Commit 6a3d1e81 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390: correct nospec auto detection init order 



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: 6e179d64 ("s390: add automatic detection of the spectre defense")
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent af4a7227

arch/s390/include/asm/nospec-branch.h

+1 −0
Original line number Diff line number Diff line
@@ -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__ */

arch/s390/kernel/nospec-branch.c

+2 −6
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ 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)) {

		/*
@@ -87,11 +87,7 @@ 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)

{
@@ -102,7 +98,7 @@ 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);

arch/s390/kernel/setup.c

+3 −0
Original line number Diff line number Diff line
@@ -894,6 +894,9 @@ 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 */

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