Let me try that again with discrete attachments. ----- Original Message ----- > > ----- Original Message ----- > > > >>> The problem happens only with module symbols, not with kallsyms. > >>> > >>> crash> sym -M > >>> c008000007810000 MODULE START: crc32c_vpmsum > >>> c008000007810000 (^R) __crc32c_vpmsum > >>> c008000007810670 (^B) crc32c_vpmsum_cra_init > >>> c008000007810690 (^B) crc32c_vpmsum_setkey > >> > >> Hi Ravi, > >> > >> I have never seen this before, but nonetheless, it does seem that Steve's > >> patch > >> to the trace.c module is the better course of action. Does it work OK for > >> you? > >> > >> Dave > > > > Dave, I see only cover letter: > > https://www.redhat.com/archives/crash-utility/2019-March/thread.html > > > > Can you please forward patches to ml as well. > > > > Sorry about that... > > Dave > > > -- > Crash-utility mailing list > Crash-utility@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/crash-utility
--- Begin Message ---
- Subject: [PATCH 3/3] trace.so: Show -t option in trace dump short help message
- From: Steven Rostedt <rostedt@xxxxxxxxxxx>
- Date: Fri, 15 Mar 2019 21:06:09 -0400
- In-reply-to: <20190315210333.4c44a088@oasis.local.home>
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> The -t option is not listed with just crash> trace dump -h As -t is the most common option for trace dump, it really should be there on the short help message. Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- extensions/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/extensions/trace.c b/extensions/trace.c index 51a1ab2..c26b6c7 100644 --- a/extensions/trace.c +++ b/extensions/trace.c @@ -1834,7 +1834,7 @@ static void cmd_ftrace(void) static char *help_ftrace[] = { "trace", "show or dump the tracing info", -"[ <show [-c <cpulist>] [-f [no]<flagname>]> | <dump [-sm] <dest-dir>> ]", +"[ <show [-c <cpulist>] [-f [no]<flagname>]> | <dump [-sm] <dest-dir>> ] | <dump -t <trace.dat> ]", "trace", " shows the current tracer and other informations.", "", -- 2.20.1
--- End Message ---
--- Begin Message ---
- Subject: [PATCH 2/3] trace.so: Do not print garbage for kallsyms "type" for modules
- From: Steven Rostedt <rostedt@xxxxxxxxxxx>
- Date: Fri, 15 Mar 2019 21:05:55 -0400
- In-reply-to: <20190315210333.4c44a088@oasis.local.home>
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> It appears that the sp->type is garbage, and writing that to the kallsyms file for trace-cmd to read, causes it to crash. trace-cmd doesn't even care about the type field so just write "m". Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- extensions/trace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/extensions/trace.c b/extensions/trace.c index 3827430..51a1ab2 100644 --- a/extensions/trace.c +++ b/extensions/trace.c @@ -2209,7 +2209,8 @@ static int save_proc_kallsyms(int fd) if (!strncmp(sp->name, "_MODULE_", strlen("_MODULE_"))) continue; - tmp_fprintf("%lx %c %s\t[%s]\n", sp->value, sp->type, + /* Currently sp->type for modules is not trusted */ + tmp_fprintf("%lx %c %s\t[%s]\n", sp->value, 'm', sp->name, lm->mod_name); } } -- 2.20.1
--- End Message ---
--- Begin Message ---
- Subject: [PATCH 1/3] trace.so: Do not record empty pages
- From: Steven Rostedt <rostedt@xxxxxxxxxxx>
- Date: Fri, 15 Mar 2019 21:05:47 -0400
- In-reply-to: <20190315210333.4c44a088@oasis.local.home>
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> The reader_page can be empty if it was never read, do not record it if it is empty. Better yet, do not record any page that is empty. The struct buffer_page "real_end" is not available in older kernels, so it needs to be tested if it exists before we can use it. Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- extensions/trace.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/extensions/trace.c b/extensions/trace.c index ad71951..3827430 100644 --- a/extensions/trace.c +++ b/extensions/trace.c @@ -43,6 +43,11 @@ static int max_buffer_available; */ static int multiple_instances_available; +/* + * buffer_page has "real_end" + */ +static int buffer_page_real_end_available; + #define koffset(struct, member) struct##_##member##_offset static int koffset(trace_array, current_trace); @@ -70,6 +75,7 @@ static int koffset(ring_buffer_per_cpu, entries); static int koffset(buffer_page, read); static int koffset(buffer_page, list); static int koffset(buffer_page, page); +static int koffset(buffer_page, real_end); static int koffset(list_head, next); @@ -229,6 +235,7 @@ static int init_offsets(void) init_offset(buffer_page, read); init_offset(buffer_page, list); init_offset(buffer_page, page); + init_offset(buffer_page, real_end); init_offset(list_head, next); @@ -281,6 +288,7 @@ static void print_offsets(void) print_offset(buffer_page, read); print_offset(buffer_page, list); print_offset(buffer_page, page); + print_offset(buffer_page, real_end); print_offset(list_head, next); @@ -295,6 +303,20 @@ static void print_offsets(void) #undef print_offset } +static int buffer_page_has_data(ulong page) +{ + uint end; + + if (!buffer_page_real_end_available) + return 1; + + /* Only write pages with data in it */ + read_value(end, page, buffer_page, real_end); + return end; +out_fail: + return 0; +} + static int ftrace_init_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) { @@ -361,7 +383,8 @@ static int ftrace_init_pages(struct ring_buffer_per_cpu *cpu_buffer, /* Setup linear pages */ - cpu_buffer->linear_pages[count++] = cpu_buffer->reader_page; + if (buffer_page_has_data(cpu_buffer->reader_page)) + cpu_buffer->linear_pages[count++] = cpu_buffer->reader_page; if (cpu_buffer->reader_page == cpu_buffer->commit_page) goto done; @@ -647,6 +670,8 @@ static int ftrace_init(void) ftrace_trace_arrays = sym_ftrace_trace_arrays->value; } + if (MEMBER_EXISTS("buffer_page", "real_end")) + buffer_page_real_end_available = 1; if (MEMBER_EXISTS("trace_array", "current_trace")) { encapsulated_current_trace = 1; -- 2.20.1
--- End Message ---
--- Begin Message ---
- Subject: [PATCH 0/3] trace.so: Make trace dump -t work again
- From: Steven Rostedt <rostedt@xxxxxxxxxxx>
- Date: Fri, 15 Mar 2019 21:03:33 -0400
Hi Dave, I gave a talk at SCaLE 17x last week and was going to demonstrate using ftrace on a system that crashes, and then pulling out the vmcore file with kexec and kdump, and then pulling out the ftrace ring buffers and creating a trace.dat file with the crash extension trace.so. Unfortunately, this wasn't working as I planned. I created the following three patches, where two fix the issue (I was getting a corrupted trace.dat file), and the third actually documents the '-t' option of the dump command. Hopefully you can accept these patches. Thanks! -- Steve ----- extensions/trace.c | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) Steven Rostedt (VMware) (3): trace.so: Do not record empty pages trace.so: Do not print garbage for kallsyms "type" for modules trace.so: Show -t option in trace dump short help message
--- End Message ---
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