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Subject[patch 5/9] kdump: Allow vmcore ELF header to be created in new kernel
From: Michael Holzheu <holzheu@linux.vnet.ibm.com>

For s390 we create the ELF header for /proc/vmcore in the second (kdump)
kernel. Currently vmcore gets the ELF header from oldmem using the global
variable "elfcorehdr_addr". This patch introduces a new value
ELFCORE_ADDR_NEWMEM for "elfcorehdr_addr" that indicates that the ELF header
is allocated in the new kernel. In this case a new architecture function
"arch_vmcore_get_elf_hdr()" is called to obtain address and length of the
ELF header.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
---
fs/proc/vmcore.c | 66 ++++++++++++++++++++++++++++++++++++---------
include/linux/crash_dump.h | 1
2 files changed, 55 insertions(+), 12 deletions(-)
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -494,14 +494,10 @@ static void __init set_vmcore_list_offse
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 = elfcorebuf_sz;

list_for_each_entry(m, vc_list, list) {
m->offset = vmcore_off;
@@ -514,14 +510,10 @@ static void __init set_vmcore_list_offse
struct list_head *vc_list)
{
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);
+ vmcore_off = elfcorebuf_sz;

list_for_each_entry(m, vc_list, list) {
m->offset = vmcore_off;
@@ -641,7 +633,7 @@ static int __init parse_crash_elf32_head
return 0;
}

-static int __init parse_crash_elf_headers(void)
+static int __init parse_crash_elf_headers_oldmem(void)
{
unsigned char e_ident[EI_NIDENT];
u64 addr;
@@ -679,6 +671,53 @@ static int __init parse_crash_elf_header
return 0;
}

+/*
+ * provide an empty default implementation here -- architecture
+ * code may override this
+ */
+int __weak arch_vmcore_get_elf_hdr(char **elfcorebuf, size_t *elfcorebuf_sz)
+{
+ return -EOPNOTSUPP;
+}
+
+static int __init parse_crash_elf_headers_newmem(void)
+{
+ unsigned char e_ident[EI_NIDENT];
+ int rc;
+
+ rc = arch_vmcore_get_elf_hdr(&elfcorebuf, &elfcorebuf_sz);
+ if (rc)
+ return rc;
+ memcpy(e_ident, elfcorebuf, EI_NIDENT);
+ if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
+ printk(KERN_WARNING "Warning: Core image elf header "
+ "not found\n");
+ rc = -EINVAL;
+ goto fail;
+ }
+ if (e_ident[EI_CLASS] == ELFCLASS64) {
+ rc = process_ptload_program_headers_elf64(elfcorebuf,
+ elfcorebuf_sz,
+ &vmcore_list);
+ if (rc)
+ goto fail;
+ set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
+ vmcore_size = get_vmcore_size_elf64(elfcorebuf);
+ } else if (e_ident[EI_CLASS] == ELFCLASS32) {
+ rc = process_ptload_program_headers_elf32(elfcorebuf,
+ elfcorebuf_sz,
+ &vmcore_list);
+ if (rc)
+ goto fail;
+ set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
+ vmcore_size = get_vmcore_size_elf32(elfcorebuf);
+ }
+ return 0;
+fail:
+ kfree(elfcorebuf);
+ return rc;
+}
+
/* Init function for vmcore module. */
static int __init vmcore_init(void)
{
@@ -687,7 +726,10 @@ static int __init vmcore_init(void)
/* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
if (!(is_vmcore_usable()))
return rc;
- rc = parse_crash_elf_headers();
+ if (elfcorehdr_addr == ELFCORE_ADDR_NEWMEM)
+ rc = parse_crash_elf_headers_newmem();
+ else
+ rc = parse_crash_elf_headers_oldmem();
if (rc) {
printk(KERN_WARNING "Kdump: vmcore not initialized\n");
return rc;
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -8,6 +8,7 @@

#define ELFCORE_ADDR_MAX (-1ULL)
#define ELFCORE_ADDR_ERR (-2ULL)
+#define ELFCORE_ADDR_NEWMEM (-3ULL)

extern unsigned long long elfcorehdr_addr;



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