arm64: kaslr: Reserve size of ARM64_MEMSTART_ALIGN in linear region

[linux-stable.git] / arch / arm64 / mm / init.c

/*
 * Based on arch/arm/mm/init.c
 *
 * Copyright (C) 1995-2005 Russell King
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/errno.h>
#include <linux/swap.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/cache.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/initrd.h>
#include <linux/gfp.h>
#include <linux/memblock.h>
#include <linux/sort.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/dma-mapping.h>
#include <linux/dma-contiguous.h>
#include <linux/efi.h>
#include <linux/swiotlb.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/crash_dump.h>

#include <asm/boot.h>
#include <asm/fixmap.h>
#include <asm/kasan.h>
#include <asm/kernel-pgtable.h>
#include <asm/memory.h>
#include <asm/numa.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/sizes.h>
#include <asm/tlb.h>
#include <asm/alternative.h>

/*
 * We need to be able to catch inadvertent references to memstart_addr
 * that occur (potentially in generic code) before arm64_memblock_init()
 * executes, which assigns it its actual value. So use a default value
 * that cannot be mistaken for a real physical address.
 */
s64 memstart_addr __ro_after_init = -1;
phys_addr_t arm64_dma_phys_limit __ro_after_init;

#ifdef CONFIG_BLK_DEV_INITRD
static int __init early_initrd(char *p)
{
        unsigned long start, size;
        char *endp;

        start = memparse(p, &endp);
        if (*endp == ',') {
                size = memparse(endp + 1, NULL);

                initrd_start = start;
                initrd_end = start + size;
        }
        return 0;
}
early_param("initrd", early_initrd);
#endif

#ifdef CONFIG_KEXEC_CORE
/*
 * reserve_crashkernel() - reserves memory for crash kernel
 *
 * This function reserves memory area given in "crashkernel=" kernel command
 * line parameter. The memory reserved is used by dump capture kernel when
 * primary kernel is crashing.
 */
static void __init reserve_crashkernel(void)
{
        unsigned long long crash_base, crash_size;
        int ret;

        ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
                                &crash_size, &crash_base);
        /* no crashkernel= or invalid value specified */
        if (ret || !crash_size)
                return;

        crash_size = PAGE_ALIGN(crash_size);

        if (crash_base == 0) {
                /* Current arm64 boot protocol requires 2MB alignment */
                crash_base = memblock_find_in_range(0, ARCH_LOW_ADDRESS_LIMIT,
                                crash_size, SZ_2M);
                if (crash_base == 0) {
                        pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
                                crash_size);
                        return;
                }
        } else {
                /* User specifies base address explicitly. */
                if (!memblock_is_region_memory(crash_base, crash_size)) {
                        pr_warn("cannot reserve crashkernel: region is not memory\n");
                        return;
                }

                if (memblock_is_region_reserved(crash_base, crash_size)) {
                        pr_warn("cannot reserve crashkernel: region overlaps reserved memory\n");
                        return;
                }

                if (!IS_ALIGNED(crash_base, SZ_2M)) {
                        pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
                        return;
                }
        }
        memblock_reserve(crash_base, crash_size);

        pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
                crash_base, crash_base + crash_size, crash_size >> 20);

        crashk_res.start = crash_base;
        crashk_res.end = crash_base + crash_size - 1;
}

static void __init kexec_reserve_crashkres_pages(void)
{
#ifdef CONFIG_HIBERNATION
        phys_addr_t addr;
        struct page *page;

        if (!crashk_res.end)
                return;

        /*
         * To reduce the size of hibernation image, all the pages are
         * marked as Reserved initially.
         */
        for (addr = crashk_res.start; addr < (crashk_res.end + 1);
                        addr += PAGE_SIZE) {
                page = phys_to_page(addr);
                SetPageReserved(page);
        }
#endif
}
#else
static void __init reserve_crashkernel(void)
{
}

static void __init kexec_reserve_crashkres_pages(void)
{
}
#endif /* CONFIG_KEXEC_CORE */

