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Fri, 26 Aug 2022 17:37:12 +0000 Received: from CO1PR10MB4531.namprd10.prod.outlook.com ([fe80::4d5c:c5e9:7d20:43c2]) by CO1PR10MB4531.namprd10.prod.outlook.com ([fe80::4d5c:c5e9:7d20:43c2%9]) with mapi id 15.20.5566.016; Fri, 26 Aug 2022 17:37:11 +0000 From: Eric DeVolder To: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, eric.devolder@oracle.com Subject: [PATCH v11 1/7] crash: move crash_prepare_elf64_headers Date: Fri, 26 Aug 2022 13:36:58 -0400 Message-Id: <20220826173704.1895-2-eric.devolder@oracle.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220826173704.1895-1-eric.devolder@oracle.com> References: <20220826173704.1895-1-eric.devolder@oracle.com> Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SJ0PR03CA0152.namprd03.prod.outlook.com (2603:10b6:a03:338::7) To CO1PR10MB4531.namprd10.prod.outlook.com (2603:10b6:303:6c::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: bb55ca67-2d7b-4876-eac6-08da87899b4f X-MS-TrafficTypeDiagnostic: MN2PR10MB3518:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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charset="utf-8" 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 --- 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 07b26df453a9..8c8c82386e8d 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -10,6 +10,7 @@ #include #include #include +#include =20 #include #include @@ -314,6 +315,105 @@ static int __init parse_crashkernel_dummy(char *arg) } early_param("crashkernel", parse_crashkernel_dummy); =20 +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 =3D 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 =3D nr_cpus + 1; + nr_phdr +=3D 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 =3D sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr); + elf_sz =3D ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN); + + buf =3D vzalloc(elf_sz); + if (!buf) + return -ENOMEM; + + ehdr =3D (Elf64_Ehdr *)buf; + phdr =3D (Elf64_Phdr *)(ehdr + 1); + memcpy(ehdr->e_ident, ELFMAG, SELFMAG); + ehdr->e_ident[EI_CLASS] =3D ELFCLASS64; + ehdr->e_ident[EI_DATA] =3D ELFDATA2LSB; + ehdr->e_ident[EI_VERSION] =3D EV_CURRENT; + ehdr->e_ident[EI_OSABI] =3D ELF_OSABI; + memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD); + ehdr->e_type =3D ET_CORE; + ehdr->e_machine =3D ELF_ARCH; + ehdr->e_version =3D EV_CURRENT; + ehdr->e_phoff =3D sizeof(Elf64_Ehdr); + ehdr->e_ehsize =3D sizeof(Elf64_Ehdr); + ehdr->e_phentsize =3D sizeof(Elf64_Phdr); + + /* Prepare one phdr of type PT_NOTE for each present CPU */ + for_each_present_cpu(cpu) { + phdr->p_type =3D PT_NOTE; + notes_addr =3D per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); + phdr->p_offset =3D phdr->p_paddr =3D notes_addr; + phdr->p_filesz =3D phdr->p_memsz =3D sizeof(note_buf_t); + (ehdr->e_phnum)++; + phdr++; + } + + /* Prepare one PT_NOTE header for vmcoreinfo */ + phdr->p_type =3D PT_NOTE; + phdr->p_offset =3D phdr->p_paddr =3D paddr_vmcoreinfo_note(); + phdr->p_filesz =3D phdr->p_memsz =3D VMCOREINFO_NOTE_SIZE; + (ehdr->e_phnum)++; + phdr++; + + /* Prepare PT_LOAD type program header for kernel text region */ + if (need_kernel_map) { + phdr->p_type =3D PT_LOAD; + phdr->p_flags =3D PF_R|PF_W|PF_X; + phdr->p_vaddr =3D (unsigned long) _text; + phdr->p_filesz =3D phdr->p_memsz =3D _end - _text; + phdr->p_offset =3D phdr->p_paddr =3D __pa_symbol(_text); + ehdr->e_phnum++; + phdr++; + } + + /* Go through all the ranges in mem->ranges[] and prepare phdr */ + for (i =3D 0; i < mem->nr_ranges; i++) { + mstart =3D mem->ranges[i].start; + mend =3D mem->ranges[i].end; + + phdr->p_type =3D PT_LOAD; + phdr->p_flags =3D PF_R|PF_W|PF_X; + phdr->p_offset =3D mstart; + + phdr->p_paddr =3D mstart; + phdr->p_vaddr =3D (unsigned long) __va(mstart); + phdr->p_filesz =3D phdr->p_memsz =3D mend - mstart + 1; + phdr->p_align =3D 0; + ehdr->e_phnum++; + pr_debug("Crash PT_LOAD ELF header. phdr=3D%p vaddr=3D0x%llx, paddr=3D0x= %llx, sz=3D0x%llx e_phnum=3D%d p_offset=3D0x%llx\n", + phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz, + ehdr->e_phnum, phdr->p_offset); + phdr++; + } + + *addr =3D buf; + *sz =3D elf_sz; + return 0; +} + Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type, void *data, size_t data_len) { diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 1d546dc97c50..8017eeb43036 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -1217,102 +1217,3 @@ int crash_exclude_mem_range(struct crash_mem *mem, mem->nr_ranges++; return 0; } - -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 =3D 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 =3D nr_cpus + 1; - nr_phdr +=3D 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 =3D sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr); - elf_sz =3D ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN); - - buf =3D vzalloc(elf_sz); - if (!buf) - return -ENOMEM; - - ehdr =3D (Elf64_Ehdr *)buf; - phdr =3D (Elf64_Phdr *)(ehdr + 