On Monday 24 October 2016 10:18 PM, Pratyush Anand wrote:
page_offset can always be calculated as 'virtual - physical' for a direct
mapping area on x86. Therefore, remove the version dependent calculation
and use this method.
Signed-off-by: Pratyush Anand <pan...@redhat.com>
---
arch/x86_64.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/arch/x86_64.c b/arch/x86_64.c
index ddf7be6bc57b..a96fd8ae00a1 100644
--- a/arch/x86_64.c
+++ b/arch/x86_64.c
@@ -44,6 +44,24 @@ get_xen_p2m_mfn(void)
return NOT_FOUND_LONG_VALUE;
}
+static int
+get_page_offset_x86_64(void)
+{
+ int i;
+ unsigned long long phys_start;
+ unsigned long long virt_start;
+
+ for (i = 0; get_pt_load(i, &phys_start, NULL, &virt_start, NULL); i++) {
+ if (virt_start >= __START_KERNEL_map) {
OK..So, this is the problem. We should have
if (virt_start < __START_KERNEL_map) {
Kernel text region lies above __START_KERNEL_map, which is linearly
mapped however not a direct mapping. Direct mapping region lies below it
instead. So, page_offset can only be calculated with a region which is
below __START_KERNEL_map.
Thanks Baoquan for finding it.
~Pratyush
+ info->page_offset = virt_start - phys_start;
+ return TRUE;
+ }
+ }
+
+ ERRMSG("Can't get any pt_load to calculate page offset.\n");
+ return FALSE;
+}
+
int
get_phys_base_x86_64(void)
{
@@ -159,10 +177,8 @@ get_versiondep_info_x86_64(void)
else
info->max_physmem_bits = _MAX_PHYSMEM_BITS_2_6_31;
- if (info->kernel_version < KERNEL_VERSION(2, 6, 27))
- info->page_offset = __PAGE_OFFSET_ORIG;
- else
- info->page_offset = __PAGE_OFFSET_2_6_27;
+ if (!get_page_offset_x86_64())
+ return FALSE;
if (info->kernel_version < KERNEL_VERSION(2, 6, 31)) {
info->vmalloc_start = VMALLOC_START_ORIG;
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