#ifdef CONFIG_CRASH_DUMP
static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
                const char *uname, int depth, void *data)
{
        const __be32 *reg;
        int len;

        if (depth != 1 || strcmp(uname, "chosen") != 0)
                return 0;

        reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
        if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
                return 1;

        elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &reg);
        elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &reg);

        return 1;
}

/*
 * reserve_elfcorehdr() - reserves memory for elf core header
 *
 * This function reserves the memory occupied by an elf core header
 * described in the device tree. This region contains all the
 * information about primary kernel's core image and is used by a dump
 * capture kernel to access the system memory on primary kernel.
 */
static void __init reserve_elfcorehdr(void)
{
        of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);

        if (!elfcorehdr_size)
                return;

        if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
                pr_warn("elfcorehdr is overlapped\n");
                return;
        }

        memblock_reserve(elfcorehdr_addr, elfcorehdr_size);

        pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
                elfcorehdr_size >> 10, elfcorehdr_addr);
}
#else
static void __init reserve_elfcorehdr(void)
{
}
#endif /* CONFIG_CRASH_DUMP */
/*
 * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
 * currently assumes that for memory starting above 4G, 32-bit devices will
 * use a DMA offset.
 */
static phys_addr_t __init max_zone_dma_phys(void)
{
        phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, 32);
        return min(offset + (1ULL << 32), memblock_end_of_DRAM());
}

#ifdef CONFIG_NUMA

static void __init zone_sizes_init(unsigned long min, unsigned long max)
{
        unsigned long max_zone_pfns[MAX_NR_ZONES]  = {0};

        if (IS_ENABLED(CONFIG_ZONE_DMA))
                max_zone_pfns[ZONE_DMA] = PFN_DOWN(max_zone_dma_phys());
        max_zone_pfns[ZONE_NORMAL] = max;

        free_area_init_nodes(max_zone_pfns);
}

#else

static void __init zone_sizes_init(unsigned long min, unsigned long max)
{
        struct memblock_region *reg;
        unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
        unsigned long max_dma = min;

        memset(zone_size, 0, sizeof(zone_size));

        /* 4GB maximum for 32-bit only capable devices */
#ifdef CONFIG_ZONE_DMA
        max_dma = PFN_DOWN(arm64_dma_phys_limit);
        zone_size[ZONE_DMA] = max_dma - min;
#endif
        zone_size[ZONE_NORMAL] = max - max_dma;

        memcpy(zhole_size, zone_size, sizeof(zhole_size));

        for_each_memblock(memory, reg) {
                unsigned long start = memblock_region_memory_base_pfn(reg);
                unsigned long end = memblock_region_memory_end_pfn(reg);

                if (start >= max)
                        continue;

#ifdef CONFIG_ZONE_DMA
                if (start < max_dma) {
                        unsigned long dma_end = min(end, max_dma);
                        zhole_size[ZONE_DMA] -= dma_end - start;
                }
#endif
                if (end > max_dma) {
                        unsigned long normal_end = min(end, max);
                        unsigned long normal_start = max(start, max_dma);
                        zhole_size[ZONE_NORMAL] -= normal_end - normal_start;
                }
        }

        free_area_init_node(0, zone_size, min, zhole_size);
}

#endif /* CONFIG_NUMA */

#ifdef CONFIG_HAVE_ARCH_PFN_VALID
int pfn_valid(unsigned long pfn)
{
        phys_addr_t addr = pfn << PAGE_SHIFT;

        if ((addr >> PAGE_SHIFT) != pfn)
                return 0;
        return memblock_is_map_memory(addr);
}
EXPORT_SYMBOL(pfn_valid);
#endif

#ifndef CONFIG_SPARSEMEM
static void __init arm64_memory_present(void)
{
}
#else
static void __init arm64_memory_present(void)
{
        struct memblock_region *reg;

        for_each_memblock(memory, reg) {
                int nid = memblock_get_region_node(reg);

                memory_present(nid, memblock_region_memory_base_pfn(reg),
                                memblock_region_memory_end_pfn(reg));
        }
}
#endif

static phys_addr_t memory_limit = (phys_addr_t)ULLONG_MAX;

/*
 * Limit the memory size that was specified via FDT.
 */
static int __init early_mem(char *p)
{
        if (!p)
                return 1;

        memory_limit = memparse(p, &p) & PAGE_MASK;
        pr_notice("Memory limited to %lldMB\n", memory_limit >> 20);

        return 0;
}
early_param("mem", early_mem);

static int __init early_init_dt_scan_usablemem(unsigned long node,
                const char *uname, int depth, void *data)
{
        struct memblock_region *usablemem = data;
        const __be32 *reg;
        int len;

        if (depth != 1 || strcmp(uname, "chosen") != 0)
                return 0;

        reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
        if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
                return 1;

        usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
        usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);

        return 1;
}

static void __init fdt_enforce_memory_region(void)
{
        struct memblock_region reg = {
                .size = 0,
        };

        of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);

        if (reg.size)
                memblock_cap_memory_range(reg.base, reg.size);
}

void __init arm64_memblock_init(void)
{
        const s64 linear_region_size = -(s64)PAGE_OFFSET;

