[PATCH] Updated: support for gzipped (ELF) core dumps
From: Jan Frey
Date: Thu Jan 13 2005 - 10:46:01 EST
Hi all,
now I managed to use lib/crc32. Obviously the patch looks a lot better
now!
Regards,
Jan
> Hi,
>
> I tried to use those "in-kernel" functions, but they seem to do little
> different CRC calculations. Unfortunately I don't have any experiences
> with CRC stuff, anyone able to help here?
>
> Regards,
> Jan
>
> > >+/* This table is needed for efficient CRC32 calculation */
> > >+static const unsigned long crc_table[8][256] = {
> > >+ {
> > >+ 0x00000000UL, 0x77073096UL, 0xee0e612cUL, 0x990951baUL, 0x076dc419UL,
> >
> > First, by using "unsigned long", you may be doubling the size on most 64 bit
> > platforms. Second, I'm pretty sure there is a standard implementation of
> > several CRCs already in the kernel - is there a reason not to use one of them
> > (e.g. a different polynomial)?
> > -
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> > Please read the FAQ at http://www.tux.org/lkml/
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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diff -ur linux-2.4.28/arch/i386/config.in linux-2.4.28-gzip-coredump/arch/i386/config.in
--- linux-2.4.28/arch/i386/config.in 2004-11-17 12:54:21.000000000 +0100
+++ linux-2.4.28-gzip-coredump/arch/i386/config.in 2005-01-10 08:45:36.000000000 +0100
@@ -479,6 +479,7 @@
bool ' Magic SysRq key' CONFIG_MAGIC_SYSRQ
bool ' Spinlock debugging' CONFIG_DEBUG_SPINLOCK
bool ' Compile the kernel with frame pointers' CONFIG_FRAME_POINTER
+ bool ' Write gzipped core dump files' CONFIG_GZIP_COREDUMPS
fi
int 'Kernel messages buffer length shift (0 = default)' CONFIG_LOG_BUF_SHIFT 0
diff -ur linux-2.4.28/Documentation/Configure.help linux-2.4.28-gzip-coredump/Documentation/Configure.help
--- linux-2.4.28/Documentation/Configure.help 2004-11-17 12:54:20.000000000 +0100
+++ linux-2.4.28-gzip-coredump/Documentation/Configure.help 2005-01-10 08:45:45.000000000 +0100
@@ -29121,6 +29121,11 @@
If unsure, say N.
+CONFIG_GZIP_COREDUMPS
+ Saying yes here makes the kernel writing core dump files in a
+ gzipped compressed format. You will have to uncompress core files
+ with gzip -d prior to usage (e.g. with gdb).
+
#
# A couple of things I keep forgetting:
# capitalize: AppleTalk, Ethernet, DOS, DMA, FAT, FTP, Internet,
diff -ur linux-2.4.28/fs/binfmt_elf.c linux-2.4.28-gzip-coredump/fs/binfmt_elf.c
--- linux-2.4.28/fs/binfmt_elf.c 2004-11-17 12:54:21.000000000 +0100
+++ linux-2.4.28-gzip-coredump/fs/binfmt_elf.c 2005-01-13 15:42:45.000000000 +0100
@@ -9,6 +9,7 @@
* Copyright 1993, 1994: Eric Youngdale (ericy@xxxxxxxx).
*/
+#include <linux/config.h>
#include <linux/module.h>
#include <linux/fs.h>
@@ -59,6 +60,18 @@
*/
#ifdef USE_ELF_CORE_DUMP
static int elf_core_dump(long signr, struct pt_regs * regs, struct file * file);
+
+#ifdef CONFIG_GZIP_COREDUMPS
+
+/*
+ * Functions added to support writing core files in gzipped format, 2004
+ * Jan Frey <jan.frey@xxxxxxxxx>
+ */
+#include <linux/zlib.h>
+#include <linux/vmalloc.h>
+#include <linux/crc32.h>
+#endif
+
#else
#define elf_core_dump NULL
#endif
@@ -941,15 +954,83 @@
* Modelled on fs/exec.c:aout_core_dump()
* Jeremy Fitzhardinge <jeremy@xxxxxxxx>
*/
+#ifdef CONFIG_GZIP_COREDUMPS
/*
- * These are the only things you should do on a core-file: use only these
- * functions to write out all the necessary info.
