Merge tag 's390-6.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Heiko Carstens:

 - With CONFIG_VMAP_STACK enabled it is not possible to load the s390
   specific diag288_wdt watchdog module. The reason is that a pointer to
   a string is passed to an inline assembly; this string however is
   located on the stack, while the instruction within the inline
   assembly expects a physicial address. Fix this by copying the string
   to a kmalloc'ed buffer.

 - The diag288_wdt watchdog module does not indicate that it accesses
   memory from an inline assembly, which it does. Add "memory" to the
   clobber list to prevent the compiler from optimizing code incorrectly
   away.

 - Pass size of the uncompressed kernel image to __decompress() call.
   Otherwise the kernel image decompressor may corrupt/overwrite an
   initrd. This was reported to happen on s390 after commit 2aa14b1ab2c4
   ("zstd: import usptream v1.5.2").

* tag 's390-6.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/decompressor: specify __decompress() buf len to avoid overflow
  watchdog: diag288_wdt: fix __diag288() inline assembly
  watchdog: diag288_wdt: do not use stack buffers for hardware data

2 files changed, 13 insertions, 4 deletions

diff --git a/arch/s390/boot/decompressor.c b/arch/s390/boot/decompressor.c
index 8dcd7af2911a07..b519a1f045d8f2 100644
--- a/arch/s390/boot/decompressor.c
+++ b/arch/s390/boot/decompressor.c
@@ -80,6 +80,6 @@ void *decompress_kernel(void)
 	void *output = (void *)decompress_offset;
 
 	__decompress(_compressed_start, _compressed_end - _compressed_start,
-		     NULL, NULL, output, 0, NULL, error);
+		     NULL, NULL, output, vmlinux.image_size, NULL, error);
 	return output;
 }
diff --git a/drivers/watchdog/diag288_wdt.c b/drivers/watchdog/diag288_wdt.c
index 4cb10877017c77..6ca5d9515d85ca 100644
--- a/drivers/watchdog/diag288_wdt.c
+++ b/drivers/watchdog/diag288_wdt.c
@@ -86,7 +86,7 @@ static int __diag288(unsigned int func, unsigned int timeout,
 		"1:\n"
 		EX_TABLE(0b, 1b)
 		: "+d" (err) : "d"(__func), "d"(__timeout),
-		  "d"(__action), "d"(__len) : "1", "cc");
+		  "d"(__action), "d"(__len) : "1", "cc", "memory");
 	return err;
 }
 
@@ -268,12 +268,21 @@ static int __init diag288_init(void)
 	char ebc_begin[] = {
 		194, 197, 199, 201, 213
 	};
+	char *ebc_cmd;
 
 	watchdog_set_nowayout(&wdt_dev, nowayout_info);
 
 	if (MACHINE_IS_VM) {
-		if (__diag288_vm(WDT_FUNC_INIT, 15,
-				 ebc_begin, sizeof(ebc_begin)) != 0) {
+		ebc_cmd = kmalloc(sizeof(ebc_begin), GFP_KERNEL);
+		if (!ebc_cmd) {
+			pr_err("The watchdog cannot be initialized\n");
+			return -ENOMEM;
+		}
+		memcpy(ebc_cmd, ebc_begin, sizeof(ebc_begin));
+		ret = __diag288_vm(WDT_FUNC_INIT, 15,
+				   ebc_cmd, sizeof(ebc_begin));
+		kfree(ebc_cmd);
+		if (ret != 0) {
 			pr_err("The watchdog cannot be initialized\n");
 			return -EINVAL;
 		}