        /* Handle linux,usable-memory-range property */
        fdt_enforce_memory_region();

        /*
         * Ensure that the linear region takes up exactly half of the kernel
         * virtual address space. This way, we can distinguish a linear address
         * from a kernel/module/vmalloc address by testing a single bit.
         */
        BUILD_BUG_ON(linear_region_size != BIT(VA_BITS - 1));

        /*
         * Select a suitable value for the base of physical memory.
         */
        memstart_addr = round_down(memblock_start_of_DRAM(),
                                   ARM64_MEMSTART_ALIGN);

        /*
         * Remove the memory that we will not be able to cover with the
         * linear mapping. Take care not to clip the kernel which may be
         * high in memory.
         */
        memblock_remove(max_t(u64, memstart_addr + linear_region_size,
                        __pa_symbol(_end)), ULLONG_MAX);
        if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {
                /* ensure that memstart_addr remains sufficiently aligned */
                memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size,
                                         ARM64_MEMSTART_ALIGN);
                memblock_remove(0, memstart_addr);
        }

        /*
         * Apply the memory limit if it was set. Since the kernel may be loaded
         * high up in memory, add back the kernel region that must be accessible
         * via the linear mapping.
         */
        if (memory_limit != (phys_addr_t)ULLONG_MAX) {
                memblock_mem_limit_remove_map(memory_limit);
                memblock_add(__pa_symbol(_text), (u64)(_end - _text));
        }

        if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
                /*
                 * Add back the memory we just removed if it results in the
                 * initrd to become inaccessible via the linear mapping.
                 * Otherwise, this is a no-op
                 */
                u64 base = initrd_start & PAGE_MASK;
                u64 size = PAGE_ALIGN(initrd_end) - base;

                /*
                 * We can only add back the initrd memory if we don't end up
                 * with more memory than we can address via the linear mapping.
                 * It is up to the bootloader to position the kernel and the
                 * initrd reasonably close to each other (i.e., within 32 GB of
                 * each other) so that all granule/#levels combinations can
                 * always access both.
                 */
                if (WARN(base < memblock_start_of_DRAM() ||
                         base + size > memblock_start_of_DRAM() +
                                       linear_region_size,
                        "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
                        initrd_start = 0;
                } else {
                        memblock_remove(base, size); /* clear MEMBLOCK_ flags */
                        memblock_add(base, size);
                        memblock_reserve(base, size);
                }
        }

        if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
                extern u16 memstart_offset_seed;
                u64 range = linear_region_size -
                            (memblock_end_of_DRAM() - memblock_start_of_DRAM());

                /*
                 * If the size of the linear region exceeds, by a sufficient
                 * margin, the size of the region that the available physical
                 * memory spans, randomize the linear region as well.
                 */
                if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
                        range /= ARM64_MEMSTART_ALIGN;
                        memstart_addr -= ARM64_MEMSTART_ALIGN *
                                         ((range * memstart_offset_seed) >> 16);
                }
        }

        /*
         * Register the kernel text, kernel data, initrd, and initial
         * pagetables with memblock.
         */
        memblock_reserve(__pa_symbol(_text), _end - _text);
#ifdef CONFIG_BLK_DEV_INITRD
        if (initrd_start) {
                memblock_reserve(initrd_start, initrd_end - initrd_start);

                /* the generic initrd code expects virtual addresses */
                initrd_start = __phys_to_virt(initrd_start);
                initrd_end = __phys_to_virt(initrd_end);
        }
#endif

        early_init_fdt_scan_reserved_mem();

