arch/s390/boot/startup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/string.h>
   3 #include <linux/elf.h>
   4 #include <asm/sections.h>
   5 #include <asm/cpu_mf.h>
   6 #include <asm/setup.h>
   7 #include <asm/kexec.h>
   8 #include <asm/sclp.h>
   9 #include <asm/diag.h>
  10 #include <asm/uv.h>
  11 #include "compressed/decompressor.h"
  12 #include "boot.h"
  13
  14 extern char __boot_data_start[], __boot_data_end[];
  15 extern char __boot_data_preserved_start[], __boot_data_preserved_end[];
  16 unsigned long __bootdata_preserved(__kaslr_offset);
  17
  18 /*
  19  * Some code and data needs to stay below 2 GB, even when the kernel would be
  20  * relocated above 2 GB, because it has to use 31 bit addresses.
  21  * Such code and data is part of the .dma section, and its location is passed
  22  * over to the decompressed / relocated kernel via the .boot.preserved.data
  23  * section.
  24  */
  25 extern char _sdma[], _edma[];
  26 extern char _stext_dma[], _etext_dma[];
  27 extern struct exception_table_entry _start_dma_ex_table[];
  28 extern struct exception_table_entry _stop_dma_ex_table[];
  29 unsigned long __bootdata_preserved(__sdma) = __pa(&_sdma);
  30 unsigned long __bootdata_preserved(__edma) = __pa(&_edma);
  31 unsigned long __bootdata_preserved(__stext_dma) = __pa(&_stext_dma);
  32 unsigned long __bootdata_preserved(__etext_dma) = __pa(&_etext_dma);
  33 struct exception_table_entry *
  34         __bootdata_preserved(__start_dma_ex_table) = _start_dma_ex_table;
  35 struct exception_table_entry *
  36         __bootdata_preserved(__stop_dma_ex_table) = _stop_dma_ex_table;
  37
  38 int _diag210_dma(struct diag210 *addr);
  39 int _diag26c_dma(void *req, void *resp, enum diag26c_sc subcode);
  40 int _diag14_dma(unsigned long rx, unsigned long ry1, unsigned long subcode);
  41 void _diag0c_dma(struct hypfs_diag0c_entry *entry);
  42 void _diag308_reset_dma(void);
  43 struct diag_ops __bootdata_preserved(diag_dma_ops) = {
  44         .diag210 = _diag210_dma,
  45         .diag26c = _diag26c_dma,
  46         .diag14 = _diag14_dma,
  47         .diag0c = _diag0c_dma,
  48         .diag308_reset = _diag308_reset_dma
  49 };
  50 static struct diag210 _diag210_tmp_dma __section(".dma.data");
  51 struct diag210 *__bootdata_preserved(__diag210_tmp_dma) = &_diag210_tmp_dma;
  52
  53 void error(char *x)
  54 {
  55         sclp_early_printk("\n\n");
  56         sclp_early_printk(x);
  57         sclp_early_printk("\n\n -- System halted");
  58
  59         disabled_wait();
  60 }
  61
  62 static void setup_lpp(void)
  63 {
  64         S390_lowcore.current_pid = 0;
  65         S390_lowcore.lpp = LPP_MAGIC;
  66         if (test_facility(40))
  67                 lpp(&S390_lowcore.lpp);
  68 }
  69
  70 #ifdef CONFIG_KERNEL_UNCOMPRESSED
  71 unsigned long mem_safe_offset(void)
  72 {
  73         return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;
  74 }
  75 #endif
  76
  77 static void rescue_initrd(unsigned long addr)
  78 {
  79         if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
  80                 return;
  81         if (!INITRD_START || !INITRD_SIZE)
  82                 return;
  83         if (addr <= INITRD_START)
  84                 return;
  85         memmove((void *)addr, (void *)INITRD_START, INITRD_SIZE);
  86         INITRD_START = addr;
  87 }
  88
  89 static void copy_bootdata(void)
  90 {
  91         if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
  92                 error(".boot.data section size mismatch");
  93         memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
  94         if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
  95                 error(".boot.preserved.data section size mismatch");
  96         memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
  97 }
  98
  99 static void handle_relocs(unsigned long offset)
 100 {
 101         Elf64_Rela *rela_start, *rela_end, *rela;
 102         int r_type, r_sym, rc;
 103         Elf64_Addr loc, val;
 104         Elf64_Sym *dynsym;
 105
 106         rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
 107         rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
 108         dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
