linux-kernel - [RHEL6.8 Patch 13/19] vmcore: calculate vmcore file size from buffer size and total size of vmcore objects

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Message-Id: <1437036437-25408-17-git-send-email-bhe@redhat.com>
Date:	Thu, 16 Jul 2015 16:47:11 +0800
From:	Baoquan He <bhe@...hat.com>
To:	linux-kernel@...r.kernel.org, ncroxon@...hat.com,
	dyoung@...hat.com, mhuang@...hat.com
Cc:	Baoquan He <bhe@...hat.com>
Subject: [RHEL6.8 Patch 13/19] vmcore: calculate vmcore file size from buffer size and total size of vmcore objects

Resolves: bz1097904
https://bugzilla.redhat.com/show_bug.cgi?id=1097904

This is back ported from upstream.

commit 591ff71664e764a3806e341370f3c758cb2e7e3c
Author: HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
Date:   Wed Jul 3 15:02:22 2013 -0700

    vmcore: calculate vmcore file size from buffer size and total size of vmcore objects

    The previous patches newly added holes before each chunk of memory and
    the holes need to be count in vmcore file size.  There are two ways to
    count file size in such a way:

    1) suppose m is a poitner to the last vmcore object in vmcore_list.
       Then file size is (m->offset + m->size), or

    2) calculate sum of size of buffers for ELF header, program headers,
       ELF note segments and objects in vmcore_list.

    Although 1) is more direct and simpler than 2), 2) seems better in that
    it reflects internal object structure of /proc/vmcore.  Thus, this patch
    changes get_vmcore_size_elf{64, 32} so that it calculates size in the
    way of 2).

    As a result, both get_vmcore_size_elf{64, 32} have the same definition.
    Merge them as get_vmcore_size.

    Signed-off-by: HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
    Acked-by: Vivek Goyal <vgoyal@...hat.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
    Cc: Atsushi Kumagai <kumagai-atsushi@....nes.nec.co.jp>
    Cc: Lisa Mitchell <lisa.mitchell@...com>
    Cc: Zhang Yanfei <zhangyanfei@...fujitsu.com>
    Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 fs/proc/vmcore.c | 44 +++++++++++---------------------------------
 1 file changed, 11 insertions(+), 33 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 6849c3f..88af2af 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -199,36 +199,15 @@ static struct vmcore* __init get_new_element(void)
 	return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
 }
 
-static u64 __init get_vmcore_size_elf64(char *elfptr, size_t elfsz)
+static u64 __init get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
+				  struct list_head *vc_list)
 {
-	int i;
 	u64 size;
-	Elf64_Ehdr *ehdr_ptr;
-	Elf64_Phdr *phdr_ptr;
-
-	ehdr_ptr = (Elf64_Ehdr *)elfptr;
-	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
-	size = elfsz;
-	for (i = 0; i < ehdr_ptr->e_phnum; i++) {
-		size += phdr_ptr->p_memsz;
-		phdr_ptr++;
-	}
-	return size;
-}
-
-static u64 __init get_vmcore_size_elf32(char *elfptr, size_t elfsz)
-{
-	int i;
-	u64 size;
-	Elf32_Ehdr *ehdr_ptr;
-	Elf32_Phdr *phdr_ptr;
+	struct vmcore *m;
 
-	ehdr_ptr = (Elf32_Ehdr *)elfptr;
-	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
-	size = elfsz;
-	for (i = 0; i < ehdr_ptr->e_phnum; i++) {
-		size += phdr_ptr->p_memsz;
-		phdr_ptr++;
+	size = elfsz + elfnotesegsz;
+	list_for_each_entry(m, vc_list, list) {
+		size += m->size;
 	}
 	return size;
 }
@@ -854,21 +833,20 @@ static int __init parse_crash_elf_headers(void)
 		rc = parse_crash_elf64_headers();
 		if (rc)
 			return rc;
-
-		/* Determine vmcore size. */
-		vmcore_size = get_vmcore_size_elf64(elfcorebuf, elfcorebuf_sz);
 	} else if (e_ident[EI_CLASS] == ELFCLASS32) {
 		rc = parse_crash_elf32_headers();
 		if (rc)
 			return rc;
-
-		/* Determine vmcore size. */
-		vmcore_size = get_vmcore_size_elf32(elfcorebuf, elfcorebuf_sz);
 	} else {
 		printk(KERN_WARNING "Warning: Core image elf header is not"
 					" sane\n");
 		return -EINVAL;
 	}
+
+	/* Determine vmcore size. */
+	vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
+					&vmcore_list);
+
 	return 0;
 }
 
-- 
2.1.0

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