Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933420Ab3CSCa1 (ORCPT ); Mon, 18 Mar 2013 22:30:27 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:47004 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933377Ab3CSCaQ (ORCPT ); Mon, 18 Mar 2013 22:30:16 -0400 From: HATAYAMA Daisuke Subject: [PATCH v3 03/21] vmcore: rearrange program headers without assuming consequtive PT_NOTE entries To: vgoyal@redhat.com, ebiederm@xmission.com, cpw@sgi.com, kumagai-atsushi@mxc.nes.nec.co.jp, lisa.mitchell@hp.com, heiko.carstens@de.ibm.com, akpm@linux-foundation.org Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, zhangyanfei@cn.fujitsu.com Date: Sat, 16 Mar 2013 13:01:04 +0900 Message-ID: <20130316040104.15064.57180.stgit@localhost6.localdomain6> In-Reply-To: <20130316040003.15064.62308.stgit@localhost6.localdomain6> References: <20130316040003.15064.62308.stgit@localhost6.localdomain6> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5695 Lines: 178 Current code assumes all PT_NOTE headers are placed at the beginning of program header table and they are consequtive. But the assumption could be broken by future changes on either kexec-tools or the 1st kernel. This patch removes the assumption and rearranges program headers as the following conditions are satisfied: - PT_NOTE entry is unique at the first entry, - the order of program headers are unchanged during this rearrangement, only their positions are changed in positive direction. - unused part that occurs in the bottom of program headers are filled with 0. Also, this patch adds one exceptional case where the number of PT_NOTE entries is somehow 0. Then, immediately go out of the function. Signed-off-by: HATAYAMA Daisuke --- fs/proc/vmcore.c | 92 +++++++++++++++++++++++++++++++++++++++++++----------- 1 files changed, 74 insertions(+), 18 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 94743d2..7d2dc4c 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -251,8 +251,7 @@ static u64 __init get_vmcore_size_elf32(char *elfptr) static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, struct list_head *vc_list) { - int i, nr_ptnote=0, rc=0; - char *tmp; + int i, j, nr_ptnote=0, i_ptnote, rc=0; Elf64_Ehdr *ehdr_ptr; Elf64_Phdr phdr, *phdr_ptr; Elf64_Nhdr *nhdr_ptr; @@ -301,6 +300,39 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, kfree(notes_section); } + if (nr_ptnote == 0) + goto out; + + phdr_ptr = (Elf64_Phdr *)(elfptr + ehdr_ptr->e_phoff); + + /* Remove unwanted PT_NOTE program headers. */ + + /* - 1st pass shifts non-PT_NOTE entries until the first + PT_NOTE entry. */ + i_ptnote = -1; + for (i = 0; i < ehdr_ptr->e_phnum; ++i) { + if (phdr_ptr[i].p_type == PT_NOTE) { + i_ptnote = i; + break; + } + } + BUG_ON(i_ptnote == -1); /* impossible case since nr_ptnote > 0. */ + memmove(phdr_ptr + 1, phdr_ptr, i_ptnote * sizeof(Elf64_Phdr)); + + /* - 2nd pass moves the remaining non-PT_NOTE entries under + the first PT_NOTE entry. */ + for (i = j = i_ptnote + 1; i < ehdr_ptr->e_phnum; i++) { + if (phdr_ptr[i].p_type != PT_NOTE) { + memmove(phdr_ptr + j, phdr_ptr + i, + sizeof(Elf64_Phdr)); + j++; + } + } + + /* - Finally, fill unused part with 0. */ + memset(phdr_ptr + ehdr_ptr->e_phnum - (nr_ptnote - 1), 0, + (nr_ptnote - 1) * sizeof(Elf64_Phdr)); + /* Prepare merged PT_NOTE program header. */ phdr.p_type = PT_NOTE; phdr.p_flags = 0; @@ -312,18 +344,14 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, phdr.p_align = 0; /* Add merged PT_NOTE program header*/ - tmp = elfptr + ehdr_ptr->e_phoff; - memcpy(tmp, &phdr, sizeof(phdr)); - tmp += sizeof(phdr); + memcpy(phdr_ptr, &phdr, sizeof(Elf64_Phdr)); - /* Remove unwanted PT_NOTE program headers. */ - i = (nr_ptnote - 1) * sizeof(Elf64_Phdr); - *elfsz = *elfsz - i; - memmove(tmp, tmp+i, ((*elfsz)-ehdr_ptr->e_phoff-sizeof(Elf64_Phdr))); + *elfsz = *elfsz - (nr_ptnote - 1) * sizeof(Elf64_Phdr); /* Modify e_phnum to reflect merged headers. */ ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1; +out: return 0; } @@ -331,8 +359,7 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, struct list_head *vc_list) { - int i, nr_ptnote=0, rc=0; - char *tmp; + int i, j, nr_ptnote=0, i_ptnote, rc=0; Elf32_Ehdr *ehdr_ptr; Elf32_Phdr phdr, *phdr_ptr; Elf32_Nhdr *nhdr_ptr; @@ -381,6 +408,39 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, kfree(notes_section); } + if (nr_ptnote == 0) + goto out; + + phdr_ptr = (Elf32_Phdr *)(elfptr + ehdr_ptr->e_phoff); + + /* Remove unwanted PT_NOTE program headers. */ + + /* - 1st pass shifts non-PT_NOTE entries until the first + PT_NOTE entry. */ + i_ptnote = -1; + for (i = 0; i < ehdr_ptr->e_phnum; ++i) { + if (phdr_ptr[i].p_type == PT_NOTE) { + i_ptnote = i; + break; + } + } + BUG_ON(i_ptnote == -1); /* impossible case since nr_ptnote > 0. */ + memmove(phdr_ptr + 1, phdr_ptr, i_ptnote * sizeof(Elf32_Phdr)); + + /* - 2nd pass moves the remaining non-PT_NOTE entries under + the first PT_NOTE entry. */ + for (i = j = i_ptnote + 1; i < ehdr_ptr->e_phnum; i++) { + if (phdr_ptr[i].p_type != PT_NOTE) { + memmove(phdr_ptr + j, phdr_ptr + i, + sizeof(Elf32_Phdr)); + j++; + } + } + + /* - Finally, fill unused part with 0. */ + memset(phdr_ptr + ehdr_ptr->e_phnum - (nr_ptnote - 1), 0, + (nr_ptnote - 1) * sizeof(Elf32_Phdr)); + /* Prepare merged PT_NOTE program header. */ phdr.p_type = PT_NOTE; phdr.p_flags = 0; @@ -392,18 +452,14 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, phdr.p_align = 0; /* Add merged PT_NOTE program header*/ - tmp = elfptr + ehdr_ptr->e_phoff; - memcpy(tmp, &phdr, sizeof(phdr)); - tmp += sizeof(phdr); + memcpy(phdr_ptr, &phdr, sizeof(Elf32_Phdr)); - /* Remove unwanted PT_NOTE program headers. */ - i = (nr_ptnote - 1) * sizeof(Elf32_Phdr); - *elfsz = *elfsz - i; - memmove(tmp, tmp+i, ((*elfsz)-ehdr_ptr->e_phoff-sizeof(Elf32_Phdr))); + *elfsz = *elfsz - (nr_ptnote - 1) * sizeof(Elf32_Phdr); /* Modify e_phnum to reflect merged headers. */ ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1; +out: return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/