[S390] kernel: Add OS info memory interface

In order to allow kdump based stand-alone dump, some information
has to be passed from the old kernel to the new dump kernel. This
is done via a the struct "os_info" that contains the following fields:
 * crashkernel base and size
 * reipl block
 * vmcoreinfo
 * init function
A pointer to os_info is stored at a well known storage location
and the whole structure as well as all fields are secured with
checksums.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/lowcore.h

@@ -154,7 +154,9 @@ struct _lowcore {
 	__u32	ipib;				/* 0x0e00 */
 	__u32	ipib_checksum;			/* 0x0e04 */
 	__u32	vmcore_info;			/* 0x0e08 */
-	__u8	pad_0x0e0c[0x0f00-0x0e0c];	/* 0x0e0c */
+	__u8	pad_0x0e0c[0x0e18-0x0e0c];	/* 0x0e0c */
+	__u32	os_info;			/* 0x0e18 */
+	__u8	pad_0x0e1c[0x0f00-0x0e1c];	/* 0x0e1c */
 
 	/* Extended facility list */
 	__u64	stfle_fac_list[32];		/* 0x0f00 */
@@ -301,7 +303,9 @@ struct _lowcore {
 	__u64	ipib;				/* 0x0e00 */
 	__u32	ipib_checksum;			/* 0x0e08 */
 	__u64	vmcore_info;			/* 0x0e0c */
-	__u8	pad_0x0e14[0x0f00-0x0e14];	/* 0x0e14 */
+	__u8	pad_0x0e14[0x0e18-0x0e14];	/* 0x0e14 */
+	__u64	os_info;			/* 0x0e18 */
+	__u8	pad_0x0e20[0x0f00-0x0e20];	/* 0x0e20 */
 
 	/* Extended facility list */
 	__u64	stfle_fac_list[32];		/* 0x0f00 */

arch/s390/include/asm/os_info.h

@@ -0,0 +1,50 @@
+/*
+ * OS info memory interface
+ *
+ * Copyright IBM Corp. 2012
+ * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
+ */
+#ifndef _ASM_S390_OS_INFO_H
+#define _ASM_S390_OS_INFO_H
+
+#define OS_INFO_VERSION_MAJOR	1
+#define OS_INFO_VERSION_MINOR	1
+#define OS_INFO_MAGIC		0x4f53494e464f535aULL /* OSINFOSZ */
+
+#define OS_INFO_VMCOREINFO	0
+#define OS_INFO_REIPL_BLOCK	1
+#define OS_INFO_INIT_FN		2
+
+struct os_info_entry {
+	u64	addr;
+	u64	size;
+	u32	csum;
+} __packed;
+
+struct os_info {
+	u64	magic;
+	u32	csum;
+	u16	version_major;
+	u16	version_minor;
+	u64	crashkernel_addr;
+	u64	crashkernel_size;
+	struct os_info_entry entry[3];
+	u8	reserved[4004];
+} __packed;
+
+void os_info_init(void);
+void os_info_entry_add(int nr, void *ptr, u64 len);
+void os_info_crashkernel_add(unsigned long base, unsigned long size);
+u32 os_info_csum(struct os_info *os_info);
+
+#ifdef CONFIG_CRASH_DUMP
+void *os_info_old_entry(int nr, unsigned long *size);
+int copy_from_oldmem(void *dest, void *src, size_t count);
+#else
+static inline void *os_info_old_entry(int nr, unsigned long *size)
+{
+	return NULL;
+}
+#endif
+
+#endif /* _ASM_S390_OS_INFO_H */

arch/s390/kernel/Makefile

@@ -23,7 +23,7 @@ CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
 obj-y	:=  bitmap.o traps.o time.o process.o base.o early.o setup.o vtime.o \
 	    processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o \
 	    debug.o irq.o ipl.o dis.o diag.o mem_detect.o sclp.o vdso.o \
-	    sysinfo.o jump_label.o lgr.o
+	    sysinfo.o jump_label.o lgr.o os_info.o
 
 obj-y	+= $(if $(CONFIG_64BIT),entry64.o,entry.o)
 obj-y	+= $(if $(CONFIG_64BIT),reipl64.o,reipl.o)

arch/s390/kernel/crash_dump.c

@@ -14,6 +14,7 @@
 #include <linux/bootmem.h>
 #include <linux/elf.h>
 #include <asm/ipl.h>
+#include <asm/os_info.h>
 
