1/* 2 * Early kernel startup code for Hexagon 3 * 4 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved. 5 * 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 and 9 * only version 2 as published by the Free Software Foundation. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 * 02110-1301, USA. 20 */ 21 22#include <linux/linkage.h> 23#include <linux/init.h> 24#include <asm/asm-offsets.h> 25#include <asm/mem-layout.h> 26#include <asm/vm_mmu.h> 27#include <asm/page.h> 28 29 __INIT 30ENTRY(stext) 31 /* 32 * VMM will already have set up true vector page, MMU, etc. 33 * To set up initial kernel identity map, we have to pass 34 * the VMM a pointer to some canonical page tables. In 35 * this implementation, we're assuming that we've got 36 * them precompiled. Generate value in R24, as we'll need 37 * it again shortly. 38 */ 39 r24.L = #LO(swapper_pg_dir) 40 r24.H = #HI(swapper_pg_dir) 41 42 /* 43 * Symbol is kernel segment address, but we need 44 * the logical/physical address. 45 */ 46 r24 = asl(r24, #2) 47 r24 = lsr(r24, #2) 48 49 r0 = r24 50 51 /* 52 * Initialize a 16MB PTE to make the virtual and physical 53 * addresses where the kernel was loaded be identical. 54 */ 55#define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X \ 56 | __HEXAGON_C_WB_L2 << 6 \ 57 | __HVM_PDE_S_4MB) 58 59 r1 = pc 60 r2.H = #0xffc0 61 r2.L = #0x0000 62 r1 = and(r1,r2) /* round PC to 4MB boundary */ 63 r2 = lsr(r1, #22) /* 4MB page number */ 64 r2 = asl(r2, #2) /* times sizeof(PTE) (4bytes) */ 65 r0 = add(r0,r2) /* r0 = address of correct PTE */ 66 r2 = #PTE_BITS 67 r1 = add(r1,r2) /* r1 = 4MB PTE for the first entry */ 68 r2.h = #0x0040 69 r2.l = #0x0000 /* 4MB */ 70 memw(r0 ++ #4) = r1 71 r1 = add(r1, r2) 72 memw(r0 ++ #4) = r1 73 74 r0 = r24 75 76 /* 77 * The subroutine wrapper around the virtual instruction touches 78 * no memory, so we should be able to use it even here. 79 */ 80 call __vmnewmap; 81 82 /* Jump into virtual address range. */ 83 84 r31.h = #hi(__head_s_vaddr_target) 85 r31.l = #lo(__head_s_vaddr_target) 86 jumpr r31 87 88 /* Insert trippy space effects. */ 89 90__head_s_vaddr_target: 91 /* 92 * Tear down VA=PA translation now that we are running 93 * in the desgnated kernel segments. 94 */ 95 r0 = #__HVM_PDE_S_INVALID 96 r1 = r24 97 loop0(1f,#0x100) 981: 99 { 100 memw(R1 ++ #4) = R0 101 }:endloop0 102 103 r0 = r24 104 call __vmnewmap 105 106 /* Go ahead and install the trap0 return so angel calls work */ 107 r0.h = #hi(_K_provisional_vec) 108 r0.l = #lo(_K_provisional_vec) 109 call __vmsetvec 110 111 /* 112 * OK, at this point we should start to be much more careful, 113 * we're going to enter C code and start touching memory 114 * in all sorts of places. 115 * This means: 116 * SGP needs to be OK 117 * Need to lock shared resources 118 * A bunch of other things that will cause 119 * all kinds of painful bugs 120 */ 121 122 /* 123 * Stack pointer should be pointed at the init task's 124 * thread stack, which should have been declared in arch/init_task.c. 125 * So uhhhhh... 126 * It's accessible via the init_thread_union, which is a union 127 * of a thread_info struct and a stack; of course, the top 128 * of the stack is not for you. The end of the stack 129 * is simply init_thread_union + THREAD_SIZE. 130 */ 131 132 {r29.H = #HI(init_thread_union); r0.H = #HI(_THREAD_SIZE); } 133 {r29.L = #LO(init_thread_union); r0.L = #LO(_THREAD_SIZE); } 134 135 /* initialize the register used to point to current_thread_info */ 136 /* Fixme: THREADINFO_REG can't be R2 because of that memset thing. */ 137 {r29 = add(r29,r0); THREADINFO_REG = r29; } 138 139 /* Hack: zero bss; */ 140 { r0.L = #LO(__bss_start); r1 = #0; r2.l = #LO(__bss_stop); } 141 { r0.H = #HI(__bss_start); r2.h = #HI(__bss_stop); } 142 143 r2 = sub(r2,r0); 144 call memset; 145 146 /* Time to make the doughnuts. */ 147 call start_kernel 148 149 /* 150 * Should not reach here. 151 */ 1521: 153 jump 1b 154 155.p2align PAGE_SHIFT 156ENTRY(external_cmdline_buffer) 157 .fill _PAGE_SIZE,1,0 158 159.data 160.p2align PAGE_SHIFT 161ENTRY(empty_zero_page) 162 .fill _PAGE_SIZE,1,0 163