From: Neil Horman <nhorman@redhat.com>
Date: Mon, 17 Dec 2007 11:41:22 -0500
Subject: [kexec] fix vmcoreinfo patch that breaks kdump
Message-id: 20071217164122.GA18867@hmsendeavour.rdu.redhat.com
O-Subject: [RHEL 5.2] Fix vmcoreinfo patch that breaks kdump (bz 424511)
Bugzilla: 424511

Recently a patch of mine was integrated into -58 to add vmcoreinfo support to
the kernel, to satisfy bz 253850.  Unfortunately, it seems to be causing 0
length vmcore files on kdump.  I've tracked the problem down to the fact that,
somewhere in my rediffing between the kernel that I did the origional backport
on, and the HEAD of the cvs tree that I posted against, some chunks were changed
in such a way that the patch stopped working.  I think the easiest thing to do
is rescind the following patch from the 5.2 kernel:
linux-2.6-misc-add-vmcoreinfo-support-to-kernel.patch
and replace it with this patch, which is identical except for the minor
differences that snuck in somehow.  I've re-applied it against the -57 tree and
confirmed that it still applies cleanly and works properly.  Sorry for the
noise.

Neil

Acked-by: Dave Anderson <anderson@redhat.com>

diff --git a/arch/i386/kernel/machine_kexec.c b/arch/i386/kernel/machine_kexec.c
index d3979a6..68dce1a 100644
--- a/arch/i386/kernel/machine_kexec.c
+++ b/arch/i386/kernel/machine_kexec.c
@@ -92,6 +92,18 @@ void machine_kexec_cleanup(struct kimage *image)
 {
 }
 
+ 
+void arch_crash_save_vmcoreinfo(void)
+{
+#ifdef CONFIG_ARCH_DISCONTIGMEM_ENABLE
+	SYMBOL(node_data);
+	LENGTH(node_data, MAX_NUMNODES);
+#endif
+#ifdef CONFIG_X86_PAE
+	CONFIG(X86_PAE);
+#endif
+}
+
 #ifndef CONFIG_XEN
 /*
  * Do not allocate memory (or fail in any way) in machine_kexec().
diff --git a/arch/ia64/kernel/machine_kexec.c b/arch/ia64/kernel/machine_kexec.c
index 2746eee..30338e5 100644
--- a/arch/ia64/kernel/machine_kexec.c
+++ b/arch/ia64/kernel/machine_kexec.c
@@ -19,6 +19,9 @@
 #include <asm/delay.h>
 #include <asm/meminit.h>
 #include <asm/machvec.h>
+#include <asm/processor.h>
+#include <linux/numa.h>
+#include <linux/mmzone.h>
 
 typedef void (*relocate_new_kernel_t)(unsigned long, unsigned long,
 		struct ia64_boot_param *, unsigned long);
@@ -140,3 +143,28 @@ void machine_kexec(struct kimage *image)
 	unw_init_running(ia64_machine_kexec, image);
 	for(;;);
 }
+
+void arch_crash_save_vmcoreinfo(void)
+{
+#ifdef CONFIG_ARCH_DISCONTIGMEM_ENABLE
+	SYMBOL(pgdat_list);
+	LENGTH(pgdat_list, MAX_NUMNODES);
+
+	SYMBOL(node_memblk);
+	LENGTH(node_memblk, NR_NODE_MEMBLKS);
+	SIZE(node_memblk_s);
+	OFFSET(node_memblk_s, start_paddr);
+	OFFSET(node_memblk_s, size);
+#endif
+#ifdef CONFIG_PGTABLE_3
+	CONFIG(PGTABLE_3);
+#elif  CONFIG_PGTABLE_4
+	CONFIG(PGTABLE_4);
+#endif
+}
+
+unsigned long paddr_vmcoreinfo_note(void)
+{
+	return ia64_tpa((unsigned long)(char *)&vmcoreinfo_note);
+}
+
diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
index af8f957..97641ee 100644
--- a/arch/ia64/mm/discontig.c
+++ b/arch/ia64/mm/discontig.c
@@ -45,7 +45,7 @@ struct early_node_data {
 static struct early_node_data mem_data[MAX_NUMNODES] __initdata;
 static nodemask_t memory_less_mask __initdata;
 
-static pg_data_t *pgdat_list[MAX_NUMNODES];
+pg_data_t *pgdat_list[MAX_NUMNODES];
 
