s390: correct nospec auto detection init order

[ Upstream commit 6a3d1e81a434fc311f224b8be77258bafc18ccc6 ]

With CONFIG_EXPOLINE_AUTO=y the call of spectre_v2_auto_early() via
early_initcall is done *after* the early_param functions. This
overwrites any settings done with the nobp/no_spectre_v2/spectre_v2
parameters. The code patching for the kernel is done after the
evaluation of the early parameters but before the early_initcall
is done. The end result is a kernel image that is patched correctly
but the kernel modules are not.

Make sure that the nospec auto detection function is called before the
early parameters are evaluated and before the code patching is done.

Fixes: 6e179d64126b ("s390: add automatic detection of the spectre defense")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/include/asm/nospec-branch.h b/arch/s390/include/asm/nospec-branch.h
index 35bf28fe4c648b7208d73dcd14abba7d0b6168a2..b4bd8c41e9d33d4f01ef8950be79f0fd02cd59c6 100644 (file)
--- a/arch/s390/include/asm/nospec-branch.h
+++ b/arch/s390/include/asm/nospec-branch.h
@@ -9,6 +9,7 @@
 extern int nospec_disable;
 
 void nospec_init_branches(void);
+void nospec_auto_detect(void);
 void nospec_revert(s32 *start, s32 *end);
 
 #endif /* __ASSEMBLY__ */

diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c
index 73c06d42792df56c41badc5584ec7bbc716539c2..9f3b5b3827435f62f1279872033a508355c6292c 100644 (file)
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -73,7 +73,7 @@ static int __init nospectre_v2_setup_early(char *str)
 }
 early_param("nospectre_v2", nospectre_v2_setup_early);
 
-static int __init spectre_v2_auto_early(void)
+void __init nospec_auto_detect(void)
 {
        if (IS_ENABLED(CC_USING_EXPOLINE)) {
                /*
@@ -88,11 +88,7 @@ static int __init spectre_v2_auto_early(void)
         * nobp setting decides what is done, this depends on the
         * CONFIG_KERNEL_NP option and the nobp/nospec parameters.
         */
-       return 0;
 }
-#ifdef CONFIG_EXPOLINE_AUTO
-early_initcall(spectre_v2_auto_early);
-#endif
 
 static int __init spectre_v2_setup_early(char *str)
 {
@@ -103,7 +99,7 @@ static int __init spectre_v2_setup_early(char *str)
        if (str && !strncmp(str, "off", 3))
                nospec_disable = 1;
        if (str && !strncmp(str, "auto", 4))
-               spectre_v2_auto_early();
+               nospec_auto_detect();
        return 0;
 }
 early_param("spectre_v2", spectre_v2_setup_early);

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 63d5cbb9a8b40fa8ca8405d436e24633b7907494..98c1f79411426a18384c2e6bcb645af91649842d 100644 (file)
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -897,6 +897,9 @@ void __init setup_arch(char **cmdline_p)
        init_mm.end_data = (unsigned long) &_edata;
        init_mm.brk = (unsigned long) &_end;
 
+       if (IS_ENABLED(CONFIG_EXPOLINE_AUTO))
+               nospec_auto_detect();
+
        parse_early_param();
 #ifdef CONFIG_CRASH_DUMP
        /* Deactivate elfcorehdr= kernel parameter */