On 02/22/24 at 09:01am, Sourabh Jain wrote: > Hello Baoquan, > > There are a lot of code movements introduced by your patch series, 'Split > crash out from kexec and clean up related config items.' > > https://lore.kernel.org/all/20240221125752.36fbfe9c307496313198b60f@xxxxxxxxxxxxxxxxxxxx/ > > Do you want me to rebase this patch series on top of the above patch series? Yes, appreciate that, that would be very helpful. Rebasing this to latest next/master. And I saw Hari's patch sereis, basically it's fine to me. It will be great if this patch can sit on that patchset. Thanks Baoquan > > On 17/02/24 13:44, Sourabh Jain wrote: > > Commit a72bbec70da2 ("crash: hotplug support for kexec_load()") > > introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses > > this flag to indicate to the kernel that it is safe to modify the > > elfcorehdr of the kdump image loaded using the kexec_load system call. > > > > However, it is possible that architectures may need to update kexec > > segments other then elfcorehdr. For example, FDT (Flatten Device Tree) > > on PowerPC. Introducing a new kexec flag for every new kexec segment > > may not be a good solution. Hence, a generic kexec flag bit, > > `KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory > > hotplug support intent between the kexec tool and the kernel for the > > kexec_load system call. > > > > Now, if the kexec tool sends KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag to > > the kernel, it indicates to the kernel that all the required kexec > > segment is skipped from SHA calculation and it is safe to update kdump > > image loaded using the kexec_load syscall. > > > > While loading the kdump image using the kexec_load syscall, the > > @update_elfcorehdr member of struct kimage is set if the kexec tool > > sends the KEXEC_UPDATE_ELFCOREHDR kexec flag. This member is later used > > to determine whether it is safe to update elfcorehdr on hotplug events. > > However, with the introduction of the KEXEC_CRASH_HOTPLUG_SUPPORT kexec > > flag, the kexec tool could mark all the required kexec segments on an > > architecture as safe to update. So rename the @update_elfcorehdr to > > @hotplug_support. If @hotplug_support is set, the kernel can safely > > update all the required kexec segments of the kdump image during > > CPU/Memory hotplug events. > > > > Introduce an architecture-specific function to process kexec flags for > > determining hotplug support. Set the @hotplug_support member of struct > > kimage for both kexec_load and kexec_file_load system calls. This > > simplifies kernel checks to identify hotplug support for the currently > > loaded kdump image by just examining the value of @hotplug_support. > > > > Signed-off-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx> > > Cc: Akhil Raj <lf32.dev@xxxxxxxxx> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxx> > > Cc: Baoquan He <bhe@xxxxxxxxxx> > > Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx> > > Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> > > Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> > > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > Cc: Dave Young <dyoung@xxxxxxxxxx> > > Cc: David Hildenbrand <david@xxxxxxxxxx> > > Cc: Eric DeVolder <eric.devolder@xxxxxxxxxx> > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > Cc: Hari Bathini <hbathini@xxxxxxxxxxxxx> > > Cc: Laurent Dufour <laurent.dufour@xxxxxxxxxx> > > Cc: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxx> > > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > > Cc: Mimi Zohar <zohar@xxxxxxxxxxxxx> > > Cc: Naveen N Rao <naveen@xxxxxxxxxx> > > Cc: Oscar Salvador <osalvador@xxxxxxx> > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > Cc: Valentin Schneider <vschneid@xxxxxxxxxx> > > Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> > > Cc: kexec@xxxxxxxxxxxxxxxxxxx > > Cc: x86@xxxxxxxxxx > > --- > > arch/x86/include/asm/kexec.h | 11 ++--------- > > arch/x86/kernel/crash.c | 28 +++++++++++++++++----------- > > drivers/base/cpu.c | 2 +- > > drivers/base/memory.c | 2 +- > > include/linux/kexec.h | 27 +++++++++++++++++---------- > > include/uapi/linux/kexec.h | 1 + > > kernel/crash_core.c | 11 ++++------- > > kernel/kexec.c | 4 ++-- > > kernel/kexec_file.c | 5 +++++ > > 9 files changed, 50 insertions(+), 41 deletions(-) > > > > diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h > > index 9bb6607e864e..8be622e82ba8 100644 > > --- a/arch/x86/include/asm/kexec.h > > +++ b/arch/x86/include/asm/kexec.h > > @@ -211,15 +211,8 @@ extern void kdump_nmi_shootdown_cpus(void); > > void arch_crash_handle_hotplug_event(struct kimage *image, void *arg); > > #define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event > > -#ifdef CONFIG_HOTPLUG_CPU > > -int arch_crash_hotplug_cpu_support(void); > > -#define crash_hotplug_cpu_support arch_crash_hotplug_cpu_support > > -#endif > > - > > -#ifdef CONFIG_MEMORY_HOTPLUG > > -int arch_crash_hotplug_memory_support(void); > > -#define crash_hotplug_memory_support arch_crash_hotplug_memory_support > > -#endif > > +int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags); > > +#define arch_crash_hotplug_support arch_crash_hotplug_support > > unsigned int arch_crash_get_elfcorehdr_size(void); > > #define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > > index 44744e9c68ec..7072aaee2ea0 100644 > > --- a/arch/x86/kernel/crash.c > > +++ b/arch/x86/kernel/crash.c > > @@ -398,20 +398,26 @@ int crash_load_segments(struct kimage *image) > > #undef pr_fmt > > #define pr_fmt(fmt) "crash hp: " fmt > > -/* These functions provide the value for the sysfs crash_hotplug nodes */ > > -#ifdef CONFIG_HOTPLUG_CPU > > -int arch_crash_hotplug_cpu_support(void) > > +int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags) > > { > > - return crash_check_update_elfcorehdr(); > > -} > > -#endif > > -#ifdef CONFIG_MEMORY_HOTPLUG > > -int arch_crash_hotplug_memory_support(void) > > -{ > > - return crash_check_update_elfcorehdr(); > > -} > > +#ifdef CONFIG_KEXEC_FILE > > + if (image->file_mode) > > + return 1; > > #endif > > + /* > > + * Initially, crash hotplug support for kexec_load was added > > + * with the KEXEC_UPDATE_ELFCOREHDR flag. Later, this > > + * functionality was expanded to accommodate multiple kexec > > + * segment updates, leading to the introduction of the > > + * KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag bit. Consequently, > > + * when the kexec tool sends either of these flags, it indicates > > + * that the required kexec segment (elfcorehdr) is excluded from > > + * the SHA calculation. > > + */ > > + return (kexec_flags & KEXEC_UPDATE_ELFCOREHDR || > > + kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT); > > +} > > unsigned int arch_crash_get_elfcorehdr_size(void) > > { > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > > index 47de0f140ba6..24eb52607151 100644 > > --- a/drivers/base/cpu.c > > +++ b/drivers/base/cpu.c > > @@ -306,7 +306,7 @@ static ssize_t crash_hotplug_show(struct device *dev, > > struct device_attribute *attr, > > char *buf) > > { > > - return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support()); > > + return sysfs_emit(buf, "%d\n", crash_check_hotplug_support()); > > } > > static DEVICE_ATTR_ADMIN_RO(crash_hotplug); > > #endif > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > > index 14f964a7719b..b80be8193970 100644 > > --- a/drivers/base/memory.c > > +++ b/drivers/base/memory.c > > @@ -514,7 +514,7 @@ static DEVICE_ATTR_RW(auto_online_blocks); > > static ssize_t crash_hotplug_show(struct device *dev, > > struct device_attribute *attr, char *buf) > > { > > - return sysfs_emit(buf, "%d\n", crash_hotplug_memory_support()); > > + return sysfs_emit(buf, "%d\n", crash_check_hotplug_support()); > > } > > static DEVICE_ATTR_RO(crash_hotplug); > > #endif > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > > index 802052d9c64b..175152b99cb7 100644 > > --- a/include/linux/kexec.h > > +++ b/include/linux/kexec.h > > @@ -317,8 +317,10 @@ struct kimage { > > /* If set, we are using file mode kexec syscall */ > > unsigned int file_mode:1; > > #ifdef CONFIG_CRASH_HOTPLUG > > - /* If set, allow changes to elfcorehdr of kexec_load'd image */ > > - unsigned int update_elfcorehdr:1; > > + /* If