 /*
  * To prevent cache aliasing effects, align per-node structures so that they
diff --git a/arch/x86_64/kernel/machine_kexec.c b/arch/x86_64/kernel/machine_kexec.c
index 162019a..efb6a0a 100644
--- a/arch/x86_64/kernel/machine_kexec.c
+++ b/arch/x86_64/kernel/machine_kexec.c
@@ -10,6 +10,7 @@
 #include <linux/kexec.h>
 #include <linux/string.h>
 #include <linux/reboot.h>
+#include <linux/numa.h>
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
@@ -237,6 +238,14 @@ void machine_kexec_cleanup(struct kimage *image)
 	return;
 }
 
+void arch_crash_save_vmcoreinfo(void)
+{
+#ifdef CONFIG_ARCH_DISCONTIGMEM_ENABLE
+	SYMBOL(node_data);
+	LENGTH(node_data, MAX_NUMNODES);
+#endif
+}
+
 #ifndef CONFIG_XEN
 /*
  * Do not allocate memory (or fail in any way) in machine_kexec().
diff --git a/include/asm-ia64/numa.h b/include/asm-ia64/numa.h
index 7d5e2cc..6a8a27c 100644
--- a/include/asm-ia64/numa.h
+++ b/include/asm-ia64/numa.h
@@ -24,6 +24,7 @@
 
 extern u16 cpu_to_node_map[NR_CPUS] __cacheline_aligned;
 extern cpumask_t node_to_cpu_mask[MAX_NUMNODES] __cacheline_aligned;
+extern pg_data_t *pgdat_list[MAX_NUMNODES];
 
 /* Stuff below this line could be architecture independent */
 
diff --git a/include/asm-x86_64/mach-xen/asm/pgtable.h b/include/asm-x86_64/mach-xen/asm/pgtable.h
index 78a24c6..e6eddf9 100644
--- a/include/asm-x86_64/mach-xen/asm/pgtable.h
+++ b/include/asm-x86_64/mach-xen/asm/pgtable.h
@@ -44,7 +44,7 @@ extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
 extern unsigned long __supported_pte_mask;
 
-#define swapper_pg_dir ((pgd_t *)NULL)
+#define swapper_pg_dir init_level4_pgt
 
 extern void nonx_setup(char *str);
 extern void paging_init(void);
diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index fa9d294..20cf067 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -21,7 +21,7 @@ extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
 extern unsigned long __supported_pte_mask;
 
-#define swapper_pg_dir ((pgd_t *)NULL)
+#define swapper_pg_dir init_level4_pgt
 
 extern void nonx_setup(const char *str);
 extern void paging_init(void);
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e731128..2e1deb2 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -10,6 +10,8 @@
 #endif
 #include <linux/ioport.h>
 #include <asm/kexec.h>
+#include <linux/elf.h>
+#include <linux/elfnote.h>
 
 /* Verify architecture specific macros are defined */
 
@@ -33,6 +35,8 @@
 #error KEXEC_ARCH not defined
 #endif
 
+#define KEXEC_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
+
 #ifndef KEXEC_ARCH_HAS_PAGE_MACROS
 #define kexec_page_to_pfn(page)  page_to_pfn(page)
 #define kexec_pfn_to_page(pfn)   pfn_to_page(pfn)
@@ -120,6 +124,32 @@ extern struct page *kimage_alloc_control_pages(struct kimage *image,
 						unsigned int order);
 extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);
+void crash_save_vmcoreinfo(void);
+void arch_crash_save_vmcoreinfo(void);
+void vmcoreinfo_append_str(const char *fmt, ...)
+	__attribute__ ((format (printf, 1, 2)));
+unsigned long paddr_vmcoreinfo_note(void);
+
+#define SYMBOL(name) \
+	vmcoreinfo_append_str("SYMBOL(%s)=%lx\n", #name, (unsigned long)&name)
+#define SIZE(name) \
+	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
+			     (unsigned long)sizeof(struct name))
+#define TYPEDEF_SIZE(name) \
+	vmcoreinfo_append_str("SIZE(%s)=%lu\n", #name, \
+			     (unsigned long)sizeof(name))
+
+#define OFFSET(name, field) \
+	vmcoreinfo_append_str("OFFSET(%s.%s)=%lu\n", #name, #field, \
+			     (unsigned long)&(((struct name *)0)->field))
+#define LENGTH(name, value) \
+	vmcoreinfo_append_str("LENGTH(%s)=%lu\n", #name, (unsigned long)value)
+#define NUMBER(name) \
+	vmcoreinfo_append_str("NUMBER(%s)=%ld\n", #name, (long)name)
+#define CONFIG(name) \
+	vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
+
+
 extern struct kimage *kexec_image;
 extern struct kimage *kexec_crash_image;
 
