On Sun, 18 Aug 2019, Thomas Gleixner wrote:
> On Sun, 18 Aug 2019, Thomas Gleixner wrote:
> >
> > Patch below. I tested this with the normal order and by installing a
> > 'timens' page unconditionally for all processes. I'll reply with the timens
> > testing hacks so you can see what I did.
>
> First hack...
And the second one.
Thanks,
tglx
8<-----------------
Subject: x86/vdso: Hack to test the time namespace path
From: Thomas Gleixner <t...@linutronix.de>
Date: Sun, 18 Aug 2019 16:49:00 +0200
Install a special TIMENS vvar page which forces the VDSO to take the time
namespace path for testing.
Not-Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
arch/x86/entry/vdso/vma.c | 34 +++++++++++++++++++++++++++++++++-
1 file changed, 33 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -84,6 +84,33 @@ static int vdso_mremap(const struct vm_s
return 0;
}
+/* Hack for testing */
+static struct page *vdso_timens_page;
+
+static int __init init_vdso_timens(void)
+{
+ struct vdso_data *vdata;
+ void *va;
+
+ vdso_timens_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!vdso_timens_page)
+ return -ENOMEM;
+
+ /* Hack: vdso data is at offset 0x80 in the page ... */
+ va = page_address(vdso_timens_page);
+ vdata = (struct vdso_data *)(va + 0x80);
+
+ vdata[0].seq = 1;
+ vdata[0].clock_mode = UINT_MAX;
+ vdata[1].seq = 1;
+ vdata[1].clock_mode = UINT_MAX;
+
+ /* All offsets are zero */
+
+ return 0;
+}
+subsys_initcall(init_vdso_timens);
+
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
@@ -106,7 +133,7 @@ static vm_fault_t vvar_fault(const struc
if (sym_offset == 0)
return VM_FAULT_SIGBUS;
- if (sym_offset == image->sym_vvar_page) {
+ if (sym_offset == image->sym_timens_page) {
return vmf_insert_pfn(vma, vmf->address,
__pa_symbol(&__vvar_page) >> PAGE_SHIFT);
} else if (sym_offset == image->sym_pvclock_page) {
@@ -123,6 +150,11 @@ static vm_fault_t vvar_fault(const struc
if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
return vmf_insert_pfn(vma, vmf->address,
vmalloc_to_pfn(tsc_pg));
+ } else if (sym_offset == image->sym_vvar_page) {
+ unsigned long pfn;
+
+ pfn = page_to_pfn(vdso_timens_page);
+ return vmf_insert_pfn(vma, vmf->address, pfn);
}
return VM_FAULT_SIGBUS;
