From f2bdacdd597d8d05c3d5f5d36273084f7ef7e6f5 Mon Sep 17 00:00:00 2001 From: HATAYAMA Daisuke Date: Wed, 3 Jul 2013 15:02:14 -0700 Subject: [PATCH] vmcore: allocate buffer for ELF headers on page-size alignment Allocate ELF headers on page-size boundary using __get_free_pages() instead of kmalloc(). Later patch will merge PT_NOTE entries into a single unique one and decrease the buffer size actually used. Keep original buffer size in variable elfcorebuf_sz_orig to kfree the buffer later and actually used buffer size with rounded up to page-size boundary in variable elfcorebuf_sz separately. The size of part of the ELF buffer exported from /proc/vmcore is elfcorebuf_sz. The merged, removed PT_NOTE entries, i.e. the range [elfcorebuf_sz, elfcorebuf_sz_orig], is filled with 0. Use size of the ELF headers as an initial offset value in set_vmcore_list_offsets_elf{64,32} and process_ptload_program_headers_elf{64,32} in order to indicate that the offset includes the holes towards the page boundary. As a result, both set_vmcore_list_offsets_elf{64,32} have the same definition. Merge them as set_vmcore_list_offsets. [akpm@linux-foundation.org: add free_elfcorebuf(), cleanups] Signed-off-by: HATAYAMA Daisuke Acked-by: Vivek Goyal Cc: KOSAKI Motohiro Cc: Atsushi Kumagai Cc: Lisa Mitchell Cc: Zhang Yanfei Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/vmcore.c | 119 ++++++++++++++++++++++++------------------------------- 1 file changed, 51 insertions(+), 68 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index ab0c92e..0b1c04e 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -32,6 +32,7 @@ static LIST_HEAD(vmcore_list); /* Stores the pointer to the buffer containing kernel elf core headers. */ static char *elfcorebuf; static size_t elfcorebuf_sz; +static size_t elfcorebuf_sz_orig; /* Total size of vmcore file. */ static u64 vmcore_size; @@ -186,7 +187,7 @@ static struct vmcore* __init get_new_element(void) return kzalloc(sizeof(struct vmcore), GFP_KERNEL); } -static u64 __init get_vmcore_size_elf64(char *elfptr) +static u64 __init get_vmcore_size_elf64(char *elfptr, size_t elfsz) { int i; u64 size; @@ -195,7 +196,7 @@ static u64 __init get_vmcore_size_elf64(char *elfptr) ehdr_ptr = (Elf64_Ehdr *)elfptr; phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); - size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr)); + size = elfsz; for (i = 0; i < ehdr_ptr->e_phnum; i++) { size += phdr_ptr->p_memsz; phdr_ptr++; @@ -203,7 +204,7 @@ static u64 __init get_vmcore_size_elf64(char *elfptr) return size; } -static u64 __init get_vmcore_size_elf32(char *elfptr) +static u64 __init get_vmcore_size_elf32(char *elfptr, size_t elfsz) { int i; u64 size; @@ -212,7 +213,7 @@ static u64 __init get_vmcore_size_elf32(char *elfptr) ehdr_ptr = (Elf32_Ehdr *)elfptr; phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); - size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr)); + size = elfsz; for (i = 0; i < ehdr_ptr->e_phnum; i++) { size += phdr_ptr->p_memsz; phdr_ptr++; @@ -294,6 +295,8 @@ static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz, i = (nr_ptnote - 1) * sizeof(Elf64_Phdr); *elfsz = *elfsz - i; memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr))); + memset(elfptr + *elfsz, 0, i); + *elfsz = roundup(*elfsz, PAGE_SIZE); /* Modify e_phnum to reflect merged headers. */ ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1; @@ -375,6 +378,8 @@ static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz, i = (nr_ptnote - 1) * sizeof(Elf32_Phdr); *elfsz = *elfsz - i; memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr))); + memset(elfptr + *elfsz, 0, i); + *elfsz = roundup(*elfsz, PAGE_SIZE); /* Modify e_phnum to reflect merged headers. */ ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1; @@ -398,8 +403,7 @@ static int __init process_ptload_program_headers_elf64(char *elfptr, phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */ /* First program header is PT_NOTE header. */ - vmcore_off = sizeof(Elf64_Ehdr) + - (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) + + vmcore_off = elfsz + phdr_ptr->p_memsz; /* Note sections */ for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { @@ -435,8 +439,7 @@ static int __init process_ptload_program_headers_elf32(char *elfptr, phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */ /* First program header is PT_NOTE header. */ - vmcore_off = sizeof(Elf32_Ehdr) + - (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) + + vmcore_off = elfsz + phdr_ptr->p_memsz; /* Note