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    Subject[PATCH v5 30/36] Hexagon: Add page-fault support.
    Signed-off-by: Richard Kuo <rkuo@codeaurora.org>
    Signed-off-by: Linas Vepstas <linas@codeaurora.org>
    Acked-by: Arnd Bergmann <arnd@arndb.de>
    ---
    arch/hexagon/include/asm/mem-layout.h | 112 +++++++++++++
    arch/hexagon/include/asm/vm_fault.h | 26 +++
    arch/hexagon/mm/init.c | 276 +++++++++++++++++++++++++++++++++
    arch/hexagon/mm/vm_fault.c | 187 ++++++++++++++++++++++
    4 files changed, 601 insertions(+), 0 deletions(-)
    create mode 100644 arch/hexagon/include/asm/mem-layout.h
    create mode 100644 arch/hexagon/include/asm/vm_fault.h
    create mode 100644 arch/hexagon/mm/init.c
    create mode 100644 arch/hexagon/mm/vm_fault.c

    diff --git a/arch/hexagon/include/asm/mem-layout.h b/arch/hexagon/include/asm/mem-layout.h
    new file mode 100644
    index 0000000..72e5dcd
    --- /dev/null
    +++ b/arch/hexagon/include/asm/mem-layout.h
    @@ -0,0 +1,112 @@
    +/*
    + * 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 */
    diff --git a/arch/hexagon/include/asm/vm_fault.h b/arch/hexagon/include/asm/vm_fault.h
    new file mode 100644
    index 0000000..cacda36
    --- /dev/null
    +++ b/arch/hexagon/include/asm/vm_fault.h
    @@ -0,0 +1,26 @@
    +/*
    + * 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
    diff --git a/arch/hexagon/mm/init.c b/arch/hexagon/mm/init.c
    new file mode 100644
    index 0000000..b57d741
    --- /dev/null
    +++ b/arch/hexagon/mm/init.c
    @@ -0,0 +1,276 @@
    +/*
    + * 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
    + */
    +}
    diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
    new file mode 100644
    index 0000000..c10b76f
    --- /dev/null
    +++ b/arch/hexagon/mm/vm_fault.c
    @@ -0,0 +1,187 @@
    +/*
    + * 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);
    +}
    --
    1.7.1

    --

    Sent by an employee of the Qualcomm Innovation Center, Inc.
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.


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