crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH_CORE

Patch series "kexec/fadump: remove dependency with CONFIG_KEXEC and
reuse crashkernel parameter for fadump", v4.

Traditionally, kdump is used to save vmcore in case of a crash.  Some
architectures like powerpc can save vmcore using architecture specific
support instead of kexec/kdump mechanism.  Such architecture specific
support also needs to reserve memory, to be used by dump capture kernel.
crashkernel parameter can be a reused, for memory reservation, by such
architecture specific infrastructure.

This patchset removes dependency with CONFIG_KEXEC for crashkernel
parameter and vmcoreinfo related code as it can be reused without kexec
support.  Also, crashkernel parameter is reused instead of
fadump_reserve_mem to reserve memory for fadump.

The first patch moves crashkernel parameter parsing and vmcoreinfo
related code under CONFIG_CRASH_CORE instead of CONFIG_KEXEC_CORE.  The
second patch reuses the definitions of append_elf_note() & final_note()
functions under CONFIG_CRASH_CORE in IA64 arch code.  The third patch
removes dependency on CONFIG_KEXEC for firmware-assisted dump (fadump)
in powerpc.  The next patch reuses crashkernel parameter for reserving
memory for fadump, instead of the fadump_reserve_mem parameter.  This
has the advantage of using all syntaxes crashkernel parameter supports,
for fadump as well.  The last patch updates fadump kernel documentation
about use of crashkernel parameter.

This patch (of 5):

Traditionally, kdump is used to save vmcore in case of a crash.  Some
architectures like powerpc can save vmcore using architecture specific
support instead of kexec/kdump mechanism.  Such architecture specific
support also needs to reserve memory, to be used by dump capture kernel.
crashkernel parameter can be a reused, for memory reservation, by such
architecture specific infrastructure.

But currently, code related to vmcoreinfo and parsing of crashkernel
parameter is built under CONFIG_KEXEC_CORE.  This patch introduces
CONFIG_CRASH_CORE and moves the above mentioned code under this config,
allowing code reuse without dependency on CONFIG_KEXEC.  There is no
functional change with this patch.

Link: http://lkml.kernel.org/r/149035338104.6881.4550894432615189948.stgit@hbathini.in.ibm.comSigned-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/Kconfig

@@ -2,7 +2,11 @@
 # General architecture dependent options
 #
 
+config CRASH_CORE
+	bool
+
 config KEXEC_CORE
+	select CRASH_CORE
 	bool
 
 config HAVE_IMA_KEXEC

include/linux/crash_core.h

+#ifndef LINUX_CRASH_CORE_H
+#define LINUX_CRASH_CORE_H
+
+#include <linux/linkage.h>
+#include <linux/elfcore.h>
+#include <linux/elf.h>
+
+#define CRASH_CORE_NOTE_NAME	   "CORE"
+#define CRASH_CORE_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
+#define CRASH_CORE_NOTE_NAME_BYTES ALIGN(sizeof(CRASH_CORE_NOTE_NAME), 4)
+#define CRASH_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)
+
+#define CRASH_CORE_NOTE_BYTES	   ((CRASH_CORE_NOTE_HEAD_BYTES * 2) +	\
+				     CRASH_CORE_NOTE_NAME_BYTES +	\
+				     CRASH_CORE_NOTE_DESC_BYTES)
+
+#define VMCOREINFO_BYTES	   (4096)
+#define VMCOREINFO_NOTE_NAME	   "VMCOREINFO"
+#define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4)
+#define VMCOREINFO_NOTE_SIZE	   ((CRASH_CORE_NOTE_HEAD_BYTES * 2) +	\
+				     VMCOREINFO_NOTE_NAME_BYTES +	\
+				     VMCOREINFO_BYTES)
+
+typedef u32 note_buf_t[CRASH_CORE_NOTE_BYTES/4];
+
+void crash_save_vmcoreinfo(void);
+void arch_crash_save_vmcoreinfo(void);
+__printf(1, 2)
+void vmcoreinfo_append_str(const char *fmt, ...);
+phys_addr_t paddr_vmcoreinfo_note(void);
+
+#define VMCOREINFO_OSRELEASE(value) \
+	vmcoreinfo_append_str("OSRELEASE=%s\n", value)
+#define VMCOREINFO_PAGESIZE(value) \
+	vmcoreinfo_append_str("PAGESIZE=%ld\n", value)
+#define VMCOREINFO_SYMBOL(name) \
+	vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name)
+#define VMCOREINFO_SIZE(name) \
+	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
+			      (unsigned long)sizeof(name))
+#define VMCOREINFO_STRUCT_SIZE(name) \
+	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
+			      (unsigned long)sizeof(struct name))
+#define VMCOREINFO_OFFSET(name, field) \
+	vmcoreinfo_append_str("OFFSET(%s.%s)=%lu\n", #name, #field, \
+			      (unsigned long)offsetof(struct name, field))
+#define VMCOREINFO_LENGTH(name, value) \
+	vmcoreinfo_append_str("LENGTH(%s)=%lu\n", #name, (unsigned long)value)
+#define VMCOREINFO_NUMBER(name) \
+	vmcoreinfo_append_str("NUMBER(%s)=%ld\n", #name, (long)name)
+#define VMCOREINFO_CONFIG(name) \
+	vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
+
+extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
+extern size_t vmcoreinfo_size;
+extern size_t vmcoreinfo_max_size;
+
+int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
+		unsigned long long *crash_size, unsigned long long *crash_base);
+int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
+		unsigned long long *crash_size, unsigned long long *crash_base);
+int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
+		unsigned long long *crash_size, unsigned long long *crash_base);
+
+#endif /* LINUX_CRASH_CORE_H */

