[PATCH 2/3] makedumpfile: make the incomplete dumpfile generated by ENOSPC error analyzable
Wang, Xiao/Wang Xiao
wangx.fnst at cn.fujitsu.com
Fri Sep 19 02:27:01 PDT 2014
Since the incomplete dumpfile generated by ENOSPC error can't be anylyzed
by crash utility, but sometimes this file may contain important information
and the panic problem won't be reproduced, then we came up with an idea to
modify the exist data of the incomplete dumpfile to make it analyzable by
crash utility. And each of those dumpfiles has a flag to indicate that it
has been modified. As there are two formats of these dumpfiles, different
methods and flags are needed to deal with each of them,
elf:
Modify the value of the PT_LOAD program header to reflect the actual size
of the incomplete dumpfile. This method can't be used to modify the dumpfile
written in flattened mode. This format use the "e_flags" of "elf header"
to indicate that it has been modified.
The method of dealing with "kdump-compressed" format dumpfiles is
implemented
in the next patch.
Signed-of-by: Wang Xiao <wangx.fnst at cn.fujitsu.com>
---
makedumpfile.c | 177
+++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 174 insertions(+), 3 deletions(-)
diff --git a/makedumpfile.c b/makedumpfile.c
index ce4a866..13f0f35 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -24,6 +24,7 @@
#include <ctype.h>
#include <sys/time.h>
#include <limits.h>
+#include <assert.h>
struct symbol_table symbol_table;
struct size_table size_table;
@@ -3621,6 +3622,155 @@ write_cache(struct cache_data *cd, void *buf,
size_t size)
}
int
+reserve_diskspace(int fd, off_t start_offset, off_t end_offset, char
*file_name)
+{
+ size_t buf_size;
+ char *buf = NULL;
+
+ int ret = FALSE;
+
+ assert(start_offset < end_offset);
+ buf_size = end_offset - start_offset;
+
+ if ((buf = malloc(buf_size)) == NULL) {
+ ERRMSG("Can't allocate memory for the size of reserved diskspace. %s\n",
+ strerror(errno));
+ return FALSE;
+ }
+
+ memset(buf, 0, buf_size);
+ if (!write_buffer(fd, start_offset, buf, buf_size, file_name))
+ goto out;
+
+ ret = TRUE;
+out:
+ if (buf != NULL) {
+ free(buf);
+ }
+
+ return ret;
+}
+
+#define DUMP_ELF_INCOMPLETE 0x1
+int
+check_and_modify_elf_headers(char *filename) {
+ int fd, i, phnum, ret = FALSE;
+ off_t file_end, offset, end_offset;
+ Elf64_Ehdr ehdr64;
+ Elf32_Ehdr ehdr32;
+
+ if ((fd = open(filename, O_RDWR)) < 0) {
+ ERRMSG("Can't open the dump file(%s). %s\n",
+ filename, strerror(errno));
+ return FALSE;
+ }
+
+ /*
+ * the is_elf64_memory() function still can be used.
+ */
+ if (is_elf64_memory()) { /* ELF64 */
+ if (!get_elf64_ehdr(fd, filename, &ehdr64)) {
+ ERRMSG("Can't get ehdr64.\n");
+ goto out_close_file;
+ }
+ phnum = ehdr64.e_phnum;
+ } else { /* ELF32 */
+ if (!get_elf32_ehdr(fd, filename, &ehdr32)) {
+ ERRMSG("Can't get ehdr32.\n");
+ goto out_close_file;
+ }
+ phnum = ehdr32.e_phnum;
+ }
+
+ file_end = lseek(fd, 0, SEEK_END);
+ if (file_end < 0) {
+ ERRMSG("Can't detect the size of %s. %s\n",
+ filename, strerror(errno));
+ goto out_close_file;
+ }
+
+ for (i = 0; i < phnum; i++) {
+ if (is_elf64_memory()) {
+ Elf64_Phdr phdr64;
+
+ if (!get_elf64_phdr(fd, filename, i, &phdr64)) {
+ ERRMSG("Can't find Phdr %d.\n", i);
+ goto out_close_file;
+ }
+
+ offset = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) * i;
+ end_offset = phdr64.p_offset + phdr64.p_filesz;
+
+ /*
+ * Check the program header and modify its value according
+ * to the actual written size.
+ */
+ if (file_end >= end_offset)
+ continue;
+ /*
+ * This is the last PT_LOAD that still has some data, but
+ * not complete.
