Kexec Archive on lore.kernel.org
 help / color / mirror / Atom feed
From: Pingfan Liu <piliu@redhat.com>
To: kexec@lists.infradead.org
Cc: Xunlei Pang <xpang@redhat.com>, Dave Young <dyoung@redhat.com>,
	kernelfans@gmail.com, Baoquan He <bhe@redhat.com>
Subject: [PATCHv2 2/2] [fs] proc/vmcore: check the dummy place holder for offline cpu to avoid warning
Date: Mon, 19 Dec 2016 10:08:47 +0800	[thread overview]
Message-ID: <1482113327-19103-2-git-send-email-piliu@redhat.com> (raw)
In-Reply-To: <1482113327-19103-1-git-send-email-piliu@redhat.com>

kexec-tools always allocates program headers for present cpus. But
when crashing, offline cpus have dummy headers. We do not copy these
dummy notes into ELF file, also have no need of warning on them.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
---
 fs/proc/vmcore.c | 46 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 8ab782d..fc6e352 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -526,9 +526,10 @@ static u64 __init get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
  */
 static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
 {
-	int i, rc=0;
+	int i, j, rc = 0;
 	Elf64_Phdr *phdr_ptr;
-	Elf64_Nhdr *nhdr_ptr;
+	Elf64_Nhdr *nhdr_ptr, *prev_ptr;
+	bool warn;
 
 	phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
@@ -536,6 +537,7 @@ static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
 		u64 offset, max_sz, sz, real_sz = 0;
 		if (phdr_ptr->p_type != PT_NOTE)
 			continue;
+		warn = true;
 		max_sz = phdr_ptr->p_memsz;
 		offset = phdr_ptr->p_offset;
 		notes_section = kmalloc(max_sz, GFP_KERNEL);
@@ -556,14 +558,27 @@ static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
 					nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
 				break;
 			}
+			prev_ptr = nhdr_ptr;
 			real_sz += sz;
 			nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
+			if ((prev_ptr->n_type == NT_DUMMY)
+			  && !strncmp(KEXEC_CORE_NOTE_NAME,
+				(char *)prev_ptr + sizeof(Elf64_Nhdr),
+				strlen(KEXEC_CORE_NOTE_NAME))) {
+				if (nhdr_ptr->n_namesz == 0) {
+					/* do not copy this dummy note */
+					real_sz = 0;
+					warn = false;
+				} else
+					pr_warn("Warning: Dummy PT_NOTE not overwritten\n");
+			}
 		}
+		if (real_sz != 0)
+			warn = false;
 		kfree(notes_section);
 		phdr_ptr->p_memsz = real_sz;
-		if (real_sz == 0) {
+		if (warn)
 			pr_warn("Warning: Zero PT_NOTE entries found\n");
-		}
 	}
 
 	return 0;
@@ -712,9 +727,10 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
  */
 static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
 {
-	int i, rc=0;
+	int i, j, rc = 0;
 	Elf32_Phdr *phdr_ptr;
-	Elf32_Nhdr *nhdr_ptr;
+	Elf32_Nhdr *nhdr_ptr, *prev_ptr;
+	bool warn;
 
 	phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
@@ -722,6 +738,7 @@ static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
 		u64 offset, max_sz, sz, real_sz = 0;
 		if (phdr_ptr->p_type != PT_NOTE)
 			continue;
+		warn = true;
 		max_sz = phdr_ptr->p_memsz;
 		offset = phdr_ptr->p_offset;
 		notes_section = kmalloc(max_sz, GFP_KERNEL);
@@ -742,14 +759,27 @@ static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
 					nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
 				break;
 			}
+			prev_ptr = nhdr_ptr;
 			real_sz += sz;
 			nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
+			if ((prev_ptr->n_type == NT_DUMMY)
+			  && !strncmp(KEXEC_CORE_NOTE_NAME,
+				(char *)prev_ptr + sizeof(Elf32_Nhdr),
+				strlen(KEXEC_CORE_NOTE_NAME))) {
+				if (nhdr_ptr->n_namesz == 0) {
+					/* do not copy this dummy note */
+					real_sz = 0;
+					warn = false;
+				} else
+					pr_warn("Warning: Dummy PT_NOTE not overwritten\n");
+			}
 		}
+		if (real_sz != 0)
+			warn = false;
 		kfree(notes_section);
 		phdr_ptr->p_memsz = real_sz;
-		if (real_sz == 0) {
+		if (warn)
 			pr_warn("Warning: Zero PT_NOTE entries found\n");
-		}
 	}
 
 	return 0;
-- 
2.7.4


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2016-12-19  2:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-19  2:08 [PATCHv2 1/2] kexec: add a dummy note for each offline cpu Pingfan Liu
2016-12-19  2:08 ` Pingfan Liu [this message]
2016-12-19  2:40   ` [PATCHv2 2/2] [fs] proc/vmcore: check the dummy place holder for offline cpu to avoid warning Dave Young
2016-12-20 15:38     ` Pratyush Anand
2016-12-21  3:26       ` Xunlei Pang
2016-12-21  3:57         ` Pratyush Anand
2016-12-21  4:52           ` Xunlei Pang
2016-12-21  7:15           ` Liu ping fan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1482113327-19103-2-git-send-email-piliu@redhat.com \
    --to=piliu@redhat.com \
    --cc=bhe@redhat.com \
    --cc=dyoung@redhat.com \
    --cc=kernelfans@gmail.com \
    --cc=kexec@lists.infradead.org \
    --cc=xpang@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox