linux/arch/s390/boot/startup.c
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   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/string.h>
   3#include <linux/elf.h>
   4#include <asm/boot_data.h>
   5#include <asm/sections.h>
   6#include <asm/cpu_mf.h>
   7#include <asm/setup.h>
   8#include <asm/kexec.h>
   9#include <asm/sclp.h>
  10#include <asm/diag.h>
  11#include <asm/uv.h>
  12#include "compressed/decompressor.h"
  13#include "boot.h"
  14
  15extern char __boot_data_start[], __boot_data_end[];
  16extern char __boot_data_preserved_start[], __boot_data_preserved_end[];
  17unsigned long __bootdata_preserved(__kaslr_offset);
  18unsigned long __bootdata(ident_map_size);
  19
  20/*
  21 * Some code and data needs to stay below 2 GB, even when the kernel would be
  22 * relocated above 2 GB, because it has to use 31 bit addresses.
  23 * Such code and data is part of the .dma section, and its location is passed
  24 * over to the decompressed / relocated kernel via the .boot.preserved.data
  25 * section.
  26 */
  27extern char _sdma[], _edma[];
  28extern char _stext_dma[], _etext_dma[];
  29extern struct exception_table_entry _start_dma_ex_table[];
  30extern struct exception_table_entry _stop_dma_ex_table[];
  31unsigned long __bootdata_preserved(__sdma) = __pa(&_sdma);
  32unsigned long __bootdata_preserved(__edma) = __pa(&_edma);
  33unsigned long __bootdata_preserved(__stext_dma) = __pa(&_stext_dma);
  34unsigned long __bootdata_preserved(__etext_dma) = __pa(&_etext_dma);
  35struct exception_table_entry *
  36        __bootdata_preserved(__start_dma_ex_table) = _start_dma_ex_table;
  37struct exception_table_entry *
  38        __bootdata_preserved(__stop_dma_ex_table) = _stop_dma_ex_table;
  39
  40int _diag210_dma(struct diag210 *addr);
  41int _diag26c_dma(void *req, void *resp, enum diag26c_sc subcode);
  42int _diag14_dma(unsigned long rx, unsigned long ry1, unsigned long subcode);
  43void _diag0c_dma(struct hypfs_diag0c_entry *entry);
  44void _diag308_reset_dma(void);
  45struct diag_ops __bootdata_preserved(diag_dma_ops) = {
  46        .diag210 = _diag210_dma,
  47        .diag26c = _diag26c_dma,
  48        .diag14 = _diag14_dma,
  49        .diag0c = _diag0c_dma,
  50        .diag308_reset = _diag308_reset_dma
  51};
  52static struct diag210 _diag210_tmp_dma __section(".dma.data");
  53struct diag210 *__bootdata_preserved(__diag210_tmp_dma) = &_diag210_tmp_dma;
  54
  55void error(char *x)
  56{
  57        sclp_early_printk("\n\n");
  58        sclp_early_printk(x);
  59        sclp_early_printk("\n\n -- System halted");
  60
  61        disabled_wait();
  62}
  63
  64static void setup_lpp(void)
  65{
  66        S390_lowcore.current_pid = 0;
  67        S390_lowcore.lpp = LPP_MAGIC;
  68        if (test_facility(40))
  69                lpp(&S390_lowcore.lpp);
  70}
  71
  72#ifdef CONFIG_KERNEL_UNCOMPRESSED
  73unsigned long mem_safe_offset(void)
  74{
  75        return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;
  76}
  77#endif
  78
  79static void rescue_initrd(unsigned long addr)
  80{
  81        if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
  82                return;
  83        if (!INITRD_START || !INITRD_SIZE)
  84                return;
  85        if (addr <= INITRD_START)
  86                return;
  87        memmove((void *)addr, (void *)INITRD_START, INITRD_SIZE);
  88        INITRD_START = addr;
  89}
  90
  91static void copy_bootdata(void)
  92{
  93        if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
  94                error(".boot.data section size mismatch");
  95        memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
  96        if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
  97                error(".boot.preserved.data section size mismatch");
  98        memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
  99}
 100
 101static void handle_relocs(unsigned long offset)
 102{
 103        Elf64_Rela *rela_start, *rela_end, *rela;
 104        int r_type, r_sym, rc;
 105        Elf64_Addr loc, val;
 106        Elf64_Sym *dynsym;
 107
 108        rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
 109        rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
 110        dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
 111        for (rela = rela_start; rela < rela_end; rela++) {
 112                loc = rela->r_offset + offset;
 113                val = rela->r_addend;
 114                r_sym = ELF64_R_SYM(rela->r_info);
 115                if (r_sym) {
 116                        if (dynsym[r_sym].st_shndx != SHN_UNDEF)
 117                                val += dynsym[r_sym].st_value + offset;
 118                } else {
 119                        /*
 120                         * 0 == undefined symbol table index (STN_UNDEF),
 121                         * used for R_390_RELATIVE, only add KASLR offset
 122                         */
 123                        val += offset;
 124                }
 125                r_type = ELF64_R_TYPE(rela->r_info);
 126                rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
 127                if (rc)
 128                        error("Unknown relocation type");
 129        }
 130}
 131
 132/*
 133 * Merge information from several sources into a single ident_map_size value.
