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}
139