Re: [Crash-utility] [External Mail]Re: [PATCH] Bugfix and optimization for ARM64 getting crash notes

Hi Dave, Above your suggestion, I made changes for patch v2. Best regards, Qiwu

-----Original Message----- From: Dave Anderson <anderson(a)redhat.com&gt; Sent: Wednesday, December 11, 2019 12:51 AM To: qiwuchen55(a)gmail.com Cc: crash-utility(a)redhat.com; 陈启武 <chenqiwu(a)xiaomi.com&gt; Subject: [External Mail]Re: [PATCH] Bugfix and optimization for ARM64 getting crash notes ----- Original Message ----- > From: chenqiwu <chenqiwu(a)xiaomi.com&gt; > > 1) ARM64 call arm64_get_crash_notes() to retrieve active task > registers when POST_VM before calling map_cpus_to_prstatus() to remap > the NT_PRSTATUS elf notes to the online cpus. It's better to call > arm64_get_crash_notes() when POST_INIT. > 2) arm64_get_crash_notes() check the sanity of NT_PRSTATUS notes only > for online cpus. If one cpu contains invalid note, it's better to > continue finding the crash notes for other online cpus. > So we can extract the backtraces for the online cpus which contain > valid note by using command "bt -a". > 3) map_cpus_to_prstatus() remap the NT_PRSTATUS notes only to the > online cpus. Make sure there must be a one-to-one relationship between > the number of online cpus and the number of notes. The code in map_cpus_to_prstatus() and map_cpus_to_prstatus_kdump_cmprs() has been in place forever. Both the nd->nt_prstatus_percpu[] and dd->nt_prstatus_percpu[] arrays are per-cpu regardless whether they are online or offline. However, since kdump only creates NT_PRSTATUS notes for on-line cpus, the "i" index is needed for each cpu, and the "j" index is needed for the existing NT_PRSTATUS notes. If a cpu is offline, its nt_prstatus_percpu[] entry will be zeroed out. I'm not arguing that the arm64 online-cpu handling may be suspect, but your patch should not be making changes to architectural-neutral code unless the issue affects all architectures. So please leave those two functions alone. Dave > > Signed-off-by: chenqiwu <chenqiwu(a)xiaomi.com&gt; > --- > arm64.c | 49 +++++++++++++++++++++++++++++-------------------- > diskdump.c | 9 +++------ > netdump.c | 4 ++-- > 3 files changed, 34 insertions(+), 28 deletions(-) > > diff --git a/arm64.c b/arm64.c > index 233029d..cbad461 100644 > --- a/arm64.c > +++ b/arm64.c > @@ -458,7 +458,7 @@ arm64_init(int when) > arm64_stackframe_init() > break; > > -case POST_VM: > +case POST_INIT: > /* > * crash_notes contains machine specific information about the > * crash. In particular, it contains CPU registers at the time @@ > -3587,7 +3587,7 @@ arm64_get_crash_notes(void) > ulong offset; > char *buf, *p; > ulong *notes_ptrs; > -ulong i; > +ulong i, j; > > if (!symbol_exists("crash_notes")) > return FALSE; > @@ -3620,12 +3620,12 @@ arm64_get_crash_notes(void) > if (!(ms->panic_task_regs = calloc((size_t)kt->cpus, sizeof(struct > arm64_pt_regs)))) > error(FATAL, "cannot calloc panic_task_regs space\n"); > > -for (i = 0; i < kt->cpus; i++) { > - > +for (i = 0, j = 0; i < kt->cpus; i++) { > if (!readmem(notes_ptrs[i], KVADDR, buf, SIZE(note_buf), > "note_buf_t", RETURN_ON_ERROR)) { > -error(WARNING, "failed to read note_buf_t\n"); > -goto fail; > +error(WARNING, "cpu#%d: failed to read note_buf_t\n", i); > +++j; > +continue; > } > > /* > @@ -3655,19 +3655,29 @@ arm64_get_crash_notes(void) > note->n_descsz == notesz) > BCOPY((char *)note, buf, notesz); > } else { > -error(WARNING, > -"cannot find NT_PRSTATUS note for cpu: %d\n", i); > +if (CRASHDEBUG(1)) > +error(WARNING, > +"cpu#%d: cannot find NT_PRSTATUS note\n", i); > +++j; > continue; > } > } > > +/* > + * Check the sanity of NT_PRSTATUS note only for each online cpu. > + * If this cpu has invalid note, continue to find the crash notes > + * for other online cpus. > + */ > if (note->n_type != NT_PRSTATUS) { > -error(WARNING, "invalid note (n_type != NT_PRSTATUS)\n"); > -goto fail; > +error(WARNING, "cpu#%d: invalid note (n_type != NT_PRSTATUS)\n", i); > +++j; > +continue; > } > -if (p[0] != 'C' || p[1] != 'O' || p[2] != 'R' || p[3] != 'E') { > -error(WARNING, "invalid note (name != \"CORE\"\n"); > -goto fail; > + > +if (!STRNEQ(p, "CORE")) { > +error(WARNING, "cpu#%d: invalid note (name != \"CORE\")\n", i); > +++j; > +continue; > } > > /* > @@ -3684,14 +3694,13 @@ arm64_get_crash_notes(void) > > FREEBUF(buf); > FREEBUF(notes_ptrs); > -return TRUE; > > -fail: > -FREEBUF(buf); > -FREEBUF(notes_ptrs); > -free(ms->panic_task_regs); > -ms->panic_task_regs = NULL; > -return FALSE; > +if (j == kt->cpus) { > +free(ms->panic_task_regs); > +ms->panic_task_regs = NULL; > +return FALSE; > +} > +return TRUE; > } > > static void > diff --git a/diskdump.c b/diskdump.c > index e88243e..12d8e9c 100644 > --- a/diskdump.c > +++ b/diskdump.c > @@ -130,12 +130,9 @@ map_cpus_to_prstatus_kdump_cmprs(void) > */ > nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS); > > -for (i = 0, j = 0; i < nrcpus; i++) { > -if (in_cpu_map(ONLINE_MAP, i)) { > -dd->nt_prstatus_percpu[i] = nt_ptr[j++]; > -dd->num_prstatus_notes = > -MAX(dd->num_prstatus_notes, i+1); > -} > +for (i = 0; i < nrcpus; i++) { > +if (in_cpu_map(ONLINE_MAP, i)) > +dd->nt_prstatus_percpu[i] = nt_ptr[i]; > } > > FREEBUF(nt_ptr); > diff --git a/netdump.c b/netdump.c > index 406416a..849638a 100644 > --- a/netdump.c > +++ b/netdump.c > @@ -97,9 +97,9 @@ map_cpus_to_prstatus(void) > */ > nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS); > > -for (i = 0, j = 0; i < nrcpus; i++) { > +for (i = 0; i < nrcpus; i++) { > if (in_cpu_map(ONLINE_MAP, i)) > -nd->nt_prstatus_percpu[i] = nt_ptr[j++]; > +nd->nt_prstatus_percpu[i] = nt_ptr[i]; > } > > FREEBUF(nt_ptr); > -- > 1.9.1 > > #/******本邮件及其附件含有小米公司的保密信息，仅限于发送给上面地址中列出的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本邮件！ This e-mail and its attachments contain confidential information from XIAOMI, which is intended only for the person or entity whose address is listed above. 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