Add a WARN_ON_ONCE() to check for passing an unreferenced dentry to dput().

[mmotm.git] / arch / sh / mm / cache-sh4.c

/*
 * arch/sh/mm/cache-sh4.c
 *
 * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
 * Copyright (C) 2001 - 2009  Paul Mundt
 * Copyright (C) 2003  Richard Curnow
 * Copyright (c) 2007 STMicroelectronics (R&D) Ltd.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/highmem.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>

/*
 * The maximum number of pages we support up to when doing ranged dcache
 * flushing. Anything exceeding this will simply flush the dcache in its
 * entirety.
 */
#define MAX_ICACHE_PAGES        32

static void __flush_cache_4096(unsigned long addr, unsigned long phys,
                               unsigned long exec_offset);

/*
 * Write back the range of D-cache, and purge the I-cache.
 *
 * Called from kernel/module.c:sys_init_module and routine for a.out format,
 * signal handler code and kprobes code
 */
static void __uses_jump_to_uncached sh4_flush_icache_range(void *args)
{
        struct flusher_data *data = args;
        unsigned long start, end;
        unsigned long flags, v;
        int i;

        start = data->addr1;
        end = data->addr2;

        /* If there are too many pages then just blow away the caches */
        if (((end - start) >> PAGE_SHIFT) >= MAX_ICACHE_PAGES) {
                local_flush_cache_all(NULL);
                return;
        }

        /*
         * Selectively flush d-cache then invalidate the i-cache.
         * This is inefficient, so only use this for small ranges.
         */
        start &= ~(L1_CACHE_BYTES-1);
        end += L1_CACHE_BYTES-1;
        end &= ~(L1_CACHE_BYTES-1);

        local_irq_save(flags);
        jump_to_uncached();

        for (v = start; v < end; v += L1_CACHE_BYTES) {
                unsigned long icacheaddr;

                __ocbwb(v);

                icacheaddr = CACHE_IC_ADDRESS_ARRAY | (v &
                                cpu_data->icache.entry_mask);

                /* Clear i-cache line valid-bit */
                for (i = 0; i < cpu_data->icache.ways; i++) {
                        __raw_writel(0, icacheaddr);
                        icacheaddr += cpu_data->icache.way_incr;
                }
        }

        back_to_cached();
        local_irq_restore(flags);
}

static inline void flush_cache_4096(unsigned long start,
                                    unsigned long phys)
{
        unsigned long flags, exec_offset = 0;

        /*
         * All types of SH-4 require PC to be uncached to operate on the I-cache.
         * Some types of SH-4 require PC to be uncached to operate on the D-cache.
         */
        if ((boot_cpu_data.flags & CPU_HAS_P2_FLUSH_BUG) ||
            (start < CACHE_OC_ADDRESS_ARRAY))
                exec_offset = cached_to_uncached;

        local_irq_save(flags);
        __flush_cache_4096(start | SH_CACHE_ASSOC,
                           virt_to_phys(phys), exec_offset);
        local_irq_restore(flags);
}

/*
 * Write back & invalidate the D-cache of the page.
 * (To avoid "alias" issues)
 */
static void sh4_flush_dcache_page(void *arg)
{
        struct page *page = arg;
#ifndef CONFIG_SMP
        struct address_space *mapping = page_mapping(page);

        if (mapping && !mapping_mapped(mapping))
                set_bit(PG_dcache_dirty, &page->flags);
        else
#endif
        {
                unsigned long phys = page_to_phys(page);
                unsigned long addr = CACHE_OC_ADDRESS_ARRAY;
                int i, n;

                /* Loop all the D-cache */
                n = boot_cpu_data.dcache.way_incr >> 12;
                for (i = 0; i < n; i++, addr += 4096)
                        flush_cache_4096(addr, phys);
        }

        wmb();
}

/* TODO: Selective icache invalidation through IC address array.. */
static void __uses_jump_to_uncached flush_icache_all(void)
{
        unsigned long flags, ccr;

        local_irq_save(flags);
        jump_to_uncached();

