[Crash-utility] Re: [PATCH] Fix get_xtime() for kernel 6.17 and higher
Hi Tao Liu,
Factoring the readmem() for "timekeeper_data" and "tk_core" is a good
idea
as we don't really need to differentiate the RETURN_ON_ERROR message.
I will send a PATCH v2.
Thanks,
Georges
|-----Original Message-----
|From: Tao Liu <ltao(a)redhat.com>
|Sent: Thursday, May 7, 2026 4:08 AM
|To: Aureau, Georges (Kernel Tools ERT) <georges.aureau(a)hpe.com>
|Cc: devel(a)lists.crash-utility.osci.io
|Subject: Re: [Crash-utility] [PATCH] Fix get_xtime() for kernel 6.17 and higher
|
|Hi Georges,
|
|Thanks for the fix. Just some nits:
|
|On Thu, Apr 30, 2026 at 3:37 AM Aureau, Georges (Kernel Tools ERT)
|<georges.aureau(a)hpe.com> wrote:
|>
|> On kernels 6.17 and higher, DATE is not displayed properly:
|> crash> sys | grep -e DATE -e REL
|> DATE: Wed Dec 31 18:00:00 CST 1969
|> RELEASE: 7.0.0-14-generic
|>
|> The function get_xtime() was enhanced to support:
|
|I checked the kernel log history:
|
|struct tk_data is introduced in v6.13 by 10f7c178a9dad803e8
|"timekeeping: Define a struct type for tk_core to make it reusable".
|and tk_core to be made to timekeeper_data[0] by 22c62b9a84b8f16ca
|"timekeeping: Introduce auxiliary timekeepers", this is in v6.17.
|
|So kernel >= v6.13 should have this patch applied before the time to be displayed
|correctly. So the kernel info is misleading and better be corrected.
|
|>
|> With this get_xtime() enhancement:
|> crash> sys | grep DATE
|> DATE: Mon Apr 27 09:19:50 CDT 2026
|>
|> Signed-off-by: Georges Aureau <georges.aureau(a)hpe.com>
|> --
|> defs.h | 1 +
|> kernel.c | 19 ++++++++++++++++++-
|> 2 files changed, 19 insertions(+), 1 deletion(-)
|>
|> diff --git a/defs.h b/defs.h
|> index a6f4372..c07b9a2 100644
|> --- a/defs.h
|> +++ b/defs.h
|> @@ -2290,6 +2290,7 @@ struct offset_table { /* stash of
commonly-
|used offsets */
|> long bpf_ringbuf_nr_pages;
|> long hrtimer_clock_base_index;
|> long klp_patch_list;
|> + long tk_data_timekeeper;
|> };
|>
|> struct size_table { /* stash of commonly-used sizes */
|> diff --git a/kernel.c b/kernel.c
|> index 8781d6a..d54e825 100644
|> --- a/kernel.c
|> +++ b/kernel.c
|> @@ -258,6 +258,7 @@ kernel_init()
|>
|> MEMBER_OFFSET_INIT(timekeeper_xtime, "timekeeper",
"xtime");
|> MEMBER_OFFSET_INIT(timekeeper_xtime_sec, "timekeeper",
|> "xtime_sec");
|> + MEMBER_OFFSET_INIT(tk_data_timekeeper, "tk_data",
|> + "timekeeper");
|> get_xtime(&kt->date);
|> if (CRASHDEBUG(1))
|> fprintf(fp, "xtime timespec.tv_sec: %lx: %s\n", @@
|> -11134,7 +11135,23 @@ get_xtime(struct timespec *date)
|> struct syment *sp;
|> uint64_t xtime_sec;
|>
|> - if (VALID_MEMBER(timekeeper_xtime) &&
|> + if (VALID_MEMBER(tk_data_timekeeper) &&
|> + VALID_MEMBER(timekeeper_xtime_sec)) {
|> + long offset = OFFSET(tk_data_timekeeper) +
|> + OFFSET(timekeeper_xtime_sec);
|> + if ((sp = kernel_symbol_search("timekeeper_data"))) {
|> + readmem(sp->value + offset, KVADDR,
|> + &xtime_sec, sizeof(uint64_t),
|> + "timekeeper_data xtime_sec",
RETURN_ON_ERROR);
|> + date->tv_sec = (__time_t)xtime_sec;
|> + } else if ((sp = kernel_symbol_search("tk_core"))) {
|> + readmem(sp->value + offset, KVADDR,
|> + &xtime_sec, sizeof(uint64_t),
|> + "tk_core xtime_sec", RETURN_ON_ERROR);
|> + date->tv_sec = (__time_t)xtime_sec;
|> + }
|
|I think we don't need distinguish timekeeper_data or tk_core's readmem(), the
|kernel data structure is unchanged, all are: struct tk_data -> member timekeeper -
|> member xtime_sec. So a simple:
|
|if ((sp = kernel_symbol_search("timekeeper_data")) || (sp =
|kernel_symbol_search("tk_core"))) {
| readmem(sp->value + offset, KVADDR,
| &xtime_sec, sizeof(uint64_t),
| "tk_data timekeeper xtime_sec", RETURN_ON_ERROR); }
|
|should work. What do you think?
|
|Thanks,
|Tao Liu
|
|
|> + }
|> + else if (VALID_MEMBER(timekeeper_xtime) &&
|> (sp = kernel_symbol_search("timekeeper"))) {
|> readmem(sp->value + OFFSET(timekeeper_xtime), KVADDR,
|> date, sizeof(struct timespec),
|> --
|> Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io To
|> unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io
|> https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/
|> Contribution Guidelines: https://github.com/crash-utility/crash/wiki
|>