Re: [PATCHv7 25/33] x86/vdso: Zap vvar pages on switch a time namspace

[kbuild test robot]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191011]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:
https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: riscv-defconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 7.4.0
reproduce:
wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot 

All errors (new ones prefixed by >>):

   kernel/time/namespace.o: In function `.L0 ':
   namespace.c:(.text+0xfc): undefined reference to `arch_get_vdso_data'
   kernel/time/namespace.o: In function `timens_install':
>> namespace.c:(.text+0x41c): undefined reference to `vdso_join_timens'
   namespace.c:(.text+0x4ce): undefined reference to `vdso_join_timens'

---
0-DAY kernel test infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation


.config.gz
Description: application/gzip

Re: [PATCHv7 25/33] x86/vdso: Zap vvar pages on switch a time namspace

[kbuild test robot]

Hi Dmitry,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.4-rc2 next-20191010]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:
https://github.com/0day-ci/linux/commits/Dmitry-Safonov/kernel-Introduce-Time-Namespace/20191014-075119
config: parisc-b180_defconfig (attached as .config)
compiler: hppa-linux-gcc (GCC) 7.4.0
reproduce:
wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=parisc 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot 

All errors (new ones prefixed by >>):

   kernel/time/namespace.o: In function `timens_set_vvar_page.isra.8.part.9':
   (.text+0x130): undefined reference to `arch_get_vdso_data'
   kernel/time/namespace.o: In function `timens_install':
>> (.text+0x6e0): undefined reference to `vdso_join_timens'
   kernel/time/namespace.o: In function `timens_on_fork':
   (.text+0x804): undefined reference to `vdso_join_timens'

---
0-DAY kernel test infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation


.config.gz
Description: application/gzip

[PATCHv7 25/33] x86/vdso: Zap vvar pages on switch a time namspace

[Dmitry Safonov]

The VVAR page layout depends on whether a task belongs to the root or
non-root time namespace. Whenever a task changes its namespace, the VVAR
page tables are cleared and then they will re-faulted with a
corresponding layout.

Co-developed-by: Andrei Vagin 
Signed-off-by: Andrei Vagin 
Signed-off-by: Dmitry Safonov 
---
 arch/x86/entry/vdso/vma.c  | 27 +++
 include/linux/time_namespace.h |  3 +++
 kernel/time/namespace.c| 10 ++
 3 files changed, 40 insertions(+)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index d6cb8a16f368..57ada3e95f8d 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -50,6 +50,7 @@ void __init init_vdso_image(const struct vdso_image *image)
image->alt_len));
 }
 
+static const struct vm_special_mapping vvar_mapping;
 struct linux_binprm;
 
 static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
@@ -127,6 +128,32 @@ static struct page *find_timens_vvar_page(struct 
vm_area_struct *vma)
 
return NULL;
 }
+
+/*
+ * The vvar page layout depends on whether a task belongs to the root or
+ * non-root time namespace. Whenever a task changes its namespace, the VVAR
+ * page tables are cleared and then they will re-faulted with a
+ * corresponding layout.
+ * See also the comment near timens_setup_vdso_data() for details.
+ */
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+   struct mm_struct *mm = task->mm;
+   struct vm_area_struct *vma;
+
+   if (down_write_killable(>mmap_sem))
+   return -EINTR;
+
+   for (vma = mm->mmap; vma; vma = vma->vm_next) {
+   unsigned long size = vma->vm_end - vma->vm_start;
+
+   if (vma_is_special_mapping(vma, _mapping))
+   zap_page_range(vma, vma->vm_start, size);
+   }
+
+   up_write(>mmap_sem);
+   return 0;
+}
 #else
 static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
 {
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index c479cfda2c3e..dcf3dbf2836b 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -30,6 +30,9 @@ struct time_namespace {
 extern struct time_namespace init_time_ns;
 
 #ifdef CONFIG_TIME_NS
+extern int vdso_join_timens(struct task_struct *task,
+   struct time_namespace *ns);
+
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
kref_get(>kref);
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index e14cd1ca387d..0dc0742ed1ee 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -280,6 +280,7 @@ static void timens_put(struct ns_common *ns)
 static int timens_install(struct nsproxy *nsproxy, struct ns_common *new)
 {
struct time_namespace *ns = to_time_ns(new);
+   int err;
 
if (!current_is_single_threaded())
return -EUSERS;
@@ -290,6 +291,10 @@ static int timens_install(struct nsproxy *nsproxy, struct 
ns_common *new)
 
timens_set_vvar_page(current, ns);
 
+   err = vdso_join_timens(current, ns);
+   if (err)
+   return err;
+
get_time_ns(ns);
put_time_ns(nsproxy->time_ns);
nsproxy->time_ns = ns;
@@ -304,6 +309,7 @@ int timens_on_fork(struct nsproxy *nsproxy, struct 
task_struct *tsk)
 {
struct ns_common *nsc = >time_ns_for_children->ns;
struct time_namespace *ns = to_time_ns(nsc);
+   int err;
 
/* create_new_namespaces() already incremented the ref counter */
if (nsproxy->time_ns == nsproxy->time_ns_for_children)
@@ -311,6 +317,10 @@ int timens_on_fork(struct nsproxy *nsproxy, struct 
task_struct *tsk)
 
timens_set_vvar_page(tsk, ns);
 
+   err = vdso_join_timens(tsk, ns);
+   if (err)
+   return err;
+
get_time_ns(ns);
put_time_ns(nsproxy->time_ns);
nsproxy->time_ns = ns;
-- 
2.23.0