This note has the following format:

long count     -- how many files are mapped
long page_size -- units for file_ofs
array of [COUNT] elements of
   long start
   long end
   long file_ofs
followed by COUNT filenames in ASCII: "FILE1" NUL "FILE2" NUL...

Compared to previous version, code is simplified
as suggested by Oleg Nesterov.

Signed-off-by: Denys Vlasenko <vda.li...@googlemail.com>

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 1b52956..8e60c38 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1372,6 +1372,72 @@ static void fill_auxv_note(struct memelfnote *note, 
struct mm_struct *mm)
        fill_note(note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
 }
 
+#define MAX_FILE_NOTE_SIZE (4*1024*1024)
+
+static void fill_files_note(struct memelfnote *note)
+{
+       struct vm_area_struct *vma;
+       struct file *file;
+       unsigned count, word_count, size, remaining;
+       long *data;
+       long *start_end_ofs;
+       char *name;
+
+       count = 0;
+       for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
+               file = vma->vm_file;
+               if (!file)
+                       continue;
+               count++;
+       }
+
+       size = count * 64;
+       word_count = 2 + 3 * count;
+ alloc:
+       if (size >= MAX_FILE_NOTE_SIZE) /* paranoia check */
+               goto err;
+       size = round_up(size, PAGE_SIZE);
+       data = vmalloc(size);
+       if (!data)
+               goto err;
+
+       start_end_ofs = data;
+       name = (void*)&start_end_ofs[word_count];
+       remaining = size - word_count * sizeof(long);
+
+       *start_end_ofs++ = count;
+       *start_end_ofs++ = PAGE_SIZE;
+       for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
+               const char *filename;
+
+               file = vma->vm_file;
+               if (!file)
+                       continue;
+               filename = d_path(&file->f_path, name, remaining);
+               if (IS_ERR(filename)) {
+                       if (PTR_ERR(filename) == -ENAMETOOLONG) {
+                               vfree(data);
+                               size = size * 5 / 4;
+                               goto alloc;
+                       }
+                       /* continue; - WRONG, we must have COUNT elements */
+                       filename = "";
+               }
+               /* d_path() fills at the end, move it to front */
+               do
+                       remaining--;
+               while ((*name++ = *filename++) != '\0');
+
+               *start_end_ofs++ = vma->vm_start;
+               *start_end_ofs++ = vma->vm_end;
+               *start_end_ofs++ = vma->vm_pgoff;
+       }
+
+       size = name - (char*)data;
+       fill_note(note, "CORE", NT_FILE, size, data);
+ err: ;
+}
+
 #ifdef CORE_DUMP_USE_REGSET
 #include <linux/regset.h>
 
@@ -1386,6 +1452,7 @@ struct elf_note_info {
        struct elf_thread_core_info *thread;
        struct memelfnote psinfo;
        struct memelfnote auxv;
+       struct memelfnote files;
        size_t size;
        int thread_notes;
 };
@@ -1562,6 +1629,9 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
        fill_auxv_note(&info->auxv, current->mm);
        info->size += notesize(&info->auxv);
 
+       fill_files_note(&info->files);
+       info->size += notesize(&info->files);
+
        return 1;
 }
 
@@ -1590,6 +1660,8 @@ static int write_note_info(struct elf_note_info *info,
                        return 0;
                if (first && !writenote(&info->auxv, file, foffset))
                        return 0;
+               if (first && !writenote(&info->files, file, foffset))
+                       return 0;
 
                for (i = 1; i < info->thread_notes; ++i)
                        if (t->notes[i].data &&
@@ -1616,6 +1688,7 @@ static void free_note_info(struct elf_note_info *info)
                kfree(t);
        }
        kfree(info->psinfo.data);
+       vfree(info->files.data);
 }
 
 #else
diff --git a/include/linux/elf.h b/include/linux/elf.h
index 999b4f5..5e6c08f 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -372,6 +372,7 @@ typedef struct elf64_shdr {
 #define NT_PRPSINFO    3
 #define NT_TASKSTRUCT  4
 #define NT_AUXV                6
+#define NT_FILE                0x46494c45
 #define NT_PRXFPREG     0x46e62b7f      /* copied from 
gdb5.1/include/elf/common.h */
 #define NT_PPC_VMX     0x100           /* PowerPC Altivec/VMX registers */
 #define NT_PPC_SPE     0x101           /* PowerPC SPE/EVR registers */

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