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arm64: assign page_offset with VA_BITS kernel configuration value

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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 vabits_actual, 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 the else branch untouched.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
This commit is contained in:
Pingfan Liu 2021-07-02 10:14:22 +08:00 committed by Kazuhito Hagio
parent 5719afc7a4
commit 167d37e347
2 changed files with 5 additions and 3 deletions
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7
arm64.c
View File

@ -220,9 +220,10 @@ 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;

1
defs.h
View File

@ -3234,6 +3234,7 @@ 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)