 #define PTR_ADD(x, y) (((char *) (x)) + ((unsigned long) (y)))
 #define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
@@ -51,7 +52,7 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 /*
  * Copy memory from old kernel
  */
-static int copy_from_oldmem(void *dest, void *src, size_t count)
+int copy_from_oldmem(void *dest, void *src, size_t count)
 {
 	unsigned long copied = 0;
 	int rc;
@@ -224,28 +225,44 @@ static void *nt_prpsinfo(void *ptr)
 }
 
 /*
- * Initialize vmcoreinfo note (new kernel)
+ * Get vmcoreinfo using lowcore->vmcore_info (new kernel)
  */
-static void *nt_vmcoreinfo(void *ptr)
+static void *get_vmcoreinfo_old(unsigned long *size)
 {
 	char nt_name[11], *vmcoreinfo;
 	Elf64_Nhdr note;
 	void *addr;
 
 	if (copy_from_oldmem(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
-		return ptr;
+		return NULL;
 	memset(nt_name, 0, sizeof(nt_name));
 	if (copy_from_oldmem(&note, addr, sizeof(note)))
-		return ptr;
+		return NULL;
 	if (copy_from_oldmem(nt_name, addr + sizeof(note), sizeof(nt_name) - 1))
-		return ptr;
+		return NULL;
 	if (strcmp(nt_name, "VMCOREINFO") != 0)
-		return ptr;
-	vmcoreinfo = kzalloc_panic(note.n_descsz + 1);
+		return NULL;
+	vmcoreinfo = kzalloc_panic(note.n_descsz);
 	if (copy_from_oldmem(vmcoreinfo, addr + 24, note.n_descsz))
+		return NULL;
+	*size = note.n_descsz;
+	return vmcoreinfo;
+}
+
+/*
+ * Initialize vmcoreinfo note (new kernel)
+ */
+static void *nt_vmcoreinfo(void *ptr)
+{
+	unsigned long size;
+	void *vmcoreinfo;
+
+	vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
+	if (!vmcoreinfo)
+		vmcoreinfo = get_vmcoreinfo_old(&size);
+	if (!vmcoreinfo)
 		return ptr;
-	vmcoreinfo[note.n_descsz + 1] = 0;
-	return nt_init(ptr, 0, vmcoreinfo, note.n_descsz, "VMCOREINFO");
+	return nt_init(ptr, 0, vmcoreinfo, size, "VMCOREINFO");
 }
 
 /*

arch/s390/kernel/ipl.c

@@ -28,6 +28,7 @@
 #include <asm/sclp.h>
 #include <asm/checksum.h>
 #include <asm/debug.h>
+#include <asm/os_info.h>
 #include "entry.h"
 
 #define IPL_PARM_BLOCK_VERSION 0
@@ -951,6 +952,13 @@ static struct attribute_group reipl_nss_attr_group = {
 	.attrs = reipl_nss_attrs,
 };
 
+static void set_reipl_block_actual(struct ipl_parameter_block *reipl_block)
+{
+	reipl_block_actual = reipl_block;
+	os_info_entry_add(OS_INFO_REIPL_BLOCK, reipl_block_actual,
+			  reipl_block->hdr.len);
+}
+
 /* reipl type */
 
 static int reipl_set_type(enum ipl_type type)
@@ -966,7 +974,7 @@ static int reipl_set_type(enum ipl_type type)
 			reipl_method = REIPL_METHOD_CCW_VM;
 		else
 			reipl_method = REIPL_METHOD_CCW_CIO;
-		reipl_block_actual = reipl_block_ccw;
+		set_reipl_block_actual(reipl_block_ccw);
 		break;
 	case IPL_TYPE_FCP:
 		if (diag308_set_works)
@@ -975,7 +983,7 @@ static int reipl_set_type(enum ipl_type type)
 			reipl_method = REIPL_METHOD_FCP_RO_VM;
 		else
 			reipl_method = REIPL_METHOD_FCP_RO_DIAG;
-		reipl_block_actual = reipl_block_fcp;
+		set_reipl_block_actual(reipl_block_fcp);
 		break;
 	case IPL_TYPE_FCP_DUMP:
 		reipl_method = REIPL_METHOD_FCP_DUMP;
@@ -985,7 +993,7 @@ static int reipl_set_type(enum ipl_type type)
 			reipl_method = REIPL_METHOD_NSS_DIAG;
 		else
 			reipl_method = REIPL_METHOD_NSS;
-		reipl_block_actual = reipl_block_nss;
+		set_reipl_block_actual(reipl_block_nss);
 		break;
 	case IPL_TYPE_UNKNOWN:
 		reipl_method = REIPL_METHOD_DEFAULT;
@@ -1257,6 +1265,29 @@ static int __init reipl_fcp_init(void)
 	return 0;
 }
 
