[Crash-utility] Re: [PATCH] arm64: section_size_bits compatible with macro definitions
Hi, Guanyou
Thank you for the patch.
On 4/17/24 19:55, devel-request(a)lists.crash-utility.osci.io wrote:
Date: Wed, 17 Apr 2024 19:55:40 +0800
From: Guanyou Chen<chenguanyou9338(a)gmail.com>
Subject: [Crash-utility] [PATCH] arm64: section_size_bits compatible
with macro definitions
To:k-hagio-ab@nec.com,devel@lists.crash-utility.osci.io, Lianbo
<lijiang(a)redhat.com>
Message-ID:
<CAHS3RMXw5Ya44Nc+fFQqXdwYvHcDnq1RG7-zPpbqTOPoCb0YUw(a)mail.gmail.com>
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Hi Kazu,
Compatible with google android GKI changes,
SECTION_SIZE_BITS = 27 when defined 4K_PAGES or 16K_PAGES.
SECTION_SIZE_BITS = 29 when defined 64K_PAGES.
Link:
https://lore.kernel.org/lkml/15cf9a2359197fee0168f820c5c904650d07939e.161...
Link:
https://lore.kernel.org/all/43843c5e092bfe3ec4c41e3c8c78a7ee35b69bb0.1611...
See:
https://cs.android.com/android/_/android/kernel/common/+/673e9ab6b64f9811...
Before android-12-gki:
crash> help -m | grep section_size_bits
section_size_bits: 30
The first PFN error, the physical address should be 0x40000000.
crash> kmem -p
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
ffffffff06e00000 200000000 ffffff80edf4fa12 ffffffff070f3640 1
4000000000002000 private
After android-12-gki:
crash> help -m | grep section
section_size_bits: 27
crash> kmem -p
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffffeffe00000 40000000 0 0 1 1000 reserved
The macro SECTION_SIZE_BITS has changed since kernel version 5.12, see:
kernel commit: f0b13ee23241 ("arm64/sparsemem: reduce SECTION_SIZE_BITS")
crash commit: 8246dce99dd2 ("arm64: Update SECTION_SIZE_BITS for kernels
= 5.12")
And later kernel exported the SECTION_SIZE_BITS in kernel version
v5.13-rc7~20^2~10:
kernel commit: 4f5aecdff25f ("crash_core, vmcoreinfo: append
'SECTION_SIZE_BITS' to vmcoreinfo")
Crash-utility also reads the value from vmcoreinfo as below:
if (arm64_get_vmcoreinfo(&machdep->section_size_bits,
"NUMBER(SECTION_SIZE_BITS)", NUM_DEC))
So I'm wondering if this issue occurs on older kernels(e.g. 5.12 or
earlier), and probably introduced some latest kernel patches(such as
kernel commit f0b13ee23241) to the old kernel. Just want to confirm this.
Signed-off-by: chenguanyou<chenguanyou(a)xiaomi.com>
---
arm64.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arm64.c b/arm64.c
index e36c723..50e22ea 100644
--- a/arm64.c
+++ b/arm64.c
@@ -1629,7 +1629,16 @@ arm64_get_section_size_bits(void)
if ((ret = get_kernel_config("CONFIG_HOTPLUG_SIZE_BITS",
&string)) == IKCONFIG_STR)
machdep->section_size_bits = atol(string);
}
- }
+
+ // arm64: reduce section size for sparsemem
+ if ((ret = get_kernel_config("CONFIG_ARM64_4K_PAGES", NULL)) ==
IKCONFIG_Y
+ || (ret = get_kernel_config("CONFIG_ARM64_16K_PAGES",
NULL)) == IKCONFIG_Y)
+ machdep->section_size_bits = _SECTION_SIZE_BITS_5_12;
+ // arm64/sparsemem: reduce SECTION_SIZE_BITS
+ else if ((ret = get_kernel_config("CONFIG_ARM64_64K_PAGES", NULL))
== IKCONFIG_Y)
+ machdep->section_size_bits = _SECTION_SIZE_BITS_5_12_64K;
+
+ }
The IKCONFIG may not be set for many distributions, but this looks like
it works well in your cases.
Thanks.
Lianbo
if (CRASHDEBUG(1))
fprintf(fp, "SECTION_SIZE_BITS: %ld\n",
machdep->section_size_bits);
-- 2.39.0