Hexagon: Add page-fault support.

/*

 * Memory layout definitions for the Hexagon architecture

 *

 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

#ifndef _ASM_HEXAGON_MEM_LAYOUT_H

#define _ASM_HEXAGON_MEM_LAYOUT_H

#include <linux/const.h>

/*

 * Have to do this for ginormous numbers, else they get printed as

 * negative numbers, which the linker no likey when you try to

 * assign it to the location counter.

 */

#define PAGE_OFFSET			_AC(0xc0000000, UL)

/*

 * LOAD_ADDRESS is the physical/linear address of where in memory

 * the kernel gets loaded. The 12 least significant bits must be zero (0)

 * due to limitations on setting the EVB

 *

 */

#ifndef LOAD_ADDRESS

#define LOAD_ADDRESS			0x00000000

#endif

#define TASK_SIZE			(PAGE_OFFSET)

/*  not sure how these are used yet  */

#define STACK_TOP			TASK_SIZE

#define STACK_TOP_MAX			TASK_SIZE

#ifndef __ASSEMBLY__

enum fixed_addresses {

	FIX_KMAP_BEGIN,

	FIX_KMAP_END,  /*  check for per-cpuism  */

	__end_of_fixed_addresses

};

#define MIN_KERNEL_SEG 0x300   /* From 0xc0000000 */

extern int max_kernel_seg;

/*

 * Start of vmalloc virtual address space for kernel;

 * supposed to be based on the amount of physical memory available

 */

#define VMALLOC_START (PAGE_OFFSET + VMALLOC_OFFSET + \

	(unsigned long)high_memory)

/* Gap between physical ram and vmalloc space for guard purposes. */

#define VMALLOC_OFFSET PAGE_SIZE

/*

 * Create the space between VMALLOC_START and FIXADDR_TOP backwards

 * from the ... "top".

 *

 * Permanent IO mappings will live at 0xfexx_xxxx

 * Hypervisor occupies the last 16MB page at 0xffxxxxxx

 */

#define FIXADDR_TOP     0xfe000000

#define FIXADDR_SIZE    (__end_of_fixed_addresses << PAGE_SHIFT)

#define FIXADDR_START   (FIXADDR_TOP - FIXADDR_SIZE)

/*

 * "permanent kernel mappings", defined as long-lasting mappings of

 * high-memory page frames into the kernel address space.

 */

#define LAST_PKMAP	PTRS_PER_PTE

#define LAST_PKMAP_MASK	(LAST_PKMAP - 1)

#define PKMAP_NR(virt)	((virt - PKMAP_BASE) >> PAGE_SHIFT)

#define PKMAP_ADDR(nr)	(PKMAP_BASE + ((nr) << PAGE_SHIFT))

/*

 * To the "left" of the fixed map space is the kmap space

 *

 * "Permanent Kernel Mappings"; fancy (or less fancy) PTE table

 * that looks like it's actually walked.

 * Need to check the alignment/shift usage; some archs use

 * PMD_MASK on this value

 */

#define PKMAP_BASE (FIXADDR_START-PAGE_SIZE*LAST_PKMAP)

/*

 * 2 pages of guard gap between where vmalloc area ends

 * and pkmap_base begins.

 */

#define VMALLOC_END (PKMAP_BASE-PAGE_SIZE*2)

#endif /*  !__ASSEMBLY__  */

#endif /* _ASM_HEXAGON_MEM_LAYOUT_H */

/*

 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

#ifndef _ASM_HEXAGON_VM_FAULT_H

#define _ASM_HEXAGON_VM_FAULT_H

extern void execute_protection_fault(struct pt_regs *);

extern void write_protection_fault(struct pt_regs *);

extern void read_protection_fault(struct pt_regs *);

#endif

/*

 * Memory subsystem initialization for Hexagon

 *

 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

#include <linux/init.h>

#include <linux/mm.h>

#include <linux/bootmem.h>

#include <asm/atomic.h>

#include <linux/highmem.h>

#include <asm/tlb.h>

#include <asm/sections.h>

#include <asm/vm_mmu.h>

/*

 * Define a startpg just past the end of the kernel image and a lastpg

 * that corresponds to the end of real or simulated platform memory.