1); - memcpy(ehdr->e_ident, ELFMAG, SELFMAG); - ehdr->e_ident[EI_CLASS] =3D ELFCLASS64; - ehdr->e_ident[EI_DATA] =3D ELFDATA2LSB; - ehdr->e_ident[EI_VERSION] =3D EV_CURRENT; - ehdr->e_ident[EI_OSABI] =3D ELF_OSABI; - memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD); - ehdr->e_type =3D ET_CORE; - ehdr->e_machine =3D ELF_ARCH; - ehdr->e_version =3D EV_CURRENT; - ehdr->e_phoff =3D sizeof(Elf64_Ehdr); - ehdr->e_ehsize =3D sizeof(Elf64_Ehdr); - ehdr->e_phentsize =3D sizeof(Elf64_Phdr); - - /* Prepare one phdr of type PT_NOTE for each present CPU */ - for_each_present_cpu(cpu) { - phdr->p_type =3D PT_NOTE; - notes_addr =3D per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); - phdr->p_offset =3D phdr->p_paddr =3D notes_addr; - phdr->p_filesz =3D phdr->p_memsz =3D sizeof(note_buf_t); - (ehdr->e_phnum)++; - phdr++; - } - - /* Prepare one PT_NOTE header for vmcoreinfo */ - phdr->p_type =3D PT_NOTE; - phdr->p_offset =3D phdr->p_paddr =3D paddr_vmcoreinfo_note(); - phdr->p_filesz =3D phdr->p_memsz =3D VMCOREINFO_NOTE_SIZE; - (ehdr->e_phnum)++; - phdr++; - - /* Prepare PT_LOAD type program header for kernel text region */ - if (need_kernel_map) { - phdr->p_type =3D PT_LOAD; - phdr->p_flags =3D PF_R|PF_W|PF_X; - phdr->p_vaddr =3D (unsigned long) _text; - phdr->p_filesz =3D phdr->p_memsz =3D _end - _text; - phdr->p_offset =3D phdr->p_paddr =3D __pa_symbol(_text); - ehdr->e_phnum++; - phdr++; - } - - /* Go through all the ranges in mem->ranges[] and prepare phdr */ - for (i =3D 0; i < mem->nr_ranges; i++) { - mstart =3D mem->ranges[i].start; - mend =3D mem->ranges[i].end; - - phdr->p_type =3D PT_LOAD; - phdr->p_flags =3D PF_R|PF_W|PF_X; - phdr->p_offset =3D mstart; - - phdr->p_paddr =3D mstart; - phdr->p_vaddr =3D (unsigned long) __va(mstart); - phdr->p_filesz =3D phdr->p_memsz =3D mend - mstart + 1; - phdr->p_align =3D 0; - ehdr->e_phnum++; - pr_debug("Crash PT_LOAD ELF header. phdr=3D%p vaddr=3D0x%llx, paddr=3D0x= %llx, sz=3D0x%llx e_phnum=3D%d p_offset=3D0x%llx\n", - phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz, - ehdr->e_phnum, phdr->p_offset); - phdr++; - } - - *addr =3D buf; - *sz =3D elf_sz; - return 0; -} --=20 2.31.1 From nobody Sat Apr 11 10:29:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F988ECAAA6 for ; Fri, 26 Aug 2022 17:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344725AbiHZRhv (ORCPT ); Fri, 26 Aug 2022 13:37:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245546AbiHZRhp (ORCPT ); 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charset="utf-8" From within crash_prepare_elf64_headers() there is a need to reference the struct kimage hotplug members. As such, this change passes the struct kimage as a parameter to the crash_prepare_elf64_headers(). The hotplug members are added in "crash: add generic infrastructure for crash hotplug support". This is preparation for later patch, no functionality change. Signed-off-by: Eric DeVolder Acked-by: Baoquan He Acked-by: David Hildenbrand --- arch/arm64/kernel/machine_kexec_file.c | 6 +++--- arch/powerpc/kexec/file_load_64.c | 2 +- arch/riscv/kernel/elf_kexec.c | 7 ++++--- arch/x86/kernel/crash.c | 2 +- include/linux/kexec.h | 7 +++++-- kernel/crash_core.c | 4 ++-- 6 files changed, 16 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/mac= hine_kexec_file.c index 889951291cc0..7f5f8243928e 100644 --- a/arch/arm64/kernel/machine_kexec_file.c +++ b/arch/arm64/kernel/machine_kexec_file.c @@ -39,7 +39,7 @@ int arch_kimage_file_post_load_cleanup(struct kimage *ima= ge) return kexec_image_post_load_cleanup_default(image); } =20 -static int prepare_elf_headers(void **addr, unsigned long *sz) +static int prepare_elf_headers(struct kimage *image, void **addr, unsigned= long *sz) { struct crash_mem *cmem; unsigned int nr_ranges; @@ -64,7 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long= *sz) } =20 /* Exclude crashkernel region */ - ret =3D crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); + ret =3D crash_exclude_mem_range(image, cmem, crashk_res.start, crashk_res= .end); if (ret) goto out; =20 @@ -74,7 +74,7 @@ static int prepare_elf_headers(void **addr, unsigned long= *sz) goto out; } =20 - ret =3D crash_prepare_elf64_headers(cmem, true, addr, sz); + ret =3D crash_prepare_elf64_headers(image, cmem, true, addr, sz); =20 out: kfree(cmem); diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_lo= ad_64.c index 349a781cea0b..a0af9966a8f0 100644 --- a/arch/powerpc/kexec/file_load_64.c +++ b/arch/powerpc/kexec/file_load_64.c @@ -798,7 +798,7 @@ static int load_elfcorehdr_segment(struct kimage *image= , struct kexec_buf *kbuf) goto out; =20 /* Setup elfcorehdr segment */ - ret =3D crash_prepare_elf64_headers(cmem, false, &headers, &headers_sz); + ret =3D crash_prepare_elf64_headers(image, cmem, false, &headers, &header= s_sz); if (ret) { pr_err("Failed to prepare elf headers for the core\n"); goto out; diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c index 