+ * gz writing support
+ * Jan Frey <jan.frey@xxxxxxxxx>
*/
-static int dump_write(struct file *file, const void *addr, int nr)
+static int gz_dump_write(struct file *file, const void *addr, int nr, u32 *crc, z_streamp zstr)
{
- return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+ const int OUT_BUF_SIZE = 100*1024;
+ int all_fine = 1;
+ void *out_buf = vmalloc(OUT_BUF_SIZE);
+
+ if (!out_buf) {
+ printk(KERN_WARNING "Failed to allocate deflate buffer");
+ return 0;
+ }
+
+ *crc = crc32_le (*crc, addr, nr);
+
+ zstr->next_in = addr;
+ zstr->avail_in = nr;
+
+ do {
+ zstr->next_out = out_buf;
+ zstr->avail_out = OUT_BUF_SIZE;
+
+ if (zlib_deflate (zstr, Z_NO_FLUSH) == Z_OK) {
+ /* new output generated */
+ all_fine = (file->f_op->write (file,
+ out_buf,
+ OUT_BUF_SIZE - zstr->avail_out,
+ &file->f_pos)
+ == (OUT_BUF_SIZE - zstr->avail_out));
+ }
+ } while ((zstr->avail_out != OUT_BUF_SIZE) && all_fine);
+
+ vfree (out_buf);
+ return all_fine;
}
+static int gz_finish (struct file *file, z_streamp zstr)
+{
+ const int OUT_BUF_SIZE = 100*1024;
+ int all_fine = 1;
+ int ret;
+ void *out_buf = vmalloc(OUT_BUF_SIZE);
+
+ if (!out_buf) {
+ printk(KERN_WARNING "Failed to allocate deflate buffer");
+ return 0;
+ }
+
+ zstr->next_in = 0;
+ zstr->avail_in = 0;
+
+ do {
+ zstr->next_out = out_buf;
+ zstr->avail_out = OUT_BUF_SIZE;
+
+ ret = zlib_deflate (zstr, Z_FINISH);
+ if ((ret == Z_OK) || (ret == Z_STREAM_END)) {
+ /* new output generated */
+ all_fine = (file->f_op->write (file,
+ out_buf,
+ OUT_BUF_SIZE - zstr->avail_out,
+ &file->f_pos)
+ == (OUT_BUF_SIZE - zstr->avail_out));
+ }
+ } while ((zstr->avail_out != OUT_BUF_SIZE) && all_fine && (ret != Z_STREAM_END));
+
+ vfree (out_buf);
+ return all_fine;
+}
+#else
+/*
+ * These are the only things you should do on a core-file: use only these
+ * functions to write out all the necessary info.
+ */
static int dump_seek(struct file *file, off_t off)
{
if (file->f_op->llseek) {
@@ -959,6 +1040,13 @@
file->f_pos = off;
return 1;
}
+#endif
+
+static int dump_write(struct file *file, const void *addr, int nr)
+{
+ return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+}
+
/*
* Decide whether a segment is worth dumping; default is yes to be
@@ -1030,11 +1118,54 @@
}
#endif
-#define DUMP_WRITE(addr, nr) \
- do { if (!dump_write(file, (addr), (nr))) return 0; } while(0)
+#ifdef CONFIG_GZIP_COREDUMPS
+#define PAD_GZ(nr, buf, crc, str) \
+ do { \
+ int cur=(nr); \
+ while (cur>1024) { \
+ gz_dump_write(file, (buf), 1024, (crc), (str)); \
+ cur-=1024; \
+ } \
+ if (cur) { \
+ gz_dump_write(file, (buf), cur, (crc), (str)); \
+ } \
+ } while(0)
+
+#define DUMP_GZ(addr, nr, crc, str) \
+ do { if (!gz_dump_write(file, (addr), (nr), (crc), (str))) return 0; } while(0)
+#else
#define DUMP_SEEK(off) \
do { if (!dump_seek(file, (off))) return 0; } while(0)
+#endif
+
+#define DUMP_WRITE(addr, nr) \
+ do { if (!dump_write(file, (addr), (nr))) return 0; } while(0)
