Re: [PATCH 1/3] kexec_load: Use new kexec flag for hotplug support

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Hello Hari,

On 10/06/24 14:22, Hari Bathini wrote:
>
>
> On 22/05/24 6:43 pm, Sourabh Jain wrote:
>> Kernel commit 79365026f869 (crash: add a new kexec flag for hotplug
>> support) has introduced a new kexec flag to generalize hotplug support.
>> The newly introduced kexec flags for hotplug allow architectures to
>> exclude all the required kexec segments from SHA calculation so that
>> the kernel can update them on hotplug events. This was not possible
>> earlier with the KEXEC_UPDATE_ELFCOREHDR kexec flags since it was added
>> only for the elfcorehdr segment.
>>
>> To enable architectures to control the list of kexec segments to exclude
>> when hotplug support is enabled, add a new architecture-specific
>> function named arch_do_exclude_segment. During the SHA calculation, this
>> function gets called to let the architecture decide whether a specific
>> kexec segment should be considered for SHA calculation or not.
>>
>> Given that the KEXEC_UPDATE_ELFCOREHDR is no longer required and was
>> colliding with the KEXEC_LIVE_UPDATE update flag, it is removed.
>>
>> Cc: Aditya Gupta <adityag@linux.ibm.com>
>> Cc: Baoquan He <bhe@redhat.com>
>> Cc: Coiby Xu <coxu@redhat.com>
>> Cc: Hari Bathini <hbathini@linux.ibm.com>
>> Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
>> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
>> ---
>>   kexec/arch/arm/kexec-arm.c             |  5 +++++
>>   kexec/arch/arm64/kexec-arm64.c         |  4 ++++
>>   kexec/arch/cris/kexec-cris.c           |  4 ++++
>>   kexec/arch/hppa/kexec-hppa.c           |  5 +++++
>>   kexec/arch/i386/kexec-x86.c            |  8 ++++++++
>>   kexec/arch/ia64/kexec-ia64.c           |  4 ++++
>>   kexec/arch/loongarch/kexec-loongarch.c |  5 +++++
>>   kexec/arch/m68k/kexec-m68k.c           |  5 +++++
>>   kexec/arch/mips/kexec-mips.c           |  4 ++++
>>   kexec/arch/ppc/kexec-ppc.c             |  4 ++++
>>   kexec/arch/ppc64/kexec-ppc64.c         |  5 +++++
>>   kexec/arch/s390/kexec-s390.c           |  5 +++++
>>   kexec/arch/sh/kexec-sh.c               |  5 +++++
>>   kexec/arch/x86_64/kexec-x86_64.c       |  5 +++++
>>   kexec/kexec-syscall.h                  |  2 +-
>>   kexec/kexec.c                          | 14 ++++++++------
>>   kexec/kexec.h                          |  2 ++
>>   17 files changed, 79 insertions(+), 7 deletions(-)
>>
>> diff --git a/kexec/arch/arm/kexec-arm.c b/kexec/arch/arm/kexec-arm.c
>> index 49f35b1..34531f9 100644
>> --- a/kexec/arch/arm/kexec-arm.c
>> +++ b/kexec/arch/arm/kexec-arm.c
>> @@ -148,3 +148,8 @@ int have_sysfs_fdt(void)
>>   {
>>       return !access(SYSFS_FDT, F_OK);
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/arm64/kexec-arm64.c 
>> b/kexec/arch/arm64/kexec-arm64.c
>> index 4a67b0d..9d052b0 100644
>> --- a/kexec/arch/arm64/kexec-arm64.c
>> +++ b/kexec/arch/arm64/kexec-arm64.c
>> @@ -1363,3 +1363,7 @@ void arch_reuse_initrd(void)
>>   void arch_update_purgatory(struct kexec_info *UNUSED(info))
>>   {
>>   }
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/cris/kexec-cris.c b/kexec/arch/cris/kexec-cris.c
>> index 3b69709..7f09121 100644
>> --- a/kexec/arch/cris/kexec-cris.c
>> +++ b/kexec/arch/cris/kexec-cris.c
>> @@ -109,3 +109,7 @@ unsigned long add_buffer(struct kexec_info *info, 
>> const void *buf,
>>                                       buf_min, buf_max, buf_end, 1);
>>   }
>>   +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/hppa/kexec-hppa.c b/kexec/arch/hppa/kexec-hppa.c
>> index 77c9739..a64dc3d 100644
>> --- a/kexec/arch/hppa/kexec-hppa.c
>> +++ b/kexec/arch/hppa/kexec-hppa.c
>> @@ -146,3 +146,8 @@ unsigned long virt_to_phys(unsigned long addr)
>>   {
>>       return addr - phys_offset;
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/i386/kexec-x86.c b/kexec/arch/i386/kexec-x86.c
>> index 444cb69..b4947a0 100644
>> --- a/kexec/arch/i386/kexec-x86.c
>> +++ b/kexec/arch/i386/kexec-x86.c
>> @@ -208,3 +208,11 @@ void arch_update_purgatory(struct kexec_info *info)
>>       elf_rel_set_symbol(&info->rhdr, "panic_kernel",
>>           &panic_kernel, sizeof(panic_kernel));
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *seg_ptr, struct 