0cb94992c15b..ffde73228108 100644 --- a/arch/riscv/kernel/elf_kexec.c +++ b/arch/riscv/kernel/elf_kexec.c @@ -118,7 +118,8 @@ static int prepare_elf64_ram_headers_callback(struct re= source *res, void *arg) return 0; } =20 -static int prepare_elf_headers(void **addr, unsigned long *sz) +static int prepare_elf_headers(struct kimage *image, + void **addr, unsigned long *sz) { struct crash_mem *cmem; unsigned int nr_ranges; @@ -140,7 +141,7 @@ static int prepare_elf_headers(void **addr, unsigned lo= ng *sz) /* Exclude crashkernel region */ ret =3D crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); if (!ret) - ret =3D crash_prepare_elf64_headers(cmem, true, addr, sz); + ret =3D crash_prepare_elf64_headers(image, cmem, true, addr, sz); =20 out: kfree(cmem); @@ -212,7 +213,7 @@ static void *elf_kexec_load(struct kimage *image, char = *kernel_buf, =20 /* Add elfcorehdr */ if (image->type =3D=3D KEXEC_TYPE_CRASH) { - ret =3D prepare_elf_headers(&headers, &headers_sz); + ret =3D prepare_elf_headers(image, &headers, &headers_sz); if (ret) { pr_err("Preparing elf core header failed\n"); goto out; diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 9730c88530fc..9ceb93c176a6 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -265,7 +265,7 @@ static int prepare_elf_headers(struct kimage *image, vo= id **addr, goto out; =20 /* By default prepare 64bit headers */ - ret =3D crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), add= r, sz); + ret =3D crash_prepare_elf64_headers(image, cmem, IS_ENABLED(CONFIG_X86_6= 4), addr, sz); =20 out: vfree(cmem); diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 13e6c4b58f07..4eefa631e0ae 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -253,8 +253,11 @@ struct crash_mem { extern int crash_exclude_mem_range(struct crash_mem *mem, unsigned long long mstart, unsigned long long mend); -extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_ker= nel_map, - void **addr, unsigned long *sz); +extern int crash_prepare_elf64_headers(struct kimage *image, + struct crash_mem *mem, + int need_kernel_map, + void **addr, + unsigned long *sz); =20 #ifndef arch_kexec_apply_relocations_add /* diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 8c8c82386e8d..0f8aa659cca4 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -315,8 +315,8 @@ static int __init parse_crashkernel_dummy(char *arg) } early_param("crashkernel", parse_crashkernel_dummy); 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charset="utf-8" CPU and memory change notifications are received in order to regenerate the elfcorehdr. To support cpu hotplug, a callback is registered to capture the CPUHP_AP_ONLINE_DYN online and offline events via cpuhp_setup_state_nocalls(). To support memory hotplug, a notifier is registered to capture the MEM_ONLINE and MEM_OFFLINE events via register_memory_notifier(). The cpu callback and memory notifiers call handle_hotplug_event() which performs needed tasks and then dispatches the event to the architecture specific arch_crash_handle_hotplug_event(). During the process, the kexec_mutex is held. Signed-off-by: Eric DeVolder Acked-by: Baoquan He --- include/linux/crash_core.h | 8 +++ include/linux/kexec.h | 26 +++++++ kernel/crash_core.c | 134 +++++++++++++++++++++++++++++++++++++ 3 files changed, 168 insertions(+) diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h index de62a722431e..3b99e69b011f 100644 --- a/include/linux/crash_core.h +++ b/include/linux/crash_core.h @@ -84,4 +84,12 @@ int parse_crashkernel_high(char *cmdline, unsigned long = long system_ram, int parse_crashkernel_low(char *cmdline, unsigned long long system_ram, unsigned long long *crash_size, unsigned long long *crash_base); =20 +#define KEXEC_CRASH_HP_REMOVE_CPU 0 +#define KEXEC_CRASH_HP_ADD_CPU 1 +#define KEXEC_CRASH_HP_REMOVE_MEMORY 2 +#define KEXEC_CRASH_HP_ADD_MEMORY 3 +#define KEXEC_CRASH_HP_INVALID_CPU -1U + +struct kimage; + #endif /* LINUX_CRASH_CORE_H */ diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 4eefa631e0ae..9597b41136ec 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -374,6 +374,13 @@ struct kimage { struct purgatory_info purgatory_info; #endif =20 +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) + bool hotplug_event; + unsigned int offlinecpu; + bool elfcorehdr_index_valid; + int elfcorehdr_index; +#endif + #ifdef CONFIG_IMA_KEXEC /* Virtual address of IMA measurement buffer for kexec syscall */ void *ima_buffer; @@ -503,6 +510,25 @@ static inline int arch_kexec_post_alloc_pages(void *va= ddr, unsigned int pages, g static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pag= es) { } #endif =20 +#ifndef arch_map_crash_pages +static inline void *arch_map_crash_pages(unsigned long paddr, + unsigned long size) +{ + return NULL; +} +#endif + +#ifndef arch_unmap_crash_pages +static inline void arch_unmap_crash_pages(void **ptr) { } +#endif + +#ifndef arch_crash_handle_hotplug_event +static inline void arch_crash_handle_hotplug_event(struct