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 000000000..d3e48bd9c
--- /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);
+}