 134 * "ident_map_size" represents the upper limit of physical memory we may ever
 135 * reach. It might not be all online memory, but also include standby (offline)
 136 * memory. "ident_map_size" could be lower then actual standby or even online
 137 * memory present, due to limiting factors. We should never go above this limit.
 138 * It is the size of our identity mapping.
 139 *
 140 * Consider the following factors:
 141 * 1. max_physmem_end - end of physical memory online or standby.
 142 *    Always <= end of the last online memory block (get_mem_detect_end()).
 143 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
 144 *    kernel is able to support.
 145 * 3. "mem=" kernel command line option which limits physical memory usage.
 146 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
 147 *    crash kernel.
 148 * 5. "hsa" size which is a memory limit when the kernel is executed during
 149 *    zfcp/nvme dump.
 150 */
 151static void setup_ident_map_size(unsigned long max_physmem_end)
 152{
 153        unsigned long hsa_size;
 154
 155        ident_map_size = max_physmem_end;
 156        if (memory_limit)
 157                ident_map_size = min(ident_map_size, memory_limit);
 158        ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS);
 159
 160#ifdef CONFIG_CRASH_DUMP
 161        if (OLDMEM_BASE) {
 162                kaslr_enabled = 0;
 163                ident_map_size = min(ident_map_size, OLDMEM_SIZE);
 164        } else if (ipl_block_valid && is_ipl_block_dump()) {
 165                kaslr_enabled = 0;
 166                if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
 167                        ident_map_size = min(ident_map_size, hsa_size);
 168        }
 169#endif
 170}
 171
 172/*
 173 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
 174 */
 175static void clear_bss_section(void)
 176{
 177        memset((void *)vmlinux.default_lma + vmlinux.image_size, 0, vmlinux.bss_size);
 178}
 179
 180/*
 181 * Set vmalloc area size to an 8th of (potential) physical memory
 182 * size, unless size has been set by kernel command line parameter.
 183 */
 184static void setup_vmalloc_size(void)
 185{
 186        unsigned long size;
 187
 188        if (vmalloc_size_set)
 189                return;
 190        size = round_up(ident_map_size / 8, _SEGMENT_SIZE);
 191        vmalloc_size = max(size, vmalloc_size);
 192}
 193
 194void startup_kernel(void)
 195{
 196        unsigned long random_lma;
 197        unsigned long safe_addr;
 198        void *img;
 199
 200        setup_lpp();
 201        store_ipl_parmblock();
 202        safe_addr = mem_safe_offset();
 203        safe_addr = read_ipl_report(safe_addr);
 204        uv_query_info();
 205        rescue_initrd(safe_addr);
 206        sclp_early_read_info();
 207        setup_boot_command_line();
 208        parse_boot_command_line();
 209        setup_ident_map_size(detect_memory());
 210        setup_vmalloc_size();
 211
 212        random_lma = __kaslr_offset = 0;
 213        if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_enabled) {
 214                random_lma = get_random_base(safe_addr);
 215                if (random_lma) {
 216                        __kaslr_offset = random_lma - vmlinux.default_lma;
 217                        img = (void *)vmlinux.default_lma;
 218                        vmlinux.default_lma += __kaslr_offset;
 219                        vmlinux.entry += __kaslr_offset;
 220                        vmlinux.bootdata_off += __kaslr_offset;
 221                        vmlinux.bootdata_preserved_off += __kaslr_offset;
 222                        vmlinux.rela_dyn_start += __kaslr_offset;
 223                        vmlinux.rela_dyn_end += __kaslr_offset;
 224                        vmlinux.dynsym_start += __kaslr_offset;
 225                }
 226        }
 227
 228        if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
 229                img = decompress_kernel();
 230                memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
 231        } else if (__kaslr_offset)
 232                memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size);
 233
 234        clear_bss_section();
 235        copy_bootdata();
 236        if (IS_ENABLED(CONFIG_RELOCATABLE))
 237                handle_relocs(__kaslr_offset);
 238
 239        if (__kaslr_offset) {
 240                /*
 241                 * Save KASLR offset for early dumps, before vmcore_info is set.
 242                 * Mark as uneven to distinguish from real vmcore_info pointer.
 243                 */
 244                S390_lowcore.vmcore_info = __kaslr_offset | 0x1UL;
 245                /* Clear non-relocated kernel */
 246                if (IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED))
 247                        memset(img, 0, vmlinux.image_size);
 248        }
 249        vmlinux.entry();
 250}
 251