 */

#define bootmem_startpg (PFN_UP(((unsigned long) _end) - PAGE_OFFSET))

unsigned long bootmem_lastpg;  /*  Should be set by platform code  */

/*  Set as variable to limit PMD copies  */

int max_kernel_seg = 0x303;

/*  think this should be (page_size-1) the way it's used...*/

unsigned long zero_page_mask;

/*  indicate pfn's of high memory  */

unsigned long highstart_pfn, highend_pfn;

/* struct mmu_gather defined in asm-generic.h;  */

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

/* Default cache attribute for newly created page tables */

unsigned long _dflt_cache_att = CACHEDEF;

/*

 * The current "generation" of kernel map, which should not roll

 * over until Hell freezes over.  Actual bound in years needs to be

 * calculated to confirm.

 */

DEFINE_SPINLOCK(kmap_gen_lock);

/*  checkpatch says don't init this to 0.  */

unsigned long long kmap_generation;

/*

 * mem_init - initializes memory

 *

 * Frees up bootmem

 * Fixes up more stuff for HIGHMEM

 * Calculates and displays memory available/used

 */

void __init mem_init(void)

{

	/*  No idea where this is actually declared.  Seems to evade LXR.  */

	totalram_pages += free_all_bootmem();

	num_physpages = bootmem_lastpg;	/*  seriously, what?  */

	printk(KERN_INFO "totalram_pages = %ld\n", totalram_pages);

	/*

	 *  To-Do:  someone somewhere should wipe out the bootmem map

	 *  after we're done?

	 */

	/*

	 * This can be moved to some more virtual-memory-specific

	 * initialization hook at some point.  Set the init_mm

	 * descriptors "context" value to point to the initial

	 * kernel segment table's physical address.

	 */

	init_mm.context.ptbase = __pa(init_mm.pgd);

}

/*

 * free_initmem - frees memory used by stuff declared with __init

 *

 * Todo:  free pages between __init_begin and __init_end; possibly

 * some devtree related stuff as well.

 */

void __init_refok free_initmem(void)

{

}

/*

 * free_initrd_mem - frees...  initrd memory.

 * @start - start of init memory

 * @end - end of init memory

 *

 * Apparently has to be passed the address of the initrd memory.

 *

 * Wrapped by #ifdef CONFIG_BLKDEV_INITRD

 */

void free_initrd_mem(unsigned long start, unsigned long end)

{

}

void sync_icache_dcache(pte_t pte)

{

	unsigned long addr;

	struct page *page;

	page = pte_page(pte);

	addr = (unsigned long) page_address(page);

	__vmcache_idsync(addr, PAGE_SIZE);

}

/*

 * In order to set up page allocator "nodes",

 * somebody has to call free_area_init() for UMA.

 *

 * In this mode, we only have one pg_data_t

 * structure: contig_mem_data.

 */

void __init paging_init(void)

{

	unsigned long zones_sizes[MAX_NR_ZONES] = {0, };

	/*

	 *  This is not particularly well documented anywhere, but

	 *  give ZONE_NORMAL all the memory, including the big holes

	 *  left by the kernel+bootmem_map which are already left as reserved

	 *  in the bootmem_map; free_area_init should see those bits and

	 *  adjust accordingly.

	 */

	zones_sizes[ZONE_NORMAL] = max_low_pfn;

	free_area_init(zones_sizes);  /*  sets up the zonelists and mem_map  */

	/*

	 * Start of high memory area.  Will probably need something more

	 * fancy if we...  get more fancy.

	 */

	high_memory = (void *)((bootmem_lastpg + 1) << PAGE_SHIFT);

}

#ifndef DMA_RESERVE

#define DMA_RESERVE		(4)

#endif

#define DMA_CHUNKSIZE		(1<<22)

#define DMA_RESERVED_BYTES	(DMA_RESERVE * DMA_CHUNKSIZE)

/*

 * Pick out the memory size.  We look for mem=size,

 * where size is "size[KkMm]"

 */

static int __init early_mem(char *p)

{

	unsigned long size;

	char *endp;

	size = memparse(p, &endp);

	bootmem_lastpg = PFN_DOWN(size);

	return 0;

}

early_param("mem", early_mem);

size_t hexagon_coherent_pool_size = (size_t) (DMA_RESERVE << 22);

void __init setup_arch_memory(void)

{

	int bootmap_size;

	/*  XXX Todo: this probably should be cleaned up  */

	u32 *segtable = (u32 *) &swapper_pg_dir[0];

	u32 *segtable_end;

	/*

	 * Set up boot memory allocator

	 *

	 * The Gorman book also talks about these functions.

