[PATCH v7 2/8] vmcore: allocate buffer for ELF headers on page-size alignment
HATAYAMA Daisuke
d.hatayama at jp.fujitsu.com
Tue May 21 22:55:43 EDT 2013
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.
Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
---
fs/proc/vmcore.c | 74 +++++++++++++++++++++++++++++++-----------------------
1 files changed, 43 insertions(+), 31 deletions(-)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index ab0c92e..0651d98 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++) {
@@ -459,7 +462,7 @@ 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,
+static void __init set_vmcore_list_offsets_elf64(char *elfptr, size_t elfsz,
struct list_head *vc_list)
{
loff_t vmcore_off;
@@ -469,8 +472,7 @@ static void __init set_vmcore_list_offsets_elf64(char *elfptr,
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;
@@ -479,7 +481,7 @@ 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,
+static void __init set_vmcore_list_offsets_elf32(char *elfptr, size_t elfsz,
struct list_head *vc_list)
{
loff_t vmcore_off;
@@ -489,8 +491,7 @@ static void __init set_vmcore_list_offsets_elf32(char *elfptr,
ehdr_ptr = (Elf32_Ehdr *)elfptr;
/* Skip Elf header and program headers. */
- vmcore_off = sizeof(Elf32_Ehdr) +
- (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
+ vmcore_off = elfsz;
list_for_each_entry(m, vc_list, list) {
m->offset = vmcore_off;
@@ -526,30 +527,35 @@ 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);
+ rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz_orig, &addr, 0);
if (rc < 0) {
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
return rc;
}
/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
if (rc) {
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
return rc;
}
rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
&vmcore_list);
if (rc) {
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
return rc;
}
- set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
+ set_vmcore_list_offsets_elf64(elfcorebuf, elfcorebuf_sz, &vmcore_list);
return 0;
}
@@ -581,30 +587,35 @@ 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);
+ rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz_orig, &addr, 0);
if (rc < 0) {
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
return rc;
}
/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
if (rc) {
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
return rc;
}
rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
&vmcore_list);
if (rc) {
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
return rc;
}
- set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
+ set_vmcore_list_offsets_elf32(elfcorebuf, elfcorebuf_sz, &vmcore_list);
return 0;
}
@@ -629,14 +640,14 @@ 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 +694,8 @@ void vmcore_cleanup(void)
list_del(&m->list);
kfree(m);
}
- kfree(elfcorebuf);
+ free_pages((unsigned long)elfcorebuf,
+ get_order(elfcorebuf_sz_orig));
elfcorebuf = NULL;
}
EXPORT_SYMBOL_GPL(vmcore_cleanup);
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