[PATCH] Updated: support for gzipped (ELF) core dumps

[Jan Frey <jan.frey@nokia.com>]

[-- Attachment #1: Type: text/plain, Size: 1334 bytes --]

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/
> -
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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@cais.com).
  */
 
+#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@nokia.com>
+ */
+#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@sw.oz.au>
  */
+#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@nokia.com>
  */
-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(&notes[i], file, empty_buf, &crc, &gz_stream))
+			goto end_coredump;
+#else
 		if (!writenote(&notes[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(&current->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