1 files changed, 143 insertions, 0 deletions
diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h
new file mode 100644
index 000000000000..5f7b9de97e8d
--- /dev/null
+++ b/include/linux/kexec_handover.h
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LINUX_KEXEC_HANDOVER_H
+#define LINUX_KEXEC_HANDOVER_H
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct kho_scratch {
+	phys_addr_t addr;
+	phys_addr_t size;
+};
+
+struct folio;
+struct page;
+
+#define DECLARE_KHOSER_PTR(name, type) \
+	union {                        \
+		phys_addr_t phys;      \
+		type ptr;              \
+	} name
+#define KHOSER_STORE_PTR(dest, val)               \
+	({                                        \
+		typeof(val) v = val;              \
+		typecheck(typeof((dest).ptr), v); \
+		(dest).phys = virt_to_phys(v);    \
+	})
+#define KHOSER_LOAD_PTR(src)                                                 \
+	({                                                                   \
+		typeof(src) s = src;                                         \
+		(typeof((s).ptr))((s).phys ? phys_to_virt((s).phys) : NULL); \
+	})
+
+struct kho_vmalloc_chunk;
+struct kho_vmalloc {
+	DECLARE_KHOSER_PTR(first, struct kho_vmalloc_chunk *);
+	unsigned int total_pages;
+	unsigned short flags;
+	unsigned short order;
+};
+
+#ifdef CONFIG_KEXEC_HANDOVER
+bool kho_is_enabled(void);
+bool is_kho_boot(void);
+
+int kho_preserve_folio(struct folio *folio);
+void kho_unpreserve_folio(struct folio *folio);
+int kho_preserve_pages(struct page *page, unsigned int nr_pages);
+void kho_unpreserve_pages(struct page *page, unsigned int nr_pages);
+int kho_preserve_vmalloc(void *ptr, struct kho_vmalloc *preservation);
+void kho_unpreserve_vmalloc(struct kho_vmalloc *preservation);
+void *kho_alloc_preserve(size_t size);
+void kho_unpreserve_free(void *mem);
+void kho_restore_free(void *mem);
+struct folio *kho_restore_folio(phys_addr_t phys);
+struct page *kho_restore_pages(phys_addr_t phys, unsigned int nr_pages);
+void *kho_restore_vmalloc(const struct kho_vmalloc *preservation);
+int kho_add_subtree(const char *name, void *fdt);
+void kho_remove_subtree(void *fdt);
+int kho_retrieve_subtree(const char *name, phys_addr_t *phys);
+
+void kho_memory_init(void);
+
+void kho_populate(phys_addr_t fdt_phys, u64 fdt_len, phys_addr_t scratch_phys,
+		  u64 scratch_len);
+#else
+static inline bool kho_is_enabled(void)
+{
+	return false;
+}
+
+static inline bool is_kho_boot(void)
+{
+	return false;
+}
+
+static inline int kho_preserve_folio(struct folio *folio)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void kho_unpreserve_folio(struct folio *folio) { }
+
+static inline int kho_preserve_pages(struct page *page, unsigned int nr_pages)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void kho_unpreserve_pages(struct page *page, unsigned int nr_pages) { }
+
+static inline int kho_preserve_vmalloc(void *ptr,
+				       struct kho_vmalloc *preservation)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void kho_unpreserve_vmalloc(struct kho_vmalloc *preservation) { }
+
+static inline void *kho_alloc_preserve(size_t size)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void kho_unpreserve_free(void *mem) { }
+static inline void kho_restore_free(void *mem) { }
+
+static inline struct folio *kho_restore_folio(phys_addr_t phys)
+{
+	return NULL;
+}
+
+static inline struct page *kho_restore_pages(phys_addr_t phys,
+					     unsigned int nr_pages)
+{
+	return NULL;
+}
+
+static inline void *kho_restore_vmalloc(const struct kho_vmalloc *preservation)
+{
+	return NULL;
+}
+
+static inline int kho_add_subtree(const char *name, void *fdt)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void kho_remove_subtree(void *fdt) { }
+
+static inline int kho_retrieve_subtree(const char *name, phys_addr_t *phys)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void kho_memory_init(void) { }
+
+static inline void kho_populate(phys_addr_t fdt_phys, u64 fdt_len,
+				phys_addr_t scratch_phys, u64 scratch_len)
+{
+}
+#endif /* CONFIG_KEXEC_HANDOVER */
+
+#endif /* LINUX_KEXEC_HANDOVER_H */