 109         for (rela = rela_start; rela < rela_end; rela++) {
 110                 loc = rela->r_offset + offset;
 111                 val = rela->r_addend;
 112                 r_sym = ELF64_R_SYM(rela->r_info);
 113                 if (r_sym) {
 114                         if (dynsym[r_sym].st_shndx != SHN_UNDEF)
 115                                 val += dynsym[r_sym].st_value + offset;
 116                 } else {
 117                         /*
 118                          * 0 == undefined symbol table index (STN_UNDEF),
 119                          * used for R_390_RELATIVE, only add KASLR offset
 120                          */
 121                         val += offset;
 122                 }
 123                 r_type = ELF64_R_TYPE(rela->r_info);
 124                 rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
 125                 if (rc)
 126                         error("Unknown relocation type");
 127         }
 128 }
 129
 130 /*
 131  * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
 132  */
 133 static void clear_bss_section(void)
 134 {
 135         memset((void *)vmlinux.default_lma + vmlinux.image_size, 0, vmlinux.bss_size);
 136 }
 137
 138 /*
 139  * Set vmalloc area size to an 8th of (potential) physical memory
 140  * size, unless size has been set by kernel command line parameter.
 141  */
 142 static void setup_vmalloc_size(void)
 143 {
 144         unsigned long size;
 145
 146         if (vmalloc_size_set)
 147                 return;
 148         size = (memory_end ?: max_physmem_end) >> 3;
 149         size = round_up(size, _SEGMENT_SIZE);
 150         vmalloc_size = max(size, vmalloc_size);
 151 }
 152
 153 void startup_kernel(void)
 154 {
 155         unsigned long random_lma;
 156         unsigned long safe_addr;
 157         void *img;
 158
 159         setup_lpp();
 160         store_ipl_parmblock();
 161         safe_addr = mem_safe_offset();
 162         safe_addr = read_ipl_report(safe_addr);
 163         uv_query_info();
 164         rescue_initrd(safe_addr);
 165         sclp_early_read_info();
 166         setup_boot_command_line();
 167         parse_boot_command_line();
 168         setup_memory_end();
 169         detect_memory();
 170         setup_vmalloc_size();
 171
 172         random_lma = __kaslr_offset = 0;
 173         if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_enabled) {
 174                 random_lma = get_random_base(safe_addr);
 175                 if (random_lma) {
 176                         __kaslr_offset = random_lma - vmlinux.default_lma;
 177                         img = (void *)vmlinux.default_lma;
 178                         vmlinux.default_lma += __kaslr_offset;
 179                         vmlinux.entry += __kaslr_offset;
 180                         vmlinux.bootdata_off += __kaslr_offset;
 181                         vmlinux.bootdata_preserved_off += __kaslr_offset;
 182                         vmlinux.rela_dyn_start += __kaslr_offset;
 183                         vmlinux.rela_dyn_end += __kaslr_offset;
 184                         vmlinux.dynsym_start += __kaslr_offset;
 185                 }
 186         }
 187
 188         if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
 189                 img = decompress_kernel();
 190                 memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
 191         } else if (__kaslr_offset)
 192                 memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size);
 193
 194         clear_bss_section();
 195         copy_bootdata();
 196         if (IS_ENABLED(CONFIG_RELOCATABLE))
 197                 handle_relocs(__kaslr_offset);
 198
 199         if (__kaslr_offset) {
 200                 /*
 201                  * Save KASLR offset for early dumps, before vmcore_info is set.
 202                  * Mark as uneven to distinguish from real vmcore_info pointer.
 203                  */
 204                 S390_lowcore.vmcore_info = __kaslr_offset | 0x1UL;
 205                 /* Clear non-relocated kernel */
 206                 if (IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED))
 207                         memset(img, 0, vmlinux.image_size);
 208         }
 209         vmlinux.entry();
 210 }