s390/early: fix sclp_early_sccb variable lifetime

BugLink: https://bugs.launchpad.net/bugs/2011425
[ Upstream commit 639886b71ddef085a0e7bb1f225b8ae3eda5c06f ]

Commit ada1da31ce34 ("s390/sclp: sort out physical vs
virtual pointers usage") fixed the notion of virtual
address for sclp_early_sccb pointer. However, it did
not take into account that kasan_early_init() can also
output messages and sclp_early_sccb should be adjusted
by the time kasan_early_init() is called.

Currently it is not a problem, since virtual and physical
addresses on s390 are the same. Nevertheless, should they
ever differ, this would cause an invalid pointer access.

Fixes: ada1da31ce34 ("s390/sclp: sort out physical vs virtual pointers usage")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 9e058ed24d5ba6b4cd73c0cc6f1937bd80535815..0dd50a5dd3795cbdcf7e2645fc337e2054e3cc4d 100644 (file)
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -290,7 +290,6 @@ static void __init sort_amode31_extable(void)
 
 void __init startup_init(void)
 {
-       sclp_early_adjust_va();
        reset_tod_clock();
        check_image_bootable();
        time_early_init();

diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index d7b8b6ad574dcc170c110e41815d801e04ef88d7..3b3bf8329e6c1c03f84c35d9fe46a13da04b8e8f 100644 (file)
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -25,6 +25,7 @@ ENTRY(startup_continue)
        larl    %r14,init_task
        stg     %r14,__LC_CURRENT
        larl    %r15,init_thread_union+THREAD_SIZE-STACK_FRAME_OVERHEAD-__PT_SIZE
+       brasl   %r14,sclp_early_adjust_va       # allow sclp_early_printk
 #ifdef CONFIG_KASAN
        brasl   %r14,kasan_early_init
 #endif

diff --git a/drivers/s390/char/sclp_early.c b/drivers/s390/char/sclp_early.c
index c1c70a161c0e21c03532a14508783f8a91e7468c..f480d6c7fd399b6b8ccb2bbd4e0b611c5719f5bf 100644 (file)
--- a/drivers/s390/char/sclp_early.c
+++ b/drivers/s390/char/sclp_early.c
@@ -163,7 +163,7 @@ static void __init sclp_early_console_detect(struct init_sccb *sccb)
                sclp.has_linemode = 1;
 }
 
-void __init sclp_early_adjust_va(void)
+void __init __no_sanitize_address sclp_early_adjust_va(void)
 {
        sclp_early_sccb = __va((unsigned long)sclp_early_sccb);
 }