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kexec: add dmesg log symbols to /proc/vmcoreinfo lists
It would be nice to be able to extract the dmesg log from a vmcore file without needing to keep the debug symbols for the running kernel handy all the time. We have a facility to do this in /proc/vmcore. This patch adds the log_buf and log_end symbols to the vmcoreinfo area so that tools (like makedumpfile) can easily extract the dmesg logs from a vmcore image. [akpm@linux-foundation.org: several fixes and cleanups] [akpm@linux-foundation.org: fix unused log_buf_kexec_setup()] [akpm@linux-foundation.org: build fix] Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Cc: Simon Horman <horms@verge.net.au> Acked-by: Vivek Goyal <vgoyal@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Simon Horman <horms@verge.net.au> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -242,6 +242,7 @@ extern struct ratelimit_state printk_ratelimit_state;
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extern int printk_ratelimit(void);
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extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
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unsigned int interval_msec);
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void log_buf_kexec_setup(void);
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#else
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static inline int vprintk(const char *s, va_list args)
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__attribute__ ((format (printf, 1, 0)));
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@ -253,6 +254,9 @@ static inline int printk_ratelimit(void) { return 0; }
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static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
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unsigned int interval_msec) \
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{ return false; }
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static inline void log_buf_kexec_setup(void)
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{
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}
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#endif
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extern int printk_needs_cpu(int cpu);
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@ -1409,6 +1409,7 @@ static int __init crash_save_vmcoreinfo_init(void)
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VMCOREINFO_OFFSET(list_head, prev);
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VMCOREINFO_OFFSET(vm_struct, addr);
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VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
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log_buf_kexec_setup();
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VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
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VMCOREINFO_NUMBER(NR_FREE_PAGES);
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VMCOREINFO_NUMBER(PG_lru);
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@ -32,6 +32,7 @@
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <linux/syscalls.h>
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#include <linux/kexec.h>
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#include <asm/uaccess.h>
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@ -135,6 +136,24 @@ static char *log_buf = __log_buf;
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static int log_buf_len = __LOG_BUF_LEN;
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static unsigned logged_chars; /* Number of chars produced since last read+clear operation */
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#ifdef CONFIG_KEXEC
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/*
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* This appends the listed symbols to /proc/vmcoreinfo
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*
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* /proc/vmcoreinfo is used by various utiilties, like crash and makedumpfile to
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* obtain access to symbols that are otherwise very difficult to locate. These
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* symbols are specifically used so that utilities can access and extract the
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* dmesg log from a vmcore file after a crash.
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*/
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void log_buf_kexec_setup(void)
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{
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VMCOREINFO_SYMBOL(log_buf);
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VMCOREINFO_SYMBOL(log_end);
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VMCOREINFO_SYMBOL(log_buf_len);
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VMCOREINFO_SYMBOL(logged_chars);
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}
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#endif
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static int __init log_buf_len_setup(char *str)
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{
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unsigned size = memparse(str, &str);
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