[PATCH v2 1/7] xen: Improve calculation of beginning of virtual address space

Daniel Kiper
2013-07-16T12:32:58Z

Xen commit 4b28bf6ae90bd83fd1113d8bdc53c3266ffeb328 (x86: re-introduce
map_domain_page() et al) once again altered virtual address space.
Current algorithm calculating its start could not cope with that change.
New version establishes this value on the base of domain_list placement
and is more generic.

Similar patch was applied to crash tool.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
---
arch/x86_64.c | 16 +++++++++++-----
makedumpfile.h | 2 --
2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/arch/x86_64.c b/arch/x86_64.c
index 8e61b20..d864a06 100644
--- a/arch/x86_64.c
+++ b/arch/x86_64.c
@@ -372,14 +372,20 @@ int get_xen_basic_info_x86_64(void)
info->xen_phys_start = info->xen_crash_info.v2->xen_phys_start;
}

+ info->xen_virt_start = SYMBOL(domain_list);
+
+ /*
+ * Xen virtual mapping is aligned to 1 GiB boundary.
+ * domain_list lives in bss which sits no more than
+ * 1 GiB below beginning of virtual address space.
+ */
+ info->xen_virt_start &= 0xffffffffc0000000;
+
if (info->xen_crash_info.com &&
- info->xen_crash_info.com->xen_major_version >= 4) {
- info->xen_virt_start = XEN_VIRT_START_V4;
+ info->xen_crash_info.com->xen_major_version >= 4)
info->directmap_virt_end = DIRECTMAP_VIRT_END_V4;
- } else {
- info->xen_virt_start = XEN_VIRT_START_V3;
+ else
info->directmap_virt_end = DIRECTMAP_VIRT_END_V3;
- }

if (SYMBOL(pgd_l4) == NOT_FOUND_SYMBOL) {
ERRMSG("Can't get pml4.\n");
diff --git a/makedumpfile.h b/makedumpfile.h
index a5826e0..1a87500 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -1473,8 +1473,6 @@ int get_xen_info_x86(void);
#define DIRECTMAP_VIRT_END_V3 (0xffff840000000000)
#define DIRECTMAP_VIRT_END_V4 (0xffff880000000000)
#define DIRECTMAP_VIRT_END (info->directmap_virt_end)
-#define XEN_VIRT_START_V3 (0xffff828c80000000)
-#define XEN_VIRT_START_V4 (0xffff82c480000000)
#define XEN_VIRT_START (info->xen_virt_start)
#define XEN_VIRT_END (XEN_VIRT_START + (1UL << 30))
#define FRAMETABLE_VIRT_START 0xffff82f600000000
--
1.7.10.4