On 2025/09/17 23:15, Lianbo Jiang wrote: > Currently, the log command will display human readable Rust > symbol name by default if any, but, sometimes still want to > print the original messages from the log buffer(do not demangle). > > In addition, if the log buffer has lines like "_R ... +" which > are not Rust symbols unexpectedly, probably the output will be > missed, that is unexpected. > > To fix above cases, add "log -R" to display human readable Rust > symbol name, otherwise still print the original messages. > > With the patch: > crash> log -R > ... > [ 2174.289360] Tainted: [S]=CPU_OUT_OF_SPEC, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE > [ 2174.297322] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.0018.072020161249 07/20/2016 > [ 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 > [ 2174.357303] init_module+0x57/0xff0 [rust_panic] > [ 2174.362456] ? __pfx_init_module+0x10/0x10 [rust_panic] > ... > > Suggested-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; Thank you for the patch, Lianbo. It looks good to me and cleans my worries.

Thanks, Kazu > --- > defs.h | 1 + > help.c | 24 +++++++++++++++++++++++- > kernel.c | 5 ++++- > printk.c | 53 +++++++++++++++++++++++++++++------------------------ > 4 files changed, 57 insertions(+), 26 deletions(-) > > diff --git a/defs.h b/defs.h > index 156ac0232906..997145cba9d2 100644 > --- a/defs.h > +++ b/defs.h > @@ -6227,6 +6227,7 @@ void parse_kernel_version(char *); > #define SHOW_LOG_CTIME (0x10) > #define SHOW_LOG_SAFE (0x20) > #define SHOW_LOG_CALLER (0x40) > +#define SHOW_LOG_RUST (0x80) > void set_cpu(int); > void clear_machdep_cache(void); > struct stack_hook *gather_text_list(struct bt_info *); > diff --git a/help.c b/help.c > index 4f071e0bd0a0..78d7a5c70e30 100644 > --- a/help.c > +++ b/help.c > @@ -4026,7 +4026,7 @@ NULL > char *help_log[] = { > "log", > "dump system message buffer", > -"[-Ttdmasc]", > +"[-TtdmascR]", > " This command dumps the kernel log_buf contents in chronological order. The", > " command supports the older log_buf formats, which may or may not contain a", > " timestamp inserted prior to each message, as well as the newer variable-length", > @@ -4053,6 +4053,8 @@ char *help_log[] = { > " the CPU id (if in CPU context) that called printk(), if available.", > " Generally available on Linux 5.1 to 5.9 kernels configured with", > " CONFIG_PRINTK_CALLER or Linux 5.10 and later kernels.", > +" -R Display the message text with human readable Rust symbol name if any,", > +" otherwise still print the original message text.", > " ", > "\nEXAMPLES", > " Dump the kernel message buffer:\n", > @@ -4231,6 +4233,26 @@ char *help_log[] = { > " [ 0.014179] [ T29] RAMDISK: [mem 0x3cf4f000-0x437bbfff]", > " [ 0.198789] [ C0] DMAR: DRHD: handling fault status reg 3", > " ...", > +" ", > +" Display the message text with human readable Rust symbol name if any,", > +" otherwise still print the original message text.\n", > +" %s> log -R", > +" ...", > +" [ 2174.289360] Tainted: [S]=CPU_OUT_OF_SPEC, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE", > +" [ 2174.297322] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.0018.072020161249 07/20/2016", > +" [ 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", > +" [ 2174.357303] init_module+0x57/0xff0 [rust_panic]", > +" [ 2174.362456] ? __pfx_init_module+0x10/0x10 [rust_panic]", > +" ...", > > NULL > }; > diff --git a/kernel.c b/kernel.c > index e4213d7a663e..e077275d7ed6 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -5136,7 +5136,7 @@ cmd_log(void) > > msg_flags = 0; > > - while ((c = getopt(argcnt, args, "Ttdmasc")) != EOF) { > + while ((c = getopt(argcnt, args, "TtdmascR")) != EOF) { > switch(c) > { > case 'T': > @@ -5160,6 +5160,9 @@ cmd_log(void) > case 'c': > msg_flags |= SHOW_LOG_CALLER; > break; > + case 'R': > + msg_flags |= SHOW_LOG_RUST; > + break; > default: > argerrs++; > break; > diff --git a/printk.c b/printk.c > index 51b618e2a434..b8fcc8e58160 100644 > --- a/printk.c > +++ b/printk.c > @@ -202,7 +202,7 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) > > text = m->text_data + begin; > > - if (text_len > BUFSIZE) { > + if ((msg_flags & SHOW_LOG_RUST) && (text_len > BUFSIZE)) { > error(WARNING, "\nThe messages could be truncated!\n"); > text_len = BUFSIZE; > } > @@ -210,36 +210,41 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) > 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)) > + else if ((msg_flags & SHOW_LOG_RUST) && (isprint(*p) || isspace(*p))) > sprintf(&buf[i], "%c", *p); > + else if (isprint(*p) || isspace(*p)) > + fputc(*p, fp); > 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 = strrchr(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_RUST) { > + char *p1 = strstr(buf, "_R"); > + if (!p1) > + p1 = strstr(buf, "_ZN"); > + char *p2 = strrchr(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); > + } else > + fprintf(fp, "%s", buf); > + } > > if (msg_flags & SHOW_LOG_DICT) { > text = info + OFFSET(printk_info_dev_info) +