+ */
+ else if (file_end >= phdr64.p_offset && file_end < end_offset)
+ phdr64.p_filesz = file_end - phdr64.p_offset;
+ else if (file_end < phdr64.p_offset) {
+ phdr64.p_offset = 0;
+ phdr64.p_filesz = 0;
+ }
+
+ if (!write_buffer(fd, offset, &phdr64,
+ sizeof(Elf64_Phdr), filename))
+ goto out_close_file;
+ } else {
+ Elf32_Phdr phdr32;
+
+ if (!get_elf32_phdr(fd, filename, i, &phdr32)) {
+ ERRMSG("Can't find Phdr %d.\n", i);
+ goto out_close_file;
+ }
+
+ offset = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr) * i;
+ end_offset = phdr32.p_offset + phdr32.p_filesz;
+
+ if (file_end >= end_offset)
+ continue;
+ else if (file_end >= phdr32.p_offset && file_end < end_offset)
+ phdr32.p_filesz = file_end - phdr32.p_offset;
+ else if (file_end < phdr32.p_offset) {
+ phdr32.p_offset = 0;
+ phdr32.p_filesz = 0;
+ }
+
+ if (!write_buffer(fd, offset, &phdr32,
+ sizeof(Elf32_Phdr), filename))
+ goto out_close_file;
+ }
+ }
+
+ /*
+ * Set the incomplete flag to the e_flags of elf header.
+ */
+ if (is_elf64_memory()) {
+ ehdr64.e_flags |= DUMP_ELF_INCOMPLETE;
+ if (!write_buffer(fd, 0, &ehdr64, sizeof(Elf64_Ehdr), filename))
+ goto out_close_file;
+ } else {
+ ehdr32.e_flags |= DUMP_ELF_INCOMPLETE;
+ if (!write_buffer(fd, 0, &ehdr32, sizeof(Elf32_Ehdr), filename))
+ goto out_close_file;
+ }
+
+ ret = TRUE;
+out_close_file:
+ if (close(fd) < 0) {
+ ERRMSG("Can't close the dump file(%s). %s\n",
+ filename, strerror(errno));
+ }
+
+ return ret;
+}
+
+int
write_cache_bufsz(struct cache_data *cd)
{
if (!cd->buf_size)
@@ -5432,6 +5582,13 @@ write_elf_header(struct cache_data *cd_header)
size_note = note.p_filesz;
/*
+ * Reserve a space to store the whole program headers.
+ */
+ if (!reserve_diskspace(cd_header->fd, cd_header->offset,
+ offset_note_dumpfile, cd_header->file_name))
+ goto out;
+
+ /*
* Modify the note size in PT_NOTE header to accomodate eraseinfo data.
* Eraseinfo will be written later.
*/
@@ -7906,10 +8063,10 @@ writeout_dumpfile(void)
goto out;
if (info->flag_cyclic) {
if (!write_elf_pages_cyclic(&cd_header, &cd_page))
- goto out;
+ goto write_cache_enospc;
} else {
if (!write_elf_pages(&cd_header, &cd_page))
- goto out;
+ goto write_cache_enospc;
}
if (!write_elf_eraseinfo(&cd_header))
goto out;
@@ -7936,6 +8093,11 @@ writeout_dumpfile(void)
}
ret = TRUE;
+write_cache_enospc:
+ if ((ret == FALSE) && info->flag_nospace && !info->flag_flatten) {
+ if (!write_cache_bufsz(&cd_header))
+ ERRMSG("This dumpfile may lost some important data.\n");
+ }
out:
free_cache_data(&cd_header);
free_cache_data(&cd_page);
@@ -8128,8 +8290,17 @@ retry:
* to create a dumpfile with it again.
*/
num_retry++;
- if ((info->dump_level = get_next_dump_level(num_retry)) < 0)
+ if ((info->dump_level = get_next_dump_level(num_retry)) < 0) {
+ if (!info->flag_flatten) {
+ if (info->flag_elf_dumpfile) {
+ if (check_and_modify_elf_headers(info->name_dumpfile))
+ MSG("This is an incomplete dumpfile,"
+ " but might analyzable.\n");
+ }
+ }
+
return FALSE;
+ }
MSG("Retry to create a dumpfile by dump_level(%d).\n",
info->dump_level);
if (!delete_dumpfile())
--
1.7.1
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