kimage *image, + unsigned int hp_action) +{ +} +#endif + #else /* !CONFIG_KEXEC_CORE */ struct pt_regs; struct task_struct; diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 0f8aa659cca4..455150205ded 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -11,6 +11,8 @@ #include #include #include +#include +#include =20 #include #include @@ -18,6 +20,7 @@ #include =20 #include "kallsyms_internal.h" +#include "kexec_internal.h" =20 /* vmcoreinfo stuff */ unsigned char *vmcoreinfo_data; @@ -611,3 +614,134 @@ static int __init crash_save_vmcoreinfo_init(void) } =20 subsys_initcall(crash_save_vmcoreinfo_init); + +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) +/* + * To accurately reflect hot un/plug changes, the elfcorehdr (which + * is passed to the crash kernel via the elfcorehdr=3D parameter) + * must be updated with the new list of CPUs and memories. + * + * In order to make changes to elfcorehdr, two conditions are needed: + * First, the segment containing the elfcorehdr must be large enough + * to permit a growing number of resources. The elfcorehdr memory is + * typically based on CONFIG_NR_CPUS and CONFIG_CRASH_MAX_MEMORY_RANGES. + * Second, purgatory must explicitly exclude the elfcorehdr from the + * list of segments it checks (since the elfcorehdr changes and thus + * would require an update to purgatory itself to update the digest). + */ +static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu) +{ + /* Obtain lock while changing crash information */ + mutex_lock(&kexec_mutex); + + /* Check kdump is loaded */ + if (kexec_crash_image) { + struct kimage *image =3D kexec_crash_image; + + if (hp_action =3D=3D KEXEC_CRASH_HP_ADD_CPU || + hp_action =3D=3D KEXEC_CRASH_HP_REMOVE_CPU) + pr_debug("crash hp: hp_action %u, cpu %u\n", hp_action, cpu); + else + pr_debug("crash hp: hp_action %u", hp_action); + + /* + * When the struct kimage is alloced, it is wiped to zero, so + * the elfcorehdr_index_valid defaults to false. Find the + * segment containing the elfcorehdr, if not already found. + * This works for both the kexec_load and kexec_file_load paths. + */ + if (!image->elfcorehdr_index_valid) { + unsigned char *ptr; + unsigned long mem, memsz; + unsigned int n; + + for (n =3D 0; n < image->nr_segments; n++) { + mem =3D image->segment[n].mem; + memsz =3D image->segment[n].memsz; + ptr =3D arch_map_crash_pages(mem, memsz); + if (ptr) { + /* The segment containing elfcorehdr */ + if (memcmp(ptr, ELFMAG, SELFMAG) =3D=3D 0) { + image->elfcorehdr_index =3D (int)n; + image->elfcorehdr_index_valid =3D true; + } + } + arch_unmap_crash_pages((void **)&ptr); + } + } + + if (!image->elfcorehdr_index_valid) { + pr_err("crash hp: unable to locate elfcorehdr segment"); + goto out; + } + + /* Needed in order for the segments to be updated */ + arch_kexec_unprotect_crashkres(); + + /* Flag to differentiate between normal load and hotplug */ + image->hotplug_event =3D true; + + /* Now invoke arch-specific update handler */ + arch_crash_handle_hotplug_event(image, hp_action); + + /* No longer handling a hotplug event */ + image->hotplug_event =3D false; + + /* Change back to read-only */ + arch_kexec_protect_crashkres(); + } + +out: + /* Release lock now that update complete */ + mutex_unlock(&kexec_mutex); +} + +static int crash_memhp_notifier(struct notifier_block *nb, unsigned long v= al, void *v) +{ + switch (val) { + case MEM_ONLINE: + handle_hotplug_event(KEXEC_CRASH_HP_ADD_MEMORY, 0); + break; + + case MEM_OFFLINE: + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_MEMORY, 0); + break; + } + return NOTIFY_OK; +} + +static struct notifier_block crash_memhp_nb =3D { + .notifier_call =3D crash_memhp_notifier, + .priority =3D 0 +}; + +static int crash_cpuhp_online(unsigned int cpu) +{ + handle_hotplug_event(KEXEC_CRASH_HP_ADD_CPU, cpu); + return 0; +} + +static int crash_cpuhp_offline(unsigned int cpu) +{ + handle_hotplug_event(KEXEC_CRASH_HP_REMOVE_CPU, cpu); + return 0; +} + +static int __init crash_hotplug_init(void) +{ + int result =3D 0; + + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) + register_memory_notifier(&crash_memhp_nb); + + if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) + result =3D cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "crash/cpuhp", + crash_cpuhp_online, + crash_cpuhp_offline); + + return result; +} + +subsys_initcall(crash_hotplug_init); +#endif --=20 2.31.1 From nobody Sat Apr 11 10:29:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3ECBECAAA6 for ; Fri, 26 Aug 2022 17:39:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344935AbiHZRjN (ORCPT ); Fri, 26 Aug 2022 13:39:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344798AbiHZRi4 (ORCPT ); Fri, 26 Aug 2022 13:38:56 -0400 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21606E2C54 for ; 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charset="utf-8" When a crash kernel is loaded via the kexec_file_load syscall, the kernel places the various