[PATCH 4.17 072/220] arm64: kpti: Use early_param for kpti= command-line option

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Will Deacon <will.deacon@xxxxxxx>

commit b5b7dd647f2d21b93f734ce890671cd908e69b0a upstream.

We inspect __kpti_forced early on as part of the cpufeature enable
callback which remaps the swapper page table using non-global entries.

Ensure that __kpti_forced has been updated to reflect the kpti=
command-line option before we start using it.

Fixes: ea1e3de85e94 ("arm64: entry: Add fake CPU feature for unmapping the kernel at EL0")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.16.x-
Reported-by: Wei Xu <xuwei5@xxxxxxxxxxxxx>
Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Tested-by: Wei Xu <xuwei5@xxxxxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/arm64/kernel/cpufeature.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -937,7 +937,7 @@ static int __init parse_kpti(char *str)
 	__kpti_forced = enabled ? 1 : -1;
 	return 0;
 }
-__setup("kpti=", parse_kpti);
+early_param("kpti", parse_kpti);
 #endif	/* CONFIG_UNMAP_KERNEL_AT_EL0 */
 
 #ifdef CONFIG_ARM64_HW_AFDBM