sections */ for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) { @@ -459,18 +462,14 @@ static int __init process_ptload_program_headers_elf32(char *elfptr, } /* Sets offset fields of vmcore elements. */ -static void __init set_vmcore_list_offsets_elf64(char *elfptr, - struct list_head *vc_list) +static void __init set_vmcore_list_offsets(size_t elfsz, + struct list_head *vc_list) { loff_t vmcore_off; - Elf64_Ehdr *ehdr_ptr; struct vmcore *m; - ehdr_ptr = (Elf64_Ehdr *)elfptr; - /* Skip Elf header and program headers. */ - vmcore_off = sizeof(Elf64_Ehdr) + - (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr); + vmcore_off = elfsz; list_for_each_entry(m, vc_list, list) { m->offset = vmcore_off; @@ -478,24 +477,10 @@ static void __init set_vmcore_list_offsets_elf64(char *elfptr, } } -/* Sets offset fields of vmcore elements. */ -static void __init set_vmcore_list_offsets_elf32(char *elfptr, - struct list_head *vc_list) +static void free_elfcorebuf(void) { - loff_t vmcore_off; - Elf32_Ehdr *ehdr_ptr; - struct vmcore *m; - - ehdr_ptr = (Elf32_Ehdr *)elfptr; - - /* Skip Elf header and program headers. */ - vmcore_off = sizeof(Elf32_Ehdr) + - (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr); - - list_for_each_entry(m, vc_list, list) { - m->offset = vmcore_off; - vmcore_off += m->size; - } + free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig)); + elfcorebuf = NULL; } static int __init parse_crash_elf64_headers(void) @@ -526,31 +511,31 @@ static int __init parse_crash_elf64_headers(void) } /* Read in all elf headers. */ - elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr); - elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL); + elfcorebuf_sz_orig = sizeof(Elf64_Ehdr) + + ehdr.e_phnum * sizeof(Elf64_Phdr); + elfcorebuf_sz = elfcorebuf_sz_orig; + elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + get_order(elfcorebuf_sz_orig)); if (!elfcorebuf) return -ENOMEM; addr = elfcorehdr_addr; - rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0); - if (rc < 0) { - kfree(elfcorebuf); - return rc; - } + rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz_orig, &addr, 0); + if (rc < 0) + goto fail; /* Merge all PT_NOTE headers into one. */ rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list); - if (rc) { - kfree(elfcorebuf); - return rc; - } + if (rc) + goto fail; rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz, &vmcore_list); - if (rc) { - kfree(elfcorebuf); - return rc; - } - set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list); + if (rc) + goto fail; + set_vmcore_list_offsets(elfcorebuf_sz, &vmcore_list); return 0; +fail: + free_elfcorebuf(); + return rc; } static int __init parse_crash_elf32_headers(void) @@ -581,31 +566,30 @@ static int __init parse_crash_elf32_headers(void) } /* Read in all elf headers. */ - elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr); - elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL); + elfcorebuf_sz_orig = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr); + elfcorebuf_sz = elfcorebuf_sz_orig; + elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + get_order(elfcorebuf_sz_orig)); if (!elfcorebuf) return -ENOMEM; addr = elfcorehdr_addr; - rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0); - if (rc < 0) { - kfree(elfcorebuf); - return rc; - } + rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz_orig, &addr, 0); + if (rc < 0) + goto fail; /* Merge all PT_NOTE headers into one. */ rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list); - if (rc) { - kfree(elfcorebuf); - return rc; - } + if (rc) + goto fail; rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz, &vmcore_list); - if (rc) { - kfree(elfcorebuf); - return rc; - } - set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list); + if (rc) + goto fail; + set_vmcore_list_offsets(elfcorebuf_sz, &vmcore_list); return 0; +fail: + free_elfcorebuf(); + return rc; } static int __init parse_crash_elf_headers(void) @@ -629,14 +613,14 @@ static int __init parse_crash_elf_headers(void) return rc; /* Determine vmcore size. */ - vmcore_size = get_vmcore_size_elf64(elfcorebuf); + 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); + vmcore_size = get_vmcore_size_elf32(elfcorebuf, elfcorebuf_sz); } else { pr_warn("Warning: Core image elf header is not sane\n"); return -EINVAL; @@ -683,7 +667,6 @@ void vmcore_cleanup(void) list_del(&m->list); kfree(m); } - kfree(elfcorebuf); - elfcorebuf = NULL; + free_elfcorebuf(); } EXPORT_SYMBOL_GPL(vmcore_cleanup); -- 2.7.4