From: "Mike Rapoport (Microsoft)" <[email protected]> A vmalloc allocation is preserved using binary structure similar to global KHO memory tracker. It's a linked list of pages where each page is an array of physical address of pages in vmalloc area.
kho_preserve_vmalloc() hands out the physical address of the head page to the caller. This address is used as the argument to kho_vmalloc_restore() to restore the mapping in the vmalloc address space and populate it with the preserved pages. Signed-off-by: Mike Rapoport (Microsoft) <[email protected]> --- include/linux/kexec_handover.h | 12 +++ kernel/kexec_handover.c | 140 +++++++++++++++++++++++++++++++++ 2 files changed, 152 insertions(+) diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h index 348844cffb13..b7bf3bf11019 100644 --- a/include/linux/kexec_handover.h +++ b/include/linux/kexec_handover.h @@ -42,8 +42,10 @@ struct kho_serialization; bool kho_is_enabled(void); int kho_preserve_folio(struct folio *folio); +int kho_preserve_vmalloc(void *ptr, phys_addr_t *preservation); int kho_preserve_phys(phys_addr_t phys, size_t size); struct folio *kho_restore_folio(phys_addr_t phys); +void *kho_restore_vmalloc(phys_addr_t preservation); int kho_add_subtree(struct kho_serialization *ser, const char *name, void *fdt); int kho_retrieve_subtree(const char *name, phys_addr_t *phys); @@ -70,11 +72,21 @@ static inline int kho_preserve_phys(phys_addr_t phys, size_t size) return -EOPNOTSUPP; } +static inline int kho_preserve_vmalloc(void *ptr, phys_addr_t *preservation) +{ + return -EOPNOTSUPP; +} + static inline struct folio *kho_restore_folio(phys_addr_t phys) { return NULL; } +static inline void *kho_restore_vmalloc(phys_addr_t preservation) +{ + return NULL; +} + static inline int kho_add_subtree(struct kho_serialization *ser, const char *name, void *fdt) { diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index ecd1ac210dbd..a11ae79d6bc9 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -18,6 +18,7 @@ #include <linux/memblock.h> #include <linux/notifier.h> #include <linux/page-isolation.h> +#include <linux/vmalloc.h> #include <asm/early_ioremap.h> @@ -733,6 +734,145 @@ int kho_preserve_phys(phys_addr_t phys, size_t size) } EXPORT_SYMBOL_GPL(kho_preserve_phys); +struct kho_vmalloc_chunk; + +struct kho_vmalloc_hdr { + DECLARE_KHOSER_PTR(next, struct kho_vmalloc_chunk *); + unsigned int total_pages; /* only valid in the first chunk */ + unsigned int num_elms; +}; + +#define KHO_VMALLOC_SIZE \ + ((PAGE_SIZE - sizeof(struct kho_vmalloc_hdr)) / \ + sizeof(phys_addr_t)) + +struct kho_vmalloc_chunk { + struct kho_vmalloc_hdr hdr; + phys_addr_t phys[KHO_VMALLOC_SIZE]; +}; + +static_assert(sizeof(struct kho_vmalloc_chunk) == PAGE_SIZE); + +static struct kho_vmalloc_chunk *new_vmalloc_chunk(struct kho_vmalloc_chunk *cur) +{ + struct kho_vmalloc_chunk *chunk; + int err; + + chunk = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!chunk) + return NULL; + + err = kho_preserve_phys(virt_to_phys(chunk), PAGE_SIZE); + if (err) + goto err_free; + if (cur) + KHOSER_STORE_PTR(cur->hdr.next, chunk); + return chunk; + +err_free: + kfree(chunk); + return NULL; +} + +static void kho_vmalloc_free_chunks(struct kho_vmalloc_chunk *first_chunk) +{ + struct kho_mem_track *track = &kho_out.ser.track; + struct kho_vmalloc_chunk *chunk = first_chunk; + + while (chunk) { + unsigned long pfn = PHYS_PFN(virt_to_phys(chunk)); + struct kho_vmalloc_chunk *tmp = chunk; + + __kho_unpreserve(track, pfn, pfn + 1); + + chunk = KHOSER_LOAD_PTR(chunk->hdr.next); + kfree(tmp); + } +} + +int kho_preserve_vmalloc(void *ptr, phys_addr_t *preservation) +{ + struct kho_vmalloc_chunk *chunk, *first_chunk; + struct vm_struct *vm = find_vm_area(ptr); + int err; + + if (!vm) + return -EINVAL; + + /* we don't support HUGE_VMAP yet */ + if (get_vm_area_page_order(vm)) + return -EOPNOTSUPP; + + chunk = new_vmalloc_chunk(NULL); + if (!chunk) + return -ENOMEM; + first_chunk = chunk; + first_chunk->hdr.total_pages = vm->nr_pages; + + for (int i = 0; i < vm->nr_pages; i++) { + phys_addr_t phys = page_to_phys(vm->pages[i]); + + err = kho_preserve_phys(phys, PAGE_SIZE); + if (err) + goto err_free; + + chunk->phys[chunk->hdr.num_elms] = phys; + chunk->hdr.num_elms++; + if (chunk->hdr.num_elms == ARRAY_SIZE(chunk->phys)) { + chunk = new_vmalloc_chunk(chunk); + if (!chunk) + goto err_free; + } + } + + *preservation = virt_to_phys(first_chunk); + return 0; + +err_free: + kho_vmalloc_free_chunks(first_chunk); + return err; +} +EXPORT_SYMBOL_GPL(kho_preserve_vmalloc); + +void *kho_restore_vmalloc(phys_addr_t preservation) +{ + struct kho_vmalloc_chunk *chunk = phys_to_virt(preservation); + unsigned int idx = 0, nr = 0; + struct page **pages; + void *ptr; + + nr = chunk->hdr.total_pages; + pages = kvmalloc_array(nr, sizeof(*pages), GFP_KERNEL); + if (!pages) + return NULL; + + while (chunk) { + struct page *page; + + for (int i = 0; i < chunk->hdr.num_elms; i++) { + page = phys_to_page(chunk->phys[i]); + kho_restore_page(page, 0); + pages[idx++] = page; + } + + page = virt_to_page(chunk); + chunk = KHOSER_LOAD_PTR(chunk->hdr.next); + kho_restore_page(page, 0); + __free_page(page); + } + + ptr = vmap(pages, nr, VM_MAP_PUT_PAGES, PAGE_KERNEL); + if (!ptr) + goto err_free_pages_array; + + return ptr; + +err_free_pages_array: + kvfree(pages); + return NULL; +} +EXPORT_SYMBOL_GPL(kho_restore_vmalloc); + /* Handling for debug/kho/out */ static struct dentry *debugfs_root; -- 2.50.1