segments (ie crash kernel, crash initrd, boot_params, elfcorehdr, purgatory, etc) in memory. For those architectures that utilize purgatory, a hash digest of the segments is calculated for integrity checking. This digest is embedded into the purgatory image prior to placing purgatory in memory. Since hotplug events cause changes to the elfcorehdr, purgatory integrity checking fails (at crash time, and no kdump created). As a result, this change explicitly excludes the elfcorehdr segment from the list of segments used to create the digest. By doing so, this permits changes to the elfcorehdr in response to hotplug events, without having to also reload purgatory due to the change to the digest. Signed-off-by: Eric DeVolder Acked-by: Baoquan He --- kernel/kexec_file.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 8017eeb43036..d0c2661b3509 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -723,6 +723,12 @@ static int kexec_calculate_store_digests(struct kimage= *image) for (j =3D i =3D 0; i < image->nr_segments; i++) { struct kexec_segment *ksegment; =20 +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) + /* Exclude elfcorehdr segment to allow future changes via hotplug */ + if (image->elfcorehdr_index_valid && (j =3D=3D image->elfcorehdr_index)) + continue; +#endif + ksegment =3D &image->segment[i]; /* * Skip purgatory as it will be modified once we put digest --=20 2.31.1 From nobody Sat Apr 11 10:29:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10AF0ECAAA6 for ; 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Fri, 26 Aug 2022 17:37:21 +0000 From: Eric DeVolder To: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, eric.devolder@oracle.com Subject: [PATCH v11 5/7] kexec: exclude hot remove cpu from elfcorehdr notes Date: Fri, 26 Aug 2022 13:37:02 -0400 Message-Id: <20220826173704.1895-6-eric.devolder@oracle.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220826173704.1895-1-eric.devolder@oracle.com> References: <20220826173704.1895-1-eric.devolder@oracle.com> Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BY5PR20CA0029.namprd20.prod.outlook.com (2603:10b6:a03:1f4::42) To CO1PR10MB4531.namprd10.prod.outlook.com (2603:10b6:303:6c::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 08bdbe8e-539b-4bc9-0b21-08da8789a18c X-MS-TrafficTypeDiagnostic: DM4PR10MB6231:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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charset="utf-8" Due to use of CPUHP_AP_ONLINE_DYN, upon CPU unplug, the CPU is still in the for_each_present_cpu() list when within the handle_hotplug_event(). Thus the CPU must be explicitly excluded when building the new list of CPUs. This change identifies in handle_hotplug_event() the CPU to be excluded, and the check for excluding the CPU in crash_prepare_elf64_headers(). Signed-off-by: Eric DeVolder Acked-by: Baoquan He --- kernel/crash_core.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 455150205ded..2f84a221b370 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -366,6 +366,11 @@ int crash_prepare_elf64_headers(struct kimage *image, = struct crash_mem *mem, =20 /* Prepare one phdr of type PT_NOTE for each present CPU */ for_each_present_cpu(cpu) { +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) + /* Skip the soon-to-be offlined cpu */ + if (image->hotplug_event && (cpu =3D=3D image->offlinecpu)) + continue; +#endif phdr->p_type =3D PT_NOTE; notes_addr =3D per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu)); phdr->p_offset =3D phdr->p_paddr =3D notes_addr; @@ -681,6 +686,16 @@ static void handle_hotplug_event(unsigned int hp_actio= n, unsigned int cpu) /* Flag to differentiate between normal load and hotplug */ image->hotplug_event =3D true; =20 + /* + * Due to use of CPUHP_AP_ONLINE_DYN, upon unplug and during + * this callback, the CPU is still in the for_each_present_cpu() + * list. Must explicitly look to exclude this CPU when building + * new list. + */ + image->offlinecpu =3D + (hp_action =3D=3D KEXEC_CRASH_HP_REMOVE_CPU) ? + cpu : KEXEC_CRASH_HP_INVALID_CPU; + /* Now invoke arch-specific update handler */ arch_crash_handle_hotplug_event(image, hp_action); =20 --=20 2.31.1 From nobody Sat Apr 11 10:29:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DACD7ECAAA6 for ; Fri, 26 Aug 2022 17:39:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344923AbiHZRjI (ORCPT ); Fri, 26 Aug 2022 13:39:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344797AbiHZRi4 (ORCPT ); Fri, 26 Aug 2022 13:38:56 -0400 Received: from mx0a-00069f02.pphosted.com (mx0a-00069f02.pphosted.com [205.220.165.