Currently makedumpfile fails on arm64 for 5.4 and newer kernels with
the following :
[9.595476] kdump-tools[513]: Starting kdump-tools:
[9.597988] kdump-tools[519]: * running makedumpfile -c -d 31 /proc/vmcore /var/crash/202009011332/dump-incomplete
[9.636915] kdump-tools[537]: calculate_plat_config: PAGE SIZE 0x1000 and VA Bits 47 not supported
[9.639652] kdump-tools[537]: get_machdep_info_arm64: Can't determine platform config values
[9.642085] kdump-tools[537]: makedumpfile Failed.
[9.643064] kdump-tools[519]: * kdump-tools: makedumpfile failed, falling back to 'cp'
The problem starts at get_versiondep_info_arm64 function.
This functions uses _stext to calculate the va_bits.
Up to 5.3 kernels the _stext would be ffff000010081000.
After commit 14c127c957c1c607 (arm64: mm: Flip kernel VA space),
_stext is ffff800010081000 which ends up the va_bits getting the value
of 47, even though the kernel configuration is 48 bits.
Now _stext has contiguous bits ffff8 and matches the 47 bits
while in the past it had ffff0 that would match the 48 bits.
The va_bits variable is already exported in vmcoreinfo and therefore
that could be solved by reading the value from there
(va_bits = NUMBER(VA_BITS)) instead of relying on _stext.
However, if we do so, the page_offset is not calculated properly.
Currently :
info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
The page_offset still depends on the _stext value.
So read the va_bits from vmcoreinfo and keep the old logic of calculating
va_bits to calculate page_offset (calc_page_offset_variable).
Signed-off-by: Ioanna Alifieraki <ioanna-maria.alifieraki@xxxxxxxxxxxxx>
---
arch/arm64.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/arm64.c b/arch/arm64.c
index 54d60b4..2b0fca3 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -290,6 +290,7 @@ int
get_versiondep_info_arm64(void)
{
ulong _stext;
+ int calc_page_offset;
_stext = get_stext_symbol();
if (!_stext) {
@@ -297,25 +298,28 @@ get_versiondep_info_arm64(void)
return FALSE;
}
+ va_bits = NUMBER(VA_BITS);
+
/* Derive va_bits as per arch/arm64/Kconfig */
if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) {
- va_bits = 36;
+ calc_page_offset = 36;
} else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) {
- va_bits = 39;
+ calc_page_offset = 39;
} else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) {
- va_bits = 42;
+ calc_page_offset = 42;
} else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) {
- va_bits = 47;
+ calc_page_offset = 47;
} else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) {
- va_bits = 48;
+ calc_page_offset = 48;
} else {
- ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n");
+ ERRMSG("Cannot find a proper _stext for calculating page_offset\n");
return FALSE;
}
- info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+ info->page_offset = (0xffffffffffffffffUL) << (calc_page_offset - 1);
DEBUG_MSG("va_bits : %d\n", va_bits);
+ DEBUG_MSG("calc_page_offset : %d\n", calc_page_offset);
DEBUG_MSG("page_offset : %lx\n", info->page_offset);
return TRUE;
--
2.17.1
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