[Crash-utility] Re: [PATCH] vmcoreinfo: read vmcoreinfo using 'vmcoreinfo_data' when unavailable in elf note

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 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&gt; Tested-by: Anushree Mathur <anushree.mathur(a)linux.ibm.com&gt; Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com&gt; --- defs.h | 1 + diskdump.c | 18 ++++++++++++++++++ kernel.c | 9 ++++----- netdump.c | 19 +++++++++++++++++++ 4 files changed, 42 insertions(+), 5 deletions(-) diff --git a/defs.h b/defs.h index 2231cb68b804..910264e12314 100644 --- a/defs.h +++ b/defs.h @@ -6166,6 +6166,7 @@ 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..30d0c87f84c1 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_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 + * thev vmcore from memory, using "vmcoreinfo_data" symbol + */ + if (is_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 adb19ad8725d..7d26a5c5a0a1 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); @@ -11852,8 +11851,8 @@ 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; @@ -11918,10 +11917,10 @@ 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 b4e2a5cb2037..c69c7a1e80db 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_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 + * thev vmcore from memory, using "vmcoreinfo_data" symbol + */ + if (is_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(); -- 2.46.2