	 * This needs to change for highmem setups.

	 */

	/* Memory size needs to be a multiple of 16M */

	bootmem_lastpg = PFN_DOWN((bootmem_lastpg << PAGE_SHIFT) &

		~((BIG_KERNEL_PAGE_SIZE) - 1));

	/*

	 * Reserve the top DMA_RESERVE bytes of RAM for DMA (uncached)

	 * memory allocation

	 */

	bootmap_size = init_bootmem(bootmem_startpg, bootmem_lastpg -

				    PFN_DOWN(DMA_RESERVED_BYTES));

	printk(KERN_INFO "bootmem_startpg:  0x%08lx\n", bootmem_startpg);

	printk(KERN_INFO "bootmem_lastpg:  0x%08lx\n", bootmem_lastpg);

	printk(KERN_INFO "bootmap_size:  %d\n", bootmap_size);

	printk(KERN_INFO "max_low_pfn:  0x%08lx\n", max_low_pfn);

	/*

	 * The default VM page tables (will be) populated with

	 * VA=PA+PAGE_OFFSET mapping.  We go in and invalidate entries

	 * higher than what we have memory for.

	 */

	/*  this is pointer arithmetic; each entry covers 4MB  */

	segtable = segtable + (PAGE_OFFSET >> 22);

	/*  this actually only goes to the end of the first gig  */

	segtable_end = segtable + (1<<(30-22));

	/*  Move forward to the start of empty pages  */

	segtable += bootmem_lastpg >> (22-PAGE_SHIFT);

	{

	    int i;

	    for (i = 1 ; i <= DMA_RESERVE ; i++)

		segtable[-i] = ((segtable[-i] & __HVM_PTE_PGMASK_4MB)

				| __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X

				| __HEXAGON_C_UNC << 6

				| __HVM_PDE_S_4MB);

	}

	printk(KERN_INFO "clearing segtable from %p to %p\n", segtable,

		segtable_end);

	while (segtable < (segtable_end-8))

		*(segtable++) = __HVM_PDE_S_INVALID;

	/* stop the pointer at the device I/O 4MB page  */

	printk(KERN_INFO "segtable = %p (should be equal to _K_io_map)\n",

		segtable);

#if 0

	/*  Other half of the early device table from vm_init_segtable. */

	printk(KERN_INFO "&_K_init_devicetable = 0x%08x\n",

		(unsigned long) _K_init_devicetable-PAGE_OFFSET);

	*segtable = ((u32) (unsigned long) _K_init_devicetable-PAGE_OFFSET) |

		__HVM_PDE_S_4KB;

	printk(KERN_INFO "*segtable = 0x%08x\n", *segtable);

#endif

	/*

	 * Free all the memory that wasn't taken up by the bootmap, the DMA

	 * reserve, or kernel itself.

	 */

	free_bootmem(PFN_PHYS(bootmem_startpg)+bootmap_size,

		     PFN_PHYS(bootmem_lastpg - bootmem_startpg) - bootmap_size -

		     DMA_RESERVED_BYTES);

	/*

	 *  The bootmem allocator seemingly just lives to feed memory

	 *  to the paging system

	 */

	printk(KERN_INFO "PAGE_SIZE=%lu\n", PAGE_SIZE);

	paging_init();  /*  See Gorman Book, 2.3  */

	/*

	 *  At this point, the page allocator is kind of initialized, but

	 *  apparently no pages are available (just like with the bootmem

	 *  allocator), and need to be freed themselves via mem_init(),

	 *  which is called by start_kernel() later on in the process

	 */

}

/*

 * Memory fault handling for Hexagon

 *

 * Copyright (c) 2010-2011 Code Aurora Forum. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

/*

 * Page fault handling for the Hexagon Virtual Machine.