        /* Flush I-cache */
        ccr = ctrl_inl(CCR);
        ccr |= CCR_CACHE_ICI;
        ctrl_outl(ccr, CCR);

        /*
         * back_to_cached() will take care of the barrier for us, don't add
         * another one!
         */

        back_to_cached();
        local_irq_restore(flags);
}

static void flush_dcache_all(void)
{
        unsigned long addr, end_addr, entry_offset;

        end_addr = CACHE_OC_ADDRESS_ARRAY +
                (current_cpu_data.dcache.sets <<
                 current_cpu_data.dcache.entry_shift) *
                        current_cpu_data.dcache.ways;

        entry_offset = 1 << current_cpu_data.dcache.entry_shift;

        for (addr = CACHE_OC_ADDRESS_ARRAY; addr < end_addr; ) {
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
                __raw_writel(0, addr); addr += entry_offset;
        }
}

static void sh4_flush_cache_all(void *unused)
{
        flush_dcache_all();
        flush_icache_all();
}

/*
 * Note : (RPC) since the caches are physically tagged, the only point
 * of flush_cache_mm for SH-4 is to get rid of aliases from the
 * D-cache.  The assumption elsewhere, e.g. flush_cache_range, is that
 * lines can stay resident so long as the virtual address they were
 * accessed with (hence cache set) is in accord with the physical
 * address (i.e. tag).  It's no different here.
 *
 * Caller takes mm->mmap_sem.
 */
static void sh4_flush_cache_mm(void *arg)
{
        struct mm_struct *mm = arg;

        if (cpu_context(smp_processor_id(), mm) == NO_CONTEXT)
                return;

        flush_dcache_all();
}

/*
 * Write back and invalidate I/D-caches for the page.
 *
 * ADDR: Virtual Address (U0 address)
 * PFN: Physical page number
 */
static void sh4_flush_cache_page(void *args)
{
        struct flusher_data *data = args;
        struct vm_area_struct *vma;
        struct page *page;
        unsigned long address, pfn, phys;
        int map_coherent = 0;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
        void *vaddr;

        vma = data->vma;
        address = data->addr1;
        pfn = data->addr2;
        phys = pfn << PAGE_SHIFT;
        page = pfn_to_page(pfn);

        if (cpu_context(smp_processor_id(), vma->vm_mm) == NO_CONTEXT)
                return;

        address &= PAGE_MASK;
        pgd = pgd_offset(vma->vm_mm, address);
        pud = pud_offset(pgd, address);
        pmd = pmd_offset(pud, address);
        pte = pte_offset_kernel(pmd, address);

        /* If the page isn't present, there is nothing to do here. */
        if (!(pte_val(*pte) & _PAGE_PRESENT))
                return;

        if ((vma->vm_mm == current->active_mm))
                vaddr = NULL;
        else {
                /*
                 * Use kmap_coherent or kmap_atomic to do flushes for
                 * another ASID than the current one.
                 */
                map_coherent = (current_cpu_data.dcache.n_aliases &&
                        !test_bit(PG_dcache_dirty, &page->flags) &&
                        page_mapped(page));
                if (map_coherent)
                        vaddr = kmap_coherent(page, address);
                else
                        vaddr = kmap_atomic(page, KM_USER0);

                address = (unsigned long)vaddr;
        }

        if (pages_do_alias(address, phys))
                flush_cache_4096(CACHE_OC_ADDRESS_ARRAY |
                        (address & shm_align_mask), phys);

        if (vma->vm_flags & VM_EXEC)
                flush_icache_all();

        if (vaddr) {
                if (map_coherent)
                        kunmap_coherent(vaddr);
                else
                        kunmap_atomic(vaddr, KM_USER0);
        }
}

