The patch titled
Subject: vmcore: reference e_phoff member explicitly to get position of program header table
has been removed from the -mm tree. Its filename was
vmcore-reference-e_phoff-member-explicitly-to-get-position-of-program-header-table.patch
This patch was dropped because it was nacked
------------------------------------------------------
From: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
Subject: vmcore: reference e_phoff member explicitly to get position of program header table
Currently, read to /proc/vmcore is done by read_oldmem() that uses
ioremap/iounmap per a single page. For example, if memory is 1GB,
ioremap/iounmap is called (1GB / 4KB)-times, that is, 262144 times. This
causes big performance degradation.
In particular, the current main user of this mmap() is makedumpfile, which
not only reads memory from /proc/vmcore but also does other processing
like filtering, compression and IO work. Update of page table and the
following TLB flush makes such processing much slow; though I have yet to
make patch for makedumpfile and yet to confirm how it's improved.
To address the issue, this patch implements mmap() on /proc/vmcore to
improve read performance. My simple benchmark shows the improvement from
200 [MiB/sec] to over 50.0 [GiB/sec].
This patch:
Currently, the code assumes that position of program header table is next
to ELF header. But future change can break the assumption on kexec-tools
and the 1st kernel. To avoid worst case, reference e_phoff member
explicitly to get position of program header table in file-offset.
Signed-off-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Signed-off-by: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/vmcore.c | 56 ++++++++++++++++++++++++++++-----------------
1 file changed, 36 insertions(+), 20 deletions(-)
diff -puN fs/proc/vmcore.c~vmcore-reference-e_phoff-member-explicitly-to-get-position-of-program-header-table fs/proc/vmcore.c
--- a/fs/proc/vmcore.c~vmcore-reference-e_phoff-member-explicitly-to-get-position-of-program-header-table
+++ a/fs/proc/vmcore.c
@@ -221,8 +221,8 @@ static u64 __init get_vmcore_size_elf64(
Elf64_Phdr *phdr_ptr;
ehdr_ptr = (Elf64_Ehdr *)elfptr;
- phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
- size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
+ phdr_ptr = (Elf64_Phdr*)(elfptr + ehdr_ptr->e_phoff);
+ size = ehdr_ptr->e_phoff + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
for (i = 0; i < ehdr_ptr->e_phnum; i++) {
size += phdr_ptr->p_memsz;
phdr_ptr++;
@@ -238,8 +238,8 @@ static u64 __init get_vmcore_size_elf32(
Elf32_Phdr *phdr_ptr;
ehdr_ptr = (Elf32_Ehdr *)elfptr;
- phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
- size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
+ phdr_ptr = (Elf32_Phdr*)(elfptr + ehdr_ptr->e_phoff);
+ size = ehdr_ptr->e_phoff + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
for (i = 0; i < ehdr_ptr->e_phnum; i++) {
size += phdr_ptr->p_memsz;
phdr_ptr++;
@@ -259,7 +259,7 @@ static int __init merge_note_headers_elf
u64 phdr_sz = 0, note_off;
ehdr_ptr = (Elf64_Ehdr *)elfptr;
- phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
+ phdr_ptr = (Elf64_Phdr*)(elfptr + ehdr_ptr->e_phoff);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
int j;
void *notes_section;
@@ -305,7 +305,7 @@ static int __init merge_note_headers_elf
/* Prepare merged PT_NOTE program header. */
phdr.p_type = PT_NOTE;
phdr.p_flags = 0;
- note_off = sizeof(Elf64_Ehdr) +
+ note_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
phdr.p_offset = note_off;
phdr.p_vaddr = phdr.p_paddr = 0;
@@ -313,14 +313,14 @@ static int __init merge_note_headers_elf
phdr.p_align = 0;
/* Add merged PT_NOTE program header*/
- tmp = elfptr + sizeof(Elf64_Ehdr);
+ tmp = elfptr + ehdr_ptr->e_phoff;
memcpy(tmp, &phdr, sizeof(phdr));
tmp += sizeof(phdr);
/* Remove unwanted PT_NOTE program headers. */
i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
*elfsz = *elfsz - i;
- memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
+ memmove(tmp, tmp+i, ((*elfsz)-ehdr_ptr->e_phoff-sizeof(Elf64_Phdr)));
/* Modify e_phnum to reflect merged headers. */
ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
@@ -340,7 +340,7 @@ static int __init merge_note_headers_elf
u64 phdr_sz = 0, note_off;
ehdr_ptr = (Elf32_Ehdr *)elfptr;
- phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
+ phdr_ptr = (Elf32_Phdr*)(elfptr + ehdr_ptr->e_phoff);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
int j;
void *notes_section;
@@ -386,7 +386,7 @@ static int __init merge_note_headers_elf
/* Prepare merged PT_NOTE program header. */
phdr.p_type = PT_NOTE;
phdr.p_flags = 0;
- note_off = sizeof(Elf32_Ehdr) +
+ note_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