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E7145E1901 for ; 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charset="utf-8" This introduces the crash_hotplug attribute for memory and CPUs for use by userspace. This change directly facilitates the udev rule for managing userspace re-loading of the crash kernel upon hot un/plug changes. For memory, this changeset introduces the crash_hotplug attribute to the /sys/devices/system/memory directory. For example: # udevadm info --attribute-walk /sys/devices/system/memory/memory81 looking at device '/devices/system/memory/memory81': KERNEL=3D=3D"memory81" SUBSYSTEM=3D=3D"memory" DRIVER=3D=3D"" ATTR{online}=3D=3D"1" ATTR{phys_device}=3D=3D"0" ATTR{phys_index}=3D=3D"00000051" ATTR{removable}=3D=3D"1" ATTR{state}=3D=3D"online" ATTR{valid_zones}=3D=3D"Movable" looking at parent device '/devices/system/memory': KERNELS=3D=3D"memory" SUBSYSTEMS=3D=3D"" DRIVERS=3D=3D"" ATTRS{auto_online_blocks}=3D=3D"offline" ATTRS{block_size_bytes}=3D=3D"8000000" ATTRS{crash_hotplug}=3D=3D"1" For CPUs, this changeset introduces the crash_hotplug attribute to the /sys/devices/system/cpu directory. For example: # udevadm info --attribute-walk /sys/devices/system/cpu/cpu0 looking at device '/devices/system/cpu/cpu0': KERNEL=3D=3D"cpu0" SUBSYSTEM=3D=3D"cpu" DRIVER=3D=3D"processor" ATTR{crash_notes}=3D=3D"277c38600" ATTR{crash_notes_size}=3D=3D"368" ATTR{online}=3D=3D"1" looking at parent device '/devices/system/cpu': KERNELS=3D=3D"cpu" SUBSYSTEMS=3D=3D"" DRIVERS=3D=3D"" ATTRS{crash_hotplug}=3D=3D"1" ATTRS{isolated}=3D=3D"" ATTRS{kernel_max}=3D=3D"8191" ATTRS{nohz_full}=3D=3D" (null)" ATTRS{offline}=3D=3D"4-7" ATTRS{online}=3D=3D"0-3" ATTRS{possible}=3D=3D"0-7" ATTRS{present}=3D=3D"0-3" With these sysfs attributes in place, it is possible to efficiently instruct the udev rule to skip crash kernel reloading. For example, the following is the proposed udev rule change for RHEL system 98-kexec.rules (as the first lines of the rule file): # The kernel handles updates to crash elfcorehdr for cpu and memory changes SUBSYSTEM=3D=3D"cpu", ATTRS{crash_hotplug}=3D=3D"1", GOTO=3D"kdump_reload_= end" SUBSYSTEM=3D=3D"memory", ATTRS{crash_hotplug}=3D=3D"1", GOTO=3D"kdump_relo= ad_end" When examined in the context of 98-kexec.rules, the above change tests if crash_hotplug is set, and if so, it skips the userspace initiated unload-then-reload of the crash kernel. Cpu and memory checks are separated in accordance with CONFIG_HOTPLUG_CPU and CONFIG_MEMORY_HOTPLUG kernel config options. If an architecture supports, for example, memory hotplug but not CPU hotplug, then the /sys/devices/system/memory/crash_hotplug attribute file is present, but the /sys/devices/system/cpu/crash_hotplug attribute file will NOT be present. Thus the udev rule will skip userspace processing of memory hot un/plug events, but the udev rule will fail for CPU events, thus allowing userspace to process cpu hot un/plug events (ie the unload-then-reload of the kdump capture kernel). Signed-off-by: Eric DeVolder Acked-by: Baoquan He --- .../admin-guide/mm/memory-hotplug.rst | 8 ++++++++ Documentation/core-api/cpu_hotplug.rst | 18 ++++++++++++++++++ drivers/base/cpu.c | 14 ++++++++++++++ drivers/base/memory.c | 13 +++++++++++++ include/linux/kexec.h | 8 ++++++++ 5 files changed, 61 insertions(+) diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentatio= n/admin-guide/mm/memory-hotplug.rst index a3c9e8ad8fa0..15fd1751a63c 100644 --- a/Documentation/admin-guide/mm/memory-hotplug.rst +++ b/Documentation/admin-guide/mm/memory-hotplug.rst @@ -293,6 +293,14 @@ The following files are currently defined: Availability depends on the CONFIG_ARCH_MEMORY_PROBE kernel configuration option. ``uevent`` read-write: generic udev file for device subsystems. +``crash_hotplug`` read-only: when changes to the system memory map + occur due to hot un/plug of memory, this file contains + '1' if the kernel updates the kdump capture kernel memory + map itself (via elfcorehdr), or '0' if userspace must update + the kdump capture kernel memory map. + + Availability depends on the CONFIG_MEMORY_HOTPLUG kernel + configuration option. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D =20 .. note:: diff --git a/Documentation/core-api/cpu_hotplug.rst b/Documentation/core-ap= i/cpu_hotplug.rst index c6f4ba2fb32d..13e33d098645 100644 --- a/Documentation/core-api/cpu_hotplug.rst +++ b/Documentation/core-api/cpu_hotplug.rst @@ -750,6 +750,24 @@ will receive all events. A script like:: =20 can process the event further. =20 +When changes to the CPUs in the system occur, the sysfs file +/sys/devices/system/cpu/crash_hotplug contains '1' if the kernel +updates the kdump capture kernel list of CPUs itself (via elfcorehdr), +or '0' if userspace must update the kdump capture kernel list of CPUs. + +The availability depends on the CONFIG_HOTPLUG_CPU kernel configuration +option. + +To skip userspace processing of CPU hot un/plug events for kdump +(ie the unload-then-reload to obtain a current list of CPUs), this sysfs +file can be used in a udev rule as follows: + + SUBSYSTEM=3D=3D"cpu", ATTRS{crash_hotplug}=3D=3D"1", GOTO=3D"kdump_reload= _end" + +For a cpu hot un/plug event, if the architecture supports kernel updates +of the elfcorehdr (which contains the list of CPUs), then the rule