+#ifdef CONFIG_GZIP_COREDUMPS
+static int writenote_gz(struct memelfnote *men, struct file *file, char *buf, u32 *crc, z_streamp zstr)
+{
+ struct elf_note en;
+ int dummy_bytes;
+
+ en.n_namesz = strlen(men->name);
+ en.n_descsz = men->datasz;
+ en.n_type = men->type;
+
+ DUMP_GZ(&en, sizeof(en), crc, zstr);
+ DUMP_GZ(men->name, en.n_namesz, crc, zstr);
+
+ dummy_bytes = roundup((unsigned long)zstr->total_in, 4) - zstr->total_in;
+ PAD_GZ(dummy_bytes, buf, crc, zstr);
+
+ DUMP_GZ(men->data, men->datasz, crc, zstr);
+
+ dummy_bytes = roundup((unsigned long)zstr->total_in, 4) - zstr->total_in;
+ PAD_GZ(dummy_bytes, buf, crc, zstr);
+
+ return 1;
+}
+#undef DUMP_GZ
+#else
static int writenote(struct memelfnote *men, struct file *file)
{
struct elf_note en;
@@ -1054,13 +1185,21 @@
}
#undef DUMP_WRITE
#undef DUMP_SEEK
+#endif
+#ifdef CONFIG_GZIP_COREDUMPS
+#define DUMP_GZ(addr, nr, crc, str) \
+ if ((size += (nr)) > limit || !gz_dump_write(file, (addr), (nr), (crc), (str))) \
+ goto end_coredump;
+#else
#define DUMP_WRITE(addr, nr) \
if ((size += (nr)) > limit || !dump_write(file, (addr), (nr))) \
goto end_coredump;
#define DUMP_SEEK(off) \
if (!dump_seek(file, (off))) \
goto end_coredump;
+#endif
+
/*
* Actual dumper
*
@@ -1085,6 +1224,39 @@
elf_fpregset_t fpu; /* NT_PRFPREG */
struct elf_prpsinfo psinfo; /* NT_PRPSINFO */
+#ifdef CONFIG_GZIP_COREDUMPS
+ z_stream gz_stream;
+ void *deflate_workspace;
+ u32 crc = ~0; /* init */
+ unsigned char gz_magic[10] = { /* gzip magic header */
+ 0x1f, 0x8b, Z_DEFLATED, 0, 0, 0, 0, 0, 0, 0x03 };
+ unsigned char *empty_buf;
+
+ deflate_workspace = vmalloc(zlib_deflate_workspacesize());
+ if (!deflate_workspace) {
+ printk(KERN_WARNING "Failed to allocate deflate workspace\n");
+ return -ENOMEM;
+ }
+
+ gz_stream.workspace = deflate_workspace;
+ if (Z_OK != zlib_deflateInit2(&gz_stream,
+ 7, /* compression level */
+ Z_DEFLATED,
+ -15, /* window bits */
+ 6, /* mem level */
+ Z_DEFAULT_STRATEGY)) {
+ printk(KERN_WARNING "deflateInit failed\n");
+ return -ENOMEM;
+ }
+
+ empty_buf = vmalloc(1024);
+ if (!empty_buf) {
+ printk(KERN_WARNING "Failed to allocate 1024 bytes for dummy buffer\n");
+ return -ENOMEM;
+ }
+ memset (empty_buf, 0, 1024);
+#endif
+
/* first copy the parameters from user space */
memset(&psinfo, 0, sizeof(psinfo));
{
@@ -1154,7 +1326,15 @@
has_dumped = 1;
current->flags |= PF_DUMPCORE;
+#ifdef CONFIG_GZIP_COREDUMPS
+ /* write gzip header */
+ DUMP_WRITE(gz_magic, 10);
+
+ /* write elf header */
+ DUMP_GZ(&elf, sizeof(elf), &crc, &gz_stream);
+#else
DUMP_WRITE(&elf, sizeof(elf));
+#endif
offset += sizeof(elf); /* Elf header */
offset += (segs+1) * sizeof(struct elf_phdr); /* Program headers */
@@ -1239,7 +1419,12 @@
phdr.p_align = 0;
offset += phdr.p_filesz;
+
+#ifdef CONFIG_GZIP_COREDUMPS
+ DUMP_GZ(&phdr, sizeof(phdr), &crc, &gz_stream);
+#else
DUMP_WRITE(&phdr, sizeof(phdr));
+#endif
}
/* Page-align dumped data */
