Re: [PATCH v3] crash utility: fix max_mapnr issue on system has over 44-bit addressing

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On 10/16/2013 03:22 AM, Dave Anderson wrote:

Hello Jingbai,

I have a few additional comments below:

----- Original Message -----
The patch will add support for new compressed dumpfile header_version 6.

This bug was posted here:
http://lists.infradead.org/pipermail/kexec/2013-September/009587.html

This patch will add 3 new fields in struct kdump_sub_header.
unsigned long long start_pfn_64;  /* header_version 6 and later */
unsigned long long end_pfn_64;    /* header_version 6 and later */
unsigned long long max_mapnr_64;  /* header_version 6 and later */

And the old "unsigned int max_mapnr" in struct disk_dump_header will
not be used anymore. But still be there for compatibility purpose.

The corresponding patch for makedumpfile can be found here:
http://lists.infradead.org/pipermail/kexec/2013-October/009727.html

Changelog:
v3:
- Fix a bug that failed to work with old split format kdumps.

v2:
- Rename max_mapnr in struct kdump_sub_header to max_mapnr_64.
- Change type of max_mapnr_64 from unsigned long to unsigned long long.
   In x86 PAE mode on x86_32 kernel, the address may exceeds 44bit limit.
- Add start_pfn_64, end_pfn_64 for struct kdump_sub_header.
- Add a 64bit max_mapnr in struct diskdump_data. The max_mapnr_64 in
   the sub-header only exists in compressed kdump file format, so can't
   be used in diskdump file format.
- Merge a patch from Dave Anderson that fixed bitmap_len issue.

v1:
- http://lists.infradead.org/pipermail/kexec/2013-September/009663.html

Signed-off-by: Jingbai Ma<jingbai.ma@xxxxxx>
Tested-by: Lisa Mitchell<lisa.mitchell@xxxxxx>
---
  diskdump.c |  122
  ++++++++++++++++++++++++++++++++++++++++++++++++------------
  diskdump.h |   17 +++++++-
  2 files changed, 112 insertions(+), 27 deletions(-)

diff --git a/diskdump.c b/diskdump.c
index 0819a3f..bb7a33e 100644
--- a/diskdump.c
+++ b/diskdump.c
@@ -40,11 +40,13 @@ struct diskdump_data {
  	struct disk_dump_sub_header	*sub_header;
  	struct kdump_sub_header		*sub_header_kdump;

+	unsigned long long	max_mapnr;	/* 64bit max_mapnr */
+
  	size_t	data_offset;
  	int	block_size;
  	int	block_shift;
  	char	*bitmap;
-	int	bitmap_len;
+	off_t	bitmap_len;
  	char	*dumpable_bitmap;
  	int	byte, bit;
  	char	*compressed_page;	/* copy of compressed page data */
@@ -170,9 +172,9 @@ add_diskdump_data(char* name)
  	dd->filename = name;

  	if (CRASHDEBUG(1))
-		fprintf(fp, "%s: start_pfn=%lu, end_pfn=%lu\n", name,
-			dd->sub_header_kdump->start_pfn,
-			dd->sub_header_kdump->end_pfn);
+		fprintf(fp, "%s: start_pfn=%llu, end_pfn=%llu\n", name,
+			dd->sub_header_kdump->start_pfn_64,
+			dd->sub_header_kdump->end_pfn_64);
  }

  static void
@@ -199,13 +201,13 @@ get_bit(char *map, int byte, int bit)
  }

  static inline int
-page_is_ram(unsigned int nr)
+page_is_ram(unsigned long nr)
  {
  	return get_bit(dd->bitmap, nr>>  3, nr&  7);
  }

  static inline int
-page_is_dumpable(unsigned int nr)
+page_is_dumpable(unsigned long nr)
  {
  	return dd->dumpable_bitmap[nr>>3]&  (1<<  (nr&  7));
  }
@@ -214,7 +216,7 @@ static inline int
  dump_is_partial(const struct disk_dump_header *header)
  {
  	return header->bitmap_blocks>=
-	    divideup(divideup(header->max_mapnr, 8), dd->block_size) * 2;
+	    divideup(divideup(dd->max_mapnr, 8), dd->block_size) * 2;
  }

