arch/arm64/kernel/elfcore.c

   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
  18 static 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 */
  24 static 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
  78 Elf_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
  90 int 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
 115 size_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
 127 int 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 }