/*
 * Write back and invalidate D-caches.
 *
 * START, END: Virtual Address (U0 address)
 *
 * NOTE: We need to flush the _physical_ page entry.
 * Flushing the cache lines for U0 only isn't enough.
 * We need to flush for P1 too, which may contain aliases.
 */
static void sh4_flush_cache_range(void *args)
{
        struct flusher_data *data = args;
        struct vm_area_struct *vma;
        unsigned long start, end;

        vma = data->vma;
        start = data->addr1;
        end = data->addr2;

        if (cpu_context(smp_processor_id(), vma->vm_mm) == NO_CONTEXT)
                return;

        /*
         * If cache is only 4k-per-way, there are never any 'aliases'.  Since
         * the cache is physically tagged, the data can just be left in there.
         */
        if (boot_cpu_data.dcache.n_aliases == 0)
                return;

        flush_dcache_all();

        if (vma->vm_flags & VM_EXEC)
                flush_icache_all();
}

/**
 * __flush_cache_4096
 *
 * @addr:  address in memory mapped cache array
 * @phys:  P1 address to flush (has to match tags if addr has 'A' bit
 *         set i.e. associative write)
 * @exec_offset: set to 0x20000000 if flush has to be executed from P2
 *               region else 0x0
 *
 * The offset into the cache array implied by 'addr' selects the
 * 'colour' of the virtual address range that will be flushed.  The
 * operation (purge/write-back) is selected by the lower 2 bits of
 * 'phys'.
 */
static void __flush_cache_4096(unsigned long addr, unsigned long phys,
                               unsigned long exec_offset)
{
        int way_count;
        unsigned long base_addr = addr;
        struct cache_info *dcache;
        unsigned long way_incr;
        unsigned long a, ea, p;
        unsigned long temp_pc;

        dcache = &boot_cpu_data.dcache;
        /* Write this way for better assembly. */
        way_count = dcache->ways;
        way_incr = dcache->way_incr;

        /*
         * Apply exec_offset (i.e. branch to P2 if required.).
         *
         * FIXME:
         *
         *      If I write "=r" for the (temp_pc), it puts this in r6 hence
         *      trashing exec_offset before it's been added on - why?  Hence
         *      "=&r" as a 'workaround'
         */
        asm volatile("mov.l 1f, %0\n\t"
                     "add   %1, %0\n\t"
                     "jmp   @%0\n\t"
                     "nop\n\t"
                     ".balign 4\n\t"
                     "1:  .long 2f\n\t"
                     "2:\n" : "=&r" (temp_pc) : "r" (exec_offset));

        /*
         * We know there will be >=1 iteration, so write as do-while to avoid
         * pointless nead-of-loop check for 0 iterations.
         */
        do {
                ea = base_addr + 4096;
                a = base_addr;
                p = phys;

                do {
                        *(volatile unsigned long *)a = p;
                        /*
                         * Next line: intentionally not p+32, saves an add, p
                         * will do since only the cache tag bits need to
                         * match.
                         */
                        *(volatile unsigned long *)(a+32) = p;
                        a += 64;
                        p += 64;
                } while (a < ea);

                base_addr += way_incr;
        } while (--way_count != 0);
}

extern void __weak sh4__flush_region_init(void);

/*
 * SH-4 has virtually indexed and physically tagged cache.
 */
void __init sh4_cache_init(void)
{
        printk("PVR=%08x CVR=%08x PRR=%08x\n",
                ctrl_inl(CCN_PVR),
                ctrl_inl(CCN_CVR),
                ctrl_inl(CCN_PRR));

        local_flush_icache_range        = sh4_flush_icache_range;
        local_flush_dcache_page         = sh4_flush_dcache_page;
        local_flush_cache_all           = sh4_flush_cache_all;
        local_flush_cache_mm            = sh4_flush_cache_mm;
        local_flush_cache_dup_mm        = sh4_flush_cache_mm;
        local_flush_cache_page          = sh4_flush_cache_page;
        local_flush_cache_range         = sh4_flush_cache_range;

        sh4__flush_region_init();
}