  static int
@@ -321,6 +323,9 @@ x86_process_elf_notes(void *note_ptr, unsigned long
size_note)
   * [40]    unsigned long   size_note;          /  header_version 4 and later
   /
   * [44]    off_t           offset_eraseinfo;   /  header_version 5 and later
   /
   * [52]    unsigned long   size_eraseinfo;     /  header_version 5 and later
   /
+ * [56]    unsigned long long   start_pfn_64;  /  header_version 6 and later
/
+ * [64]    unsigned long long   end_pfn_64;    /  header_version 6 and later
/
+ * [72]    unsigned long long   max_mapnr_64;  /  header_version 6 and later
/
   * };
   *
   * But when compiled on an ARM processor, each 64-bit "off_t" would be
   pushed
@@ -337,7 +342,10 @@ x86_process_elf_notes(void *note_ptr, unsigned long
size_note)
   * [40]    off_t           offset_note;        /  header_version 4 and later
   /
   * [48]    unsigned long   size_note;          /  header_version 4 and later
   /
   * [56]    off_t           offset_eraseinfo;   /  header_version 5 and later
   /
- * [62]    unsigned long   size_eraseinfo;     /  header_version 5 and later
/
+ * [64]    unsigned long   size_eraseinfo;     /  header_version 5 and later
/
+ * [72]    unsigned long long   start_pfn_64;  /  header_version 6 and later
/
+ * [80]    unsigned long long   end_pfn_64;    /  header_version 6 and later
/
+ * [88]    unsigned long long   max_mapnr_64;  /  header_version 6 and later
/
   * };
   *
   */
@@ -357,6 +365,10 @@ struct kdump_sub_header_ARM_target {
  	int 		pad3;
          off_t           offset_eraseinfo;   /* header_version 5 and later */
          unsigned long   size_eraseinfo;     /* header_version 5 and later */
+	int		pad4;
+	unsigned long long start_pfn_64;    /* header_version 6 and later */
+	unsigned long long end_pfn_64;      /* header_version 6 and later */
+	unsigned long long max_mapnr_64;    /* header_version 6 and later */
  };

  static void
@@ -380,6 +392,15 @@ arm_kdump_header_adjust(int header_version)
  		kdsh->offset_eraseinfo = kdsh_ARM_target->offset_eraseinfo;
  		kdsh->size_eraseinfo = kdsh_ARM_target->size_eraseinfo;
  	}
+	if (header_version>= 6) {
+		kdsh->start_pfn_64 = kdsh_ARM_target->start_pfn_64;
+		kdsh->end_pfn_64 = kdsh_ARM_target->end_pfn_64;
+		kdsh->max_mapnr_64 = kdsh_ARM_target->map_mapnr_64;
+	} else {
+		kdsh->start_pfn_64 = kdsh_ARM_target->start_pfn;
+		kdsh->end_pfn_64 = kdsh_ARM_target->end_pfn;
+		kdsh->max_mapnr_64 = dd->map_mapnr;
+	}
  }
  #endif  /* __i386__&&  ARM */

@@ -390,7 +411,10 @@ read_dump_header(char *file)
  	struct disk_dump_sub_header *sub_header = NULL;
  	struct kdump_sub_header *sub_header_kdump = NULL;
  	size_t size;
-	int bitmap_len;
+	off_t bitmap_len;
+	char *bufptr;
+	size_t len;
+	size_t bytes_read;
  	int block_size = (int)sysconf(_SC_PAGESIZE);
  	off_t offset;
  	const off_t failed = (off_t)-1;
@@ -540,8 +564,27 @@ restart:
  #if defined(__i386__)&&  defined(ARM)
  		arm_kdump_header_adjust(header->header_version);
  #endif
+		/* use 64bit max_mapnr in compressed kdump file sub-header */
+		if (header->header_version>= 6)
+			dd->max_mapnr = dd->sub_header_kdump->max_mapnr_64;
+		else {
+			dd->sub_header_kdump->start_pfn_64
+				= dd->sub_header_kdump->start_pfn;
+			dd->sub_header_kdump->end_pfn_64
+				= dd->sub_header_kdump->end_pfn;
+		}
+	} else {
+		/* the 64bit max_mapnr only exists in sub-header of compressed
+		 * kdump file, if it's not a compressed kdump file, we have to
+		 * use the old 32bit max_mapnr in dumpfile header.
+		 * max_mapnr may be truncated here.
+		 */
+		 dd->max_mapnr = header->max_mapnr;
  	}

The additional "} else {" segment above doesn't make sense because either
DISKDUMP_VALID() or KDUMP_CMPRS_VALID() are true, so the "else" part will
never be executed.