+static int __init reipl_type_init(void)
+{
+	enum ipl_type reipl_type = ipl_info.type;
+	struct ipl_parameter_block *reipl_block;
+	unsigned long size;
+
+	reipl_block = os_info_old_entry(OS_INFO_REIPL_BLOCK, &size);
+	if (!reipl_block)
+		goto out;
+	/*
+	 * If we have an OS info reipl block, this will be used
+	 */
+	if (reipl_block->hdr.pbt == DIAG308_IPL_TYPE_FCP) {
+		memcpy(reipl_block_fcp, reipl_block, size);
+		reipl_type = IPL_TYPE_FCP;
+	} else if (reipl_block->hdr.pbt == DIAG308_IPL_TYPE_CCW) {
+		memcpy(reipl_block_ccw, reipl_block, size);
+		reipl_type = IPL_TYPE_CCW;
+	}
+out:
+	return reipl_set_type(reipl_type);
+}
+
 static int __init reipl_init(void)
 {
 	int rc;
@@ -1278,10 +1309,7 @@ static int __init reipl_init(void)
 	rc = reipl_nss_init();
 	if (rc)
 		return rc;
-	rc = reipl_set_type(ipl_info.type);
-	if (rc)
-		return rc;
-	return 0;
+	return reipl_type_init();
 }
 
 static struct shutdown_action __refdata reipl_action = {

arch/s390/kernel/os_info.c

@@ -0,0 +1,169 @@
+/*
+ * OS info memory interface
+ *
+ * Copyright IBM Corp. 2012
+ * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
+ */
+
+#define KMSG_COMPONENT "os_info"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/crash_dump.h>
+#include <linux/kernel.h>
+#include <asm/checksum.h>
+#include <asm/lowcore.h>
+#include <asm/system.h>
+#include <asm/os_info.h>
+
+/*
+ * OS info structure has to be page aligned
+ */
+static struct os_info os_info __page_aligned_data;
+
+/*
+ * Compute checksum over OS info structure
+ */
+u32 os_info_csum(struct os_info *os_info)
+{
+	int size = sizeof(*os_info) - offsetof(struct os_info, version_major);
+	return csum_partial(&os_info->version_major, size, 0);
+}
+
+/*
+ * Add crashkernel info to OS info and update checksum
+ */
+void os_info_crashkernel_add(unsigned long base, unsigned long size)
+{
+	os_info.crashkernel_addr = (u64)(unsigned long)base;
+	os_info.crashkernel_size = (u64)(unsigned long)size;
+	os_info.csum = os_info_csum(&os_info);
+}
+
+/*
+ * Add OS info entry and update checksum
+ */
+void os_info_entry_add(int nr, void *ptr, u64 size)
+{
+	os_info.entry[nr].addr = (u64)(unsigned long)ptr;
+	os_info.entry[nr].size = size;
+	os_info.entry[nr].csum = csum_partial(ptr, size, 0);
+	os_info.csum = os_info_csum(&os_info);
+}
+
+/*
+ * Initialize OS info struture and set lowcore pointer
+ */
+void __init os_info_init(void)
+{
+	void *ptr = &os_info;
+
+	os_info.version_major = OS_INFO_VERSION_MAJOR;
+	os_info.version_minor = OS_INFO_VERSION_MINOR;
+	os_info.magic = OS_INFO_MAGIC;
+	os_info.csum = os_info_csum(&os_info);
+	copy_to_absolute_zero(&S390_lowcore.os_info, &ptr, sizeof(ptr));
+}
+
+#ifdef CONFIG_CRASH_DUMP
+
+static struct os_info *os_info_old;
+
+/*
+ * Allocate and copy OS info entry from oldmem
+ */
+static void os_info_old_alloc(int nr, int align)
+{
+	unsigned long addr, size = 0;
+	char *buf, *buf_align, *msg;
+	u32 csum;
+
+	addr = os_info_old->entry[nr].addr;
+	if (!addr) {
+		msg = "not available";
+		goto fail;
+	}
+	size = os_info_old->entry[nr].size;
+	buf = kmalloc(size + align - 1, GFP_KERNEL);
+	if (!buf) {
+		msg = "alloc failed";
+		goto fail;
+	}
+	buf_align = PTR_ALIGN(buf, align);
+	if (copy_from_oldmem(buf_align, (void *) addr, size)) {
+		msg = "copy failed";
+		goto fail_free;
+	}
+	csum = csum_partial(buf_align, size, 0);
+	if (csum != os_info_old->entry[nr].csum) {
+		msg = "checksum failed";
+		goto fail_free;
+	}
+	os_info_old->entry[nr].addr = (u64)(unsigned long)buf_align;
+	msg = "copied";
+	goto out;
+fail_free:
+	kfree(buf);
+fail:
+	os_info_old->entry[nr].addr = 0;
+out:
+	pr_info("entry %i: %s (addr=0x%lx size=%lu)\n",
+		nr, msg, addr, size);
+}
+
+/*
+ * Initialize os info and os info entries from oldmem
+ */
+static void os_info_old_init(void)
+{
+	static int os_info_init;
+	unsigned long addr;
+
+	if (os_info_init)
+		return;
+	if (!OLDMEM_BASE)
+		goto fail;
+	if (copy_from_oldmem(&addr, &S390_lowcore.os_info, sizeof(addr)))
+		goto fail;
+	if (addr == 0 || addr % PAGE_SIZE)
+		goto fail;
+	os_info_old = kzalloc(sizeof(*os_info_old), GFP_KERNEL);
+	if (!os_info_old)
+		goto fail;
+	if (copy_from_oldmem(os_info_old, (void *) addr, sizeof(*os_info_old)))
+		goto fail_free;
+	if (os_info_old->magic != OS_INFO_MAGIC)
+		goto fail_free;
+	if (os_info_old->csum != os_info_csum(os_info_old))
+		goto fail_free;
+	if (os_info_old->version_major > OS_INFO_VERSION_MAJOR)
+		goto fail_free;
+	os_info_old_alloc(OS_INFO_VMCOREINFO, 1);
+	os_info_old_alloc(OS_INFO_REIPL_BLOCK, 1);
+	os_info_old_alloc(OS_INFO_INIT_FN, PAGE_SIZE);
+	pr_info("crashkernel: addr=0x%lx size=%lu\n",
+		(unsigned long) os_info_old->crashkernel_addr,
+		(unsigned long) os_info_old->crashkernel_size);
+	os_info_init = 1;
+	return;
+fail_free:
+	kfree(os_info_old);
+fail:
+	os_info_init = 1;
+	os_info_old = NULL;
+}
+
+/*
+ * Return pointer to os infor entry and its size
+ */
+void *os_info_old_entry(int nr, unsigned long *size)
+{
+	os_info_old_init();
+
+	if (!os_info_old)
+		return NULL;
+	if (!os_info_old->entry[nr].addr)
+		return NULL;
+	*size = (unsigned long) os_info_old->entry[nr].size;
+	return (void *)(unsigned long)os_info_old->entry[nr].addr;
+}
+#endif

