diff options
Diffstat (limited to 'arch/s390/boot/startup.c')
| -rw-r--r-- | arch/s390/boot/startup.c | 378 |
1 files changed, 378 insertions, 0 deletions
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c new file mode 100644 index 0000000000..d3e48bd9c3 --- /dev/null +++ b/arch/s390/boot/startup.c @@ -0,0 +1,378 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/string.h> +#include <linux/elf.h> +#include <asm/boot_data.h> +#include <asm/sections.h> +#include <asm/maccess.h> +#include <asm/cpu_mf.h> +#include <asm/setup.h> +#include <asm/kasan.h> +#include <asm/kexec.h> +#include <asm/sclp.h> +#include <asm/diag.h> +#include <asm/uv.h> +#include <asm/abs_lowcore.h> +#include <asm/physmem_info.h> +#include "decompressor.h" +#include "boot.h" +#include "uv.h" + +unsigned long __bootdata_preserved(__kaslr_offset); +unsigned long __bootdata_preserved(__abs_lowcore); +unsigned long __bootdata_preserved(__memcpy_real_area); +pte_t *__bootdata_preserved(memcpy_real_ptep); +unsigned long __bootdata_preserved(VMALLOC_START); +unsigned long __bootdata_preserved(VMALLOC_END); +struct page *__bootdata_preserved(vmemmap); +unsigned long __bootdata_preserved(vmemmap_size); +unsigned long __bootdata_preserved(MODULES_VADDR); +unsigned long __bootdata_preserved(MODULES_END); +unsigned long __bootdata_preserved(max_mappable); +unsigned long __bootdata(ident_map_size); + +u64 __bootdata_preserved(stfle_fac_list[16]); +u64 __bootdata_preserved(alt_stfle_fac_list[16]); +struct oldmem_data __bootdata_preserved(oldmem_data); + +struct machine_info machine; + +void error(char *x) +{ + sclp_early_printk("\n\n"); + sclp_early_printk(x); + sclp_early_printk("\n\n -- System halted"); + + disabled_wait(); +} + +static void detect_facilities(void) +{ + if (test_facility(8)) { + machine.has_edat1 = 1; + __ctl_set_bit(0, 23); + } + if (test_facility(78)) + machine.has_edat2 = 1; + if (test_facility(130)) + machine.has_nx = 1; +} + +static void setup_lpp(void) +{ + S390_lowcore.current_pid = 0; + S390_lowcore.lpp = LPP_MAGIC; + if (test_facility(40)) + lpp(&S390_lowcore.lpp); +} + +#ifdef CONFIG_KERNEL_UNCOMPRESSED +unsigned long mem_safe_offset(void) +{ + return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size; +} +#endif + +static void rescue_initrd(unsigned long min, unsigned long max) +{ + unsigned long old_addr, addr, size; + + if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD)) + return; + if (!get_physmem_reserved(RR_INITRD, &addr, &size)) + return; + if (addr >= min && addr + size <= max) + return; + old_addr = addr; + physmem_free(RR_INITRD); + addr = physmem_alloc_top_down(RR_INITRD, size, 0); + memmove((void *)addr, (void *)old_addr, size); +} + +static void copy_bootdata(void) +{ + if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size) + error(".boot.data section size mismatch"); + memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size); + if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size) + error(".boot.preserved.data section size mismatch"); + memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size); +} + +static void handle_relocs(unsigned long offset) +{ + Elf64_Rela *rela_start, *rela_end, *rela; + int r_type, r_sym, rc; + Elf64_Addr loc, val; + Elf64_Sym *dynsym; + + rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start; + rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end; + dynsym = (Elf64_Sym *) vmlinux.dynsym_start; + for (rela = rela_start; rela < rela_end; rela++) { + loc = rela->r_offset + offset; + val = rela->r_addend; + r_sym = ELF64_R_SYM(rela->r_info); + if (r_sym) { + if (dynsym[r_sym].st_shndx != SHN_UNDEF) + val += dynsym[r_sym].st_value + offset; + } else { + /* + * 0 == undefined symbol table index (STN_UNDEF), + * used for R_390_RELATIVE, only add KASLR offset + */ + val += offset; + } + r_type = ELF64_R_TYPE(rela->r_info); + rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0); + if (rc) + error("Unknown relocation type"); + } +} + +/* + * Merge information from several sources into a single ident_map_size value. + * "ident_map_size" represents the upper limit of physical memory we may ever + * reach. It might not be all online memory, but also include standby (offline) + * memory. "ident_map_size" could be lower then actual standby or even online + * memory present, due to limiting factors. We should never go above this limit. + * It is the size of our identity mapping. + * + * Consider the following factors: + * 1. max_physmem_end - end of physical memory online or standby. + * Always >= end of the last online memory range (get_physmem_online_end()). + * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the + * kernel is able to support. + * 3. "mem=" kernel command line option which limits physical memory usage. + * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as + * crash kernel. + * 5. "hsa" size which is a memory limit when the kernel is executed during + * zfcp/nvme dump. + */ +static void setup_ident_map_size(unsigned long max_physmem_end) +{ + unsigned long hsa_size; + + ident_map_size = max_physmem_end; + if (memory_limit) + ident_map_size = min(ident_map_size, memory_limit); + ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS); + +#ifdef CONFIG_CRASH_DUMP + if (oldmem_data.start) { + __kaslr_enabled = 0; + ident_map_size = min(ident_map_size, oldmem_data.size); + } else if (ipl_block_valid && is_ipl_block_dump()) { + __kaslr_enabled = 0; + if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size) + ident_map_size = min(ident_map_size, hsa_size); + } +#endif +} + +static unsigned long setup_kernel_memory_layout(void) +{ + unsigned long vmemmap_start; + unsigned long asce_limit; + unsigned long rte_size; + unsigned long pages; + unsigned long vsize; + unsigned long vmax; + + pages = ident_map_size / PAGE_SIZE; + /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */ + vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page); + + /* choose kernel address space layout: 4 or 3 levels. */ + vsize = round_up(ident_map_size, _REGION3_SIZE) + vmemmap_size + + MODULES_LEN + MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE; + vsize = size_add(vsize, vmalloc_size); + if (IS_ENABLED(CONFIG_KASAN) || (vsize > _REGION2_SIZE)) { + asce_limit = _REGION1_SIZE; + rte_size = _REGION2_SIZE; + } else { + asce_limit = _REGION2_SIZE; + rte_size = _REGION3_SIZE; + } + + /* + * Forcing modules and vmalloc area under the ultravisor + * secure storage limit, so that any vmalloc allocation + * we do could be used to back secure guest storage. + */ + vmax = adjust_to_uv_max(asce_limit); +#ifdef CONFIG_KASAN + /* force vmalloc and modules below kasan shadow */ + vmax = min(vmax, KASAN_SHADOW_START); +#endif + __memcpy_real_area = round_down(vmax - MEMCPY_REAL_SIZE, PAGE_SIZE); + __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE, + sizeof(struct lowcore)); + MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE); + MODULES_VADDR = MODULES_END - MODULES_LEN; + VMALLOC_END = MODULES_VADDR; + + /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ + vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE)); + VMALLOC_START = VMALLOC_END - vmalloc_size; + + /* split remaining virtual space between 1:1 mapping & vmemmap array */ + pages = VMALLOC_START / (PAGE_SIZE + sizeof(struct page)); + pages = SECTION_ALIGN_UP(pages); + /* keep vmemmap_start aligned to a top level region table entry */ + vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size); + vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS); + /* maximum mappable address as seen by arch_get_mappable_range() */ + max_mappable = vmemmap_start; + /* make sure identity map doesn't overlay with vmemmap */ + ident_map_size = min(ident_map_size, vmemmap_start); + vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page); + /* make sure vmemmap doesn't overlay with vmalloc area */ + VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START); + vmemmap = (struct page *)vmemmap_start; + + return asce_limit; +} + +/* + * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's. + */ +static void clear_bss_section(unsigned long vmlinux_lma) +{ + memset((void *)vmlinux_lma + vmlinux.image_size, 0, vmlinux.bss_size); +} + +/* + * Set vmalloc area size to an 8th of (potential) physical memory + * size, unless size has been set by kernel command line parameter. + */ +static void setup_vmalloc_size(void) +{ + unsigned long size; + + if (vmalloc_size_set) + return; + size = round_up(ident_map_size / 8, _SEGMENT_SIZE); + vmalloc_size = max(size, vmalloc_size); +} + +static void offset_vmlinux_info(unsigned long offset) +{ + *(unsigned long *)(&vmlinux.entry) += offset; + vmlinux.bootdata_off += offset; + vmlinux.bootdata_preserved_off += offset; + vmlinux.rela_dyn_start += offset; + vmlinux.rela_dyn_end += offset; + vmlinux.dynsym_start += offset; + vmlinux.init_mm_off += offset; + vmlinux.swapper_pg_dir_off += offset; + vmlinux.invalid_pg_dir_off += offset; +#ifdef CONFIG_KASAN + vmlinux.kasan_early_shadow_page_off += offset; + vmlinux.kasan_early_shadow_pte_off += offset; + vmlinux.kasan_early_shadow_pmd_off += offset; + vmlinux.kasan_early_shadow_pud_off += offset; + vmlinux.kasan_early_shadow_p4d_off += offset; +#endif +} + +void startup_kernel(void) +{ + unsigned long max_physmem_end; + unsigned long vmlinux_lma = 0; + unsigned long amode31_lma = 0; + unsigned long asce_limit; + unsigned long safe_addr; + void *img; + psw_t psw; + + setup_lpp(); + safe_addr = mem_safe_offset(); + + /* + * Reserve decompressor memory together with decompression heap, buffer and + * memory which might be occupied by uncompressed kernel at default 1Mb + * position (if KASLR is off or failed). + */ + physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr); + if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size) + physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size); + oldmem_data.start = parmarea.oldmem_base; + oldmem_data.size = parmarea.oldmem_size; + + store_ipl_parmblock(); + read_ipl_report(); + uv_query_info(); + sclp_early_read_info(); + setup_boot_command_line(); + parse_boot_command_line(); + detect_facilities(); + sanitize_prot_virt_host(); + max_physmem_end = detect_max_physmem_end(); + setup_ident_map_size(max_physmem_end); + setup_vmalloc_size(); + asce_limit = setup_kernel_memory_layout(); + /* got final ident_map_size, physmem allocations could be performed now */ + physmem_set_usable_limit(ident_map_size); + detect_physmem_online_ranges(max_physmem_end); + save_ipl_cert_comp_list(); + rescue_initrd(safe_addr, ident_map_size); + + if (kaslr_enabled()) { + vmlinux_lma = randomize_within_range(vmlinux.image_size + vmlinux.bss_size, + THREAD_SIZE, vmlinux.default_lma, + ident_map_size); + if (vmlinux_lma) { + __kaslr_offset = vmlinux_lma - vmlinux.default_lma; + offset_vmlinux_info(__kaslr_offset); + } + } + vmlinux_lma = vmlinux_lma ?: vmlinux.default_lma; + physmem_reserve(RR_VMLINUX, vmlinux_lma, vmlinux.image_size + vmlinux.bss_size); + + if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) { + img = decompress_kernel(); + memmove((void *)vmlinux_lma, img, vmlinux.image_size); + } else if (__kaslr_offset) { + img = (void *)vmlinux.default_lma; + memmove((void *)vmlinux_lma, img, vmlinux.image_size); + memset(img, 0, vmlinux.image_size); + } + + /* vmlinux decompression is done, shrink reserved low memory */ + physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end); + if (kaslr_enabled()) + amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G); + amode31_lma = amode31_lma ?: vmlinux.default_lma - vmlinux.amode31_size; + physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size); + + /* + * The order of the following operations is important: + * + * - handle_relocs() must follow clear_bss_section() to establish static + * memory references to data in .bss to be used by setup_vmem() + * (i.e init_mm.pgd) + * + * - setup_vmem() must follow handle_relocs() to be able using + * static memory references to data in .bss (i.e init_mm.pgd) + * + * - copy_bootdata() must follow setup_vmem() to propagate changes to + * bootdata made by setup_vmem() + */ + clear_bss_section(vmlinux_lma); + handle_relocs(__kaslr_offset); + setup_vmem(asce_limit); + copy_bootdata(); + + /* + * Save KASLR offset for early dumps, before vmcore_info is set. + * Mark as uneven to distinguish from real vmcore_info pointer. + */ + S390_lowcore.vmcore_info = __kaslr_offset ? __kaslr_offset | 0x1UL : 0; + + /* + * Jump to the decompressed kernel entry point and switch DAT mode on. + */ + psw.addr = vmlinux.entry; + psw.mask = PSW_KERNEL_BITS; + __load_psw(psw); +} |