skips +the unload-then-reload of the kdump capture kernel. + Kernel Inline Documentations Reference =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 4c98849577d4..fedbf87f9d13 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -293,6 +293,17 @@ static ssize_t print_cpus_nohz_full(struct device *dev, static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL); #endif =20 +#ifdef CONFIG_HOTPLUG_CPU +#include +static ssize_t crash_hotplug_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + return sprintf(buf, "%d\n", crash_hotplug_cpu_support()); +} +static DEVICE_ATTR_ADMIN_RO(crash_hotplug); +#endif + static void cpu_device_release(struct device *dev) { /* @@ -469,6 +480,9 @@ static struct attribute *cpu_root_attrs[] =3D { #ifdef CONFIG_NO_HZ_FULL &dev_attr_nohz_full.attr, #endif +#ifdef CONFIG_HOTPLUG_CPU + &dev_attr_crash_hotplug.attr, +#endif #ifdef CONFIG_GENERIC_CPU_AUTOPROBE &dev_attr_modalias.attr, #endif diff --git a/drivers/base/memory.c b/drivers/base/memory.c index bc60c9cd3230..b754918c3dac 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -483,6 +483,16 @@ static ssize_t auto_online_blocks_store(struct device = *dev, =20 static DEVICE_ATTR_RW(auto_online_blocks); =20 +#ifdef CONFIG_MEMORY_HOTPLUG +#include +static ssize_t crash_hotplug_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "%d\n", crash_hotplug_memory_support()); +} +static DEVICE_ATTR_RO(crash_hotplug); +#endif + /* * Some architectures will have custom drivers to do this, and * will not need to do it from userspace. The fake hot-add code @@ -887,6 +897,9 @@ static struct attribute *memory_root_attrs[] =3D { =20 &dev_attr_block_size_bytes.attr, &dev_attr_auto_online_blocks.attr, +#ifdef CONFIG_MEMORY_HOTPLUG + &dev_attr_crash_hotplug.attr, +#endif NULL }; =20 diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 9597b41136ec..a48577a36fb8 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -529,6 +529,14 @@ static inline void arch_crash_handle_hotplug_event(str= uct kimage *image, } #endif =20 +#ifndef crash_hotplug_cpu_support +static inline int crash_hotplug_cpu_support(void) { return 0; } +#endif + +#ifndef crash_hotplug_memory_support +static inline int crash_hotplug_memory_support(void) { return 0; } +#endif + #else /* !CONFIG_KEXEC_CORE */ struct pt_regs; struct task_struct; --=20 2.31.1 From nobody Sat Apr 11 10:29:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E77DCECAAA6 for ; 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Fri, 26 Aug 2022 17:37:27 +0000 From: Eric DeVolder To: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, eric.devolder@oracle.com Subject: [PATCH v11 7/7] x86/crash: Add x86 crash hotplug support Date: Fri, 26 Aug 2022 13:37:04 -0400 Message-Id: <20220826173704.1895-8-eric.devolder@oracle.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220826173704.1895-1-eric.devolder@oracle.com> References: <20220826173704.1895-1-eric.devolder@oracle.com> Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BY5PR17CA0044.namprd17.prod.outlook.com (2603:10b6:a03:167::21) To CO1PR10MB4531.namprd10.prod.outlook.com (2603:10b6:303:6c::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 1524d9c8-ccc9-49d3-b4ab-08da8789a4e1 X-MS-TrafficTypeDiagnostic: MN2PR10MB3518:EE_ X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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charset="utf-8" For x86_64, when CPU or memory is hot un/plugged, the crash elfcorehdr, which describes the CPUs and memory in the system, must also be updated. When loading the crash kernel via kexec_load or kexec_file_load, the elfcorehdr is identified at run time in crash_core:handle_hotplug_event(). To update the elfcorehdr for x86_64, a new elfcorehdr must be generated from the available CPUs and memory. The new elfcorehdr is prepared into a buffer, and then installed over the top of the existing elfcorehdr. In the patch 'kexec: exclude elfcorehdr from the segment digest' the need to update purgatory due to the change in elfcorehdr was eliminated. As a result, no changes to purgatory or boot_params (as the elfcorehdr=3D kernel command line parameter pointer remains unchanged and correct) are needed, just elfcorehdr. To accommodate a growing number of resources via hotplug, the elfcorehdr segment must be sufficiently large enough to accommodate changes, see the CRASH_MAX_MEMORY_RANGES configure item. With this change, crash hotplug for kexec_file_load syscall is supported. The kexec_load is also supported, but also requires a corresponding change to userspace kexec-tools. Signed-off-by: Eric DeVolder Acked-by: Baoquan He --- arch/x86/Kconfig | 11 ++++ arch/x86/include/asm/kexec.h | 20 +++++++ arch/x86/kernel/crash.c | 102 +++++++++++++++++++++++++++++++++++ 3 files changed, 133 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f9920f1341c8..cdfc9b2fdf98 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2056,6 +2056,17 @@ config CRASH_DUMP (CONFIG_RELOCATABLE=3Dy). For