s390: clean .bss before running uncompressed kernel

Clean uncompressed kernel .bss section in the startup code before
the uncompressed kernel is executed. At this point of time initrd and
certificates have been already rescued. Uncompressed kernel .bss size
is known from vmlinux_info. It is also taken into consideration during
uncompressed kernel positioning by kaslr (so it is safe to clean it).

With that uncompressed kernel is starting with .bss section zeroed and
no .bss section usage restrictions apply. Which makes chkbss checks for
uncompressed kernel objects obsolete and they can be removed.

early_nobss.c is also not needed anymore. Parts of it which are still
relevant are moved to early.c. Kasan initialization code is now called
directly from head64 (early.c is instrumented and should not be
executed before kasan shadow memory is set up).

Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 6312fed48530..b432d63d0b37 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -32,6 +32,21 @@
 #include <asm/boot_data.h>
 #include "entry.h"
 
+static void __init reset_tod_clock(void)
+{
+	u64 time;
+
+	if (store_tod_clock(&time) == 0)
+		return;
+	/* TOD clock not running. Set the clock to Unix Epoch. */
+	if (set_tod_clock(TOD_UNIX_EPOCH) != 0 || store_tod_clock(&time) != 0)
+		disabled_wait();
+
+	memset(tod_clock_base, 0, 16);
+	*(__u64 *) &tod_clock_base[1] = TOD_UNIX_EPOCH;
+	S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;
+}
+
 /*
  * Initialize storage key for kernel pages
  */
@@ -301,6 +316,7 @@ static void __init check_image_bootable(void)
 
 void __init startup_init(void)
 {
+	reset_tod_clock();
 	check_image_bootable();
 	time_early_init();
 	init_kernel_storage_key();