1 files changed, 143 insertions, 0 deletions
diff --git a/arch/arm64/kernel/elfcore.c b/arch/arm64/kernel/elfcore.c
new file mode 100644
index 000000000000..27ef7ad3ffd2
--- /dev/null
+++ b/arch/arm64/kernel/elfcore.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/coredump.h>
+#include <linux/elfcore.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+
+#include <asm/cpufeature.h>
+#include <asm/mte.h>
+
+#define for_each_mte_vma(vmi, vma)					\
+	if (system_supports_mte())					\
+		for_each_vma(vmi, vma)					\
+			if (vma->vm_flags & VM_MTE)
+
+static unsigned long mte_vma_tag_dump_size(struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & VM_DONTDUMP)
+		return 0;
+
+	return vma_pages(vma) * MTE_PAGE_TAG_STORAGE;
+}
+
+/* Derived from dump_user_range(); start/end must be page-aligned */
+static int mte_dump_tag_range(struct coredump_params *cprm,
+			      unsigned long start, unsigned long end)
+{
+	int ret = 1;
+	unsigned long addr;
+	void *tags = NULL;
+
+	for (addr = start; addr < end; addr += PAGE_SIZE) {
+		struct page *page = get_dump_page(addr);
+
+		/*
+		 * get_dump_page() returns NULL when encountering an empty
+		 * page table entry that would otherwise have been filled with
+		 * the zero page. Skip the equivalent tag dump which would
+		 * have been all zeros.
+		 */
+		if (!page) {
+			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
+			continue;
+		}
+
+		/*
+		 * Pages mapped in user space as !pte_access_permitted() (e.g.
+		 * PROT_EXEC only) may not have the PG_mte_tagged flag set.
+		 */
+		if (!test_bit(PG_mte_tagged, &page->flags)) {
+			put_page(page);
+			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
+			continue;
+		}
+
+		if (!tags) {
+			tags = mte_allocate_tag_storage();
+			if (!tags) {
+				put_page(page);
+				ret = 0;
+				break;
+			}
+		}
+
+		mte_save_page_tags(page_address(page), tags);
+		put_page(page);
+		if (!dump_emit(cprm, tags, MTE_PAGE_TAG_STORAGE)) {
+			mte_free_tag_storage(tags);
+			ret = 0;
+			break;
+		}
+	}
+
+	if (tags)
+		mte_free_tag_storage(tags);
+
+	return ret;
+}
+
+Elf_Half elf_core_extra_phdrs(void)
+{
+	struct vm_area_struct *vma;
+	int vma_count = 0;
+	VMA_ITERATOR(vmi, current->mm, 0);
+
+	for_each_mte_vma(vmi, vma)
+		vma_count++;
+
+	return vma_count;
+}
+
+int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)
+{
+	struct vm_area_struct *vma;
+	VMA_ITERATOR(vmi, current->mm, 0);
+
+	for_each_mte_vma(vmi, vma) {
+		struct elf_phdr phdr;
+
+		phdr.p_type = PT_AARCH64_MEMTAG_MTE;
+		phdr.p_offset = offset;
+		phdr.p_vaddr = vma->vm_start;
+		phdr.p_paddr = 0;
+		phdr.p_filesz = mte_vma_tag_dump_size(vma);
+		phdr.p_memsz = vma->vm_end - vma->vm_start;
+		offset += phdr.p_filesz;
+		phdr.p_flags = 0;
+		phdr.p_align = 0;
+
+		if (!dump_emit(cprm, &phdr, sizeof(phdr)))
+			return 0;
+	}
+
+	return 1;
+}
+
+size_t elf_core_extra_data_size(void)
+{
+	struct vm_area_struct *vma;
+	size_t data_size = 0;
+	VMA_ITERATOR(vmi, current->mm, 0);
+
+	for_each_mte_vma(vmi, vma)
+		data_size += mte_vma_tag_dump_size(vma);
+
+	return data_size;
+}
+
+int elf_core_write_extra_data(struct coredump_params *cprm)
+{
+	struct vm_area_struct *vma;
+	VMA_ITERATOR(vmi, current->mm, 0);
+
+	for_each_mte_vma(vmi, vma) {
+		if (vma->vm_flags & VM_DONTDUMP)
+			continue;
+
+		if (!mte_dump_tag_range(cprm, vma->vm_start, vma->vm_end))
+			return 0;
+	}
+
+	return 1;
+}