WSL2-Linux-Kernel/arch/arc/mm/init.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/memblock.h>
#ifdef CONFIG_BLK_DEV_INITRD
#include <linux/initrd.h>
#endif
#include <linux/of_fdt.h>
#include <linux/swap.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <asm/page.h>
#include <asm/sections.h>
#include <asm/arcregs.h>

pgd_t swapper_pg_dir[PTRS_PER_PGD] __aligned(PAGE_SIZE);
char empty_zero_page[PAGE_SIZE] __aligned(PAGE_SIZE);
EXPORT_SYMBOL(empty_zero_page);

static const unsigned long low_mem_start = CONFIG_LINUX_RAM_BASE;
static unsigned long low_mem_sz;

#ifdef CONFIG_HIGHMEM
static unsigned long min_high_pfn, max_high_pfn;
static phys_addr_t high_mem_start;
static phys_addr_t high_mem_sz;
unsigned long arch_pfn_offset;
EXPORT_SYMBOL(arch_pfn_offset);
#endif

long __init arc_get_mem_sz(void)
{
	return low_mem_sz;
}

/* User can over-ride above with "mem=nnn[KkMm]" in cmdline */
static int __init setup_mem_sz(char *str)
{
	low_mem_sz = memparse(str, NULL) & PAGE_MASK;

	/* early console might not be setup yet - it will show up later */
	pr_info("\"mem=%s\": mem sz set to %ldM\n", str, TO_MB(low_mem_sz));

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

void __init early_init_dt_add_memory_arch(u64 base, u64 size)
{
	int in_use = 0;

	if (!low_mem_sz) {
		if (base != low_mem_start)
			panic("CONFIG_LINUX_RAM_BASE != DT memory { }");

		low_mem_sz = size;
		in_use = 1;
		memblock_add_node(base, size, 0, MEMBLOCK_NONE);
	} else {
#ifdef CONFIG_HIGHMEM
		high_mem_start = base;
		high_mem_sz = size;
		in_use = 1;
		memblock_add_node(base, size, 1, MEMBLOCK_NONE);
		memblock_reserve(base, size);
#endif
	}

	pr_info("Memory @ %llx [%lldM] %s\n",
		base, TO_MB(size), !in_use ? "Not used":"");
}

bool arch_has_descending_max_zone_pfns(void)
{
	return !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
}

/*
 * First memory setup routine called from setup_arch()
 * 1. setup swapper's mm @init_mm
 * 2. Count the pages we have and setup bootmem allocator
 * 3. zone setup
 */
void __init setup_arch_memory(void)
{
	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };

	setup_initial_init_mm(_text, _etext, _edata, _end);

	/* first page of system - kernel .vector starts here */
	min_low_pfn = virt_to_pfn(CONFIG_LINUX_RAM_BASE);

	/* Last usable page of low mem */
	max_low_pfn = max_pfn = PFN_DOWN(low_mem_start + low_mem_sz);

	/*------------- bootmem allocator setup -----------------------*/

	/*
	 * seed the bootmem allocator after any DT memory node parsing or
	 * "mem=xxx" cmdline overrides have potentially updated @arc_mem_sz
	 *
	 * Only low mem is added, otherwise we have crashes when allocating
	 * mem_map[] itself. NO_BOOTMEM allocates mem_map[] at the end of
	 * avail memory, ending in highmem with a > 32-bit address. However
	 * it then tries to memset it with a truncaed 32-bit handle, causing
	 * the crash
	 */

	memblock_reserve(CONFIG_LINUX_LINK_BASE,
			 __pa(_end) - CONFIG_LINUX_LINK_BASE);

#ifdef CONFIG_BLK_DEV_INITRD
	if (phys_initrd_size) {
		memblock_reserve(phys_initrd_start, phys_initrd_size);
		initrd_start = (unsigned long)__va(phys_initrd_start);
		initrd_end = initrd_start + phys_initrd_size;
	}
#endif

	early_init_fdt_reserve_self();
	early_init_fdt_scan_reserved_mem();

	memblock_dump_all();

	/*----------------- node/zones setup --------------------------*/
	max_zone_pfn[ZONE_NORMAL] = max_low_pfn;

#ifdef CONFIG_HIGHMEM
	/*
	 * On ARC (w/o PAE) HIGHMEM addresses are actually smaller (0 based)
	 * than addresses in normal aka low memory (0x8000_0000 based).
	 * Even with PAE, the huge peripheral space hole would waste a lot of
	 * mem with single contiguous mem_map[].
	 * Thus when HIGHMEM on ARC is enabled the memory map corresponding
	 * to the hole is freed and ARC specific version of pfn_valid()
	 * handles the hole in the memory map.
	 */

	min_high_pfn = PFN_DOWN(high_mem_start);
	max_high_pfn = PFN_DOWN(high_mem_start + high_mem_sz);

	/*
	 * max_high_pfn should be ok here for both HIGHMEM and HIGHMEM+PAE.
	 * For HIGHMEM without PAE max_high_pfn should be less than
	 * min_low_pfn to guarantee that these two regions don't overlap.
	 * For PAE case highmem is greater than lowmem, so it is natural
	 * to use max_high_pfn.
	 *
	 * In both cases, holes should be handled by pfn_valid().
	 */
	max_zone_pfn[ZONE_HIGHMEM] = max_high_pfn;

	high_memory = (void *)(min_high_pfn << PAGE_SHIFT);

	arch_pfn_offset = min(min_low_pfn, min_high_pfn);
	kmap_init();

#else /* CONFIG_HIGHMEM */
	/* pfn_valid() uses this when FLATMEM=y and HIGHMEM=n */
	max_mapnr = max_low_pfn - min_low_pfn;

#endif /* CONFIG_HIGHMEM */

	free_area_init(max_zone_pfn);
}

static void __init highmem_init(void)
{
#ifdef CONFIG_HIGHMEM
	unsigned long tmp;

	memblock_phys_free(high_mem_start, high_mem_sz);
	for (tmp = min_high_pfn; tmp < max_high_pfn; tmp++)
		free_highmem_page(pfn_to_page(tmp));
#endif
}

/*
 * mem_init - initializes memory
 *
 * Frees up bootmem
 * Calculates and displays memory available/used
 */
void __init mem_init(void)
{
	memblock_free_all();
	highmem_init();

	BUILD_BUG_ON((PTRS_PER_PGD * sizeof(pgd_t)) > PAGE_SIZE);
	BUILD_BUG_ON((PTRS_PER_PUD * sizeof(pud_t)) > PAGE_SIZE);
	BUILD_BUG_ON((PTRS_PER_PMD * sizeof(pmd_t)) > PAGE_SIZE);
	BUILD_BUG_ON((PTRS_PER_PTE * sizeof(pte_t)) > PAGE_SIZE);
}

#ifdef CONFIG_HIGHMEM
int pfn_valid(unsigned long pfn)
{
	return (pfn >= min_high_pfn && pfn <= max_high_pfn) ||
		(pfn >= min_low_pfn && pfn <= max_low_pfn);
}
EXPORT_SYMBOL(pfn_valid);
#endif