Hi lianbo, This patch LGTM, but I'm unsure if this patch has relations with the ppc64 bug: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01649.html.

So I will leave it here and merge after the ppc64 bug is resolved. Thanks, Tao Liu On Thu, Sep 18, 2025 at 3:22 PM lijiang <lijiang(a)redhat.com&gt; wrote: > > On Thu, Sep 18, 2025 at 9:50 AM HAGIO KAZUHITO(萩尾　一仁) <k-hagio-ab(a)nec.com&gt; wrote: >> >> On 2025/09/17 23:15, Lianbo Jiang wrote: >>> Currently, the log command will display human readable Rust >>> symbol name by default if any, but, sometimes still want to >>> print the original messages from the log buffer(do not demangle). >>> >>> In addition, if the log buffer has lines like "_R ... +" which >>> are not Rust symbols unexpectedly, probably the output will be >>> missed, that is unexpected. >>> >>> To fix above cases, add "log -R" to display human readable Rust >>> symbol name, otherwise still print the original messages. >>> >>> With the patch: >>> crash> log -R >>> ... >>> [ 2174.289360] Tainted: [S]=CPU_OUT_OF_SPEC, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE >>> [ 2174.297322] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.0018.072020161249 07/20/2016 >>> [ 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 >>> [ 2174.357303] init_module+0x57/0xff0 [rust_panic] >>> [ 2174.362456] ? __pfx_init_module+0x10/0x10 [rust_panic] >>> ... >>> >>> Suggested-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; >>> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; >> >> Thank you for the patch, Lianbo. It looks good to me and cleans my worries. >> > > Np. This looks better to me. > > Lianbo > >> >> Thanks, >> Kazu >> >>> --- >>> defs.h | 1 + >>> help.c | 24 +++++++++++++++++++++++- >>> kernel.c | 5 ++++- >>> printk.c | 53 +++++++++++++++++++++++++++++------------------------ >>> 4 files changed, 57 insertions(+), 26 deletions(-) >>> >>> diff --git a/defs.h b/defs.h >>> index 156ac0232906..997145cba9d2 100644 >>> --- a/defs.h >>> +++ b/defs.h >>> @@ -6227,6 +6227,7 @@ void parse_kernel_version(char *); >>> #define SHOW_LOG_CTIME (0x10) >>> #define SHOW_LOG_SAFE (0x20) >>> #define SHOW_LOG_CALLER (0x40) >>> +#define SHOW_LOG_RUST (0x80) >>> void set_cpu(int); >>> void clear_machdep_cache(void); >>> struct stack_hook *gather_text_list(struct bt_info *); >>> diff --git a/help.c b/help.c >>> index 4f071e0bd0a0..78d7a5c70e30 100644 >>> --- a/help.c >>> +++ b/help.c >>> @@ -4026,7 +4026,7 @@ NULL >>> char *help_log[] = { >>> "log", >>> "dump system message buffer", >>> -"[-Ttdmasc]", >>> +"[-TtdmascR]", >>> " This command dumps the kernel log_buf contents in chronological order. The", >>> " command supports the older log_buf formats, which may or may not contain a", >>> " timestamp inserted prior to each message, as well as the newer variable-length", >>> @@ -4053,6 +4053,8 @@ char *help_log[] = { >>> " the CPU id (if in CPU context) that called printk(), if available.", >>> " Generally available on Linux 5.1 to 5.9 kernels configured with", >>> " CONFIG_PRINTK_CALLER or Linux 5.10 and later kernels.", >>> +" -R Display the message text with human readable Rust symbol name if any,", >>> +" otherwise still print the original message text.", >>> " ", >>> "\nEXAMPLES", >>> " Dump the kernel message buffer:\n", >>> @@ -4231,6 +4233,26 @@ char *help_log[] = { >>> " [ 0.014179] [ T29] RAMDISK: [mem 0x3cf4f000-0x437bbfff]", >>> " [ 0.198789] [ C0] DMAR: DRHD: handling fault status reg 3", >>> " ...", >>> +" ", >>> +" Display the message text with human readable Rust symbol name if any,", >>> +" otherwise still print the original message text.\n", >>> +" %s> log -R", >>> +" ...", >>> +" [ 2174.289360] Tainted: [S]=CPU_OUT_OF_SPEC, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE", >>> +" [ 2174.297322] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.0018.072020161249 07/20/2016", >>> +" [ 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", >>> +" [ 2174.357303] init_module+0x57/0xff0 [rust_panic]", >>> +" [ 2174.362456] ? __pfx_init_module+0x10/0x10 [rust_panic]", >>> +" ...", >>> >>> NULL >>> }; >>> diff --git a/kernel.c b/kernel.c >>> index e4213d7a663e..e077275d7ed6 100644 >>> --- a/kernel.c >>> +++ b/kernel.c >>> @@ -5136,7 +5136,7 @@ cmd_log(void) >>> >>> msg_flags = 0; >>> >>> - while ((c = getopt(argcnt, args, "Ttdmasc")) != EOF) { >>> + while ((c = getopt(argcnt, args, "TtdmascR")) != EOF) { >>> switch(c) >>> { >>> case 'T': >>> @@ -5160,6 +5160,9 @@ cmd_log(void) >>> case 'c': >>> msg_flags |= SHOW_LOG_CALLER; >>> break; >>> + case 'R': >>> + msg_flags |= SHOW_LOG_RUST; >>> + break; >>> default: >>> argerrs++; >>> break; >>> diff --git a/printk.c b/printk.c >>> index 51b618e2a434..b8fcc8e58160 100644 >>> --- a/printk.c >>> +++ b/printk.c >>> @@ -202,7 +202,7 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) >>> >>> text = m->text_data + begin; >>> >>> - if (text_len > BUFSIZE) { >>> + if ((msg_flags & SHOW_LOG_RUST) && (text_len > BUFSIZE)) { >>> error(WARNING, "\nThe messages could be truncated!\n"); >>> text_len = BUFSIZE; >>> } >>> @@ -210,36 +210,41 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) >>> 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)) >>> + else if ((msg_flags & SHOW_LOG_RUST) && (isprint(*p) || isspace(*p))) >>> sprintf(&buf[i], "%c", *p); >>> + else if (isprint(*p) || isspace(*p)) >>> + fputc(*p, fp); >>> 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 = strrchr(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_RUST) { >>> + char *p1 = strstr(buf, "_R"); >>> + if (!p1) >>> + p1 = strstr(buf, "_ZN"); >>> + char *p2 = strrchr(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); >>> + } else >>> + fprintf(fp, "%s", buf); >>> + } >>> >>> if (msg_flags & SHOW_LOG_DICT) { >>> text = info + OFFSET(printk_info_dev_info) + -- 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