        /* 4GB maximum for 32-bit only capable devices */
        if (IS_ENABLED(CONFIG_ZONE_DMA))
                arm64_dma_phys_limit = max_zone_dma_phys();
        else
                arm64_dma_phys_limit = PHYS_MASK + 1;

        reserve_crashkernel();

        reserve_elfcorehdr();

        high_memory = __va(memblock_end_of_DRAM() - 1) + 1;

        dma_contiguous_reserve(arm64_dma_phys_limit);

        memblock_allow_resize();
}

void __init bootmem_init(void)
{
        unsigned long min, max;

        min = PFN_UP(memblock_start_of_DRAM());
        max = PFN_DOWN(memblock_end_of_DRAM());

        early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT);

        max_pfn = max_low_pfn = max;

        arm64_numa_init();
        /*
         * Sparsemem tries to allocate bootmem in memory_present(), so must be
         * done after the fixed reservations.
         */
        arm64_memory_present();

        sparse_init();
        zone_sizes_init(min, max);

        memblock_dump_all();
}

#ifndef CONFIG_SPARSEMEM_VMEMMAP
static inline void free_memmap(unsigned long start_pfn, unsigned long end_pfn)
{
        struct page *start_pg, *end_pg;
        unsigned long pg, pgend;

        /*
         * Convert start_pfn/end_pfn to a struct page pointer.
         */
        start_pg = pfn_to_page(start_pfn - 1) + 1;
        end_pg = pfn_to_page(end_pfn - 1) + 1;

        /*
         * Convert to physical addresses, and round start upwards and end
         * downwards.
         */
        pg = (unsigned long)PAGE_ALIGN(__pa(start_pg));
        pgend = (unsigned long)__pa(end_pg) & PAGE_MASK;

        /*
         * If there are free pages between these, free the section of the
         * memmap array.
         */
        if (pg < pgend)
                free_bootmem(pg, pgend - pg);
}

/*
 * The mem_map array can get very big. Free the unused area of the memory map.
 */
static void __init free_unused_memmap(void)
{
        unsigned long start, prev_end = 0;
        struct memblock_region *reg;

        for_each_memblock(memory, reg) {
                start = __phys_to_pfn(reg->base);

#ifdef CONFIG_SPARSEMEM
                /*
                 * Take care not to free memmap entries that don't exist due
                 * to SPARSEMEM sections which aren't present.
                 */
                start = min(start, ALIGN(prev_end, PAGES_PER_SECTION));
#endif
                /*
                 * If we had a previous bank, and there is a space between the
                 * current bank and the previous, free it.
                 */
                if (prev_end && prev_end < start)
                        free_memmap(prev_end, start);

                /*
                 * Align up here since the VM subsystem insists that the
                 * memmap entries are valid from the bank end aligned to
                 * MAX_ORDER_NR_PAGES.
                 */
                prev_end = ALIGN(__phys_to_pfn(reg->base + reg->size),
                                 MAX_ORDER_NR_PAGES);
        }

#ifdef CONFIG_SPARSEMEM
        if (!IS_ALIGNED(prev_end, PAGES_PER_SECTION))
                free_memmap(prev_end, ALIGN(prev_end, PAGES_PER_SECTION));
#endif
}
#endif  /* !CONFIG_SPARSEMEM_VMEMMAP */

/*
 * mem_init() marks the free areas in the mem_map and tells us how much memory
 * is free.  This is done after various parts of the system have claimed their
 * memory after the kernel image.
 */
void __init mem_init(void)
{
        if (swiotlb_force == SWIOTLB_FORCE ||
            max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
                swiotlb_init(1);
        else
                swiotlb_force = SWIOTLB_NO_FORCE;

        set_max_mapnr(pfn_to_page(max_pfn) - mem_map);

#ifndef CONFIG_SPARSEMEM_VMEMMAP
        free_unused_memmap();
#endif
        /* this will put all unused low memory onto the freelists */
        free_all_bootmem();

        kexec_reserve_crashkres_pages();

        mem_init_print_info(NULL);

#define MLK(b, t) b, t, ((t) - (b)) >> 10
#define MLM(b, t) b, t, ((t) - (b)) >> 20
#define MLG(b, t) b, t, ((t) - (b)) >> 30
#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)