include/linux/kexec.h

@@ -14,17 +14,15 @@
 
 #if !defined(__ASSEMBLY__)
 
+#include <linux/crash_core.h>
 #include <asm/io.h>
 
 #include <uapi/linux/kexec.h>
 
 #ifdef CONFIG_KEXEC_CORE
 #include <linux/list.h>
-#include <linux/linkage.h>
 #include <linux/compat.h>
 #include <linux/ioport.h>
-#include <linux/elfcore.h>
-#include <linux/elf.h>
 #include <linux/module.h>
 #include <asm/kexec.h>
 
@@ -62,19 +60,15 @@
 #define KEXEC_CRASH_MEM_ALIGN PAGE_SIZE
 #endif
 
-#define KEXEC_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
-#define KEXEC_CORE_NOTE_NAME "CORE"
-#define KEXEC_CORE_NOTE_NAME_BYTES ALIGN(sizeof(KEXEC_CORE_NOTE_NAME), 4)
-#define KEXEC_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)
+#define KEXEC_CORE_NOTE_NAME	CRASH_CORE_NOTE_NAME
+
 /*
  * The per-cpu notes area is a list of notes terminated by a "NULL"
  * note header.  For kdump, the code in vmcore.c runs in the context
  * of the second kernel to combine them into one note.
  */
 #ifndef KEXEC_NOTE_BYTES
-#define KEXEC_NOTE_BYTES ( (KEXEC_NOTE_HEAD_BYTES * 2) +		\
-			    KEXEC_CORE_NOTE_NAME_BYTES +		\
-			    KEXEC_CORE_NOTE_DESC_BYTES )
+#define KEXEC_NOTE_BYTES	CRASH_CORE_NOTE_BYTES
 #endif
 
 /*
@@ -256,33 +250,6 @@ extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);
 int kexec_crash_loaded(void);
 void crash_save_cpu(struct pt_regs *regs, int cpu);
-void crash_save_vmcoreinfo(void);
-void arch_crash_save_vmcoreinfo(void);
-__printf(1, 2)
-void vmcoreinfo_append_str(const char *fmt, ...);
-phys_addr_t paddr_vmcoreinfo_note(void);
-
-#define VMCOREINFO_OSRELEASE(value) \
-	vmcoreinfo_append_str("OSRELEASE=%s\n", value)
-#define VMCOREINFO_PAGESIZE(value) \
-	vmcoreinfo_append_str("PAGESIZE=%ld\n", value)
-#define VMCOREINFO_SYMBOL(name) \
-	vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name)
-#define VMCOREINFO_SIZE(name) \
-	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
-			      (unsigned long)sizeof(name))
-#define VMCOREINFO_STRUCT_SIZE(name) \
-	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
-			      (unsigned long)sizeof(struct name))
-#define VMCOREINFO_OFFSET(name, field) \
-	vmcoreinfo_append_str("OFFSET(%s.%s)=%lu\n", #name, #field, \
-			      (unsigned long)offsetof(struct name, field))
-#define VMCOREINFO_LENGTH(name, value) \
-	vmcoreinfo_append_str("LENGTH(%s)=%lu\n", #name, (unsigned long)value)
-#define VMCOREINFO_NUMBER(name) \
-	vmcoreinfo_append_str("NUMBER(%s)=%ld\n", #name, (long)name)
-#define VMCOREINFO_CONFIG(name) \
-	vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
 
 extern struct kimage *kexec_image;
 extern struct kimage *kexec_crash_image;
@@ -303,31 +270,15 @@ extern int kexec_load_disabled;
 #define KEXEC_FILE_FLAGS	(KEXEC_FILE_UNLOAD | KEXEC_FILE_ON_CRASH | \
 				 KEXEC_FILE_NO_INITRAMFS)
 
