s390/zcore: conditionally clear memory on reipl

Currently zcore_reipl_write() always use DIAG308_LOAD_CLEAR to ipl the
system (used by ngdump and zfcpdump to ipl the original kernel after
dumping).
Instead of 'always clear' check OS_INFO_FLAG_REIPL_CLEAR flag and use
either LOAD_CLEAR or LOAD_NORMAL diag308 subcode accordingly.
For that read os_info and check for the valid os_info flags entry
in zcore_reipl_init(). Do not return error on failure (e.g. os_info
checksum error) in order to continue dump processing, considering
that os_info could be corrupted on the panicked system.

Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/drivers/s390/char/zcore.c b/drivers/s390/char/zcore.c
index 599f547310f8f4412795cc2d0071406d6640d384..942c73a11ca35c6cd3e3898e98632e0a769fce5f 100644 (file)
--- a/drivers/s390/char/zcore.c
+++ b/drivers/s390/char/zcore.c
@@ -51,6 +51,7 @@ static struct dentry *zcore_dir;
 static struct dentry *zcore_reipl_file;
 static struct dentry *zcore_hsa_file;
 static struct ipl_parameter_block *zcore_ipl_block;
+static unsigned long os_info_flags;
 
 static DEFINE_MUTEX(hsa_buf_mutex);
 static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
@@ -139,7 +140,13 @@ static ssize_t zcore_reipl_write(struct file *filp, const char __user *buf,
 {
        if (zcore_ipl_block) {
                diag308(DIAG308_SET, zcore_ipl_block);
-               diag308(DIAG308_LOAD_CLEAR, NULL);
+               if (os_info_flags & OS_INFO_FLAG_REIPL_CLEAR)
+                       diag308(DIAG308_LOAD_CLEAR, NULL);
+               /* Use special diag308 subcode for CCW normal ipl */
+               if (zcore_ipl_block->pb0_hdr.pbt == IPL_PBT_CCW)
+                       diag308(DIAG308_LOAD_NORMAL_DUMP, NULL);
+               else
+                       diag308(DIAG308_LOAD_NORMAL, NULL);
        }
        return count;
 }
@@ -212,7 +219,10 @@ static int __init check_sdias(void)
  */
 static int __init zcore_reipl_init(void)
 {
+       struct os_info_entry *entry;
        struct ipib_info ipib_info;
+       unsigned long os_info_addr;
+       struct os_info *os_info;
        int rc;
 
        rc = memcpy_hsa_kernel(&ipib_info, __LC_DUMP_REIPL, sizeof(ipib_info));
@@ -234,6 +244,35 @@ static int __init zcore_reipl_init(void)
                free_page((unsigned long) zcore_ipl_block);
                zcore_ipl_block = NULL;
        }
+       /*
+        * Read the bit-flags field from os_info flags entry.
+        * Return zero even for os_info read or entry checksum errors in order
+        * to continue dump processing, considering that os_info could be
+        * corrupted on the panicked system.
+        */
+       os_info = (void *)__get_free_page(GFP_KERNEL);
+       if (!os_info)
+               return -ENOMEM;
+       rc = memcpy_hsa_kernel(&os_info_addr, __LC_OS_INFO, sizeof(os_info_addr));
+       if (rc)
+               goto out;
+       if (os_info_addr < sclp.hsa_size)
+               rc = memcpy_hsa_kernel(os_info, os_info_addr, PAGE_SIZE);
+       else
+               rc = memcpy_real(os_info, os_info_addr, PAGE_SIZE);
+       if (rc || os_info_csum(os_info) != os_info->csum)
+               goto out;
+       entry = &os_info->entry[OS_INFO_FLAGS_ENTRY];
+       if (entry->addr && entry->size) {
+               if (entry->addr < sclp.hsa_size)
+                       rc = memcpy_hsa_kernel(&os_info_flags, entry->addr, sizeof(os_info_flags));
+               else
+                       rc = memcpy_real(&os_info_flags, entry->addr, sizeof(os_info_flags));
+               if (rc || (__force u32)csum_partial(&os_info_flags, entry->size, 0) != entry->csum)
+                       os_info_flags = 0;
+       }
+out:
+       free_page((unsigned long)os_info);
        return 0;
 }