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Message-Id: <1684812184-5849-1-git-send-email-yangtiezhu@loongson.cn>
Date: Tue, 23 May 2023 11:23:04 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>,
Christian Brauner <brauner@...nel.org>,
Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Vincenzo Frascino <vincenzo.frascino@....com>
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
loongson-kernel@...ts.loongnix.cn
Subject: [PATCH v2] LoongArch: Add support to clone a time namespace
When execute the following command to test clone3 on LoongArch:
# cd tools/testing/selftests/clone3 && make && ./clone3
we can see the following error info:
# [5719] Trying clone3() with flags 0x80 (size 0)
# Invalid argument - Failed to create new process
# [5719] clone3() with flags says: -22 expected 0
not ok 18 [5719] Result (-22) is different than expected (0)
This is because if CONFIG_TIME_NS is not set, but the flag
CLONE_NEWTIME (0x80) is used to clone a time namespace, it
will return -EINVAL in copy_time_ns().
Here is the related code in include/linux/time_namespace.h:
#ifdef CONFIG_TIME_NS
...
struct time_namespace *copy_time_ns(unsigned long flags,
struct user_namespace *user_ns,
struct time_namespace *old_ns);
...
#else
...
static inline
struct time_namespace *copy_time_ns(unsigned long flags,
struct user_namespace *user_ns,
struct time_namespace *old_ns)
{
if (flags & CLONE_NEWTIME)
return ERR_PTR(-EINVAL);
return old_ns;
}
...
#endif
Here is the complete call stack:
clone3()
kernel_clone()
copy_process()
copy_namespaces()
create_new_namespaces()
copy_time_ns()
clone_time_ns()
Because CONFIG_TIME_NS depends on GENERIC_VDSO_TIME_NS, select
GENERIC_VDSO_TIME_NS to enable CONFIG_TIME_NS to build the real
implementation of copy_time_ns() in kernel/time/namespace.c.
Additionally, it needs to define some arch dependent functions
such as __arch_get_timens_vdso_data(), arch_get_vdso_data() and
vdso_join_timens(), then the failed test can be fixed.
At the same time, modify the layout of vvar to expand a page size
for timens_data, and also map it to zero pfn before creating time
namespace.
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
arch/loongarch/Kconfig | 1 +
arch/loongarch/include/asm/vdso/gettimeofday.h | 7 +++
arch/loongarch/kernel/vdso.c | 63 +++++++++++++++++++++++---
3 files changed, 65 insertions(+), 6 deletions(-)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index d38b066..93b167f 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -80,6 +80,7 @@ config LOONGARCH
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL
+ select GENERIC_VDSO_TIME_NS
select GPIOLIB
select HAS_IOPORT
select HAVE_ARCH_AUDITSYSCALL
diff --git a/arch/loongarch/include/asm/vdso/gettimeofday.h b/arch/loongarch/include/asm/vdso/gettimeofday.h
index 7b2cd37..1af88ac 100644
--- a/arch/loongarch/include/asm/vdso/gettimeofday.h
+++ b/arch/loongarch/include/asm/vdso/gettimeofday.h
@@ -94,6 +94,13 @@ static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
return get_vdso_data();
}
+#ifdef CONFIG_TIME_NS
+static __always_inline
+const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
+{
+ return get_vdso_data() + PAGE_SIZE;
+}
+#endif
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
diff --git a/arch/loongarch/kernel/vdso.c b/arch/loongarch/kernel/vdso.c
index eaebd2e..5bb2b4f 100644
--- a/arch/loongarch/kernel/vdso.c
+++ b/arch/loongarch/kernel/vdso.c
@@ -14,6 +14,7 @@
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/time_namespace.h>
#include <linux/timekeeper_internal.h>
#include <asm/page.h>
@@ -22,7 +23,22 @@
#include <vdso/vsyscall.h>
#include <generated/vdso-offsets.h>
+/*
+ * The layout of vvar:
+ *
+ * high
+ * +----------------+----------------+
+ * | timens_data | PAGE_SIZE |
+ * +----------------+----------------+
+ * | vdso_data | |
+ * | vdso_pcpu_data | VDSO_DATA_SIZE |
+ * +----------------+----------------+
+ * low
+ */
+#define VVAR_SIZE (VDSO_DATA_SIZE + PAGE_SIZE)
+
extern char vdso_start[], vdso_end[];
+extern unsigned long zero_pfn;
/* Kernel-provided data used by the VDSO. */
static union {
@@ -73,6 +89,37 @@ static int __init init_vdso(void)
}
subsys_initcall(init_vdso);
+#ifdef CONFIG_TIME_NS
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+ return (struct vdso_data *)(vvar_page);
+}
+
+/*
+ * The vvar mapping contains data for a specific time namespace, so when a
+ * task changes namespace we must unmap its vvar data for the old namespace.
+ * Subsequent faults will map in data for the new namespace.
+ *
+ * For more details see timens_setup_vdso_data().
+ */
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+ struct mm_struct *mm = task->mm;
+ struct vm_area_struct *vma;
+
+ VMA_ITERATOR(vmi, mm, 0);
+
+ mmap_read_lock(mm);
+ for_each_vma(vmi, vma) {
+ if (vma_is_special_mapping(vma, &vdso_info.data_mapping))
+ zap_vma_pages(vma);
+ }
+ mmap_read_unlock(mm);
+
+ return 0;
+}
+#endif
+
static unsigned long vdso_base(void)
{
unsigned long base = STACK_TOP;
@@ -88,7 +135,7 @@ static unsigned long vdso_base(void)
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
int ret;
- unsigned long vvar_size, size, data_addr, vdso_addr;
+ unsigned long size, data_addr, vdso_addr;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct loongarch_vdso_info *info = current->thread.vdso;
@@ -100,17 +147,16 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
* Determine total area size. This includes the VDSO data itself
* and the data pages.
*/
- vvar_size = VDSO_DATA_SIZE;
- size = vvar_size + info->size;
+ size = VVAR_SIZE + info->size;
data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
if (IS_ERR_VALUE(data_addr)) {
ret = data_addr;
goto out;
}
- vdso_addr = data_addr + VDSO_DATA_SIZE;
+ vdso_addr = data_addr + VVAR_SIZE;
- vma = _install_special_mapping(mm, data_addr, vvar_size,
+ vma = _install_special_mapping(mm, data_addr, VVAR_SIZE,
VM_READ | VM_MAYREAD,
&info->data_mapping);
if (IS_ERR(vma)) {
@@ -121,7 +167,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
/* Map VDSO data page. */
ret = remap_pfn_range(vma, data_addr,
virt_to_phys(&loongarch_vdso_data) >> PAGE_SHIFT,
- vvar_size, PAGE_READONLY);
+ VDSO_DATA_SIZE, PAGE_READONLY);
+ if (ret)
+ goto out;
+
+ ret = remap_pfn_range(vma, data_addr + VDSO_DATA_SIZE, zero_pfn,
+ PAGE_SIZE, PAGE_READONLY);
if (ret)
goto out;
--
2.1.0
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