-#define VMCOREINFO_BYTES           (4096)
-#define VMCOREINFO_NOTE_NAME       "VMCOREINFO"
-#define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4)
-#define VMCOREINFO_NOTE_SIZE       (KEXEC_NOTE_HEAD_BYTES*2 + VMCOREINFO_BYTES \
-				    + VMCOREINFO_NOTE_NAME_BYTES)
-
 /* Location of a reserved region to hold the crash kernel.
  */
 extern struct resource crashk_res;
 extern struct resource crashk_low_res;
-typedef u32 note_buf_t[KEXEC_NOTE_BYTES/4];
 extern note_buf_t __percpu *crash_notes;
-extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
-extern size_t vmcoreinfo_size;
-extern size_t vmcoreinfo_max_size;
 
 /* flag to track if kexec reboot is in progress */
 extern bool kexec_in_progress;
 
-int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
-		unsigned long long *crash_size, unsigned long long *crash_base);
-int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
-		unsigned long long *crash_size, unsigned long long *crash_base);
-int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
-		unsigned long long *crash_size, unsigned long long *crash_base);
 int crash_shrink_memory(unsigned long new_size);
 size_t crash_get_memory_size(void);
 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);

include/linux/printk.h

@@ -198,7 +198,7 @@ extern void wake_up_klogd(void);
 
 char *log_buf_addr_get(void);
 u32 log_buf_len_get(void);
-void log_buf_kexec_setup(void);
+void log_buf_vmcoreinfo_setup(void);
 void __init setup_log_buf(int early);
 __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...);
 void dump_stack_print_info(const char *log_lvl);
@@ -246,7 +246,7 @@ static inline u32 log_buf_len_get(void)
 	return 0;
 }
 
-static inline void log_buf_kexec_setup(void)
+static inline void log_buf_vmcoreinfo_setup(void)
 {
 }
 

kernel/Makefile

@@ -59,6 +59,7 @@ obj-$(CONFIG_MODULES) += module.o
 obj-$(CONFIG_MODULE_SIG) += module_signing.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
+obj-$(CONFIG_CRASH_CORE) += crash_core.o
 obj-$(CONFIG_KEXEC_CORE) += kexec_core.o
 obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_KEXEC_FILE) += kexec_file.o

kernel/ksysfs.c

@@ -125,6 +125,10 @@ static ssize_t kexec_crash_size_store(struct kobject *kobj,
 }
 KERNEL_ATTR_RW(kexec_crash_size);
 
+#endif /* CONFIG_KEXEC_CORE */
+
+#ifdef CONFIG_CRASH_CORE
+
 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 			       struct kobj_attribute *attr, char *buf)
 {
@@ -134,7 +138,7 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj,
 }
 KERNEL_ATTR_RO(vmcoreinfo);
 
-#endif /* CONFIG_KEXEC_CORE */
+#endif /* CONFIG_CRASH_CORE */
 
 /* whether file capabilities are enabled */
 static ssize_t fscaps_show(struct kobject *kobj,
@@ -219,6 +223,8 @@ static struct attribute * kernel_attrs[] = {
 	&kexec_loaded_attr.attr,
 	&kexec_crash_loaded_attr.attr,
 	&kexec_crash_size_attr.attr,
+#endif
+#ifdef CONFIG_CRASH_CORE
 	&vmcoreinfo_attr.attr,
 #endif
 #ifndef CONFIG_TINY_RCU

kernel/printk/printk.c

@@ -32,7 +32,7 @@
 #include <linux/bootmem.h>
 #include <linux/memblock.h>
 #include <linux/syscalls.h>
-#include <linux/kexec.h>
+#include <linux/crash_core.h>
 #include <linux/kdb.h>
 #include <linux/ratelimit.h>
 #include <linux/kmsg_dump.h>
@@ -1002,7 +1002,7 @@ const struct file_operations kmsg_fops = {
 	.release = devkmsg_release,
 };
 
-#ifdef CONFIG_KEXEC_CORE
+#ifdef CONFIG_CRASH_CORE
 /*
  * This appends the listed symbols to /proc/vmcore
  *
@@ -1011,7 +1011,7 @@ const struct file_operations kmsg_fops = {
  * symbols are specifically used so that utilities can access and extract the
  * dmesg log from a vmcore file after a crash.
  */
-void log_buf_kexec_setup(void)
+void log_buf_vmcoreinfo_setup(void)
 {
 	VMCOREINFO_SYMBOL(log_buf);
 	VMCOREINFO_SYMBOL(log_buf_len);