more details see Documentation/admin-guide/kdump/kdump.rst =20 +config CRASH_MAX_MEMORY_RANGES + depends on CRASH_DUMP && KEXEC_FILE && (HOTPLUG_CPU || MEMORY_HOTPLUG) + int + default 32768 + help + For the kexec_file_load path, specify the maximum number of + memory regions, eg. as represented by the 'System RAM' entries + in /proc/iomem, that the elfcorehdr buffer/segment can accommodate. + This value is combined with NR_CPUS and multiplied by Elf64_Phdr + size to determine the final buffer size. + config KEXEC_JUMP bool "kexec jump" depends on KEXEC && HIBERNATION diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h index a3760ca796aa..432073385b2d 100644 --- a/arch/x86/include/asm/kexec.h +++ b/arch/x86/include/asm/kexec.h @@ -212,6 +212,26 @@ typedef void crash_vmclear_fn(void); extern crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss; extern void kdump_nmi_shootdown_cpus(void); =20 +void *arch_map_crash_pages(unsigned long paddr, unsigned long size); +#define arch_map_crash_pages arch_map_crash_pages + +void arch_unmap_crash_pages(void **ptr); +#define arch_unmap_crash_pages arch_unmap_crash_pages + +void arch_crash_handle_hotplug_event(struct kimage *image, + unsigned int hp_action); +#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event + +#ifdef CONFIG_HOTPLUG_CPU +static inline int crash_hotplug_cpu_support(void) { return 1; } +#define crash_hotplug_cpu_support crash_hotplug_cpu_support +#endif + +#ifdef CONFIG_MEMORY_HOTPLUG +static inline int crash_hotplug_memory_support(void) { return 1; } +#define crash_hotplug_memory_support crash_hotplug_memory_support +#endif + #endif /* __ASSEMBLY__ */ =20 #endif /* _ASM_X86_KEXEC_H */ diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 9ceb93c176a6..8fc7d678ac72 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -25,6 +25,7 @@ #include #include #include +#include =20 #include #include @@ -397,7 +398,18 @@ int crash_load_segments(struct kimage *image) image->elf_headers =3D kbuf.buffer; image->elf_headers_sz =3D kbuf.bufsz; =20 +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) + /* Ensure elfcorehdr segment large enough for hotplug changes */ + kbuf.memsz =3D + (CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES) * + sizeof(Elf64_Phdr); + /* Mark as usable to crash kernel, else crash kernel fails on boot */ + image->elf_headers_sz =3D kbuf.memsz; + image->elfcorehdr_index =3D image->nr_segments; + image->elfcorehdr_index_valid =3D true; +#else kbuf.memsz =3D kbuf.bufsz; +#endif kbuf.buf_align =3D ELF_CORE_HEADER_ALIGN; kbuf.mem =3D KEXEC_BUF_MEM_UNKNOWN; ret =3D kexec_add_buffer(&kbuf); @@ -412,3 +424,93 @@ int crash_load_segments(struct kimage *image) return ret; } #endif /* CONFIG_KEXEC_FILE */ + +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) +/* + * NOTE: The addresses and sizes passed to this routine have + * already been fully aligned on page boundaries. There is no + * need for massaging the address or size. + */ +void *arch_map_crash_pages(unsigned long paddr, unsigned long size) +{ + void *ptr =3D NULL; + + if (size > 0) { + struct page *page =3D pfn_to_page(paddr >> PAGE_SHIFT); + + ptr =3D kmap_local_page(page); + } + + return ptr; +} + +void arch_unmap_crash_pages(void **ptr) +{ + if (ptr) { + if (*ptr) + kunmap_local(*ptr); + *ptr =3D NULL; + } +} + +/** + * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes + * @image: the active struct kimage + * @hp_action: the hot un/plug action being handled + * + * To accurately reflect hot un/plug changes, the new elfcorehdr + * is prepared in a kernel buffer, and then it is written on top + * of the existing/old elfcorehdr. + */ +void arch_crash_handle_hotplug_event(struct kimage *image, + unsigned int hp_action) +{ + struct kexec_segment *ksegment; + unsigned char *ptr =3D NULL; + unsigned long elfsz =3D 0; + void *elfbuf =3D NULL; + unsigned long mem, memsz; + + /* + * Elfcorehdr_index_valid checked in crash_core:handle_hotplug_event() + */ + ksegment =3D &image->segment[image->elfcorehdr_index]; + mem =3D ksegment->mem; + memsz =3D ksegment->memsz; + + /* + * Create the new elfcorehdr reflecting the changes to CPU and/or + * memory resources. + */ + if (prepare_elf_headers(image, &elfbuf, &elfsz)) { + pr_err("crash hp: unable to prepare elfcore headers"); + goto out; + } + if (elfsz > memsz) { + pr_err("crash hp: update elfcorehdr elfsz %lu > memsz %lu", + elfsz, memsz); + goto out; + } + + /* + * At this point, we are all but assured of success. + * Copy new elfcorehdr into destination. + */ + ptr =3D arch_map_crash_pages(mem, memsz); + if (ptr) { + /* + * Temporarily invalidate the crash image while the + * elfcorehdr is updated. + */ + xchg(&kexec_crash_image, NULL); + memcpy_flushcache((void *)ptr, elfbuf, elfsz); + xchg(&kexec_crash_image, image); + } + arch_unmap_crash_pages((void **)&ptr); + pr_debug("crash hp: re-loaded elfcorehdr at 0x%lx\n", mem); + +out: + if (elfbuf) + vfree(elfbuf); +} +#endif --=20 2.31.1