[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>

1 files changed, 169 insertions, 0 deletions

diff --git a/arch/s390/kernel/os_info.c b/arch/s390/kernel/os_info.c
new file mode 100644
index 000000000000..bbe522672e06
--- /dev/null
+++ b/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