set, it is safe to update kexec segments that are > > + * excluded from SHA calculation. > > + */ > > + unsigned int hotplug_support:1; > > #endif > > #ifdef ARCH_HAS_KIMAGE_ARCH > > @@ -396,9 +398,10 @@ bool kexec_load_permitted(int kexec_image_type); > > /* List of defined/legal kexec flags */ > > #ifndef CONFIG_KEXEC_JUMP > > -#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR) > > +#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_UPDATE_ELFCOREHDR | KEXEC_CRASH_HOTPLUG_SUPPORT) > > #else > > -#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR) > > +#define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT | KEXEC_UPDATE_ELFCOREHDR | \ > > + KEXEC_CRASH_HOTPLUG_SUPPORT) > > #endif > > /* List of defined/legal kexec file flags */ > > @@ -486,14 +489,18 @@ static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { > > static inline void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) { } > > #endif > > -int crash_check_update_elfcorehdr(void); > > +int crash_check_hotplug_support(void); > > -#ifndef crash_hotplug_cpu_support > > -static inline int crash_hotplug_cpu_support(void) { return 0; } > > -#endif > > +#ifndef arch_crash_hotplug_support > > +static inline int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags) > > +{ > > -#ifndef crash_hotplug_memory_support > > -static inline int crash_hotplug_memory_support(void) { return 0; } > > +#ifdef CONFIG_KEXEC_FILE > > + if (image->file_mode) > > + return 1; > > +#endif > > + return kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT; > > +} > > #endif > > #ifndef crash_get_elfcorehdr_size > > diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h > > index c17bb096ea68..5ae1741ea8ea 100644 > > --- a/include/uapi/linux/kexec.h > > +++ b/include/uapi/linux/kexec.h > > @@ -13,6 +13,7 @@ > > #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 > > /* > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > > index b692ec5955de..3142884a5a5b 100644 > > --- a/kernel/crash_core.c > > +++ b/kernel/crash_core.c > > @@ -886,7 +886,7 @@ static DEFINE_MUTEX(__crash_hotplug_lock); > > * It reflects the kernel's ability/permission to update the crash > > * elfcorehdr directly. > > */ > > -int crash_check_update_elfcorehdr(void) > > +int crash_check_hotplug_support(void) > > { > > int rc = 0; > > @@ -898,10 +898,7 @@ int crash_check_update_elfcorehdr(void) > > return 0; > > } > > if (kexec_crash_image) { > > - if (kexec_crash_image->file_mode) > > - rc = 1; > > - else > > - rc = kexec_crash_image->update_elfcorehdr; > > + rc = kexec_crash_image->hotplug_support; > > } > > /* Release lock now that update complete */ > > kexec_unlock(); > > @@ -942,8 +939,8 @@ static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu, > > image = kexec_crash_image; > > - /* Check that updating elfcorehdr is permitted */ > > - if (!(image->file_mode || image->update_elfcorehdr)) > > + /* Check that kexec segments update is permitted */ > > + if (!image->hotplug_support) > > goto out; > > if (hp_action == KEXEC_CRASH_HP_ADD_CPU || > > diff --git a/kernel/kexec.c b/kernel/kexec.c > > index 8f35a5a42af8..9dc5b7ed5b73 100644 > > --- a/kernel/kexec.c > > +++ b/kernel/kexec.c > > @@ -130,8 +130,8 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments, > > image->preserve_context = 1; > > #ifdef CONFIG_CRASH_HOTPLUG > > - if (flags & KEXEC_UPDATE_ELFCOREHDR) > > - image->update_elfcorehdr = 1; > > + if ((flags & KEXEC_ON_CRASH) && arch_crash_hotplug_support(image, flags)) > > + image->hotplug_support = 1; > > #endif > > ret = machine_kexec_prepare(image); > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > > index bef2f6f2571b..4dddf9264a69 100644 > > --- a/kernel/kexec_file.c > > +++ b/kernel/kexec_file.c > > @@ -373,6 +373,11 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, > > if (ret) > > goto out; > > +#ifdef CONFIG_CRASH_HOTPLUG > > + if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image, flags)) > > + image->hotplug_support = 1; > > +#endif > > + > > ret = machine_kexec_prepare(image); > > if (ret) > > goto out; > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
