[PATCH] powerpc vdso updates

This patch cleans up some locking & error handling in the ppc vdso and
moves the vdso base pointer from the thread struct to the mm context
where it more logically belongs. It brings the powerpc implementation
closer to Ingo's new x86 one and also adds an arch_vma_name() function
allowing to print [vsdo] in /proc/<pid>/maps if Ingo's x86 vdso patch is
also applied.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

7 files changed, 47 insertions, 29 deletions

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 01e3c08cb550..22f078984845 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -757,10 +757,10 @@ static int handle_rt_signal(unsigned long sig, struct k_sigaction *ka,
 
         /* Save user registers on the stack */
         frame = &rt_sf->uc.uc_mcontext;
-        if (vdso32_rt_sigtramp && current->thread.vdso_base) {
+        if (vdso32_rt_sigtramp && current->mm->context.vdso_base) {
                 if (save_user_regs(regs, frame, 0))
                         goto badframe;
-                regs->link = current->thread.vdso_base + vdso32_rt_sigtramp;
+                regs->link = current->mm->context.vdso_base + vdso32_rt_sigtramp;
         } else {
                 if (save_user_regs(regs, frame, __NR_rt_sigreturn))
                         goto badframe;
@@ -1029,10 +1029,10 @@ static int handle_signal(unsigned long sig, struct k_sigaction *ka,
             || __put_user(sig, &sc->signal))
                 goto badframe;
 
-        if (vdso32_sigtramp && current->thread.vdso_base) {
+        if (vdso32_sigtramp && current->mm->context.vdso_base) {
                 if (save_user_regs(regs, &frame->mctx, 0))
                         goto badframe;
-                regs->link = current->thread.vdso_base + vdso32_sigtramp;
+                regs->link = current->mm->context.vdso_base + vdso32_sigtramp;
         } else {
                 if (save_user_regs(regs, &frame->mctx, __NR_sigreturn))
                         goto badframe;
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 27f65b95184d..23ba69c26913 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -394,8 +394,8 @@ static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
         current->thread.fpscr.val = 0;
 
         /* Set up to return from userspace. */
-        if (vdso64_rt_sigtramp && current->thread.vdso_base) {
-                regs->link = current->thread.vdso_base + vdso64_rt_sigtramp;
+        if (vdso64_rt_sigtramp && current->mm->context.vdso_base) {
+                regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp;
         } else {
                 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
                 if (err)
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 573afb68d69e..bc3e15be3087 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -223,6 +223,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
         struct vm_area_struct *vma;
         unsigned long vdso_pages;
         unsigned long vdso_base;
+        int rc;
 
 #ifdef CONFIG_PPC64
         if (test_thread_flag(TIF_32BIT)) {
@@ -237,20 +238,13 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
         vdso_base = VDSO32_MBASE;
 #endif
 
-        current->thread.vdso_base = 0;
+        current->mm->context.vdso_base = 0;
 
         /* vDSO has a problem and was disabled, just don't "enable" it for the
          * process
          */
         if (vdso_pages == 0)
                 return 0;
-
-        vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
-        if (vma == NULL)
-                return -ENOMEM;
-
-        memset(vma, 0, sizeof(*vma));
-
         /* Add a page to the vdso size for the data page */
         vdso_pages ++;
 
@@ -259,17 +253,23 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
          * at vdso_base which is the "natural" base for it, but we might fail
          * and end up putting it elsewhere.
          */
+        down_write(&mm->mmap_sem);
         vdso_base = get_unmapped_area(NULL, vdso_base,
                                       vdso_pages << PAGE_SHIFT, 0, 0);
-        if (vdso_base & ~PAGE_MASK) {
-                kmem_cache_free(vm_area_cachep, vma);
-                return (int)vdso_base;
+        if (IS_ERR_VALUE(vdso_base)) {
+                rc = vdso_base;
+                goto fail_mmapsem;
         }
 
-        current->thread.vdso_base = vdso_base;
 
+        /* Allocate a VMA structure and fill it up */
+        vma = kmem_cache_zalloc(vm_area_cachep, SLAB_KERNEL);
+        if (vma == NULL) {
+                rc = -ENOMEM;
+                goto fail_mmapsem;
+        }
         vma->vm_mm = mm;
-        vma->vm_start = current->thread.vdso_base;
+        vma->vm_start = vdso_base;
         vma->vm_end = vma->vm_start + (vdso_pages << PAGE_SHIFT);
 
