| Message ID | 20221120232508.327554-4-sourabhjain@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | In kernel handling of CPU hotplug events for crash kernel | expand |
On 11/20/22 17:25, Sourabh Jain wrote: > On architectures like PowerPC the crash notes are available for all > possible CPUs. So let's populate the elfcorehdr for all possible > CPUs having crash notes to avoid updating elfcorehdr during in-kernel > crash update on CPU hotplug events. > > The similar technique was used in kexec-tool for kexec_load case. > > Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com> > --- > kernel/crash_core.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index bca1b198d9e55..f6cccdcadc9f3 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -364,16 +364,19 @@ int crash_prepare_elf64_headers(struct kimage *image, struct crash_mem *mem, > ehdr->e_ehsize = sizeof(Elf64_Ehdr); > ehdr->e_phentsize = sizeof(Elf64_Phdr); > > - /* Prepare one phdr of type PT_NOTE for each present CPU */ > - for_each_present_cpu(cpu) { > + /* Prepare one phdr of type PT_NOTE for possible CPU with crash note. */ > + for_each_possible_cpu(cpu) { > if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { > /* Skip the soon-to-be offlined cpu */ > if (image->hotplug_event && (cpu == image->offlinecpu)) > continue; > } > > - phdr->p_type = PT_NOTE; > notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); > + if (!notes_addr) > + continue; > + > + phdr->p_type = PT_NOTE; > phdr->p_offset = phdr->p_paddr = notes_addr; > phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t); > (ehdr->e_phnum)++; > I did a quick test of this for x86_64 and it works. Reviewed-by: Eric DeVolder <eric.devolder@oracle.com>
On 22/11/22 23:28, Eric DeVolder wrote: > > > On 11/20/22 17:25, Sourabh Jain wrote: >> On architectures like PowerPC the crash notes are available for all >> possible CPUs. So let's populate the elfcorehdr for all possible >> CPUs having crash notes to avoid updating elfcorehdr during in-kernel >> crash update on CPU hotplug events. >> >> The similar technique was used in kexec-tool for kexec_load case. >> >> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com> >> --- >> kernel/crash_core.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index bca1b198d9e55..f6cccdcadc9f3 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -364,16 +364,19 @@ int crash_prepare_elf64_headers(struct kimage >> *image, struct crash_mem *mem, >> ehdr->e_ehsize = sizeof(Elf64_Ehdr); >> ehdr->e_phentsize = sizeof(Elf64_Phdr); >> - /* Prepare one phdr of type PT_NOTE for each present CPU */ >> - for_each_present_cpu(cpu) { >> + /* Prepare one phdr of type PT_NOTE for possible CPU with crash >> note. */ >> + for_each_possible_cpu(cpu) { >> if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { >> /* Skip the soon-to-be offlined cpu */ >> if (image->hotplug_event && (cpu == image->offlinecpu)) >> continue; >> } >> - phdr->p_type = PT_NOTE; >> notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, >> cpu)); >> + if (!notes_addr) >> + continue; >> + >> + phdr->p_type = PT_NOTE; >> phdr->p_offset = phdr->p_paddr = notes_addr; >> phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t); >> (ehdr->e_phnum)++; >> > > I did a quick test of this for x86_64 and it works. > > Reviewed-by: Eric DeVolder <eric.devolder@oracle.com> Thanks for testing it out. - Sourabh Jain
diff --git a/kernel/crash_core.c b/kernel/crash_core.c index bca1b198d9e55..f6cccdcadc9f3 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -364,16 +364,19 @@ int crash_prepare_elf64_headers(struct kimage *image, struct crash_mem *mem, ehdr->e_ehsize = sizeof(Elf64_Ehdr); ehdr->e_phentsize = sizeof(Elf64_Phdr); - /* Prepare one phdr of type PT_NOTE for each present CPU */ - for_each_present_cpu(cpu) { + /* Prepare one phdr of type PT_NOTE for possible CPU with crash note. */ + for_each_possible_cpu(cpu) { if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { /* Skip the soon-to-be offlined cpu */ if (image->hotplug_event && (cpu == image->offlinecpu)) continue; } - phdr->p_type = PT_NOTE; notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); + if (!notes_addr) + continue; + + phdr->p_type = PT_NOTE; phdr->p_offset = phdr->p_paddr = notes_addr; phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t); (ehdr->e_phnum)++;
On architectures like PowerPC the crash notes are available for all possible CPUs. So let's populate the elfcorehdr for all possible CPUs having crash notes to avoid updating elfcorehdr during in-kernel crash update on CPU hotplug events. The similar technique was used in kexec-tool for kexec_load case. Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com> --- kernel/crash_core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)