2 files changed, 45 insertions, 0 deletions

diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm/pgtable.h
index c90ea5bfa1b4..d7546c94da52 100644
--- a/arch/xtensa/include/asm/pgtable.h
+++ b/arch/xtensa/include/asm/pgtable.h
@@ -410,6 +410,10 @@ typedef pte_t *pte_addr_t;
 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
 #define __HAVE_ARCH_PTEP_MKDIRTY
 #define __HAVE_ARCH_PTE_SAME
+/* We provide our own get_unmapped_area to cope with
+ * SHM area cache aliasing for userland.
+ */
+#define HAVE_ARCH_UNMAPPED_AREA
 
 #include <asm-generic/pgtable.h>
 
diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index 54fa8425cee2..5d3f7a119ed1 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -36,6 +36,10 @@ syscall_t sys_call_table[__NR_syscall_count] /* FIXME __cacheline_aligned */= {
 #include <uapi/asm/unistd.h>
 };
 
+#define COLOUR_ALIGN(addr, pgoff) \
+        ((((addr) + SHMLBA - 1) & ~(SHMLBA - 1)) + \
+         (((pgoff) << PAGE_SHIFT) & (SHMLBA - 1)))
+
 asmlinkage long xtensa_shmat(int shmid, char __user *shmaddr, int shmflg)
 {
         unsigned long ret;
@@ -52,3 +56,40 @@ asmlinkage long xtensa_fadvise64_64(int fd, int advice,
 {
         return sys_fadvise64_64(fd, offset, len, advice);
 }
+
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
+                unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+        struct vm_area_struct *vmm;
+
+        if (flags & MAP_FIXED) {
+                /* We do not accept a shared mapping if it would violate
+                 * cache aliasing constraints.
+                 */
+                if ((flags & MAP_SHARED) &&
+                                ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
+                        return -EINVAL;
+                return addr;
+        }
+
+        if (len > TASK_SIZE)
+                return -ENOMEM;
+        if (!addr)
+                addr = TASK_UNMAPPED_BASE;
+
+        if (flags & MAP_SHARED)
+                addr = COLOUR_ALIGN(addr, pgoff);
+        else
+                addr = PAGE_ALIGN(addr);
+
+        for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
+                /* At this point:  (!vmm || addr < vmm->vm_end). */
+                if (TASK_SIZE - len < addr)
+                        return -ENOMEM;
+                if (!vmm || addr + len <= vmm->vm_start)
+                        return addr;
+                addr = vmm->vm_end;
+                if (flags & MAP_SHARED)
+                        addr = COLOUR_ALIGN(addr, pgoff);
+        }
+}