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