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s390/zcore: conditionally clear memory on reipl

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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>
This commit is contained in:
Mikhail Zaslonko 2023-05-09 17:38:15 +02:00 committed by Alexander Gordeev
parent 31e9ccc67c
commit 9f70bc890a
1 changed files with 40 additions and 1 deletions
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41
drivers/s390/char/zcore.c
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@ -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;
}