phdr.p_offset = note_off;
phdr.p_vaddr = phdr.p_paddr = 0;
@@ -394,14 +394,14 @@ static int __init merge_note_headers_elf
phdr.p_align = 0;
/* Add merged PT_NOTE program header*/
- tmp = elfptr + sizeof(Elf32_Ehdr);
+ tmp = elfptr + ehdr_ptr->e_phoff;
memcpy(tmp, &phdr, sizeof(phdr));
tmp += sizeof(phdr);
/* Remove unwanted PT_NOTE program headers. */
i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
*elfsz = *elfsz - i;
- memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
+ memmove(tmp, tmp+i, ((*elfsz)-ehdr_ptr->e_phoff-sizeof(Elf32_Phdr)));
/* Modify e_phnum to reflect merged headers. */
ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
@@ -422,10 +422,10 @@ static int __init process_ptload_program
struct vmcore *new;
ehdr_ptr = (Elf64_Ehdr *)elfptr;
- phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
+ phdr_ptr = (Elf64_Phdr*)(elfptr + ehdr_ptr->e_phoff); /* PT_NOTE hdr */
/* First program header is PT_NOTE header. */
- vmcore_off = sizeof(Elf64_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
phdr_ptr->p_memsz; /* Note sections */
@@ -459,10 +459,10 @@ static int __init process_ptload_program
struct vmcore *new;
ehdr_ptr = (Elf32_Ehdr *)elfptr;
- phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
+ phdr_ptr = (Elf32_Phdr*)(elfptr + ehdr_ptr->e_phoff); /* PT_NOTE hdr */
/* First program header is PT_NOTE header. */
- vmcore_off = sizeof(Elf32_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
phdr_ptr->p_memsz; /* Note sections */
@@ -496,7 +496,7 @@ static void __init set_vmcore_list_offse
ehdr_ptr = (Elf64_Ehdr *)elfptr;
/* Skip Elf header and program headers. */
- vmcore_off = sizeof(Elf64_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);
list_for_each_entry(m, vc_list, list) {
@@ -516,7 +516,7 @@ static void __init set_vmcore_list_offse
ehdr_ptr = (Elf32_Ehdr *)elfptr;
/* Skip Elf header and program headers. */
- vmcore_off = sizeof(Elf32_Ehdr) +
+ vmcore_off = ehdr_ptr->e_phoff +
(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
list_for_each_entry(m, vc_list, list) {
@@ -558,11 +558,19 @@ static int __init parse_crash_elf64_head
if (!elfcorebuf)
return -ENOMEM;
addr = elfcorehdr_addr;
- rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
+ rc = read_from_oldmem(elfcorebuf, sizeof(Elf64_Ehdr), &addr, 0);
if (rc < 0) {
kfree(elfcorebuf);
return rc;
}
+ addr = elfcorehdr_addr + ehdr.e_phoff;
+ rc = read_from_oldmem(elfcorebuf + sizeof(Elf64_Ehdr),
+ ehdr.e_phnum * sizeof(Elf64_Phdr), &addr, 0);
+ if (rc < 0) {
+ kfree(elfcorebuf);
+ return rc;
+ }
+ ((Elf64_Ehdr *)elfcorebuf)->e_phoff = sizeof(Elf64_Ehdr);
/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
@@ -613,11 +621,19 @@ static int __init parse_crash_elf32_head
if (!elfcorebuf)
return -ENOMEM;
addr = elfcorehdr_addr;
- rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
+ rc = read_from_oldmem(elfcorebuf, sizeof(Elf32_Ehdr), &addr, 0);
+ if (rc < 0) {
+ kfree(elfcorebuf);
+ return rc;
+ }
+ addr = elfcorehdr_addr + ehdr.e_phoff;
+ rc = read_from_oldmem(elfcorebuf + sizeof(Elf32_Ehdr),
+ ehdr.e_phnum * sizeof(Elf32_Phdr), &addr, 0);
if (rc < 0) {
kfree(elfcorebuf);
return rc;
}
+ ((Elf32_Ehdr *)elfcorebuf)->e_phoff = sizeof(Elf32_Ehdr);
/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
_
Patches currently in -mm which might be from d.hatayama@xxxxxxxxxxxxxx are
vmcore-clean-up-by-removing-unnecessary-variable.patch
vmcore-rearrange-program-headers-without-assuming-consequtive-pt_note-entries.patch
vmcore-sysfs-export-elf-note-segment-size-instead-of-vmcoreinfo-data-size.patch
vmcore-allocate-buffer-for-elf-headers-on-page-size-alignment.patch
vmcore-round-up-buffer-size-of-elf-headers-by-page_size.patch
vmcore-procfs-introduce-a-flag-to-distinguish-objects-copied-in-2nd-kernel.patch
vmcore-copy-non-page-size-aligned-head-and-tail-pages-in-2nd-kernel.patch
vmcore-modify-vmcore-clean-up-function-to-free-buffer-on-2nd-kernel.patch
vmcore-clean-up-read_vmcore.patch
vmcore-read-buffers-for-vmcore-objects-copied-from-old-memory.patch
vmcore-allocate-per-cpu-crash_notes-objects-on-page-size-boundary.patch
kexec-allocate-vmcoreinfo-note-buffer-on-page-size-boundary.patch
kexec-elf-introduce-nt_vmcore_debuginfo-note-type.patch
elf-introduce-nt_vmcore_pad-type.patch
kexec-fill-note-buffers-by-nt_vmcore_pad-notes-in-page-size-boundary.patch
vmcore-check-nt_vmcore_pad-as-a-mark-indicating-the-end-of-elf-note-buffer.patch
vmcore-check-if-vmcore-objects-satify-mmaps-page-size-boundary-requirement.patch
vmcore-round-up-offset-of-vmcore-object-in-page-size-boundary.patch
vmcore-count-holes-generated-by-round-up-operation-for-vmcore-size.patch
vmcore-introduce-mmap_vmcore.patch
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