7:54 a.m.
Few vmcores don't have vmcoreinfo elf note, such as those created using
virsh-dump.
On architectures such as PowerPC64, vmcoreinfo is mandatory to fetch the
first_vmalloc_address, for vmcores of upstream linux, since crash-utility commit:
commit 5b24e363a898 ("get vmalloc start address from vmcoreinfo")
Try reading from the 'vmcoreinfo_data' symbol instead, if the vmcoreinfo
crash tries to read in case of diskdump/netdump is empty/missing.
The approach to read 'vmcoreinfo_data' was used for a live kernel, which can be
reused in the case of missing vmcoreinfo note also, as the
'vmcoreinfo_data' symbol is available with vmcore too
Note though, till GDB interface is not initialised, reading from
vmcoreinfo_data symbol is not done, so behaviour is same as previously
with no vmcoreinfo (only till GDB interface is not initialised)
Hence rename 'vmcoreinfo_read_string' in kernel.c to
'vmcoreinfo_read_from_memory', and use it in netdump.c and diskdump.c
too.
Reported-by: Anushree Mathur <anushree.mathur(a)linux.ibm.com>
Tested-by: Anushree Mathur <anushree.mathur(a)linux.ibm.com>
Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com>
---
Changelog
=========
v2:
+ rename 'is_vmcoreinfo_empty' to netdump/diskdump variants in
netdump.c and diskdump.c respectively
---
---
defs.h | 1 +
diskdump.c | 18 ++++++++++++++++++
kernel.c | 17 ++++++++++++-----
netdump.c | 19 +++++++++++++++++++
4 files changed, 50 insertions(+), 5 deletions(-)
diff --git a/defs.h b/defs.h
index 156ac0232906..d28484ec44f9 100644
--- a/defs.h
+++ b/defs.h
@@ -6218,6 +6218,7 @@ void dump_kernel_table(int);
void dump_bt_info(struct bt_info *, char *where);
void dump_log(int);
void parse_kernel_version(char *);
+char *vmcoreinfo_read_from_memory(const char *);
#define LOG_LEVEL(v) ((v) & 0x07)
#define SHOW_LOG_LEVEL (0x1)
diff --git a/diskdump.c b/diskdump.c
index ce3cbb7b12dd..de907551153d 100644
--- a/diskdump.c
+++ b/diskdump.c
@@ -1041,6 +1041,13 @@ pfn_to_pos(ulong pfn)
return desc_pos;
}
+/**
+ * Check if vmcoreinfo in vmcore is missing/empty
+ */
+static bool is_diskdump_vmcoreinfo_empty(void)
+{
+ return (dd->sub_header_kdump->size_vmcoreinfo == 0);
+}
/*
* Determine whether a file is a diskdump creation, and if TRUE,
@@ -1088,6 +1095,17 @@ is_diskdump(char *file)
pc->read_vmcoreinfo = vmcoreinfo_read_string;
+ /*
+ * vmcoreinfo can be empty in case of dump collected via virsh-dump
+ *
+ * check if vmcoreinfo is not available in vmcore, and try to read
+ * the vmcoreinfo from memory, using "vmcoreinfo_data" symbol
+ */
+ if (is_diskdump_vmcoreinfo_empty()) {
+ error(WARNING, "vmcoreinfo is empty, will read from symbols\n");
+ pc->read_vmcoreinfo = vmcoreinfo_read_from_memory;
+ }
+
if ((pc->flags2 & GET_LOG) && KDUMP_CMPRS_VALID()) {
pc->dfd = dd->dfd;
pc->readmem = read_diskdump;
diff --git a/kernel.c b/kernel.c
index e4213d7a663e..0e17874c503c 100644
--- a/kernel.c
+++ b/kernel.c
@@ -99,7 +99,6 @@ static ulong dump_audit_skb_queue(ulong);
static ulong __dump_audit(char *);
static void dump_audit(void);
static void dump_printk_safe_seq_buf(int);
-static char *vmcoreinfo_read_string(const char *);
static void check_vmcoreinfo(void);
static int is_pvops_xen(void);
static int get_linux_banner_from_vmlinux(char *, size_t);
@@ -11892,8 +11891,8 @@ dump_printk_safe_seq_buf(int msg_flags)
* Returns a string (that has to be freed by the caller) that contains the
* value for key or NULL if the key has not been found.
*/
-static char *
-vmcoreinfo_read_string(const char *key)
+char *
+vmcoreinfo_read_from_memory(const char *key)
{
char *buf, *value_string, *p1, *p2;
size_t value_length;
@@ -11903,6 +11902,14 @@ vmcoreinfo_read_string(const char *key)
buf = value_string = NULL;
+ if (!(pc->flags & GDB_INIT)) {
+ /*
+ * GDB interface hasn't been initialised yet, so can't
+ * access vmcoreinfo_data
+ */
+ return NULL;
+ }
+
switch (get_symbol_type("vmcoreinfo_data", NULL, NULL))
{
case TYPE_CODE_PTR:
@@ -11958,10 +11965,10 @@ check_vmcoreinfo(void)
switch (get_symbol_type("vmcoreinfo_data", NULL, NULL))
{
case TYPE_CODE_PTR:
- pc->read_vmcoreinfo = vmcoreinfo_read_string;
+ pc->read_vmcoreinfo = vmcoreinfo_read_from_memory;
break;
case TYPE_CODE_ARRAY:
- pc->read_vmcoreinfo = vmcoreinfo_read_string;
+ pc->read_vmcoreinfo = vmcoreinfo_read_from_memory;
break;
}
}
diff --git a/netdump.c b/netdump.c
index c7ff009e7f90..69100a92e067 100644
--- a/netdump.c
+++ b/netdump.c
@@ -111,6 +111,14 @@ map_cpus_to_prstatus(void)
FREEBUF(nt_ptr);
}
+/**
+ * Check if vmcoreinfo in vmcore is missing/empty
+ */
+static bool is_netdump_vmcoreinfo_empty(void)
+{
+ return (nd->size_vmcoreinfo == 0);
+}
+
/*
* Determine whether a file is a netdump/diskdump/kdump creation,
* and if TRUE, initialize the vmcore_data structure.
@@ -464,6 +472,17 @@ is_netdump(char *file, ulong source_query)
pc->read_vmcoreinfo = vmcoreinfo_read_string;
+ /*
+ * vmcoreinfo can be empty in case of dump collected via virsh-dump
+ *
+ * check if vmcoreinfo is not available in vmcore, and try to read
+ * the vmcoreinfo from memory, using "vmcoreinfo_data" symbol
+ */
+ if (is_netdump_vmcoreinfo_empty()) {
+ error(WARNING, "vmcoreinfo is empty, will read from symbols\n");
+ pc->read_vmcoreinfo = vmcoreinfo_read_from_memory;
+ }
+
if ((source_query == KDUMP_LOCAL) &&
(pc->flags2 & GET_OSRELEASE))
kdump_get_osrelease();
--
2.50.1