On RHEL9, crash hits a bug when executing "crash /proc/kcore" :
seek error: kernel virtual address: ffff6a0f3fff0000 type: "pmd page"
The kernel virtual address does not vary with va_actual bits, instead,
is determined by configuration value. But crash does not observe this
fact.
Since this disagreement only happens if 52-bits kernel on 48 bits platform,
it can be handled only if "phys_offset_nominal < 0".
Signed-off-by: Pingfan Liu <piliu@xxxxxxxxxx>
Cc: HAGIO KAZUHITO <k-hagio-ab@xxxxxxx>
Cc: Lianbo Jiang <lijiang@xxxxxxxxxx>
Cc: Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx>
To: crash-utility@xxxxxxxxxx
---
arm64.c | 10 +++++++++-
defs.h | 1 +
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/arm64.c b/arm64.c
index f1bac84..7cc19e8 100644
--- a/arm64.c
+++ b/arm64.c
@@ -221,7 +221,15 @@ arm64_init(int when)
arm64_calc_VA_BITS();
arm64_calc_KERNELPACMASK();
ms = machdep->machspec;
- if (ms->VA_BITS_ACTUAL) {
+ /* For 52-bits kernel running on 48 bits platform */
+ if (ms->phys_offset_nominal < 0) {
+ ms->page_offset = ARM64_FLIP_PAGE_OFFSET;
+ /* useless on arm64 */
+ machdep->identity_map_base = ARM64_FLIP_PAGE_OFFSET;
+ machdep->kvbase = ARM64_FLIP_PAGE_OFFSET;
+ ms->userspace_top = ARM64_USERSPACE_TOP_ACTUAL;
+ /* For 52-bits on 52-bits platform, or 48-bits on 48 */
+ } else if (ms->VA_BITS_ACTUAL) {
ms->page_offset = ARM64_FLIP_PAGE_OFFSET_ACTUAL;
machdep->identity_map_base = ARM64_FLIP_PAGE_OFFSET_ACTUAL;
machdep->kvbase = ARM64_FLIP_PAGE_OFFSET_ACTUAL;
diff --git a/defs.h b/defs.h
index 1007c69..f804212 100644
--- a/defs.h
+++ b/defs.h
@@ -3224,6 +3224,7 @@ typedef signed int s32;
#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
<< (machdep->machspec->VA_BITS - 1))
/* kernels > v5.4 the kernel VA space is flipped */
+#define ARM64_FLIP_PAGE_OFFSET (-(1UL) << machdep->machspec->CONFIG_ARM64_VA_BITS)
#define ARM64_FLIP_PAGE_OFFSET_ACTUAL ((0xffffffffffffffffUL) \
- ((1UL) << machdep->machspec->VA_BITS_ACTUAL) + 1)
--
2.29.2
--
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