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    Subject[PATCH v3 59/71] ARC: Add support for ioremap_prot API
    Date
    From: Gilad Ben-Yossef <gilad@benyossef.com>

    Implement ioremap_prot() to allow mapping IO memory with variable
    protection
    via TLB.

    Implementing this allows the /dev/mem driver to use its generic access()
    VMA callback, which in turn allows ptrace to examine data in memory
    mapped regions mapped via /dev/mem, such as Arc DCCM.

    The end result is that it is possible to examine values of variables
    placed into DCCM in user space programs via GDB.

    CC: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
    CC: Noam Camus <noamc@ezchip.com>
    Acked-by: Vineet Gupta <vgupta@synopsys.com>
    Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
    Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
    ---
    arch/arc/Kconfig | 1 +
    arch/arc/include/asm/io.h | 2 +
    arch/arc/include/asm/page.h | 3 ++
    arch/arc/mm/ioremap.c | 48 ++++++++++++++++++++++++++++++++----------
    4 files changed, 42 insertions(+), 12 deletions(-)

    diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
    index cd4ad61..2dab40d 100644
    --- a/arch/arc/Kconfig
    +++ b/arch/arc/Kconfig
    @@ -25,6 +25,7 @@ config ARC
    select HAVE_ARCH_KGDB
    select HAVE_ARCH_TRACEHOOK
    select HAVE_GENERIC_HARDIRQS
    + select HAVE_IOREMAP_PROT
    select HAVE_IRQ_WORK
    select HAVE_KPROBES
    select HAVE_KRETPROBES
    diff --git a/arch/arc/include/asm/io.h b/arch/arc/include/asm/io.h
    index d20051b..473424d 100644
    --- a/arch/arc/include/asm/io.h
    +++ b/arch/arc/include/asm/io.h
    @@ -16,6 +16,8 @@
    #define PCI_IOBASE ((void __iomem *)0)

    extern void __iomem *ioremap(unsigned long physaddr, unsigned long size);
    +extern void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
    + unsigned long flags);
    extern void iounmap(const void __iomem *addr);

    #define ioremap_nocache(phy, sz) ioremap(phy, sz)
    diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
    index dfe1f8a..bdf5461 100644
    --- a/arch/arc/include/asm/page.h
    +++ b/arch/arc/include/asm/page.h
    @@ -48,6 +48,8 @@ typedef unsigned long pgtable_t;
    #define __pgd(x) ((pgd_t) { (x) })
    #define __pgprot(x) ((pgprot_t) { (x) })

    +#define pte_pgprot(x) __pgprot(pte_val(x))
    +
    #else /* !STRICT_MM_TYPECHECKS */

    typedef unsigned long pte_t;
    @@ -60,6 +62,7 @@ typedef unsigned long pgtable_t;
    #define pgprot_val(x) (x)
    #define __pte(x) (x)
    #define __pgprot(x) (x)
    +#define pte_pgprot(x) (x)

    #endif

    diff --git a/arch/arc/mm/ioremap.c b/arch/arc/mm/ioremap.c
    index 52518b6..3e5c92c 100644
    --- a/arch/arc/mm/ioremap.c
    +++ b/arch/arc/mm/ioremap.c
    @@ -16,25 +16,49 @@

    void __iomem *ioremap(unsigned long paddr, unsigned long size)
    {
    - unsigned long vaddr;
    - struct vm_struct *area;
    - unsigned long off, end;
    - const pgprot_t prot = PAGE_KERNEL_NO_CACHE;
    + unsigned long end;

    /* Don't allow wraparound or zero size */
    end = paddr + size - 1;
    if (!size || (end < paddr))
    return NULL;

    - /* If the region is h/w uncached, nothing special needed */
    + /* If the region is h/w uncached, avoid MMU mappings */
    if (paddr >= ARC_UNCACHED_ADDR_SPACE)
    return (void __iomem *)paddr;

    + return ioremap_prot(paddr, size, PAGE_KERNEL_NO_CACHE);
    +}
    +EXPORT_SYMBOL(ioremap);
    +
    +/*
    + * ioremap with access flags
    + * Cache semantics wise it is same as ioremap - "forced" uncached.
    + * However unline vanilla ioremap which bypasses ARC MMU for addresses in
    + * ARC hardware uncached region, this one still goes thru the MMU as caller
    + * might need finer access control (R/W/X)
    + */
    +void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
    + unsigned long flags)
    +{
    + void __iomem *vaddr;
    + struct vm_struct *area;
    + unsigned long off, end;
    + pgprot_t prot = __pgprot(flags);
    +
    + /* Don't allow wraparound, zero size */
    + end = paddr + size - 1;
    + if ((!size) || (end < paddr))
    + return NULL;
    +
    /* An early platform driver might end up here */
    if (!slab_is_available())
    return NULL;

    - /* Mappings have to be page-aligned, page-sized */
    + /* force uncached */
    + prot = pgprot_noncached(prot);
    +
    + /* Mappings have to be page-aligned */
    off = paddr & ~PAGE_MASK;
    paddr &= PAGE_MASK;
    size = PAGE_ALIGN(end + 1) - paddr;
    @@ -45,17 +69,17 @@ void __iomem *ioremap(unsigned long paddr, unsigned long size)
    area = get_vm_area(size, VM_IOREMAP);
    if (!area)
    return NULL;
    -
    area->phys_addr = paddr;
    - vaddr = (unsigned long)area->addr;
    - if (ioremap_page_range(vaddr, vaddr + size, paddr, prot)) {
    - vfree(area->addr);
    + vaddr = (void __iomem *)area->addr;
    + if (ioremap_page_range((unsigned long)vaddr,
    + (unsigned long)vaddr + size, paddr, prot)) {
    + vunmap((void __force *)vaddr);
    return NULL;
    }
    -
    return (void __iomem *)(off + (char __iomem *)vaddr);
    }
    -EXPORT_SYMBOL(ioremap);
    +EXPORT_SYMBOL(ioremap_prot);
    +

    void iounmap(const void __iomem *addr)
    {
    --
    1.7.4.1


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