 * Can also be called by a native port emulating the HVM

 * execptions.

 */

#include <asm/pgtable.h>

#include <asm/traps.h>

#include <asm/uaccess.h>

#include <linux/mm.h>

#include <linux/signal.h>

#include <linux/module.h>

#include <linux/hardirq.h>

/*

 * Decode of hardware exception sends us to one of several

 * entry points.  At each, we generate canonical arguments

 * for handling by the abstract memory management code.

 */

#define FLT_IFETCH     -1

#define FLT_LOAD        0

#define FLT_STORE       1

/*

 * Canonical page fault handler

 */

void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)

{

	struct vm_area_struct *vma;

	struct mm_struct *mm = current->mm;

	siginfo_t info;

	int si_code = SEGV_MAPERR;

	int fault;

	const struct exception_table_entry *fixup;

	/*

	 * If we're in an interrupt or have no user context,

	 * then must not take the fault.

	 */

	if (unlikely(in_interrupt() || !mm))

		goto no_context;

	local_irq_enable();

	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);

	if (!vma)

		goto bad_area;

	if (vma->vm_start <= address)

		goto good_area;

	if (!(vma->vm_flags & VM_GROWSDOWN))

		goto bad_area;

	if (expand_stack(vma, address))

		goto bad_area;

good_area:

	/* Address space is OK.  Now check access rights. */

	si_code = SEGV_ACCERR;

	switch (cause) {

	case FLT_IFETCH:

		if (!(vma->vm_flags & VM_EXEC))

			goto bad_area;

		break;

	case FLT_LOAD:

		if (!(vma->vm_flags & VM_READ))

			goto bad_area;

		break;

	case FLT_STORE:

		if (!(vma->vm_flags & VM_WRITE))

			goto bad_area;

		break;

	}

	fault = handle_mm_fault(mm, vma, address, (cause > 0));

	/* The most common case -- we are done. */

	if (likely(!(fault & VM_FAULT_ERROR))) {

		if (fault & VM_FAULT_MAJOR)

			current->maj_flt++;

		else

			current->min_flt++;

		up_read(&mm->mmap_sem);

		return;

	}

	up_read(&mm->mmap_sem);

	/* Handle copyin/out exception cases */

	if (!user_mode(regs))

		goto no_context;

	if (fault & VM_FAULT_OOM) {

		pagefault_out_of_memory();

		return;

	}

	/* User-mode address is in the memory map, but we are

	 * unable to fix up the page fault.

	 */

	if (fault & VM_FAULT_SIGBUS) {

		info.si_signo = SIGBUS;

		info.si_code = BUS_ADRERR;

	}

	/* Address is not in the memory map */

	else {

		info.si_signo = SIGSEGV;

		info.si_code = SEGV_ACCERR;

	}

	info.si_errno = 0;

	info.si_addr = (void __user *)address;

	force_sig_info(info.si_code, &info, current);

	return;

bad_area:

	up_read(&mm->mmap_sem);

	if (user_mode(regs)) {

		info.si_signo = SIGSEGV;

		info.si_errno = 0;

		info.si_code = si_code;

		info.si_addr = (void *)address;

		force_sig_info(SIGSEGV, &info, current);

		return;

	}

	/* Kernel-mode fault falls through */

no_context:

	fixup = search_exception_tables(pt_elr(regs));

	if (fixup) {

		pt_set_elr(regs, fixup->fixup);

		return;

	}

	/* Things are looking very, very bad now */

	bust_spinlocks(1);

	printk(KERN_EMERG "Unable to handle kernel paging request at "

		"virtual address 0x%08lx, regs %p\n", address, regs);

	die("Bad Kernel VA", regs, SIGKILL);

}

void read_protection_fault(struct pt_regs *regs)

{

	unsigned long badvadr = pt_badva(regs);

	do_page_fault(badvadr, FLT_LOAD, regs);

}

void write_protection_fault(struct pt_regs *regs)

{

	unsigned long badvadr = pt_badva(regs);

	do_page_fault(badvadr, FLT_STORE, regs);

}

void execute_protection_fault(struct pt_regs *regs)

{

	unsigned long badvadr = pt_badva(regs);

	do_page_fault(badvadr, FLT_IFETCH, regs);

}