[PATCH 1/3] kexec_load: Use new kexec flag for hotplug support
Aditya Gupta
adityag at linux.ibm.com
Tue May 28 04:33:01 PDT 2024
Hello sourabh,
On Wed, May 22, 2024 at 06:43:51PM GMT, 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 at linux.ibm.com>
> Cc: Baoquan He <bhe at redhat.com>
> Cc: Coiby Xu <coxu at redhat.com>
> Cc: Hari Bathini <hbathini at linux.ibm.com>
> Cc: Mahesh Salgaonkar <mahesh at linux.ibm.com>
> Signed-off-by: Sourabh Jain <sourabhjain at 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))
> +{
> + return 0;
> +}
Should all arch_do_exclude_segment return 1 for elfcorehdr ? Please
refer my below comment.
> diff --git a/kexec/kexec-syscall.h b/kexec/kexec-syscall.h
> index 73e5254..4675c46 100644
> --- a/kexec/kexec-syscall.h
> +++ b/kexec/kexec-syscall.h
> @@ -112,7 +112,7 @@ static inline long kexec_file_load(int kernel_fd, int initrd_fd,
>
> #define KEXEC_ON_CRASH 0x00000001
> #define KEXEC_PRESERVE_CONTEXT 0x00000002
> -#define KEXEC_UPDATE_ELFCOREHDR 0x00000004
> +#define KEXEC_CRASH_HOTPLUG_SUPPORT 0x00000008
> #define KEXEC_ARCH_MASK 0xffff0000
>
> /* Flags for kexec file based system call */
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index 222f79e..034cea6 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -701,10 +701,13 @@ static void update_purgatory(struct kexec_info *info)
> continue;
> }
>
> - /* Don't include elfcorehdr in the checksum, if hotplug
> - * support enabled.
> + /*
> + * Let architecture decide which segments to exclude from checksum
> + * if hotplug support is enabled.
> */
> - if (do_hotplug && (info->segment[i].mem == (void *)info->elfcorehdr)) {
> + if (do_hotplug && arch_do_exclude_segment(&info->segment[i], info)) {
> + dbgprintf("Skipping segment mem: 0x%lx from SHA calculation\n",
> + (unsigned long)info->segment[i].mem);
> continue;
> }
Current behaviour seems to skip elfcorehdr segment in all architectures.
But now as all architectures are returning 0 in arch_do_exclude_segment,
will elfcorehdr still be skipped ?
Rest all looks good to me.
Thanks,
Aditya Gupta
>
> @@ -1651,7 +1654,6 @@ int main(int argc, char *argv[])
> die("--load-live-update can only be used with xen\n");
> }
>
> - /* NOTE: Xen KEXEC_LIVE_UPDATE and KEXEC_UPDATE_ELFCOREHDR collide */
> if (do_hotplug) {
> const char *ces = "/sys/kernel/crash_elfcorehdr_size";
> char *buf, *endptr = NULL;
> @@ -1665,8 +1667,8 @@ int main(int argc, char *argv[])
> if (!elfcorehdrsz || (endptr && *endptr != '\0'))
> die("Path %s does not exist, the kernel needs CONFIG_CRASH_HOTPLUG\n", ces);
> dbgprintf("ELFCOREHDR_SIZE %lu\n", elfcorehdrsz);
> - /* Indicate to the kernel it is ok to modify the elfcorehdr */
> - kexec_flags |= KEXEC_UPDATE_ELFCOREHDR;
> + /* Indicate to the kernel it is ok to modify the relevant kexec segments */
> + kexec_flags |= KEXEC_CRASH_HOTPLUG_SUPPORT;
> }
>
> fileind = optind;
> diff --git a/kexec/kexec.h b/kexec/kexec.h
> index 1004aff..2d758c9 100644
> --- a/kexec/kexec.h
> +++ b/kexec/kexec.h
> @@ -307,6 +307,8 @@ extern int do_hotplug;
> #define BOOTLOADER_VERSION PACKAGE_VERSION
>
> void arch_usage(void);
> +/* Return non-zero if segment needs to be excluded from SHA calculation, else 0. */
> +int arch_do_exclude_segment(struct kexec_segment *seg_ptr, struct kexec_info *info);
> int arch_process_options(int argc, char **argv);
> int arch_compat_trampoline(struct kexec_info *info);
> void arch_update_purgatory(struct kexec_info *info);
> --
> 2.44.0
>
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