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Message-Id: <1348103478-24805-1-git-send-email-vda.linux@googlemail.com>
Date: Thu, 20 Sep 2012 03:11:18 +0200
From: Denys Vlasenko <vda.linux@...glemail.com>
To: Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Amerigo Wang <amwang@...hat.com>,
"Jonathan M. Foote" <jmfoote@...t.org>,
Roland McGrath <roland@...k.frob.com>,
Pedro Alves <palves@...hat.com>
Cc: Denys Vlasenko <vda.linux@...glemail.com>
Subject: [PATCH -mm v3] coredump: extend core dump note section to contain file names of mapped files
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...
Changes since previous version:
* reworked the way we count file-backed vmas,
* switched to memmove for filename copying instead of open-coded loop,
* fixed note generation for compat coredump.
Signed-off-by: Denys Vlasenko <vda.linux@...glemail.com>
---
fs/binfmt_elf.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++--
fs/compat_binfmt_elf.c | 1 +
include/linux/elf.h | 1 +
3 files changed, 106 insertions(+), 4 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index d33ee58..1c7d660 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -36,6 +36,9 @@
#include <asm/param.h>
#include <asm/page.h>
+#ifndef user_long_t
+#define user_long_t long
+#endif
#ifndef user_siginfo_t
#define user_siginfo_t siginfo_t
#endif
@@ -1384,6 +1387,92 @@ static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata);
}
+#define MAX_FILE_NOTE_SIZE (4*1024*1024)
+/*
+ * Format of NT_FILE note:
+ *
+ * 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...
+ */
+static void fill_files_note(struct memelfnote *note)
+{
+ struct vm_area_struct *vma;
+ unsigned count, size, names_ofs, remaining, n;
+ user_long_t *data;
+ user_long_t *start_end_ofs;
+ char *name_base, *name_curpos;
+
+ /* *Estimated* file count and total data size needed */
+ count = current->mm->map_count;
+ size = count * 64;
+
+ names_ofs = (2 + 3 * count) * sizeof(data[0]);
+ 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 + 2;
+ name_base = name_curpos = ((char*)data) + names_ofs;
+ remaining = size - names_ofs;
+ count = 0;
+ for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
+ struct file *file;
+ const char *filename;
+
+ file = vma->vm_file;
+ if (!file)
+ continue;
+ filename = d_path(&file->f_path, name_curpos, remaining);
+ if (IS_ERR(filename)) {
+ if (PTR_ERR(filename) == -ENAMETOOLONG) {
+ vfree(data);
+ size = size * 5 / 4;
+ goto alloc;
+ }
+ continue;
+ }
+
+ /* d_path() fills at the end, move name down */
+ /* n = strlen(filename) + 1: */
+ n = (name_curpos + remaining) - filename;
+ remaining = filename - name_curpos;
+ memmove(name_curpos, filename, n);
+ name_curpos += n;
+
+ *start_end_ofs++ = vma->vm_start;
+ *start_end_ofs++ = vma->vm_end;
+ *start_end_ofs++ = vma->vm_pgoff;
+ count++;
+ }
+
+ /* Now we know exact count of files, can store it */
+ data[0] = count;
+ data[1] = PAGE_SIZE;
+ /*
+ * Count usually is less than current->mm->map_count,
+ * we need to move filenames down.
+ */
+ n = current->mm->map_count - count;
+ if (n != 0) {
+ unsigned shift_bytes = n * 3 * sizeof(data[0]);
+ memmove(name_base - shift_bytes, name_base, name_curpos - name_base);
+ name_curpos -= shift_bytes;
+ }
+
+ size = name_curpos - (char*)data;
+ fill_note(note, "CORE", NT_FILE, size, data);
+ err: ;
+}
+
#ifdef CORE_DUMP_USE_REGSET
#include <linux/regset.h>
@@ -1399,6 +1488,7 @@ struct elf_note_info {
struct memelfnote psinfo;
struct memelfnote signote;
struct memelfnote auxv;
+ struct memelfnote files;
user_siginfo_t csigdata;
size_t size;
int thread_notes;
@@ -1579,6 +1669,9 @@ 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;
}
@@ -1609,6 +1702,8 @@ 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 &&
@@ -1635,6 +1730,7 @@ static void free_note_info(struct elf_note_info *info)
kfree(t);
}
kfree(info->psinfo.data);
+ vfree(info->files.data);
}
#else
@@ -1711,7 +1807,7 @@ static int elf_note_info_init(struct elf_note_info *info)
INIT_LIST_HEAD(&info->thread_list);
/* Allocate space for ELF notes */
- info->notes = kmalloc(7 * sizeof(struct memelfnote), GFP_KERNEL);
+ info->notes = kmalloc(8 * sizeof(struct memelfnote), GFP_KERNEL);
if (!info->notes)
return 0;
info->psinfo = kmalloc(sizeof(*info->psinfo), GFP_KERNEL);
@@ -1781,10 +1877,11 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
fill_note(info->notes + 1, "CORE", NT_PRPSINFO,
sizeof(*info->psinfo), info->psinfo);
- info->numnote = 2;
+ fill_siginfo_note(info->notes + 2, &info->csigdata, siginfo);
+ fill_auxv_note(info->notes + 3, current->mm);
+ fill_files_note(info->notes + 4);
- fill_siginfo_note(&info->notes[info->numnote++], &info->csigdata, siginfo);
- fill_auxv_note(&info->notes[info->numnote++], current->mm);
+ info->numnote = 5;
/* Try to dump the FPU. */
info->prstatus->pr_fpvalid = elf_core_copy_task_fpregs(current, regs,
@@ -1846,6 +1943,9 @@ static void free_note_info(struct elf_note_info *info)
kfree(list_entry(tmp, struct elf_thread_status, list));
}
+ /* Free data allocated by fill_files_note(): */
+ vfree(info->notes[4].data);
+
kfree(info->prstatus);
kfree(info->psinfo);
kfree(info->notes);
diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index c9550c5..e89425f 100644
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c
@@ -41,6 +41,7 @@
/*
* Some data types as stored in coredump.
*/
+#define user_long_t compat_long_t
#define user_siginfo_t compat_siginfo_t
#define copy_siginfo_to_user copy_siginfo_to_user32
diff --git a/include/linux/elf.h b/include/linux/elf.h
index dc62da7..59ef406 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -377,6 +377,7 @@ typedef struct elf64_shdr {
* in the future to accomodate more fields, don't assume it is fixed!
*/
#define NT_SIGINFO 0x53494749
+#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 */
--
1.7.7.6
--
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