Hi qiwu,
On Sun, Jul 14, 2024 at 5:29 PM <qiwu.chen@xxxxxxxxxxxxx> wrote:
>
> 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.
Could you explain why removing it can fix the issue? I cannot get a
clue by reading the message. Also please put the root cause into the
patch log as well.
>
> 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")
Looks like you have fixed 2 regressions, and I don't see the 2
regressions are related to each other(correct me if I'm wrong), If so
I would prefer you to send 2 individual patches, each dealing with
only one regression. So we can track the patch history easier.
> 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)) {
Do you determine the android-12-GKI by checking
CONFIG_ANDROID_KABI_RESERVE? If so could you also write it into the
code comments, for people who don't have an android kernel background.
> 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) {
I think machdep->section_size_bits should be initialized as 0 at the
start of arm64_get_section_size_bits(), the exit block will assume its
value to be 0 if error happens.
> + 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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