@@ -144,12 +174,24 @@ extern struct kimage *kexec_crash_image;
 
 #define KEXEC_FLAGS    (KEXEC_ON_CRASH)  /* List of defined/legal kexec flags */
 
+#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;
 typedef u32 note_buf_t[MAX_NOTE_BYTES/4];
 extern note_buf_t *crash_notes;
 
+extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
+extern size_t vmcoreinfo_size;
+extern size_t vmcoreinfo_max_size;
+
 #else /* !CONFIG_KEXEC */
 struct pt_regs;
 struct task_struct;
diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 822b295..839cde8 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -30,7 +30,17 @@ struct new_utsname {
 	char domainname[65];
 };
 
+#ifdef __KERNEL__
+
+#include <linux/kref.h>
+
+struct uts_namespace {
+	struct kref kref;
+	struct new_utsname name;
+};
+
 extern struct new_utsname system_utsname;
+extern struct uts_namespace init_uts_ns;
 
 extern struct rw_semaphore uts_sem;
 
@@ -39,4 +49,6 @@ static inline struct new_utsname *init_utsname(void)
 	return &system_utsname;
 }
 
+#endif /* __KERNEL__ */
+
 #endif
diff --git a/init/version.c b/init/version.c
index e290802..04bd77a 100644
--- a/init/version.c
+++ b/init/version.c
@@ -29,6 +29,22 @@ struct new_utsname system_utsname = {
 
 EXPORT_SYMBOL(system_utsname);
 
+struct uts_namespace init_uts_ns = {
+        .kref = {
+                .refcount       = ATOMIC_INIT(2),
+        },
+        .name = {
+                .sysname        = UTS_SYSNAME,
+                .nodename       = UTS_NODENAME,
+                .release        = UTS_RELEASE,
+                .version        = UTS_VERSION,
+                .machine        = UTS_MACHINE,
+                .domainname     = UTS_DOMAINNAME,
+        },
+};
+
+EXPORT_SYMBOL_GPL(init_uts_ns);
+
 const char linux_banner[] =
 	"Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
 	LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n";
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 9db23d6..dbb6313 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -20,16 +20,29 @@
 #include <linux/syscalls.h>
 #include <linux/ioport.h>
 #include <linux/hardirq.h>
+#include <linux/elf.h>
+#include <linux/elfcore.h>
+#include <linux/utsrelease.h>
+#include <linux/utsname.h>
+#include <linux/numa.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/system.h>
 #include <asm/semaphore.h>
+#include <asm/sections.h>
 
 /* Per cpu memory for storing cpu states in case of system crash. */
 note_buf_t* crash_notes;
 
+/* vmcoreinfo stuff */
+unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
+u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
+size_t vmcoreinfo_size;
+size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
+
+
 /* Location of the reserved area for the crash kernel */
 struct resource crashk_res = {
 	.name  = "Crash kernel",
@@ -1106,6 +1119,7 @@ void crash_kexec(struct pt_regs *regs)
 		if (kexec_crash_image) {
 			struct pt_regs fixed_regs;
 			crash_setup_regs(&fixed_regs, regs);
+			crash_save_vmcoreinfo();
 			machine_crash_shutdown(&fixed_regs);
 			machine_kexec(kexec_crash_image);
 		}
@@ -1113,6 +1127,34 @@ void crash_kexec(struct pt_regs *regs)
 	}
 }
 
