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 vabits_actual related kernel commit is introduced after arm64 mm
layout flip commit, so changes are safe under the condition if
(ms->VA_BITS_ACTUAL), and keep else branch untouched.
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
---
v1 -> v2:
use ms->VA_BITS_ACTUAL as the hints for memory layout flip
---
arm64.c | 7 ++++---
defs.h | 1 +
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/arm64.c b/arm64.c
index e7f4028..b256c63 100644
--- a/arm64.c
+++ b/arm64.c
@@ -228,9 +228,10 @@ arm64_init(int when)
/* vabits_actual introduced after mm flip, so it should be flipped layout */
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;
+ 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;
} else {
ms->page_offset = ARM64_PAGE_OFFSET;
diff --git a/defs.h b/defs.h
index f9f4f88..88eaa5d 100644
--- a/defs.h
+++ b/defs.h
@@ -3223,6 +3223,7 @@ 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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