On Tue, Sep 16, 2025 at 2:26 PM lijiang <[email protected]> wrote:

> On Tue, Sep 16, 2025 at 12:51 PM HAGIO KAZUHITO(萩尾 一仁) <[email protected]>
> wrote:
>
>> Hi Lianbo, Tao,
>>
>> Just a report, with this patch (99bb57ac98af), I observed that
>> the log command printed a couple of empty lines (only timestamps).
>> Could you reproduce this at your end?
>>
>
> Thank you for reporting this, Kazu.
> I will check it, and did not see it before this.
>

Could you please try this one? Kazu.

diff --git a/printk.c b/printk.c
index ae28c4f..51b618e 100644
--- a/printk.c
+++ b/printk.c
@@ -221,7 +221,7 @@ dump_record(struct prb_map *m, unsigned long id, int
msg_flags)
        char *p1 = strstr(buf, "_R");
        if (!p1)
                p1 = strstr(buf, "_ZN");
-       char *p2 = strchrnul(buf, '+');
+       char *p2 = strrchr(buf, '+');
        if (p1 && p2) {
                char mangled[BUFSIZE] = {0};
                char demangled[BUFSIZE] = {0};

I did not reproduce it, but I guess that this should be related to the
strchrnul(), let's replace it with the strrchr().