The patch works because you follow the above section with this piece:

+	if (header->header_version<  6)
+		dd->max_mapnr = header->max_mapnr;
+
  	/* read memory bitmap */
  	bitmap_len = block_size * header->bitmap_blocks;
  	dd->bitmap_len = bitmap_len;
@@ -571,11 +614,27 @@ restart:
  				DISKDUMP_VALID() ? "diskdump" : "compressed kdump");
  			goto err;
  		}
+#ifdef OLDWAY
  		if (read(dd->dfd, dd->bitmap, bitmap_len)<  bitmap_len) {
  			error(INFO, "%s: cannot read memory bitmap\n",
  				DISKDUMP_VALID() ? "diskdump" : "compressed kdump");
  			goto err;
  		}
+#else
+		bufptr = dd->bitmap;
+		len = bitmap_len;
+		while (len) {
+			bytes_read = read(dd->dfd, bufptr, len);
+			if (bytes_read<  0) {
+				error(INFO, "%s: cannot read memory bitmap\n",
+					DISKDUMP_VALID() ? "diskdump"
+					: "compressed kdump");
+				goto err;
+			}
+			len -= bytes_read;
+			bufptr += bytes_read;
+		}
+#endif

You can get rid of the "#ifdef OLDWAY" section -- I left that there when
I gave Lisa my debug version of the function so that the difference would
be obvious.

  	}

  	if (dump_is_partial(header))
@@ -679,13 +738,13 @@ restart:
  	}

  	if (!is_split) {
-		max_sect_len = divideup(header->max_mapnr, BITMAP_SECT_LEN);
+		max_sect_len = divideup(dd->max_mapnr, BITMAP_SECT_LEN);
  		pfn = 0;
  		dd->filename = file;
  	}
  	else {
-		ulong start = sub_header_kdump->start_pfn;
-		ulong end = sub_header_kdump->end_pfn;
+		unsigned long long start = sub_header_kdump->start_pfn_64;
+		unsigned long long end = sub_header_kdump->end_pfn_64;
  		max_sect_len = divideup(end - start + 1, BITMAP_SECT_LEN);
  		pfn = start;
  	}
@@ -727,8 +786,9 @@ pfn_to_pos(ulong pfn)
  	ulong p1, p2;

  	if (KDUMP_SPLIT()) {
-		p1 = pfn - dd->sub_header_kdump->start_pfn;
-		p2 = round(p1, BITMAP_SECT_LEN) + dd->sub_header_kdump->start_pfn;
+		p1 = pfn - dd->sub_header_kdump->start_pfn_64;
+		p2 = round(p1, BITMAP_SECT_LEN)
+			+ dd->sub_header_kdump->start_pfn_64;
  	}
  	else {
  		p1 = pfn;
@@ -1034,12 +1094,12 @@ read_diskdump(int fd, void *bufptr, int cnt, ulong
addr, physaddr_t paddr)
  	if (KDUMP_SPLIT()) {
  		/* Find proper dd */
  		int i;
-		unsigned long start_pfn;
-		unsigned long end_pfn;
+		unsigned long long start_pfn;
+		unsigned long long end_pfn;

  		for (i=0; i<num_dumpfiles; i++) {
-			start_pfn = dd_list[i]->sub_header_kdump->start_pfn;
-			end_pfn = dd_list[i]->sub_header_kdump->end_pfn;
+			start_pfn = dd_list[i]->sub_header_kdump->start_pfn_64;
+			end_pfn = dd_list[i]->sub_header_kdump->end_pfn_64;
  			if ((pfn>= start_pfn)&&  (pfn<= end_pfn))	{
  				dd = dd_list[i];
  				break;
@@ -1058,14 +1118,14 @@ read_diskdump(int fd, void *bufptr, int cnt, ulong
addr, physaddr_t paddr)
  	curpaddr = paddr&  ~((physaddr_t)(dd->block_size-1));
  	page_offset = paddr&  ((physaddr_t)(dd->block_size-1));

-	if ((pfn>= dd->header->max_mapnr) || !page_is_ram(pfn)) {
+	if ((pfn>= dd->max_mapnr) || !page_is_ram(pfn)) {
  		if (CRASHDEBUG(8)) {
  			fprintf(fp, "read_diskdump: SEEK_ERROR: "
  			    "paddr/pfn: %llx/%lx ",
  				(ulonglong)paddr, pfn);
-			if (pfn>= dd->header->max_mapnr)
-				fprintf(fp, "max_mapnr: %x\n",
-					dd->header->max_mapnr);
+			if (pfn>= dd->max_mapnr)
+				fprintf(fp, "max_mapnr: %llx\n",
+					dd->max_mapnr);
  			else
  				fprintf(fp, "!page_is_ram\n");
  		}
@@ -1517,7 +1577,7 @@ __diskdump_memory_dump(FILE *fp)
  	fprintf(fp, "          block_size: %d\n", dh->block_size);
  	fprintf(fp, "        sub_hdr_size: %d\n", dh->sub_hdr_size);
  	fprintf(fp, "       bitmap_blocks: %u\n", dh->bitmap_blocks);
-	fprintf(fp, "           max_mapnr: %u\n", dh->max_mapnr);
+	fprintf(fp, "           max_mapnr: %llu\n", dd->max_mapnr);

Please display the original dh->max_mapnr as it exists in the dumpfile
header, regardless whether it is the obsolete version or not.