         /*
@@ -282,23 +282,38 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
          * It's fine to use that for setting breakpoints in the vDSO code
          * pages though
          */
-        vma->vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+        vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
         vma->vm_flags |= mm->def_flags;
         vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
         vma->vm_ops = &vdso_vmops;
 
-        down_write(&mm->mmap_sem);
-        if (insert_vm_struct(mm, vma)) {
-                up_write(&mm->mmap_sem);
-                kmem_cache_free(vm_area_cachep, vma);
-                return -ENOMEM;
-        }
+        /* Insert new VMA */
+        rc = insert_vm_struct(mm, vma);
+        if (rc)
+                goto fail_vma;
+
+        /* Put vDSO base into mm struct and account for memory usage */
+        current->mm->context.vdso_base = vdso_base;
         mm->total_vm += (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
         up_write(&mm->mmap_sem);
-
         return 0;
+
+ fail_vma:
+        kmem_cache_free(vm_area_cachep, vma);
+ fail_mmapsem:
+        up_write(&mm->mmap_sem);
+        return rc;
+}
+
+const char *arch_vma_name(struct vm_area_struct *vma)
+{
+        if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
+                return "[vdso]";
+        return NULL;
 }
 
+
+
 static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
                                   unsigned long *size)
 {
diff --git a/include/asm-powerpc/elf.h b/include/asm-powerpc/elf.h
index 94d228f9c6ac..319655ce66c0 100644
--- a/include/asm-powerpc/elf.h
+++ b/include/asm-powerpc/elf.h
@@ -294,7 +294,7 @@ do {									\
         NEW_AUX_ENT(AT_DCACHEBSIZE, dcache_bsize);                      \
         NEW_AUX_ENT(AT_ICACHEBSIZE, icache_bsize);                      \
         NEW_AUX_ENT(AT_UCACHEBSIZE, ucache_bsize);                      \
-        VDSO_AUX_ENT(AT_SYSINFO_EHDR, current->thread.vdso_base)        \
+        VDSO_AUX_ENT(AT_SYSINFO_EHDR, current->mm->context.vdso_base)   \
 } while (0)
 
 /* PowerPC64 relocations defined by the ABIs */
diff --git a/include/asm-powerpc/mmu.h b/include/asm-powerpc/mmu.h
index 31f721994bd8..96e47d1ce979 100644
--- a/include/asm-powerpc/mmu.h
+++ b/include/asm-powerpc/mmu.h
@@ -360,6 +360,7 @@ typedef struct {
 #ifdef CONFIG_HUGETLB_PAGE
         u16 low_htlb_areas, high_htlb_areas;
 #endif
+        unsigned long vdso_base;
 } mm_context_t;
 
 
diff --git a/include/asm-powerpc/page.h b/include/asm-powerpc/page.h
index ae610b620487..a315d0c0d96a 100644
--- a/include/asm-powerpc/page.h
+++ b/include/asm-powerpc/page.h
@@ -192,6 +192,9 @@ extern void copy_user_page(void *to, void *from, unsigned long vaddr,
                 struct page *p);
 extern int page_is_ram(unsigned long pfn);
 
+struct vm_area_struct;
+extern const char *arch_vma_name(struct vm_area_struct *vma);
+
 #include <asm-generic/memory_model.h>
 #endif /* __ASSEMBLY__ */
 
diff --git a/include/asm-powerpc/processor.h b/include/asm-powerpc/processor.h
index 93f83efeb310..d5c7ef1cca26 100644
--- a/include/asm-powerpc/processor.h
+++ b/include/asm-powerpc/processor.h
@@ -153,7 +153,6 @@ struct thread_struct {
         unsigned long   start_tb;       /* Start purr when proc switched in */
         unsigned long   accum_tb;       /* Total accumilated purr for process */
 #endif
-        unsigned long   vdso_base;      /* base of the vDSO library */
         unsigned long   dabr;           /* Data address breakpoint register */
 #ifdef CONFIG_ALTIVEC
         /* Complete AltiVec register set */