From a895dc8f2a17f7dac9d3d63de1cea4720557625d Mon Sep 17 00:00:00 2001

From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>

Date: Thu, 12 Dec 2013 16:40:12 +0900

Subject: [PATCH 1/2] [PATCH] Add --non-mmap option to disable mmap() manually.

When --non-mmap option is specified, makedumpfile doesn't use

mmap() even if /proc/vmcore supports mmap().

Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>

---

 makedumpfile.8 | 11 +++++++++++

 makedumpfile.c | 29 +++++++++++++++++++----------

 makedumpfile.h |  9 +++++++++

 print_info.c   |  6 ++++++

 4 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/makedumpfile-1.5.4/makedumpfile.8 b/makedumpfile-1.5.4/makedumpfile.8

index f50a011..227b6f7 100644

--- a/makedumpfile-1.5.4/makedumpfile.8

+++ b/makedumpfile-1.5.4/makedumpfile.8

@@ -395,6 +395,17 @@ If you feel the cyclic mode is too slow, please try this mode.

 # makedumpfile \-\-non\-cyclic \-d 31 \-x vmlinux /proc/vmcore dumpfile

 .TP

+\fB\-\-non\-mmap\fR

+Never use \fBmmap(2)\fR to read \fIVMCORE\fR even if it supports \fBmmap(2)\fR.

+Generally, reading \fIVMCORE\fR with \fBmmap(2)\fR is faster than without it,

+so ordinary users don't need to specify this option.

+This option is mainly for debugging.

+.br

+.B Example:

+.br

+# makedumpfile \-\-non\-mmap \-d 31 \-x vmlinux /proc/vmcore dumpfile

+

+.TP

 \fB\-\-xen-syms\fR \fIXEN-SYMS\fR

 Specify the \fIXEN-SYMS\fR with debug information to analyze the xen's memory usage.

 This option extracts the part of xen and domain-0.

diff --git a/makedumpfile-1.5.4/makedumpfile.c b/makedumpfile-1.5.4/makedumpfile.c

index 600fb5d..b3af28b 100644

--- a/makedumpfile-1.5.4/makedumpfile.c

+++ b/makedumpfile-1.5.4/makedumpfile.c

@@ -272,7 +272,7 @@ update_mmap_range(off_t offset, int initial) {

 static int

 is_mapped_with_mmap(off_t offset) {

-	if (info->flag_usemmap

+	if (info->flag_usemmap == MMAP_ENABLE

 	    && offset >= info->mmap_start_offset

 	    && offset < info->mmap_end_offset)

 		return TRUE;

@@ -320,7 +320,7 @@ read_from_vmcore(off_t offset, void *bufptr, unsigned long size)

 {

 	const off_t failed = (off_t)-1;

-	if (info->flag_usemmap) {

+	if (info->flag_usemmap == MMAP_ENABLE) {

 		if (!read_with_mmap(offset, bufptr, size)) {

 			ERRMSG("Can't read the dump memory(%s) with mmap().\n",

 			       info->name_memory);

@@ -3175,14 +3175,14 @@ out:

 	if (info->dump_level & DL_EXCLUDE_FREE)

 		setup_page_is_buddy();

-	if (!initialize_mmap()) {

-		/* this kernel does not support mmap of vmcore */

-		DEBUG_MSG("Kernel can't mmap vmcore, using reads.\n");

-		info->flag_usemmap = FALSE;

+	if (info->flag_usemmap == MMAP_TRY && initialize_mmap()) {

+		DEBUG_MSG("mmap() is available on the kernel.\n");

+		info->flag_usemmap = MMAP_ENABLE;

 	} else {

-		DEBUG_MSG("read %s with mmap()\n", info->name_memory);

-		info->flag_usemmap = TRUE;

-	}

+		DEBUG_MSG("The kernel doesn't support mmap(),");

+		DEBUG_MSG("read() will be used instead.\n");

+		info->flag_usemmap = MMAP_DISABLE;

+        }

 	return TRUE;

 }

@@ -8947,6 +8947,7 @@ static struct option longopts[] = {

 	{"non-cyclic", no_argument, NULL, OPT_NON_CYCLIC},

 	{"cyclic-buffer", required_argument, NULL, OPT_CYCLIC_BUFFER},

 	{"eppic", required_argument, NULL, OPT_EPPIC},

+	{"non-mmap", no_argument, NULL, OPT_NON_MMAP},

 	{0, 0, 0, 0}

 };

@@ -8972,7 +8973,12 @@ main(int argc, char *argv[])

 	 * By default, makedumpfile works in constant memory space.

 	 */

 	info->flag_cyclic = TRUE;

-	

+

+	/*

+	 * By default, makedumpfile try to use mmap(2) to read /proc/vmcore.

+	 */

+	info->flag_usemmap = MMAP_TRY;

+

 	info->block_order = DEFAULT_ORDER;

 	message_level = DEFAULT_MSG_LEVEL;

 	while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:lpRvXx:", longopts,

@@ -9069,6 +9075,9 @@ main(int argc, char *argv[])

 		case OPT_NON_CYCLIC:

 			info->flag_cyclic = FALSE;

 			break;

+		case OPT_NON_MMAP:

+			info->flag_usemmap = MMAP_DISABLE;

+			break;

 		case OPT_XEN_VMCOREINFO:

 			info->flag_read_vmcoreinfo = 1;

 			info->name_vmcoreinfo = optarg;

diff --git a/makedumpfile-1.5.4/makedumpfile.h b/makedumpfile-1.5.4/makedumpfile.h

index 517e16e..fe88eff 100644

--- a/makedumpfile-1.5.4/makedumpfile.h

+++ b/makedumpfile-1.5.4/makedumpfile.h

@@ -128,6 +128,14 @@ enum {

 	MADDR_XEN

 };

+/*

+ * State of mmap(2)

+ */

+enum {

+	MMAP_DISABLE,

+	MMAP_TRY,

+	MMAP_ENABLE,

+};

 static inline int

 test_bit(int nr, unsigned long addr)

@@ -1741,6 +1749,7 @@ struct elf_prstatus {

 #define OPT_NON_CYCLIC          OPT_START+10

 #define OPT_CYCLIC_BUFFER       OPT_START+11

 #define OPT_EPPIC               OPT_START+12

+#define OPT_NON_MMAP            OPT_START+13

 /*

  * Function Prototype.

diff --git a/makedumpfile-1.5.4/print_info.c b/makedumpfile-1.5.4/print_info.c

index d7a8600..90b6cee 100644

--- a/makedumpfile-1.5.4/print_info.c

+++ b/makedumpfile-1.5.4/print_info.c

@@ -196,6 +196,12 @@ print_usage(void)

 	MSG("      same as v1.4.4 or before.\n");

 	MSG("      If you feel the cyclic mode is too slow, please try this mode.\n");

 	MSG("\n");

+	MSG("  [--non-mmap]:\n");

+	MSG("      Never use mmap(2) to read VMCORE even if it supports mmap(2).\n");

+	MSG("      Generally, reading VMCORE with mmap(2) is faster than without it,\n");

+	MSG("      so ordinary users don't need to specify this option.\n");

+	MSG("      This option is mainly for debugging.\n");

+	MSG("\n");

 	MSG("  [--xen-syms XEN-SYMS]:\n");

 	MSG("      Specify the XEN-SYMS to analyze Xen's memory usage.\n");

 	MSG("\n");

-- 

1.8.4.2