+static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
+                            size_t data_len)
+{
+	struct elf_note note;
+
+	note.n_namesz = strlen(name) + 1;
+	note.n_descsz = data_len;
+	note.n_type   = type;
+	memcpy(buf, &note, sizeof(note));
+	buf += (sizeof(note) + 3)/4;
+	memcpy(buf, name, note.n_namesz);
+	buf += (note.n_namesz + 3)/4;
+	memcpy(buf, data, note.n_descsz);
+	buf += (note.n_descsz + 3)/4;
+
+	return buf;
+}
+
+static void final_note(u32 *buf)
+{
+	struct elf_note note;
+
+	note.n_namesz = 0;
+	note.n_descsz = 0;
+	note.n_type   = 0;
+	memcpy(buf, &note, sizeof(note));
+}
+
 static int __init crash_notes_memory_init(void)
 {
 	/* Allocate memory for saving cpu registers. */
@@ -1125,3 +1167,106 @@ static int __init crash_notes_memory_init(void)
 	return 0;
 }
 module_init(crash_notes_memory_init)
+
+void crash_save_vmcoreinfo(void)
+{
+	u32 *buf;
+
+	if (!vmcoreinfo_size)
+		return;
+
+	vmcoreinfo_append_str("CRASHTIME=%ld", get_seconds());
+
+	buf = (u32 *)vmcoreinfo_note;
+
+	buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
+			      vmcoreinfo_size);
+
+	final_note(buf);
+}
+
+void vmcoreinfo_append_str(const char *fmt, ...)
+{
+	va_list args;
+	char buf[0x50];
+	int r;
+
+	va_start(args, fmt);
+	r = vsnprintf(buf, sizeof(buf), fmt, args);
+	va_end(args);
+
+	if (r + vmcoreinfo_size > vmcoreinfo_max_size)
+		r = vmcoreinfo_max_size - vmcoreinfo_size;
+
+	memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
+
+	vmcoreinfo_size += r;
+}
+
+/*
+ * provide an empty default implementation here -- architecture
+ * code may override this
+ */
+void __attribute__ ((weak)) arch_crash_save_vmcoreinfo(void)
+{}
+
+#ifndef __pa_symbol
+#define __pa_symbol __pa
+#endif
+unsigned long __attribute__ ((weak)) paddr_vmcoreinfo_note(void)
+{
+	return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note);
+}
+
+static int __init crash_save_vmcoreinfo_init(void)
+{
+	vmcoreinfo_append_str("OSRELEASE=%s\n", init_uts_ns.name.release);
+	vmcoreinfo_append_str("PAGESIZE=%ld\n", PAGE_SIZE);
+
+	SYMBOL(init_uts_ns);
+	SYMBOL(node_online_map);
+	SYMBOL(swapper_pg_dir);
+	SYMBOL(_stext);
+
+#ifndef CONFIG_NEED_MULTIPLE_NODES
+	SYMBOL(mem_map);
+	SYMBOL(contig_page_data);
+#endif
+#ifdef CONFIG_SPARSEMEM
+	SYMBOL(mem_section);
+	LENGTH(mem_section, NR_SECTION_ROOTS);
+	SIZE(mem_section);
+	OFFSET(mem_section, section_mem_map);
+#endif
+	SIZE(page);
+	SIZE(pglist_data);
+	SIZE(zone);
+	SIZE(free_area);
+	SIZE(list_head);
+	TYPEDEF_SIZE(nodemask_t);
+	OFFSET(page, flags);
+	OFFSET(page, _count);
+	OFFSET(page, mapping);
+	OFFSET(page, lru);
+	OFFSET(pglist_data, node_zones);
+	OFFSET(pglist_data, nr_zones);
+#ifdef CONFIG_FLAT_NODE_MEM_MAP
+	OFFSET(pglist_data, node_mem_map);
+#endif
+	OFFSET(pglist_data, node_start_pfn);
+	OFFSET(pglist_data, node_spanned_pages);
+	OFFSET(pglist_data, node_id);
+	OFFSET(zone, free_area);
+	OFFSET(zone, vm_stat);
+	OFFSET(zone, spanned_pages);
+	OFFSET(free_area, free_list);
+	OFFSET(list_head, next);
+	OFFSET(list_head, prev);
+	LENGTH(zone.free_area, MAX_ORDER);
+
+	arch_crash_save_vmcoreinfo();
+
+	return 0;
+}
+
+module_init(crash_save_vmcoreinfo_init)
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index e0ffe4a..6ea6c10 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -60,6 +60,15 @@ static ssize_t kexec_crash_loaded_show(struct subsystem *subsys, char *page)
 	return sprintf(page, "%d\n", !!kexec_crash_image);
 }
 KERNEL_ATTR_RO(kexec_crash_loaded);
+
+static ssize_t vmcoreinfo_show(struct kset *kset, char *page)
+{
+	return sprintf(page, "%lx %x\n",
+		       paddr_vmcoreinfo_note(),
+		       (unsigned int)vmcoreinfo_max_size);
+}
+KERNEL_ATTR_RO(vmcoreinfo);
+
 #endif /* CONFIG_KEXEC */
 
 decl_subsys(kernel, NULL, NULL);
@@ -73,6 +82,7 @@ static struct attribute * kernel_attrs[] = {
 #ifdef CONFIG_KEXEC
 	&kexec_loaded_attr.attr,
 	&kexec_crash_loaded_attr.attr,
+	&vmcoreinfo_attr.attr,
 #endif
 	NULL
 };