1 /* 2 * prepare to run common code 3 * 4 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 5 */ 6 7 #include <linux/init.h> 8 #include <linux/linkage.h> 9 #include <linux/types.h> 10 #include <linux/kernel.h> 11 #include <linux/string.h> 12 #include <linux/percpu.h> 13 #include <linux/start_kernel.h> 14 15 #include <asm/processor.h> 16 #include <asm/proto.h> 17 #include <asm/smp.h> 18 #include <asm/setup.h> 19 #include <asm/desc.h> 20 #include <asm/pgtable.h> 21 #include <asm/tlbflush.h> 22 #include <asm/sections.h> 23 #include <asm/kdebug.h> 24 #include <asm/e820.h> 25 26 static void __init zap_identity_mappings(void) 27 { 28 pgd_t *pgd = pgd_offset_k(0UL); 29 pgd_clear(pgd); 30 __flush_tlb_all(); 31 } 32 33 /* Don't add a printk in there. printk relies on the PDA which is not initialized 34 yet. */ 35 static void __init clear_bss(void) 36 { 37 memset(__bss_start, 0, 38 (unsigned long) __bss_stop - (unsigned long) __bss_start); 39 } 40 41 static void __init copy_bootdata(char *real_mode_data) 42 { 43 char * command_line; 44 45 memcpy(&boot_params, real_mode_data, sizeof boot_params); 46 if (boot_params.hdr.cmd_line_ptr) { 47 command_line = __va(boot_params.hdr.cmd_line_ptr); 48 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE); 49 } 50 } 51 52 #define BIOS_EBDA_SEGMENT 0x40E 53 #define BIOS_LOWMEM_KILOBYTES 0x413 54 55 /* 56 * The BIOS places the EBDA/XBDA at the top of conventional 57 * memory, and usually decreases the reported amount of 58 * conventional memory (int 0x12) too. This also contains a 59 * workaround for Dell systems that neglect to reserve EBDA. 60 * The same workaround also avoids a problem with the AMD768MPX 61 * chipset: reserve a page before VGA to prevent PCI prefetch 62 * into it (errata #56). Usually the page is reserved anyways, 63 * unless you have no PS/2 mouse plugged in. 64 */ 65 static void __init reserve_ebda_region(void) 66 { 67 unsigned int lowmem, ebda_addr; 68 69 /* To determine the position of the EBDA and the */ 70 /* end of conventional memory, we need to look at */ 71 /* the BIOS data area. In a paravirtual environment */ 72 /* that area is absent. We'll just have to assume */ 73 /* that the paravirt case can handle memory setup */ 74 /* correctly, without our help. */ 75 if (paravirt_enabled()) 76 return; 77 78 /* end of low (conventional) memory */ 79 lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES); 80 lowmem <<= 10; 81 82 /* start of EBDA area */ 83 ebda_addr = *(unsigned short *)__va(BIOS_EBDA_SEGMENT); 84 ebda_addr <<= 4; 85 86 /* Fixup: bios puts an EBDA in the top 64K segment */ 87 /* of conventional memory, but does not adjust lowmem. */ 88 if ((lowmem - ebda_addr) <= 0x10000) 89 lowmem = ebda_addr; 90 91 /* Fixup: bios does not report an EBDA at all. */ 92 /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */ 93 if ((ebda_addr == 0) && (lowmem >= 0x9f000)) 94 lowmem = 0x9f000; 95 96 /* Paranoia: should never happen, but... */ 97 if ((lowmem == 0) || (lowmem >= 0x100000)) 98 lowmem = 0x9f000; 99 100 /* reserve all memory between lowmem and the 1MB mark */ 101 reserve_early(lowmem, 0x100000, "BIOS reserved"); 102 } 103 104 void __init x86_64_start_kernel(char * real_mode_data) 105 { 106 int i; 107 108 /* 109 * Build-time sanity checks on the kernel image and module 110 * area mappings. (these are purely build-time and produce no code) 111 */ 112 BUILD_BUG_ON(MODULES_VADDR < KERNEL_IMAGE_START); 113 BUILD_BUG_ON(MODULES_VADDR-KERNEL_IMAGE_START < KERNEL_IMAGE_SIZE); 114 BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE); 115 BUILD_BUG_ON((KERNEL_IMAGE_START & ~PMD_MASK) != 0); 116 BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0); 117 BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL)); 118 BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == 119 (__START_KERNEL & PGDIR_MASK))); 120 121 /* clear bss before set_intr_gate with early_idt_handler */ 122 clear_bss(); 123 124 /* Make NULL pointers segfault */ 125 zap_identity_mappings(); 126 127 /* Cleanup the over mapped high alias */ 128 cleanup_highmap(); 129 130 for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) { 131 #ifdef CONFIG_EARLY_PRINTK 132 set_intr_gate(i, &early_idt_handlers[i]); 133 #else 134 set_intr_gate(i, early_idt_handler); 135 #endif 136 } 137 load_idt((const struct desc_ptr *)&idt_descr); 138 139 early_printk("Kernel alive\n"); 140 141 for (i = 0; i < NR_CPUS; i++) 142 cpu_pda(i) = &boot_cpu_pda[i]; 143 144 pda_init(0); 145 copy_bootdata(__va(real_mode_data)); 146 147 reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS"); 148 149 /* Reserve INITRD */ 150 if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) { 151 unsigned long ramdisk_image = boot_params.hdr.ramdisk_image; 152 unsigned long ramdisk_size = boot_params.hdr.ramdisk_size; 153 unsigned long ramdisk_end = ramdisk_image + ramdisk_size; 154 reserve_early(ramdisk_image, ramdisk_end, "RAMDISK"); 155 } 156 157 reserve_ebda_region(); 158 159 /* 160 * At this point everything still needed from the boot loader 161 * or BIOS or kernel text should be early reserved or marked not 162 * RAM in e820. All other memory is free game. 163 */ 164 165 start_kernel(); 166 } 167