[PATCH v1 7/9] powerpc/vdso: Move vdso datapage up front

[Christophe Leroy]

Move the vdso datapage in front of the VDSO area,
before vdso test.

This will allow to remove the __kernel_datapage_offset symbol
and simplify __get_datapage() in the following patch.

Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
 arch/powerpc/include/asm/mmu_context.h |  4 +++-
 arch/powerpc/kernel/vdso.c             | 22 ++++++++++------------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h 
b/arch/powerpc/include/asm/mmu_context.h
index 7f3658a97384..be18ad12bb54 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -262,7 +262,9 @@ extern void arch_exit_mmap(struct mm_struct *mm);
 static inline void arch_unmap(struct mm_struct *mm,
                              unsigned long start, unsigned long end)
 {
-       if (start <= mm->context.vdso_base && mm->context.vdso_base < end)
+       unsigned long vdso_base = mm->context.vdso_base - PAGE_SIZE;
+
+       if (start <= vdso_base && vdso_base < end)
                mm->context.vdso_base = 0;
 }
 
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index b9270923452e..1d72c4b7672f 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -124,7 +124,7 @@ static int vdso_mremap(unsigned long vdso_pages,
        if (new_size != vdso_size)
                return -EINVAL;
 
-       current->mm->context.vdso_base = (unsigned long)new_vma->vm_start;
+       current->mm->context.vdso_base = (unsigned long)new_vma->vm_start + 
PAGE_SIZE;
 
        return 0;
 }
@@ -217,7 +217,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, 
int uses_interp)
         * install_special_mapping or the perf counter mmap tracking code
         * will fail to recognise it as a vDSO (since arch_vma_name fails).
         */
-       current->mm->context.vdso_base = vdso_base;
+       current->mm->context.vdso_base = vdso_base + PAGE_SIZE;
 
        /*
         * our vma flags don't have VM_WRITE so by default, the process isn't
@@ -516,8 +516,7 @@ static __init int vdso_fixup_datapage(struct lib32_elfinfo 
*v32,
                return -1;
        }
        *((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) =
-               (vdso64_pages << PAGE_SHIFT) -
-               (sym64->st_value - VDSO64_LBASE);
+               (sym64->st_value - VDSO64_LBASE) - PAGE_SIZE;
 #endif /* CONFIG_PPC64 */
 
 #ifdef CONFIG_VDSO32
@@ -528,8 +527,7 @@ static __init int vdso_fixup_datapage(struct lib32_elfinfo 
*v32,
                return -1;
        }
        *((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
-               (vdso32_pages << PAGE_SHIFT) -
-               (sym32->st_value - VDSO32_LBASE);
+               (sym32->st_value - VDSO32_LBASE) - PAGE_SIZE;
 #endif
 
        return 0;
@@ -771,10 +769,10 @@ static int __init vdso_init(void)
                if (!pagelist)
                        goto alloc_failed;
 
-               for (i = 0; i < vdso32_pages; i++)
-                       pagelist[i] = virt_to_page(vdso32_kbase + i * 
PAGE_SIZE);
+               pagelist[0] = virt_to_page(vdso_data);
 
-               pagelist[i++] = virt_to_page(vdso_data);
+               for (i = 0; i < vdso32_pages; i++)
+                       pagelist[i + 1] = virt_to_page(vdso32_kbase + i * 
PAGE_SIZE);
 
                vdso32_spec.pages = pagelist;
        }
@@ -784,10 +782,10 @@ static int __init vdso_init(void)
                if (!pagelist)
                        goto alloc_failed;
 
-               for (i = 0; i < vdso64_pages; i++)
-                       pagelist[i] = virt_to_page(vdso64_kbase + i * 
PAGE_SIZE);
+               pagelist[0] = virt_to_page(vdso_data);
 
-               pagelist[i++] = virt_to_page(vdso_data);
+               for (i = 0; i < vdso64_pages; i++)
+                       pagelist[i + 1] = virt_to_page(vdso64_kbase + i * 
PAGE_SIZE);
 
                vdso64_spec.pages = pagelist;
        }
-- 
2.25.0