linux-kernel - [PATCH 4.9 031/101] arm64: kpti: Use early

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Message-Id: <20180701160758.404235963@linuxfoundation.org>
Date:   Sun,  1 Jul 2018 18:21:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wei Xu <xuwei5@...ilicon.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH 4.9 031/101] arm64: kpti: Use early_param for kpti= command-line option

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

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

From: Will Deacon <will.deacon@....com>

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@...r.kernel.org> # 4.16.x-
Reported-by: Wei Xu <xuwei5@...ilicon.com>
Tested-by: Sudeep Holla <sudeep.holla@....com>
Tested-by: Wei Xu <xuwei5@...ilicon.com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
@@ -826,7 +826,7 @@ 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 */
 
 static const struct arm64_cpu_capabilities arm64_features[] = {