[Crash-utility]=?eucgb2312_cn?q?=B4=F0=B8=B4=3A_=5BExternal_Mail=5D=5BPATCH=5D_arm64=3A_fix_regression_for_the_determination_of_VA=5FBITS_and_section=5Fsize=5Fbits?=

[陈冠有 <chenguanyou@xxxxxxxxxx>]

> vmcoreinfo : vabits_actual: 27

MTK vmcore?

See: https://lists.crash-utility.osci.io/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx/thread/LUCYZ5JBGEH2R422JFPJC5IUPMDRGCRS/

---

发件人: qiwu.chen@xxxxxxxxxxxxx <qiwu.chen@xxxxxxxxxxxxx>
发送时间: 2024年7月14日 13:29:20
收件人: devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
主题: [External Mail] [PATCH] arm64: fix regression for the determination of VA_BITS and section_size_bits

 

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1. The commit f02c8e87 will cause a regression issue for the determination of VA_BITS
on Linux 4.19 and earlier kernels, the crash session fails during initialization with
the error message due to get a wrong vabits_actual:
vmcoreinfo : vabits_actual: 27
crash: invalid kernel virtual address: ffffffa890a41318  type: "kernel_config_data"
WARNING: cannot read kernel_config_data
crash: invalid kernel virtual address: ffffffa89106db50  type: "possible"
WARNING: cannot read cpu_possible_map
crash: invalid kernel virtual address: ffffffa89106db48  type: "present"
WARNING: cannot read cpu_present_map
crash: invalid kernel virtual address: ffffffa89106db40  type: "online"
WARNING: cannot read cpu_online_map
crash: invalid kernel virtual address: ffffffa89106db58  type: "active"
WARNING: cannot read cpu_active_map
crash: invalid kernel virtual address: ffffffa89143cb80  type: "shadow_timekeeper xtime_sec"
crash: invalid kernel virtual address: ffffffa89107b76c  type: "init_uts_ns"
WARNING: invalid linux_banner pointer: ffffffa890a30018
crash: vmlinux and SYS_COREDUMP do not match!

Fix it by remove arm64_set_va_bits_by_tcr() if vabits_actual is missing.

2. The commit 568c6f04 will cause a regression issue for the determination of section_size_bits
on Linux 5.12 and earlier kernels. The section_size_bits compatible with linux upstream and
android GKI changes should be:
Before android-12-GKI or Linux 5.12:
        SECTION_SIZE_BITS = 30

After android-12-gki:
    SECTION_SIZE_BITS = 27 when defined 4K_PAGES or 16K_PAGES.
    SECTION_SIZE_BITS = 29 when defined 64K_PAGES.

Fixes: f02c8e87 ("arm64: use TCR_EL1_T1SZ to get the correct info if vabits_actual is missing")
Fixes: 568c6f04 ("arm64: section_size_bits compatible with macro definitions")
Signed-off-by: qiwu.chen <qiwu.chen@xxxxxxxxxxxxx>
---
 arm64.c | 37 ++++++++++++++++++-------------------
 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/arm64.c b/arm64.c
index b3040d7..176c465 100644
--- a/arm64.c
+++ b/arm64.c
@@ -1613,8 +1613,15 @@ arm64_get_section_size_bits(void)
 {
        int ret;
        char *string;
+       bool is_ikconfig_avail;

-       if (THIS_KERNEL_VERSION >= LINUX(5,12,0)) {
+       if (arm64_get_vmcoreinfo(&machdep->section_size_bits, "NUMBER(SECTION_SIZE_BITS)", NUM_DEC))
+               goto exit;
+
+       is_ikconfig_avail = kt->ikconfig_flags & IKCONFIG_AVAIL ? TRUE : FALSE;
+       /* The commit reduce section size for arm64 sparsemem is introduced on linux-v5.12 and android-12-GKI */
+       if (THIS_KERNEL_VERSION >= LINUX(5,12,0) || (is_ikconfig_avail &&
+               get_kernel_config("CONFIG_ANDROID_KABI_RESERVE", NULL) == IKCONFIG_Y)) {
                if (machdep->pagesize == 65536)
                        machdep->section_size_bits = _SECTION_SIZE_BITS_5_12_64K;
                else
@@ -1622,24 +1629,18 @@ arm64_get_section_size_bits(void)
        } else
                machdep->section_size_bits = _SECTION_SIZE_BITS;

-       if (arm64_get_vmcoreinfo(&machdep->section_size_bits, "NUMBER(SECTION_SIZE_BITS)", NUM_DEC)) {
-               /* nothing */
-       } else if (kt->ikconfig_flags & IKCONFIG_AVAIL) {
-               if ((ret = get_kernel_config("CONFIG_MEMORY_HOTPLUG", NULL)) == IKCONFIG_Y) {
-                       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;
-               else if ((ret = get_kernel_config("CONFIG_ARM64_64K_PAGES", NULL)) == IKCONFIG_Y)
-                       machdep->section_size_bits = _SECTION_SIZE_BITS_5_12_64K;
+       /* section_size_bits for arm64 vendor special case */
+       if (is_ikconfig_avail && get_kernel_config("CONFIG_MEMORY_HOTPLUG", NULL) == IKCONFIG_Y) {
+               if (get_kernel_config("CONFIG_HOTPLUG_SIZE_BITS", &string) == IKCONFIG_STR)
+                       machdep->section_size_bits = atol(string);
        }

-       if (CRASHDEBUG(1))
-               fprintf(fp, "SECTION_SIZE_BITS: %ld\n", machdep->section_size_bits);
+exit:
+       if (machdep->section_size_bits) {
+               if (CRASHDEBUG(1))
+                       fprintf(fp, "SECTION_SIZE_BITS: %ld\n", machdep->section_size_bits);
+       } else
+               error(FATAL, "cannot determine SECTION_SIZE_BITS\n");
 }

 /*
@@ -4733,8 +4734,6 @@ arm64_calc_VA_BITS(void)
                 */
                machdep->flags |= FLIPPED_VM;
                return;
-       } else if (arm64_set_va_bits_by_tcr()) {
-               return;
        } 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);
--
2.25.1
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