Messages in this thread |  | | Date | Thu, 12 Jan 2023 11:23:18 -0600 | | Subject | Re: [PATCH v15 1/7] crash: move crash_prepare_elf64_headers() | | From | Eric DeVolder <> |
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On 1/8/23 23:05, Sourabh Jain wrote: > > On 09/12/22 21:06, Eric DeVolder wrote: >> At the outcome of this patch set, the crash_prepare_elf64_headers() >> is utilized on both the kexec_file_load() and kexec_load() paths. As >> such, need to move this function out of kexec_file.c and into a >> common location crash_core.c. >> >> No functionality change. >> >> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com> >> Acked-by: Baoquan He <bhe@redhat.com> >> --- >> kernel/crash_core.c | 100 ++++++++++++++++++++++++++++++++++++++++++++ >> kernel/kexec_file.c | 99 ------------------------------------------- >> 2 files changed, 100 insertions(+), 99 deletions(-) >> >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index a0eb4d5cf557..46c160d14045 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -10,6 +10,7 @@ >> #include <linux/utsname.h> >> #include <linux/vmalloc.h> >> #include <linux/sizes.h> >> +#include <linux/kexec.h> >> #include <asm/page.h> >> #include <asm/sections.h> >> @@ -314,6 +315,105 @@ static int __init parse_crashkernel_dummy(char *arg) >> } >> early_param("crashkernel", parse_crashkernel_dummy); >> +int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map, >> + void **addr, unsigned long *sz) >> +{ >> + Elf64_Ehdr *ehdr; >> + Elf64_Phdr *phdr; >> + unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz; >> + unsigned char *buf; >> + unsigned int cpu, i; >> + unsigned long long notes_addr; >> + unsigned long mstart, mend; >> + >> + /* extra phdr for vmcoreinfo ELF note */ >> + nr_phdr = nr_cpus + 1; >> + nr_phdr += mem->nr_ranges; >> + >> + /* >> + * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping >> + * area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64). >> + * I think this is required by tools like gdb. So same physical >> + * memory will be mapped in two ELF headers. One will contain kernel >> + * text virtual addresses and other will have __va(physical) addresses. >> + */ >> + >> + nr_phdr++; >> + elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr); >> + elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN); > Seems like above function is out of CONFIG_KEXEC_FILE but some of the > structure/attributes like crash_mem and ELF_CORE_HEADER_ALIGN are > still defined under CONFIG_KEXEC_FILE (look for include/linux/kexec.h). > > This leads to kernel build issue when CONFIG_KEXEC_FILE is disabled. > > Thanks, > Sourabh Jain
After looking into this for a bit, to allow hotplug without kexec_file would require quite a bit of code movement. Why? Because hotplug is basically built on top of (part of) the infrastructure that was needed for kexec_file.
I'd be inclined to suggest that KEXEC_FILE be a required dependency for CRASH_HOTPLUG, ie:
config CRASH_HOTPLUG bool "Update the crash elfcorehdr on system configuration changes" default n - depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) + depends on CRASH_DUMP && KEXEC_FILE && (HOTPLUG_CPU || MEMORY_HOTPLUG)
If that isn't feasible, then it would appear quite a bit of surgery is needed to properly separate out the items hotplug needs from kexec_file.
Thoughts? eric
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