul@179 | 86 | |
| paul@179 | 87 | /* Map the global object table for the task. */ |
| paul@179 | 88 | |
| paul@194 | 89 | init_page_table(STAGE2_PAGE_TABLE, user_address((u32) &_got_start), user_address((u32) &_got_copy_start), STAGE2_PAGESIZE, TLB_READ, task); |
| paul@179 | 90 | |
| paul@179 | 91 | /* Map all shared pages for the task. */ |
| paul@179 | 92 | |
| paul@194 | 93 | for (address = (u32) &_payload_start; address < (u32) &_got_start; address += STAGE2_PAGESIZE * 2) |
| paul@179 | 94 | { |
| paul@194 | 95 | init_page_table(STAGE2_PAGE_TABLE, user_address(address), user_address(address), STAGE2_PAGESIZE, TLB_READ, task); |
| paul@179 | 96 | } |
| paul@179 | 97 | |
| paul@194 | 98 | for (address = (u32) &_got_copy_end + STAGE2_PAGESIZE * 2; address < (u32) &_memory_end; address += STAGE2_PAGESIZE * 2) |
| paul@179 | 99 | { |
| paul@194 | 100 | init_page_table(STAGE2_PAGE_TABLE, user_address(address), user_address(address), STAGE2_PAGESIZE, TLB_WRITE, task); |
| paul@179 | 101 | } |
| paul@156 | 102 | } |
| paul@156 | 103 | |
| paul@165 | 104 | void start_task_now() |
| paul@165 | 105 | { |
| paul@171 | 106 | invoke_task(current_task, current_registers, current_stack_pointer); |
| paul@165 | 107 | } |
| paul@165 | 108 | |
| paul@156 | 109 | void switch_task() |
| paul@156 | 110 | { |
| paul@156 | 111 | /* Switch the current task. */ |
| paul@156 | 112 | |
| paul@156 | 113 | current_task++; |
| paul@166 | 114 | if (current_task == max_tasks) current_task = 1; |
| paul@160 | 115 | init_task(); |
| paul@156 | 116 | } |
