[Devel] [PATCH RHEL7 COMMIT] x86/arch_prctl/vdso: add ARCH_MAP_VDSO_*
Konstantin Khorenko
khorenko at virtuozzo.com
Thu Aug 11 02:28:05 PDT 2016
The commit is pushed to "branch-rh7-3.10.0-327.22.2.vz7.16.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.22.2.vz7.16.5
------>
commit e7054163687a860c1f7a584d7d6912eb3edc8dfc
Author: Dmitry Safonov <dsafonov at virtuozzo.com>
Date: Thu Aug 11 13:28:04 2016 +0400
x86/arch_prctl/vdso: add ARCH_MAP_VDSO_*
Add API to change vdso blob type with arch_prctl.
As this is usefull only by needs of CRIU, expose
this interface under CONFIG_CHECKPOINT_RESTORE.
Cc: Andy Lutomirski <luto at kernel.org>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: "H. Peter Anvin" <hpa at zytor.com>
[Differences to vanilla patches:
o API only for 32-bit vDSO mapping
o unmap previous vdso just by mm->context.vdso pointer]
Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
---
arch/x86/include/asm/elf.h | 4 ++
arch/x86/include/uapi/asm/prctl.h | 6 +++
arch/x86/kernel/process_64.c | 13 +++++
arch/x86/vdso/vdso32-setup.c | 105 ++++++++++++++++++++++++++++++--------
4 files changed, 107 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 5518cbc..e114fff 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -336,6 +336,10 @@ extern int x32_setup_additional_pages(struct linux_binprm *bprm,
extern int syscall32_setup_pages(struct linux_binprm *, int exstack);
#define compat_arch_setup_additional_pages syscall32_setup_pages
+#ifdef CONFIG_X86_64
+extern int do_map_compat_vdso(unsigned long addr);
+#endif
+
extern unsigned long arch_randomize_brk(struct mm_struct *mm);
#define arch_randomize_brk arch_randomize_brk
diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 3ac5032..405e860 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -6,4 +6,10 @@
#define ARCH_GET_FS 0x1003
#define ARCH_GET_GS 0x1004
+#ifdef CONFIG_CHECKPOINT_RESTORE
+# define ARCH_MAP_VDSO_X32 0x2001
+# define ARCH_MAP_VDSO_32 0x2002
+# define ARCH_MAP_VDSO_64 0x2003
+#endif
+
#endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3c5a3c1..2485430 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -554,6 +554,19 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
break;
}
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ case ARCH_MAP_VDSO_32:
+ return do_map_compat_vdso(addr);
+
+ /*
+ * x32 and 64 vDSO remap API is omitted for simplicity.
+ * We do need 32-bit vDSO blob mapping for compatible
+ * applications Restore, but not x32/64 (at least, for now).
+ */
+ case ARCH_MAP_VDSO_X32:
+ case ARCH_MAP_VDSO_64:
+#endif
+
default:
ret = -EINVAL;
break;
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index d49dffa..5056d0e 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -416,6 +416,37 @@ out:
return pages;
}
+/* Call under mm->mmap_sem */
+static int __arch_setup_additional_pages(unsigned long addr, bool compat)
+{
+ struct mm_struct *mm = current->mm;
+ int ret;
+
+ current->mm->context.vdso = (void *)addr;
+
+ if (compat_uses_vma || !compat) {
+ struct page **pages = uts_prep_vdso_pages_locked(compat);
+ if (IS_ERR(pages))
+ return PTR_ERR(pages);
+
+ /*
+ * MAYWRITE to allow gdb to COW and set breakpoints
+ */
+ ret = install_special_mapping(mm, addr, PAGE_SIZE,
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ pages);
+
+ if (ret)
+ return ret;
+ }
+
+ current_thread_info()->sysenter_return =
+ VDSO32_SYMBOL(addr, SYSENTER_RETURN);
+
+ return 0;
+}
+
/* Setup a VMA at program startup for the vsyscall page */
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
@@ -450,41 +481,73 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
}
}
- current->mm->context.vdso = (void *)addr;
+ ret = __arch_setup_additional_pages(addr, compat);
+ if (ret)
+ current->mm->context.vdso = NULL;
- if (compat_uses_vma || !compat) {
- struct page **pages = uts_prep_vdso_pages_locked(compat);
- if (IS_ERR(pages)) {
- ret = PTR_ERR(pages);
- goto up_fail;
- }
+up_fail:
- /*
- * MAYWRITE to allow gdb to COW and set breakpoints
- */
- ret = install_special_mapping(mm, addr, PAGE_SIZE,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
- pages);
+ up_write(&mm->mmap_sem);
- if (ret)
- goto up_fail;
+ return ret;
+}
+
+#ifdef CONFIG_X86_64
+
+int do_map_compat_vdso(unsigned long req_addr)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long vdso_addr;
+ struct vm_area_struct *vdso_vma;
+ int ret;
+ bool compat;
+
+ if (vdso_enabled == VDSO_DISABLED)
+ return -ENOENT;
+
+ down_write(&mm->mmap_sem);
+
+ compat = (vdso_enabled == VDSO_COMPAT);
+ /* Maybe we can omit this check, but yet let it be for safety */
+ if (compat && req_addr != VDSO_HIGH_BASE) {
+ ret = -EFAULT;
+ goto up_fail;
}
- current_thread_info()->sysenter_return =
- VDSO32_SYMBOL(addr, SYSENTER_RETURN);
+ /* Don't wanna copy security checks like security_mmap_addr() */
+ vdso_addr = get_unmapped_area(NULL, req_addr, PAGE_SIZE, 0, 0);
+ if (IS_ERR_VALUE(vdso_addr)) {
+ ret = vdso_addr;
+ goto up_fail;
+ }
+
+ if (req_addr != vdso_addr) {
+ ret = -EFAULT;
+ goto up_fail;
+ }
- up_fail:
+ /*
+ * Firstly, unmap old vdso - as install_special_mapping may not
+ * do rlimit/cgroup accounting right - get rid of the old one by
+ * remove_vma().
+ */
+ vdso_vma = find_vma_intersection(mm, (unsigned long)mm->context.vdso,
+ (unsigned long)mm->context.vdso +
+ PAGE_SIZE*init_uts_ns.vdso.nr_pages);
+ if (vdso_vma)
+ do_munmap(mm, vdso_vma->vm_start,
+ vdso_vma->vm_end - vdso_vma->vm_start);
+
+ ret = __arch_setup_additional_pages(req_addr, compat);
if (ret)
current->mm->context.vdso = NULL;
+up_fail:
up_write(&mm->mmap_sem);
return ret;
}
-#ifdef CONFIG_X86_64
-
subsys_initcall(sysenter_setup);
#ifdef CONFIG_SYSCTL
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