1/* 2 * Early kernel startup code for Hexagon 3 * 4 * Copyright (c) 2010-2013, The Linux Foundation. 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#include <asm/hexagon_vm.h> 29 30#define SEGTABLE_ENTRIES #0x0e0 31 32 __INIT 33ENTRY(stext) 34 /* 35 * VMM will already have set up true vector page, MMU, etc. 36 * To set up initial kernel identity map, we have to pass 37 * the VMM a pointer to some canonical page tables. In 38 * this implementation, we're assuming that we've got 39 * them precompiled. Generate value in R24, as we'll need 40 * it again shortly. 41 */ 42 r24.L = #LO(swapper_pg_dir) 43 r24.H = #HI(swapper_pg_dir) 44 45 /* 46 * Symbol is kernel segment address, but we need 47 * the logical/physical address. 48 */ 49 r25 = pc; 50 r2.h = #0xffc0; 51 r2.l = #0x0000; 52 r25 = and(r2,r25); /* R25 holds PHYS_OFFSET now */ 53 r1.h = #HI(PAGE_OFFSET); 54 r1.l = #LO(PAGE_OFFSET); 55 r24 = sub(r24,r1); /* swapper_pg_dir - PAGE_OFFSET */ 56 r24 = add(r24,r25); /* + PHYS_OFFSET */ 57 58 r0 = r24; /* aka __pa(swapper_pg_dir) */ 59 60 /* 61 * Initialize page dir to make the virtual and physical 62 * addresses where the kernel was loaded be identical. 63 * Done in 4MB chunks. 64 */ 65#define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X \ 66 | __HEXAGON_C_WB_L2 << 6 \ 67 | __HVM_PDE_S_4MB) 68 69 /* 70 * Get number of VA=PA entries; only really needed for jump 71 * to hyperspace; gets blown away immediately after 72 */ 73 74 { 75 r1.l = #LO(_end); 76 r2.l = #LO(stext); 77 r3 = #1; 78 } 79 { 80 r1.h = #HI(_end); 81 r2.h = #HI(stext); 82 r3 = asl(r3, #22); 83 } 84 { 85 r1 = sub(r1, r2); 86 r3 = add(r3, #-1); 87 } /* r1 = _end - stext */ 88 r1 = add(r1, r3); /* + (4M-1) */ 89 r26 = lsr(r1, #22); /* / 4M = # of entries */ 90 91 r1 = r25; 92 r2.h = #0xffc0; 93 r2.l = #0x0000; /* round back down to 4MB boundary */ 94 r1 = and(r1,r2); 95 r2 = lsr(r1, #22) /* 4MB page number */ 96 r2 = asl(r2, #2) /* times sizeof(PTE) (4bytes) */ 97 r0 = add(r0,r2) /* r0 = address of correct PTE */ 98 r2 = #PTE_BITS 99 r1 = add(r1,r2) /* r1 = 4MB PTE for the first entry */ 100 r2.h = #0x0040 101 r2.l = #0x0000 /* 4MB increments */ 102 loop0(1f,r26); 1031: 104 memw(r0 ++ #4) = r1 105 { r1 = add(r1, r2); } :endloop0 106 107 /* Also need to overwrite the initial 0xc0000000 entries */ 108 /* PAGE_OFFSET >> (4MB shift - 4 bytes per entry shift) */ 109 R1.H = #HI(PAGE_OFFSET >> (22 - 2)) 110 R1.L = #LO(PAGE_OFFSET >> (22 - 2)) 111 112 r0 = add(r1, r24); /* advance to 0xc0000000 entry */ 113 r1 = r25; 114 r2.h = #0xffc0; 115 r2.l = #0x0000; /* round back down to 4MB boundary */ 116 r1 = and(r1,r2); /* for huge page */ 117 r2 = #PTE_BITS 118 r1 = add(r1,r2); 119 r2.h = #0x0040 120 r2.l = #0x0000 /* 4MB increments */ 121 122 loop0(1f,SEGTABLE_ENTRIES); 1231: 124 memw(r0 ++ #4) = r1; 125 { r1 = add(r1,r2); } :endloop0 126 127 r0 = r24; 128 129 /* 130 * The subroutine wrapper