Thanks.
Lianbo


>
> Thanks.
> Lianbo
>
>
>> $ diff -u log.pre log.cur
>> --- log.pre     2025-09-16 13:14:31.022206514 +0900
>> +++ log.cur     2025-09-16 13:14:56.220390987 +0900
>> @@ -210,7 +210,7 @@
>>   [    0.169375] clocksource: jiffies: mask: 0xffffffff max_cycles:
>> 0xffffffff, max_idle_ns: 1911260446275000 ns
>>   [    0.169375] futex hash table entries: 1024 (order: 4, 65536 bytes,
>> linear)
>>   [    0.169375] pinctrl core: initialized pinctrl subsystem
>> -[    0.172925] NET: Registered PF_NETLINK/PF_ROUTE protocol family
>> +[    0.172925]
>>   [    0.172983] DMA: preallocated 512 KiB GFP_KERNEL pool for atomic
>> allocations
>>   [    0.172986] DMA: preallocated 512 KiB GFP_KERNEL|GFP_DMA pool for
>> atomic allocations
>>   [    0.172988] DMA: preallocated 512 KiB GFP_KERNEL|GFP_DMA32 pool for
>> atomic allocations
>> @@ -807,7 +807,7 @@
>>   [771438.513231]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
>>   [771438.513423] RIP: 0033:0x7fbd9f8fda57
>>   [771438.513576] Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7
>> 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f
>> 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
>> -[771438.514251] RSP: 002b:00007ffee0de2b98 EFLAGS: 00000246 ORIG_RAX:
>> 0000000000000001
>> +[771438.514251]
>>   [771438.514534] RAX: ffffffffffffffda RBX: 0000000000000002 RCX:
>> 00007fbd9f8fda57
>>   [771438.514800] RDX: 0000000000000002 RSI: 00005647ccc0a330 RDI:
>> 0000000000000001
>>   [771438.515066] RBP: 00005647ccc0a330 R08: 0000000000000003 R09:
>> 0000000000000000
>>
>> log.cur: 99bb57ac98afd89fcf23f0c8bc637821dcbd278f
>> log.pre: a5942e3acfd9330d101cc65ef2e19e627233ddf6
>>   vmcore: panic by sysrq-trigger on 5.14.0-427.13.1.el9_4.x86_64
>> (found also on 6.17-rc6)
>>
>> Thanks,
>> Kazu
>>
>> On 2025/09/15 10:19, Tao Liu wrote:
>> > applied:
>> https://github.com/crash-utility/crash/commit/99bb57ac98afd89fcf23f0c8bc637821dcbd278f
>> >
>> > On Wed, Sep 10, 2025 at 2:33 PM Tao Liu <[email protected]> wrote:
>> >>
>> >> Hi lianbo,
>> >>
>> >> Thanks for the v2, LGTM, ack.
>> >>
>> >>
>> >> On Mon, Sep 8, 2025 at 8:42 PM Lianbo Jiang <[email protected]>
>> wrote:
>> >>>
>> >>> Without the patch:
>> >>>    crash> log
>> >>>    ...
>> >>>    [ 2174.308966] Call Trace:
>> >>>    [ 2174.311693]  <TASK>
>> >>>    [ 2174.314033]  dump_stack_lvl+0x5d/0x80
>> >>>    [ 2174.318125]  panic+0x156/0x32a
>> >>>    [ 2174.321539]
>> _RNvCscb18lrEyTSA_10rust_panic10area_in_hp+0xf7/0x120 [rust_panic]
>> >>>    [ 2174.329700]  ? console_unlock+0x9c/0x140
>> >>>    [ 2174.334080]  ? irq_work_queue+0x2d/0x50
>> >>>    [ 2174.338352]  ? __pfx_init_module+0x10/0x10 [rust_panic]
>> >>>    [ 2174.344183]
>> _RNvMCscb18lrEyTSA_10rust_panicNtB2_10HelloPanic8step_two+0x20/0xe0
>> [rust_panic]
>> >>>    [ 2174.353698]  ? _printk+0x6b/0x90
>> >>>    ...
>> >>>
>> >>> With the patch:
>> >>>    crash> log
>> >>>    ...
>> >>>    [ 2174.308966] Call Trace:
>> >>>    [ 2174.311693]  <TASK>
>> >>>    [ 2174.314033]  dump_stack_lvl+0x5d/0x80
>> >>>    [ 2174.318125]  panic+0x156/0x32a
>> >>>    [ 2174.321539]  rust_panic::area_in_hp+0xf7/0x120 [rust_panic]
>> >>>    [ 2174.329700]  ? console_unlock+0x9c/0x140
>> >>>    [ 2174.334080]  ? irq_work_queue+0x2d/0x50
>> >>>    [ 2174.338352]  ? __pfx_init_module+0x10/0x10 [rust_panic]
>> >>>    [ 2174.344183]  <rust_panic::HelloPanic>::step_two+0x20/0xe0
>> [rust_panic]
>> >>>    [ 2174.353698]  ? _printk+0x6b/0x90
>> >>>    ...
>> >>>
>> >>> Signed-off-by: Lianbo Jiang <[email protected]>
>> >>> ---
>> >>> Note:
>> >>> 1. Add some checks to avoid the risk of buffer overflow.
>> >>>
>> >>>   Makefile |  2 +-
>> >>>   printk.c | 33 ++++++++++++++++++++++++++++++++-
>> >>>   2 files changed, 33 insertions(+), 2 deletions(-)
>> >>>
>> >>> diff --git a/Makefile b/Makefile
>> >>> index fc1c9588dcfa..b277129f6df2 100644
>> >>> --- a/Makefile
>> >>> +++ b/Makefile
>> >>> @@ -421,7 +421,7 @@ kernel.o: ${GENERIC_HFILES} kernel.c
>> >>>          ${CC} -c ${CRASH_CFLAGS} kernel.c -I${BFD_DIRECTORY}
>> -I${GDB_INCLUDE_DIRECTORY} ${WARNING_OPTIONS} ${WARNING_ERROR}
>> >>>
>> >>>   printk.o: ${GENERIC_HFILES} printk.c
>> >>> -       ${CC} -c ${CRASH_CFLAGS} printk.c ${WARNING_OPTIONS}
>> ${WARNING_ERROR}
>> >>> +       ${CC} -c ${CRASH_CFLAGS} printk.c -I${GDB_INCLUDE_DIRECTORY}
>> ${WARNING_OPTIONS} ${WARNING_ERROR}
>> >>>
>> >>>   gdb_interface.o: ${GENERIC_HFILES} gdb_interface.c
>> >>>          ${CC} -c ${CRASH_CFLAGS} gdb_interface.c ${WARNING_OPTIONS}
>> ${WARNING_ERROR}
>> >>> diff --git a/printk.c b/printk.c
>> >>> index 95db7e607e4c..ae28c4fa0b21 100644
>> >>> --- a/printk.c
>> >>> +++ b/printk.c
>> >>> @@ -1,5 +1,6 @@
>> >>>   #include "defs.h"
>> >>>   #include <ctype.h>
>> >>> +#include "demangle.h"
>> >>>
>> >>>   /* convenience struct for passing many values to helper functions */
>> >>>   struct prb_map {
>> >>> @@ -201,14 +202,44 @@ dump_record(struct prb_map *m, unsigned long
>> id, int msg_flags)
>> >>>
>> >>>          text = m->text_data + begin;
>> >>>
>> >>> +       if (text_len > BUFSIZE) {
>> >>> +               error(WARNING, "\nThe messages could be
>> truncated!\n");
>> >>> +               text_len = BUFSIZE;
>> >>> +       }
>> >>> +
>> >>>          for (i = 0, p = text; i < text_len; i++, p++) {
>> >>>                  if (*p == '\n')
>> >>>                          fprintf(fp, "\n%s", space(ilen));
>> >>>                  else if (isprint(*p) || isspace(*p))
>> >>> -                       fputc(*p, fp);
>> >>> +                       sprintf(&buf[i], "%c", *p);
>> >>>                  else
>> >>>                          fputc('.', fp);
>> >>>          }
>> >>> +       /*
>> >>> +        * Try to demangle a mangled Rust symbol(calltrace) from log
>> buffer
>> >>> +        */
>> >>> +       char *p1 = strstr(buf, "_R");
>> >>> +       if (!p1)
>> >>> +               p1 = strstr(buf, "_ZN");
>> >>> +       char *p2 = strchrnul(buf, '+');
>> >>> +       if (p1 && p2) {
>> >>> +               char mangled[BUFSIZE] = {0};
>> >>> +               char demangled[BUFSIZE] = {0};
>> >>> +               char *res;
>> >>> +               size_t slen = p1 - buf;
>> >>> +
>> >>> +               if (slen)
>> >>> +                       memcpy(demangled, buf, slen);
>> >>> +
>> >>> +               memcpy(mangled, p1, p2-p1);
>> >>> +               res = rust_demangle(mangled, DMGL_RUST);
>> >>> +               if (res) {
>> >>> +                       snprintf(demangled+slen, BUFSIZE-slen,
>> "%s%s", res, p2);
>> >>> +                       fprintf(fp, "%s",demangled);
>> >>> +                       free(res);
>> >>> +               }
>> >>> +       } else
>> >>> +               fprintf(fp, "%s", buf);
>> >>>
>> >>>          if (msg_flags & SHOW_LOG_DICT) {
>> >>>                  text = info + OFFSET(printk_info_dev_info) +
>> >>> --
>> >>> 2.50.1
>> >>>
>> > --
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>
>
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