// SPDX-License-Identifier: GPL-2.0 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "decompressor.h" #include "boot.h" #include "uv.h" struct vm_layout __bootdata_preserved(vm_layout); 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); u64 __bootdata_preserved(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; local_ctl_set_bit(0, CR0_EDAT_BIT); } if (test_facility(78)) machine.has_edat2 = 1; if (test_facility(130)) machine.has_nx = 1; } static int cmma_test_essa(void) { unsigned long reg1, reg2, tmp = 0; int rc = 1; psw_t old; /* Test ESSA_GET_STATE */ asm volatile( " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n" " epsw %[reg1],%[reg2]\n" " st %[reg1],0(%[psw_pgm])\n" " st %[reg2],4(%[psw_pgm])\n" " larl %[reg1],1f\n" " stg %[reg1],8(%[psw_pgm])\n" " .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n" " la %[rc],0\n" "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n" : [reg1] "=&d" (reg1), [reg2] "=&a" (reg2), [rc] "+&d" (rc), [tmp] "=&d" (tmp), "+Q" (S390_lowcore.program_new_psw), "=Q" (old) : [psw_old] "a" (&old), [psw_pgm] "a" (&S390_lowcore.program_new_psw), [cmd] "i" (ESSA_GET_STATE) : "cc", "memory"); return rc; } static void cmma_init(void) { if (!cmma_flag) return; if (cmma_test_essa()) { cmma_flag = 0; return; } if (test_facility(147)) cmma_flag = 2; } 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 static unsigned long mem_safe_offset(void) { return (unsigned long)_compressed_start; } static void deploy_kernel(void *output) { void *uncompressed_start = (void *)_compressed_start; if (output == uncompressed_start) return; memmove(output, uncompressed_start, vmlinux.image_size); memset(uncompressed_start, 0, vmlinux.image_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 kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr, unsigned long offset, unsigned long phys_offset) { int *reloc; long loc; /* Adjust R_390_64 relocations */ for (reloc = (int *)__vmlinux_relocs_64_start; reloc < (int *)__vmlinux_relocs_64_end; reloc++) { loc = (long)*reloc + phys_offset; if (loc < min_addr || loc > max_addr) error("64-bit relocation outside of kernel!\n"); *(u64 *)loc += offset - __START_KERNEL; } } static void kaslr_adjust_got(unsigned long offset) { u64 *entry; /* * Adjust GOT entries, except for ones for undefined weak symbols * that resolved to zero. This also skips the first three reserved * entries on s390x that are zero. */ for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++) { if (*entry) *entry += offset - __START_KERNEL; } } /* * 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 } #define FIXMAP_SIZE round_up(MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore)) static unsigned long get_vmem_size(unsigned long identity_size, unsigned long vmemmap_size, unsigned long vmalloc_size, unsigned long rte_size) { unsigned long max_mappable, vsize; max_mappable = max(identity_size, MAX_DCSS_ADDR); vsize = round_up(SZ_2G + max_mappable, rte_size) + round_up(vmemmap_size, rte_size) + FIXMAP_SIZE + MODULES_LEN + KASLR_LEN; return size_add(vsize, vmalloc_size); } static unsigned long setup_kernel_memory_layout(unsigned long kernel_size) { unsigned long vmemmap_start; unsigned long kernel_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. */ BUILD_BUG_ON(!IS_ALIGNED(__START_KERNEL, THREAD_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(__NO_KASLR_START_KERNEL, THREAD_SIZE)); BUILD_BUG_ON(__NO_KASLR_END_KERNEL > _REGION1_SIZE); vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE); if (IS_ENABLED(CONFIG_KASAN) || __NO_KASLR_END_KERNEL > _REGION2_SIZE || (vsize > _REGION2_SIZE && kaslr_enabled())) { asce_limit = _REGION1_SIZE; if (__NO_KASLR_END_KERNEL > _REGION2_SIZE) { rte_size = _REGION2_SIZE; vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION2_SIZE); } else { rte_size = _REGION3_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. * * Assume the secure storage limit always exceeds _REGION2_SIZE, * otherwise asce_limit and rte_size would have been adjusted. */ vmax = adjust_to_uv_max(asce_limit); #ifdef CONFIG_KASAN BUILD_BUG_ON(__NO_KASLR_END_KERNEL > KASAN_SHADOW_START); /* force vmalloc and modules below kasan shadow */ vmax = min(vmax, KASAN_SHADOW_START); #endif vsize = min(vsize, vmax); if (kaslr_enabled()) { unsigned long kernel_end, kaslr_len, slots, pos; kaslr_len = max(KASLR_LEN, vmax - vsize); slots = DIV_ROUND_UP(kaslr_len - kernel_size, THREAD_SIZE); if (get_random(slots, &pos)) pos = 0; kernel_end = vmax - pos * THREAD_SIZE; kernel_start = round_down(kernel_end - kernel_size, THREAD_SIZE); } else if (vmax < __NO_KASLR_END_KERNEL || vsize > __NO_KASLR_END_KERNEL) { kernel_start = round_down(vmax - kernel_size, THREAD_SIZE); decompressor_printk("The kernel base address is forced to %lx\n", kernel_start); } else { kernel_start = __NO_KASLR_START_KERNEL; } __kaslr_offset = kernel_start; MODULES_END = round_down(kernel_start, _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 */ vsize = (VMALLOC_END - FIXMAP_SIZE) / 2; vsize = round_down(vsize, _SEGMENT_SIZE); vmalloc_size = min(vmalloc_size, vsize); VMALLOC_START = VMALLOC_END - vmalloc_size; __memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE); __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore)); /* split remaining virtual space between 1:1 mapping & vmemmap array */ pages = __abs_lowcore / (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(__abs_lowcore - pages * sizeof(struct page), rte_size); /* 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 absolute lowcore area */ if (vmemmap_start + vmemmap_size > __abs_lowcore) { vmemmap_size = SECTION_ALIGN_DOWN(ident_map_size / PAGE_SIZE) * sizeof(struct page); ident_map_size = vmemmap_size / sizeof(struct page) * PAGE_SIZE; } vmemmap = (struct page *)vmemmap_start; /* maximum address for which linear mapping could be created (DCSS, memory) */ BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS)); max_mappable = max(ident_map_size, MAX_DCSS_ADDR); max_mappable = min(max_mappable, vmemmap_start); __identity_base = round_down(vmemmap_start - max_mappable, rte_size); 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 kernel_start) { memset((void *)kernel_start + 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 kaslr_adjust_vmlinux_info(long offset) { vmlinux.bootdata_off += offset; vmlinux.bootdata_preserved_off += offset; vmlinux.got_start += offset; vmlinux.got_end += 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 } static void fixup_vmlinux_info(void) { vmlinux.entry -= __START_KERNEL; kaslr_adjust_vmlinux_info(-__START_KERNEL); } void startup_kernel(void) { unsigned long kernel_size = vmlinux.image_size + vmlinux.bss_size; unsigned long nokaslr_offset_phys, kaslr_large_page_offset; unsigned long amode31_lma = 0; unsigned long max_physmem_end; unsigned long asce_limit; unsigned long safe_addr; psw_t psw; fixup_vmlinux_info(); setup_lpp(); /* * Non-randomized kernel physical start address must be _SEGMENT_SIZE * aligned (see blow). */ nokaslr_offset_phys = ALIGN(mem_safe_offset(), _SEGMENT_SIZE); safe_addr = PAGE_ALIGN(nokaslr_offset_phys + kernel_size); /* * Reserve decompressor memory together with decompression heap, * buffer and memory which might be occupied by uncompressed kernel * (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(); cmma_init(); 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(kernel_size); /* 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); /* * __kaslr_offset_phys must be _SEGMENT_SIZE aligned, so the lower * 20 bits (the offset within a large page) are zero. Copy the last * 20 bits of __kaslr_offset, which is THREAD_SIZE aligned, to * __kaslr_offset_phys. * * With this the last 20 bits of __kaslr_offset_phys and __kaslr_offset * are identical, which is required to allow for large mappings of the * kernel image. */ kaslr_large_page_offset = __kaslr_offset & ~_SEGMENT_MASK; if (kaslr_enabled()) { unsigned long end = ident_map_size - kaslr_large_page_offset; __kaslr_offset_phys = randomize_within_range(kernel_size, _SEGMENT_SIZE, 0, end); } if (!__kaslr_offset_phys) __kaslr_offset_phys = nokaslr_offset_phys; __kaslr_offset_phys |= kaslr_large_page_offset; kaslr_adjust_vmlinux_info(__kaslr_offset_phys); physmem_reserve(RR_VMLINUX, __kaslr_offset_phys, kernel_size); deploy_kernel((void *)__kaslr_offset_phys); /* vmlinux decompression is done, shrink reserved low memory */ physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end); /* * In case KASLR is enabled the randomized location of .amode31 * section might overlap with .vmlinux.relocs section. To avoid that * the below randomize_within_range() could have been called with * __vmlinux_relocs_64_end as the lower range address. However, * .amode31 section is written to by the decompressed kernel - at * that time the contents of .vmlinux.relocs is not needed anymore. * Conversly, .vmlinux.relocs is read only by the decompressor, even * before the kernel started. Therefore, in case the two sections * overlap there is no risk of corrupting any data. */ if (kaslr_enabled()) amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G); if (!amode31_lma) amode31_lma = __kaslr_offset_phys - vmlinux.amode31_size; physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size); /* * The order of the following operations is important: * * - kaslr_adjust_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 kaslr_adjust_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(__kaslr_offset_phys); kaslr_adjust_relocs(__kaslr_offset_phys, __kaslr_offset_phys + vmlinux.image_size, __kaslr_offset, __kaslr_offset_phys); kaslr_adjust_got(__kaslr_offset); setup_vmem(__kaslr_offset, __kaslr_offset + kernel_size, 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_phys ? __kaslr_offset_phys | 0x1UL : 0; /* * Jump to the decompressed kernel entry point and switch DAT mode on. */ psw.addr = __kaslr_offset + vmlinux.entry; psw.mask = PSW_KERNEL_BITS; __load_psw(psw); }