OpenRISC: Memory management

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 283 insertions, 0 deletions

diff --git a/arch/openrisc/mm/init.c b/arch/openrisc/mm/init.c
new file mode 100644
index 000000000000..359dcb20fe85
--- /dev/null
+++ b/arch/openrisc/mm/init.c
@@ -0,0 +1,283 @@
+/*
+ * OpenRISC idle.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/bootmem.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/blkdev.h>	/* for initrd_* */
+#include <linux/pagemap.h>
+#include <linux/memblock.h>
+
+#include <asm/system.h>
+#include <asm/segment.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/dma.h>
+#include <asm/io.h>
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+#include <asm/kmap_types.h>
+#include <asm/fixmap.h>
+#include <asm/tlbflush.h>
+
+int mem_init_done;
+
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+
+static void __init zone_sizes_init(void)
+{
+	unsigned long zones_size[MAX_NR_ZONES];
+
+	/* Clear the zone sizes */
+	memset(zones_size, 0, sizeof(zones_size));
+
+	/*
+	 * We use only ZONE_NORMAL
+	 */
+	zones_size[ZONE_NORMAL] = max_low_pfn;
+
+	free_area_init(zones_size);
+}
+
+extern const char _s_kernel_ro[], _e_kernel_ro[];
+
+/*
+ * Map all physical memory into kernel's address space.
+ *
+ * This is explicitly coded for two-level page tables, so if you need
+ * something else then this needs to change.
+ */
+static void __init map_ram(void)
+{
+	unsigned long v, p, e;
+	pgprot_t prot;
+	pgd_t *pge;
+	pud_t *pue;
+	pmd_t *pme;
+	pte_t *pte;
+	/* These mark extents of read-only kernel pages...
+	 * ...from vmlinux.lds.S
+	 */
+	struct memblock_region *region;
+
+	v = PAGE_OFFSET;
+
+	for_each_memblock(memory, region) {
+		p = (u32) region->base & PAGE_MASK;
+		e = p + (u32) region->size;
+
+		v = (u32) __va(p);
+		pge = pgd_offset_k(v);
+
+		while (p < e) {
+			int j;
+			pue = pud_offset(pge, v);
+			pme = pmd_offset(pue, v);
+
+			if ((u32) pue != (u32) pge || (u32) pme != (u32) pge) {
+				panic("%s: OR1K kernel hardcoded for "
+				      "two-level page tables",
+				     __func__);
+			}
+
+			/* Alloc one page for holding PTE's... */
+			pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+			set_pmd(pme, __pmd(_KERNPG_TABLE + __pa(pte)));
+
+			/* Fill the newly allocated page with PTE'S */
+			for (j = 0; p < e && j < PTRS_PER_PGD;
+			     v += PAGE_SIZE, p += PAGE_SIZE, j++, pte++) {
+				if (v >= (u32) _e_kernel_ro ||
+				    v < (u32) _s_kernel_ro)
+					prot = PAGE_KERNEL;
+				else
+					prot = PAGE_KERNEL_RO;
+
+				set_pte(pte, mk_pte_phys(p, prot));
+			}
+
+			pge++;
+		}
+
+		printk(KERN_INFO "%s: Memory: 0x%x-0x%x\n", __func__,
+		       region->base, region->base + region->size);
+	}
+}
+
+void __init paging_init(void)
+{
+	extern void tlb_init(void);
+
+	unsigned long end;
+	int i;
+
+	printk(KERN_INFO "Setting up paging and PTEs.\n");
+
+	/* clear out the init_mm.pgd that will contain the kernel's mappings */
+
+	for (i = 0; i < PTRS_PER_PGD; i++)
+		swapper_pg_dir[i] = __pgd(0);
+
+	/* make sure the current pgd table points to something sane
+	 * (even if it is most probably not used until the next
+	 *  switch_mm)
+	 */
+	current_pgd = init_mm.pgd;
+
+	end = (unsigned long)__va(max_low_pfn * PAGE_SIZE);
+
+	map_ram();
+
+	zone_sizes_init();
+
+	/* self modifying code ;) */
+	/* Since the old TLB miss handler has been running up until now,
+	 * the kernel pages are still all RW, so we can still modify the
+	 * text directly... after this change and a TLB flush, the kernel
+	 * pages will become RO.