@@ -1264,14 +1449,27 @@
if (vma->vm_flags & VM_EXEC) phdr.p_flags |= PF_X;
phdr.p_align = ELF_EXEC_PAGESIZE;
+#ifdef CONFIG_GZIP_COREDUMPS
+ DUMP_GZ(&phdr, sizeof(phdr), &crc, &gz_stream);
+#else
DUMP_WRITE(&phdr, sizeof(phdr));
+#endif
}
- for(i = 0; i < numnote; i++)
+ for(i = 0; i < numnote; i++) {
+#ifdef CONFIG_GZIP_COREDUMPS
+ if (!writenote_gz(¬es[i], file, empty_buf, &crc, &gz_stream))
+ goto end_coredump;
+#else
if (!writenote(¬es[i], file))
goto end_coredump;
-
+#endif
+ }
+#ifdef CONFIG_GZIP_COREDUMPS
+ PAD_GZ (dataoff-gz_stream.total_in, empty_buf, &crc, &gz_stream);
+#else
DUMP_SEEK(dataoff);
+#endif
for(vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
unsigned long addr;
@@ -1290,16 +1488,28 @@
struct vm_area_struct *vma;
if (get_user_pages(current, current->mm, addr, 1, 0, 1,
- &page, &vma) <= 0) {
- DUMP_SEEK (file->f_pos + PAGE_SIZE);
+ &page, &vma) <= 0) {
+#ifdef CONFIG_GZIP_COREDUMPS
+ PAD_GZ(PAGE_SIZE, empty_buf, &crc, &gz_stream);
+#else
+ DUMP_SEEK (file->f_pos + PAGE_SIZE);
+#endif
} else {
- if (page == ZERO_PAGE(addr)) {
- DUMP_SEEK (file->f_pos + PAGE_SIZE);
+ if (page == ZERO_PAGE(addr)) {
+#ifdef CONFIG_GZIP_COREDUMPS
+ PAD_GZ(PAGE_SIZE, empty_buf, &crc, &gz_stream);
+#else
+ DUMP_SEEK (file->f_pos + PAGE_SIZE);
+#endif
} else {
void *kaddr;
flush_cache_page(vma, addr);
kaddr = kmap(page);
+#ifdef CONFIG_GZIP_COREDUMPS
+ DUMP_GZ(kaddr, PAGE_SIZE, &crc, &gz_stream);
+#else
DUMP_WRITE(kaddr, PAGE_SIZE);
+#endif
flush_page_to_ram(page);
kunmap(page);
}
@@ -1308,15 +1518,37 @@
}
}
+#ifndef CONFIG_GZIP_COREDUMPS
if ((off_t) file->f_pos != offset) {
/* Sanity check */
printk("elf_core_dump: file->f_pos (%ld) != offset (%ld)\n",
(off_t) file->f_pos, offset);
}
+#endif
- end_coredump:
+end_coredump:
+#ifdef CONFIG_GZIP_COREDUMPS
+ gz_finish (file, &gz_stream);
+ zlib_deflateEnd (&gz_stream);
+
+ gz_magic[0] = (~crc & 0x000000FF);
+ gz_magic[1] = (~crc & 0x0000FF00) >> 8;
+ gz_magic[2] = (~crc & 0x00FF0000) >> 16;
+ gz_magic[3] = (~crc & 0xFF000000) >> 24;
+ gz_magic[4] = (gz_stream.total_in & 0x000000FF);
+ gz_magic[5] = (gz_stream.total_in & 0x0000FF00) >> 8;
+ gz_magic[6] = (gz_stream.total_in & 0x00FF0000) >> 16;
+ gz_magic[7] = (gz_stream.total_in & 0xFF000000) >> 24;
+ dump_write (file, gz_magic, 8);
+#endif
set_fs(fs);
up_write(¤t->mm->mmap_sem);
+
+#ifdef CONFIG_GZIP_COREDUMPS
+ vfree (deflate_workspace);
+ vfree (empty_buf);
+#endif
+
return has_dumped;
}
#endif /* USE_ELF_CORE_DUMP */
diff -ur linux-2.4.28/lib/Config.in linux-2.4.28-gzip-coredump/lib/Config.in
--- linux-2.4.28/lib/Config.in 2003-11-28 19:26:21.000000000 +0100
+++ linux-2.4.28-gzip-coredump/lib/Config.in 2005-01-10 08:46:00.000000000 +0100
@@ -27,7 +27,8 @@
fi
fi
-if [ "$CONFIG_PPP_DEFLATE" = "y" -o \
+if [ "$CONFIG_GZIP_COREDUMPS" = "y" -o \
+ "$CONFIG_PPP_DEFLATE" = "y" -o \
"$CONFIG_CRYPTO_DEFLATE" = "y" -o \
"$CONFIG_JFFS2_FS" = "y" ]; then
define_tristate CONFIG_ZLIB_DEFLATE y