1// SPDX-License-Identifier: GPL-2.0-only
  2
  3#include <linux/coredump.h>
  4#include <linux/elfcore.h>
  5#include <linux/kernel.h>
  6#include <linux/mm.h>
  7
  8#include <asm/cpufeature.h>
  9#include <asm/mte.h>
 10
 11#define for_each_mte_vma(cprm, i, m)					\
 12	if (system_supports_mte())					\
 13		for (i = 0, m = cprm->vma_meta;				\
 14		     i < cprm->vma_count;				\
 15		     i++, m = cprm->vma_meta + i)			\
 16			if (m->flags & VM_MTE)
 17
 18static unsigned long mte_vma_tag_dump_size(struct core_vma_metadata *m)
 19{
 20	return (m->dump_size >> PAGE_SHIFT) * MTE_PAGE_TAG_STORAGE;
 21}
 22
 23/* Derived from dump_user_range(); start/end must be page-aligned */
 24static int mte_dump_tag_range(struct coredump_params *cprm,
 25			      unsigned long start, unsigned long len)
 26{
 27	int ret = 1;
 28	unsigned long addr;
 29	void *tags = NULL;
 30
 31	for (addr = start; addr < start + len; addr += PAGE_SIZE) {
 32		struct page *page = get_dump_page(addr);
 33
 34		/*
 35		 * get_dump_page() returns NULL when encountering an empty
 36		 * page table entry that would otherwise have been filled with
 37		 * the zero page. Skip the equivalent tag dump which would
 38		 * have been all zeros.
 39		 */
 40		if (!page) {
 41			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
 42			continue;
 43		}
 44
 45		/*
 46		 * Pages mapped in user space as !pte_access_permitted() (e.g.
 47		 * PROT_EXEC only) may not have the PG_mte_tagged flag set.
 48		 */
 49		if (!page_mte_tagged(page)) {
 50			put_page(page);
 51			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
 52			continue;
 53		}
 54
 55		if (!tags) {
 56			tags = mte_allocate_tag_storage();
 57			if (!tags) {
 58				put_page(page);
 59				ret = 0;
 60				break;
 61			}
 62		}
 63
 64		mte_save_page_tags(page_address(page), tags);
 65		put_page(page);
 66		if (!dump_emit(cprm, tags, MTE_PAGE_TAG_STORAGE)) {
 67			ret = 0;
 68			break;
 69		}
 70	}
 71
 72	if (tags)
 73		mte_free_tag_storage(tags);
 74
 75	return ret;
 76}
 77
 78Elf_Half elf_core_extra_phdrs(struct coredump_params *cprm)
 79{
 80	int i;
 81	struct core_vma_metadata *m;
 82	int vma_count = 0;
 83
 84	for_each_mte_vma(cprm, i, m)
 85		vma_count++;
 86
 87	return vma_count;
 88}
 89
 90int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)
 91{
 92	int i;
 93	struct core_vma_metadata *m;
 94
 95	for_each_mte_vma(cprm, i, m) {
 96		struct elf_phdr phdr;
 97
 98		phdr.p_type = PT_AARCH64_MEMTAG_MTE;
 99		phdr.p_offset = offset;
100		phdr.p_vaddr = m->start;
101		phdr.p_paddr = 0;
102		phdr.p_filesz = mte_vma_tag_dump_size(m);
103		phdr.p_memsz = m->end - m->start;
104		offset += phdr.p_filesz;
105		phdr.p_flags = 0;
106		phdr.p_align = 0;
107
108		if (!dump_emit(cprm, &phdr, sizeof(phdr)))
109			return 0;
110	}
111
112	return 1;
113}
114
115size_t elf_core_extra_data_size(struct coredump_params *cprm)
116{
117	int i;
118	struct core_vma_metadata *m;
119	size_t data_size = 0;
120
121	for_each_mte_vma(cprm, i, m)
122		data_size += mte_vma_tag_dump_size(m);
123
124	return data_size;
125}
126
127int elf_core_write_extra_data(struct coredump_params *cprm)
128{
129	int i;
130	struct core_vma_metadata *m;
131
132	for_each_mte_vma(cprm, i, m) {
133		if (!mte_dump_tag_range(cprm, m->start, m->dump_size))
134			return 0;
135	}
136
137	return 1;
138}