+	 */
+	{
+		extern unsigned long dtlb_miss_handler;
+		extern unsigned long itlb_miss_handler;
+
+		unsigned long *dtlb_vector = __va(0x900);
+		unsigned long *itlb_vector = __va(0xa00);
+
+		printk(KERN_INFO "dtlb_miss_handler %p\n", &dtlb_miss_handler);
+		*dtlb_vector = ((unsigned long)&dtlb_miss_handler -
+				(unsigned long)dtlb_vector) >> 2;
+
+		printk(KERN_INFO "itlb_miss_handler %p\n", &itlb_miss_handler);
+		*itlb_vector = ((unsigned long)&itlb_miss_handler -
+				(unsigned long)itlb_vector) >> 2;
+	}
+
+	/* Invalidate instruction caches after code modification */
+	mtspr(SPR_ICBIR, 0x900);
+	mtspr(SPR_ICBIR, 0xa00);
+
+	/* New TLB miss handlers and kernel page tables are in now place.
+	 * Make sure that page flags get updated for all pages in TLB by
+	 * flushing the TLB and forcing all TLB entries to be recreated
+	 * from their page table flags.
+	 */
+	flush_tlb_all();
+}
+
+/* References to section boundaries */
+
+extern char _stext, _etext, _edata, __bss_start, _end;
+extern char __init_begin, __init_end;
+
+static int __init free_pages_init(void)
+{
+	int reservedpages, pfn;
+
+	/* this will put all low memory onto the freelists */
+	totalram_pages = free_all_bootmem();
+
+	reservedpages = 0;
+	for (pfn = 0; pfn < max_low_pfn; pfn++) {
+		/*
+		 * Only count reserved RAM pages
+		 */
+		if (PageReserved(mem_map + pfn))
+			reservedpages++;
+	}
+
+	return reservedpages;
+}
+
+static void __init set_max_mapnr_init(void)
+{
+	max_mapnr = num_physpages = max_low_pfn;
+}
+
+void __init mem_init(void)
+{
+	int codesize, reservedpages, datasize, initsize;
+
+	if (!mem_map)
+		BUG();
+
+	set_max_mapnr_init();
+
+	high_memory = (void *)__va(max_low_pfn * PAGE_SIZE);
+
+	/* clear the zero-page */
+	memset((void *)empty_zero_page, 0, PAGE_SIZE);
+
+	reservedpages = free_pages_init();
+
+	codesize = (unsigned long)&_etext - (unsigned long)&_stext;
+	datasize = (unsigned long)&_edata - (unsigned long)&_etext;
+	initsize = (unsigned long)&__init_end - (unsigned long)&__init_begin;
+
+	printk(KERN_INFO
+	       "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
+	       (unsigned long)nr_free_pages() << (PAGE_SHIFT - 10),
+	       max_mapnr << (PAGE_SHIFT - 10), codesize >> 10,
+	       reservedpages << (PAGE_SHIFT - 10), datasize >> 10,
+	       initsize >> 10, (unsigned long)(0 << (PAGE_SHIFT - 10))
+	    );
+
+	printk("mem_init_done ...........................................\n");
+	mem_init_done = 1;
+	return;
+}
+
+#ifdef CONFIG_BLK_DEV_INITRD
+void free_initrd_mem(unsigned long start, unsigned long end)
+{
+	printk(KERN_INFO "Freeing initrd memory: %ldk freed\n",
+	       (end - start) >> 10);
+
+	for (; start < end; start += PAGE_SIZE) {
+		ClearPageReserved(virt_to_page(start));
+		init_page_count(virt_to_page(start));
+		free_page(start);
+		totalram_pages++;
+	}
+}
+#endif
+
+void free_initmem(void)
+{
+	unsigned long addr;
+
+	addr = (unsigned long)(&__init_begin);
+	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
+		ClearPageReserved(virt_to_page(addr));
+		init_page_count(virt_to_page(addr));
+		free_page(addr);
+		totalram_pages++;
+	}
+	printk(KERN_INFO "Freeing unused kernel memory: %luk freed\n",
+	       ((unsigned long)&__init_end -
+		(unsigned long)&__init_begin) >> 10);
+}