[Crash-utility] [PATCH] arm64: use TCR_EL1_T1SZ to get the correct info if vabits_actual is missing
After kernel patch:
"0d9b1ffefabe arm64: mm: make vabits_actual a build time constant if
possible"
the "vabits_actual" is not compiled to kernel symbols when "VA_BITS >
48"
is false.
So the crash will not find the "vabits_actual" symbol, and it will
fail in the end.
This patch introduces the arm64_set_va_bits_by_tcr(), and if crash cannot
find "vabits_actual" symbol, it will use the TCR_EL1_T1SZ register to get
the correct VA_BITS_ACTUAL/VA_BITS/VA_START.
Tested this patch with:
1.) the live mode with /proc/kcore
2.) the kdump file with /proc/vmcore.
Signed-off-by: Huang Shijie <shijie(a)os.amperecomputing.com>
---
arm64.c | 50 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 33 insertions(+), 17 deletions(-)
diff --git a/arm64.c b/arm64.c
index b6b7aa1..3a613f9 100644
--- a/arm64.c
+++ b/arm64.c
@@ -4586,6 +4586,35 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
(vaddr >= ms->modules_vaddr && vaddr <=
ms->modules_end));
}
+/* Return TRUE if we succeed, return FALSE on failure. */
+static int arm64_set_va_bits_by_tcr()
+{
+ ulong value;
+ char *string;
+
+ if ((string = pc->read_vmcoreinfo("NUMBER(TCR_EL1_T1SZ)")) ||
+ (string = pc->read_vmcoreinfo("NUMBER(tcr_el1_t1sz)"))) {
+ /* See ARMv8 ARM for the description of
+ * TCR_EL1.T1SZ and how it can be used
+ * to calculate the vabits_actual
+ * supported by underlying kernel.
+ *
+ * Basically:
+ * vabits_actual = 64 - T1SZ;
+ */
+ value = 64 - strtoll(string, NULL, 0);
+ if (CRASHDEBUG(1))
+ fprintf(fp, "vmcoreinfo : vabits_actual: %ld\n", value);
+ free(string);
+ machdep->machspec->VA_BITS_ACTUAL = value;
+ machdep->machspec->VA_BITS = value;
+ machdep->machspec->VA_START =
_VA_START(machdep->machspec->VA_BITS_ACTUAL);
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
static void
arm64_calc_VA_BITS(void)
{
@@ -4616,23 +4645,8 @@ arm64_calc_VA_BITS(void)
} else if (ACTIVE())
error(FATAL, "cannot determine VA_BITS_ACTUAL: please use /proc/kcore\n");
else {
- if ((string = pc->read_vmcoreinfo("NUMBER(TCR_EL1_T1SZ)")) ||
- (string = pc->read_vmcoreinfo("NUMBER(tcr_el1_t1sz)"))) {
- /* See ARMv8 ARM for the description of
- * TCR_EL1.T1SZ and how it can be used
- * to calculate the vabits_actual
- * supported by underlying kernel.
- *
- * Basically:
- * vabits_actual = 64 - T1SZ;
- */
- value = 64 - strtoll(string, NULL, 0);
- if (CRASHDEBUG(1))
- fprintf(fp, "vmcoreinfo : vabits_actual: %ld\n", value);
- free(string);
- machdep->machspec->VA_BITS_ACTUAL = value;
- machdep->machspec->VA_BITS = value;
- machdep->machspec->VA_START =
_VA_START(machdep->machspec->VA_BITS_ACTUAL);
+ if (arm64_set_va_bits_by_tcr()) {
+ /* nothing */
} else if (machdep->machspec->VA_BITS_ACTUAL) {
machdep->machspec->VA_BITS = machdep->machspec->VA_BITS_ACTUAL;
machdep->machspec->VA_START =
_VA_START(machdep->machspec->VA_BITS_ACTUAL);
@@ -4654,6 +4668,8 @@ arm64_calc_VA_BITS(void)
*/
machdep->flags |= FLIPPED_VM;
return;
+ } else if (arm64_set_va_bits_by_tcr()) {
+ return;
}
if (!(sp = symbol_search("swapper_pg_dir")) &&
--
2.30.2