        pr_notice("Virtual kernel memory layout:\n");
#ifdef CONFIG_KASAN
        pr_notice("    kasan   : 0x%16lx - 0x%16lx   (%6ld GB)\n",
                MLG(KASAN_SHADOW_START, KASAN_SHADOW_END));
#endif
        pr_notice("    modules : 0x%16lx - 0x%16lx   (%6ld MB)\n",
                MLM(MODULES_VADDR, MODULES_END));
        pr_notice("    vmalloc : 0x%16lx - 0x%16lx   (%6ld GB)\n",
                MLG(VMALLOC_START, VMALLOC_END));
        pr_notice("      .text : 0x%p" " - 0x%p" "   (%6ld KB)\n",
                MLK_ROUNDUP(_text, _etext));
        pr_notice("    .rodata : 0x%p" " - 0x%p" "   (%6ld KB)\n",
                MLK_ROUNDUP(__start_rodata, __init_begin));
        pr_notice("      .init : 0x%p" " - 0x%p" "   (%6ld KB)\n",
                MLK_ROUNDUP(__init_begin, __init_end));
        pr_notice("      .data : 0x%p" " - 0x%p" "   (%6ld KB)\n",
                MLK_ROUNDUP(_sdata, _edata));
        pr_notice("       .bss : 0x%p" " - 0x%p" "   (%6ld KB)\n",
                MLK_ROUNDUP(__bss_start, __bss_stop));
        pr_notice("    fixed   : 0x%16lx - 0x%16lx   (%6ld KB)\n",
                MLK(FIXADDR_START, FIXADDR_TOP));
        pr_notice("    PCI I/O : 0x%16lx - 0x%16lx   (%6ld MB)\n",
                MLM(PCI_IO_START, PCI_IO_END));
#ifdef CONFIG_SPARSEMEM_VMEMMAP
        pr_notice("    vmemmap : 0x%16lx - 0x%16lx   (%6ld GB maximum)\n",
                MLG(VMEMMAP_START, VMEMMAP_START + VMEMMAP_SIZE));
        pr_notice("              0x%16lx - 0x%16lx   (%6ld MB actual)\n",
                MLM((unsigned long)phys_to_page(memblock_start_of_DRAM()),
                    (unsigned long)virt_to_page(high_memory)));
#endif
        pr_notice("    memory  : 0x%16lx - 0x%16lx   (%6ld MB)\n",
                MLM(__phys_to_virt(memblock_start_of_DRAM()),
                    (unsigned long)high_memory));

#undef MLK
#undef MLM
#undef MLK_ROUNDUP

        /*
         * Check boundaries twice: Some fundamental inconsistencies can be
         * detected at build time already.
         */
#ifdef CONFIG_COMPAT
        BUILD_BUG_ON(TASK_SIZE_32                       > TASK_SIZE_64);
#endif

#ifdef CONFIG_SPARSEMEM_VMEMMAP
        /*
         * Make sure we chose the upper bound of sizeof(struct page)
         * correctly when sizing the VMEMMAP array.
         */
        BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT));
#endif

        if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {
                extern int sysctl_overcommit_memory;
                /*
                 * On a machine this small we won't get anywhere without
                 * overcommit, so turn it on by default.
                 */
                sysctl_overcommit_memory = OVERCOMMIT_ALWAYS;
        }
}

void free_initmem(void)
{
        free_reserved_area(lm_alias(__init_begin),
                           lm_alias(__init_end),
                           0, "unused kernel");
        /*
         * Unmap the __init region but leave the VM area in place. This
         * prevents the region from being reused for kernel modules, which
         * is not supported by kallsyms.
         */
        unmap_kernel_range((u64)__init_begin, (u64)(__init_end - __init_begin));
}

#ifdef CONFIG_BLK_DEV_INITRD

static int keep_initrd __initdata;

void __init free_initrd_mem(unsigned long start, unsigned long end)
{
        if (!keep_initrd)
                free_reserved_area((void *)start, (void *)end, 0, "initrd");
}

static int __init keepinitrd_setup(char *__unused)
{
        keep_initrd = 1;
        return 1;
}

__setup("keepinitrd", keepinitrd_setup);
#endif

/*
 * Dump out memory limit information on panic.
 */
static int dump_mem_limit(struct notifier_block *self, unsigned long v, void *p)
{
        if (memory_limit != (phys_addr_t)ULLONG_MAX) {
                pr_emerg("Memory Limit: %llu MB\n", memory_limit >> 20);
        } else {
                pr_emerg("Memory Limit: none\n");
        }
        return 0;
}

static struct notifier_block mem_limit_notifier = {
        .notifier_call = dump_mem_limit,
};

static int __init register_mem_limit_dumper(void)
{
        atomic_notifier_chain_register(&panic_notifier_list,
                                       &mem_limit_notifier);
        return 0;
}
__initcall(register_mem_limit_dumper);