On Tue, Sep 30, 2025 at 3:11 PM Mikhail Zaslonko <zaslonko(a)linux.ibm.com&gt; wrote: > Hello, > > On 9/30/2025 7:04 AM, Tao Liu wrote: >> Hi lianbo, >> >> This patch LGTM, but I'm unsure if this patch has relations with the >> ppc64 bug: > https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01649.html > . > > This patch resolves the issue with the blank lines in the log (since you > put back > fputc(*p, fp) for character wise writing in case of regular 'log/dmesg' > command). > > BUT, if I use the new 'log -R' option, the blank lines are back again! > Hi, Mikhail I hacked the following code based on the v2( https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01636.html), can you try if that can work for you?

--- printk.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/printk.c b/printk.c index b8fcc8e..d9427c6 100644 --- a/printk.c +++ b/printk.c @@ -116,7 +116,7 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) uint64_t ts_nsec; ulonglong nanos; ulonglong seq; - int ilen = 0, i; + int ilen = 0, i, nlines; char *desc, *info, *text, *p; ulong rem; @@ -207,11 +207,23 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) text_len = BUFSIZE; } - for (i = 0, p = text; i < text_len; i++, p++) { - if (*p == '\n') + for (i = 0, nlines = 0, p = text; i < text_len; i++, p++) { + if (*p == '\n') { + if ((msg_flags & SHOW_LOG_RUST) && (i != text_len - 1)) { + nlines++; + if (strlen(buf)) { + fprintf(fp, "%s", buf); + memset(buf, 0, strlen(buf)); + } + } fprintf(fp, "\n%s", space(ilen)); - else if ((msg_flags & SHOW_LOG_RUST) && (isprint(*p) || isspace(*p))) - sprintf(&buf[i], "%c", *p); + } else if ((msg_flags & SHOW_LOG_RUST) && (isprint(*p) || isspace(*p))) { + if (nlines >= 1) { + fputc(*p, fp); + } + else + sprintf(&buf[i], "%c", *p);

+ } else if (isprint(*p) || isspace(*p)) fputc(*p, fp); else