Your new "dd->max_mapnr" should be displayed further down in the function
where the other diskdump_data fields are shown.

  	fprintf(fp, "    total_ram_blocks: %u\n", dh->total_ram_blocks);
  	fprintf(fp, "       device_blocks: %u\n", dh->device_blocks);
  	fprintf(fp, "      written_blocks: %u\n", dh->written_blocks);
@@ -1662,6 +1722,20 @@ __diskdump_memory_dump(FILE *fp)
  				dump_eraseinfo(fp);
  			}
  		}
+		if (dh->header_version>= 6) {
+			fprintf(fp, "           start_pfn_64: ");
+			if (KDUMP_SPLIT())
+				fprintf(fp, "%lld (0x%llx)\n",
+					kdsh->start_pfn_64, kdsh->start_pfn_64);
+			else
+				fprintf(fp, "(unused)\n");
+			fprintf(fp, "             end_pfn_64: ");
+			if (KDUMP_SPLIT())
+				fprintf(fp, "%lld (0x%llx)\n",
+					kdsh->end_pfn_64, kdsh->end_pfn_64);
+			else
+				fprintf(fp, "(unused)\n");
+		}
  		fprintf(fp, "\n");
  	} else
          	fprintf(fp, "(n/a)\n\n");
@@ -1670,7 +1744,7 @@ __diskdump_memory_dump(FILE *fp)
  	fprintf(fp, "        block_size: %d\n", dd->block_size);
  	fprintf(fp, "       block_shift: %d\n", dd->block_shift);
  	fprintf(fp, "            bitmap: %lx\n", (ulong)dd->bitmap);
-	fprintf(fp, "        bitmap_len: %d\n", dd->bitmap_len);
+	fprintf(fp, "        bitmap_len: %ld\n", dd->bitmap_len);
  	fprintf(fp, "   dumpable_bitmap: %lx\n", (ulong)dd->dumpable_bitmap);
  	fprintf(fp, "              byte: %d\n", dd->byte);
  	fprintf(fp, "               bit: %d\n", dd->bit);
diff --git a/diskdump.h b/diskdump.h
index 9ab10b6..0492351 100644
--- a/diskdump.h
+++ b/diskdump.h
@@ -42,7 +42,9 @@ struct disk_dump_header {
  						   header in blocks */
  	unsigned int		bitmap_blocks;	/* Size of Memory bitmap in
  						   block */
-	unsigned int		max_mapnr;	/* = max_mapnr */
+	unsigned int		max_mapnr;	/* = max_mapnr, 32bit only,
+						   full 64bit in sub header.
+						   Do NOT use this anymore! */

You can change this comment to read "obsolete" so that it is similar to Daisuke's
suggestion for makedumpfile.

  	unsigned int		total_ram_blocks;/* Number of blocks should be
  						   written */
  	unsigned int		device_blocks;	/* Number of total blocks in
@@ -61,14 +63,23 @@ struct kdump_sub_header {
  	unsigned long	phys_base;
  	int		dump_level;         /* header_version 1 and later */
  	int		split;              /* header_version 2 and later */
-	unsigned long	start_pfn;          /* header_version 2 and later */
-	unsigned long	end_pfn;            /* header_version 2 and later */
+	unsigned long	start_pfn;          /* header_version 2 and later,
+					       32bit only, full 64bit in
+					       start_pfn_64.
+					       Do not use this anymore! */
+	unsigned long	end_pfn;            /* header_version 2 and later,
+					       32bit only, full 64bit in
+					       end_pfn_64.

Same here...

+					       Do not use this anymore! */
  	off_t		offset_vmcoreinfo;  /* header_version 3 and later */
  	unsigned long	size_vmcoreinfo;    /* header_version 3 and later */
  	off_t		offset_note;        /* header_version 4 and later */
  	unsigned long	size_note;          /* header_version 4 and later */
  	off_t		offset_eraseinfo;   /* header_version 5 and later */
  	unsigned long	size_eraseinfo;     /* header_version 5 and later */
+	unsigned long long start_pfn_64;    /* header_version 6 and later */
+	unsigned long long end_pfn_64;      /* header_version 6 and later */
+	unsigned long long max_mapnr_64;    /* header_version 6 and later */
  };

  /* page flags */

Thanks,
   Dave



I will fix all these issues and send out a new patch.
Thanks!


--
Thanks,
Jingbai Ma

--
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