arch/s390/kernel/setup.c

@@ -62,6 +62,7 @@
 #include <asm/ebcdic.h>
 #include <asm/kvm_virtio.h>
 #include <asm/diag.h>
+#include <asm/os_info.h>
 #include "entry.h"
 
 long psw_kernel_bits	= PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_ASC_PRIMARY |
@@ -778,6 +779,7 @@ static void __init reserve_crashkernel(void)
 	pr_info("Reserving %lluMB of memory at %lluMB "
 		"for crashkernel (System RAM: %luMB)\n",
 		crash_size >> 20, crash_base >> 20, memory_end >> 20);
+	os_info_crashkernel_add(crash_base, crash_size);
 #endif
 }
 
@@ -1057,6 +1059,7 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
+	os_info_init();
 	setup_ipl();
 	setup_memory_end();
 	setup_addressing_mode();

arch/s390/kernel/smp.c

@@ -41,6 +41,7 @@
 #include <asm/sclp.h>
 #include <asm/vdso.h>
 #include <asm/debug.h>
+#include <asm/os_info.h>
 #include "entry.h"
 
 enum {
@@ -826,6 +827,17 @@ void __noreturn cpu_die(void)
 
 #endif /* CONFIG_HOTPLUG_CPU */
 
+static void smp_call_os_info_init_fn(void)
+{
+	int (*init_fn)(void);
+	unsigned long size;
+
+	init_fn = os_info_old_entry(OS_INFO_INIT_FN, &size);
+	if (!init_fn)
+		return;
+	init_fn();
+}
+
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	/* request the 0x1201 emergency signal external interrupt */
@@ -834,6 +846,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	/* request the 0x1202 external call external interrupt */
 	if (register_external_interrupt(0x1202, do_ext_call_interrupt) != 0)
 		panic("Couldn't request external interrupt 0x1202");
+	smp_call_os_info_init_fn();
 	smp_detect_cpus();
 }