>> kexec_info *info)
>> +{
>> +    if (info->elfcorehdr == (unsigned long) seg_ptr->mem)
>> +        return 1;
>> +
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/ia64/kexec-ia64.c b/kexec/arch/ia64/kexec-ia64.c
>> index 418d997..8d9c1f3 100644
>> --- a/kexec/arch/ia64/kexec-ia64.c
>> +++ b/kexec/arch/ia64/kexec-ia64.c
>> @@ -245,3 +245,7 @@ void arch_update_purgatory(struct kexec_info 
>> *UNUSED(info))
>>   {
>>   }
>>   +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/loongarch/kexec-loongarch.c 
>> b/kexec/arch/loongarch/kexec-loongarch.c
>> index 32a42d2..9a50ff6 100644
>> --- a/kexec/arch/loongarch/kexec-loongarch.c
>> +++ b/kexec/arch/loongarch/kexec-loongarch.c
>> @@ -378,3 +378,8 @@ unsigned long add_buffer(struct kexec_info *info, 
>> const void *buf,
>>       return add_buffer_phys_virt(info, buf, bufsz, memsz, buf_align,
>>                       buf_min, buf_max, buf_end, 1);
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/m68k/kexec-m68k.c b/kexec/arch/m68k/kexec-m68k.c
>> index cb54927..0c7dbaf 100644
>> --- a/kexec/arch/m68k/kexec-m68k.c
>> +++ b/kexec/arch/m68k/kexec-m68k.c
>> @@ -108,3 +108,8 @@ void add_segment(struct kexec_info *info, const 
>> void *buf, size_t bufsz,
>>   {
>>       add_segment_phys_virt(info, buf, bufsz, base, memsz, 1);
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/mips/kexec-mips.c b/kexec/arch/mips/kexec-mips.c
>> index d8cbea8..94224ee 100644
>> --- a/kexec/arch/mips/kexec-mips.c
>> +++ b/kexec/arch/mips/kexec-mips.c
>> @@ -189,3 +189,7 @@ unsigned long add_buffer(struct kexec_info *info, 
>> const void *buf,
>>                       buf_min, buf_max, buf_end, 1);
>>   }
>>   +int arch_do_exclude_segment(const void *UNUSED(seg_ptr), struct 
>> kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/ppc/kexec-ppc.c b/kexec/arch/ppc/kexec-ppc.c
>> index 03bec36..c8af870 100644
>> --- a/kexec/arch/ppc/kexec-ppc.c
>> +++ b/kexec/arch/ppc/kexec-ppc.c
>> @@ -966,3 +966,7 @@ void arch_update_purgatory(struct kexec_info 
>> *UNUSED(info))
>>   {
>>   }
>>   +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/ppc64/kexec-ppc64.c 
>> b/kexec/arch/ppc64/kexec-ppc64.c
>> index bd5274c..fb27b6b 100644
>> --- a/kexec/arch/ppc64/kexec-ppc64.c
>> +++ b/kexec/arch/ppc64/kexec-ppc64.c
>> @@ -967,3 +967,8 @@ int arch_compat_trampoline(struct kexec_info 
>> *UNUSED(info))
>>   void arch_update_purgatory(struct kexec_info *UNUSED(info))
>>   {
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/s390/kexec-s390.c b/kexec/arch/s390/kexec-s390.c
>> index 33ba6b9..0561ee7 100644
>> --- a/kexec/arch/s390/kexec-s390.c
>> +++ b/kexec/arch/s390/kexec-s390.c
>> @@ -267,3 +267,8 @@ int get_crash_kernel_load_range(uint64_t *start, 
>> uint64_t *end)
>>   {
>>       return parse_iomem_single("Crash kernel\n", start, end);
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>> diff --git a/kexec/arch/sh/kexec-sh.c b/kexec/arch/sh/kexec-sh.c
>> index ce341c8..f84c40c 100644
>> --- a/kexec/arch/sh/kexec-sh.c
>> +++ b/kexec/arch/sh/kexec-sh.c
>> @@ -257,3 +257,8 @@ unsigned long add_buffer(struct kexec_info *info, 
>> const void *buf,
>>       return add_buffer_phys_virt(info, buf, bufsz, memsz, buf_align,
>>                       buf_min, buf_max, buf_end, 1);
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>> +    return 0;
>> +}
>
>> diff --git a/kexec/arch/x86_64/kexec-x86_64.c 
>> b/kexec/arch/x86_64/kexec-x86_64.c
>> index ffd84f0..42af90a 100644
>> --- a/kexec/arch/x86_64/kexec-x86_64.c
>> +++ b/kexec/arch/x86_64/kexec-x86_64.c
>> @@ -188,3 +188,8 @@ void arch_update_purgatory(struct kexec_info *info)
>>       elf_rel_set_symbol(&info->rhdr, "panic_kernel",
>>                   &panic_kernel, sizeof(panic_kernel));
>>   }
>> +
>> +int arch_do_exclude_segment(struct kexec_segment *UNUSED(seg_ptr), 
>> struct kexec_info *UNUSED(info))
>> +{
>
> This should also be similar to i386, no?
> Except for that, rest looks good..

In kexec tools, hotplug support for the kexec_load syscall is not yet 
enabled for x86_64.
Hence, the function returns 0.

>
> Acked-by: Hari Bathini <hbathini@linux.ibm.com>

Thank you for reviewing and giving an Ack to the patch.

- Sourabh Jain

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