around the virtual instruction touches 131 * no memory, so we should be able to use it even here. 132 * Note that in this version, R1 and R2 get "clobbered"; see 133 * vm_ops.S 134 */ 135 r1 = #VM_TRANS_TYPE_TABLE 136 call __vmnewmap; 137 138 /* Jump into virtual address range. */ 139 140 r31.h = #hi(__head_s_vaddr_target) 141 r31.l = #lo(__head_s_vaddr_target) 142 jumpr r31 143 144 /* Insert trippy space effects. */ 145 146__head_s_vaddr_target: 147 /* 148 * Tear down VA=PA translation now that we are running 149 * in kernel virtual space. 150 */ 151 r0 = #__HVM_PDE_S_INVALID 152 153 r1.h = #0xffc0; 154 r1.l = #0x0000; 155 r2 = r25; /* phys_offset */ 156 r2 = and(r1,r2); 157 158 r1.l = #lo(swapper_pg_dir) 159 r1.h = #hi(swapper_pg_dir) 160 r2 = lsr(r2, #22) /* 4MB page number */ 161 r2 = asl(r2, #2) /* times sizeof(PTE) (4bytes) */ 162 r1 = add(r1,r2); 163 loop0(1f,r26) 164 1651: 166 { 167 memw(R1 ++ #4) = R0 168 }:endloop0 169 170 r0 = r24 171 r1 = #VM_TRANS_TYPE_TABLE 172 call __vmnewmap 173 174 /* Go ahead and install the trap0 return so angel calls work */ 175 r0.h = #hi(_K_provisional_vec) 176 r0.l = #lo(_K_provisional_vec) 177 call __vmsetvec 178 179 /* 180 * OK, at this point we should start to be much more careful, 181 * we're going to enter C code and start touching memory 182 * in all sorts of places. 183 * This means: 184 * SGP needs to be OK 185 * Need to lock shared resources 186 * A bunch of other things that will cause 187 * all kinds of painful bugs 188 */ 189 190 /* 191 * Stack pointer should be pointed at the init task's 192 * thread stack, which should have been declared in arch/init_task.c. 193 * So uhhhhh... 194 * It's accessible via the init_thread_union, which is a union 195 * of a thread_info struct and a stack; of course, the top 196 * of the stack is not for you. The end of the stack 197 * is simply init_thread_union + THREAD_SIZE. 198 */ 199 200 {r29.H = #HI(init_thread_union); r0.H = #HI(_THREAD_SIZE); } 201 {r29.L = #LO(init_thread_union); r0.L = #LO(_THREAD_SIZE); } 202 203 /* initialize the register used to point to current_thread_info */ 204 /* Fixme: THREADINFO_REG can't be R2 because of that memset thing. */ 205 {r29 = add(r29,r0); THREADINFO_REG = r29; } 206 207 /* Hack: zero bss; */ 208 { r0.L = #LO(__bss_start); r1 = #0; r2.l = #LO(__bss_stop); } 209 { r0.H = #HI(__bss_start); r2.h = #HI(__bss_stop); } 210 211 r2 = sub(r2,r0); 212 call memset; 213 214 /* Set PHYS_OFFSET; should be in R25 */ 215#ifdef CONFIG_HEXAGON_PHYS_OFFSET 216 r0.l = #LO(__phys_offset); 217 r0.h = #HI(__phys_offset); 218 memw(r0) = r25; 219#endif 220 221 /* Time to make the doughnuts. */ 222 call start_kernel 223 224 /* 225 * Should not reach here. 226 */ 2271: 228 jump 1b 229 230.p2align PAGE_SHIFT 231ENTRY(external_cmdline_buffer) 232 .fill _PAGE_SIZE,1,0 233 234.data 235.p2align PAGE_SHIFT 236ENTRY(empty_zero_page) 237 .fill _PAGE_SIZE,1,0 238