From: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
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@xxxxxxxxxxxx>
CC: Noam Camus <noamc@xxxxxxxxxx>
Acked-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
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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