From: James Morse <james.morse@arm.com>
Date: Fri, 23 Feb 2018 14:31:42 +0000 (+0800)
Subject: arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early
X-Git-Tag: C0P2-H0.0--20200415~109
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=8af8958bca687f1d6bc5f0e32b8c2e604ac8681a;p=linux.git

arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early

commit edf298cfce47 upstream.
Alex Shi rewrite this commit on func this_cpu_has_cap(). The following commit
log is still meaningful.

    this_cpu_has_cap() tests caps->desc not caps->matches, so it stops
    walking the list when it finds a 'silent' feature, instead of
    walking to the end of the list.

    Prior to v4.6's 644c2ae198412 ("arm64: cpufeature: Test 'matches' pointer
    to find the end of the list") we always tested desc to find the end of
    a capability list. This was changed for dubious things like PAN_NOT_UAO.
    v4.7's e3661b128e53e ("arm64: Allow a capability to be checked on
    single CPU") added this_cpu_has_cap() using the old desc style test.

    CC: Suzuki K Poulose <suzuki.poulose@arm.com>
    Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    Acked-by: Marc Zyngier <marc.zyngier@arm.com>
    Signed-off-by: James Morse <james.morse@arm.com>
    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
    Signed-off-by: Will Deacon <will.deacon@arm.com>

Signed-off-by: Alex Shi <alex.shi@linaro.org>
---

diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
index 1943cf623366..718140af469c 100644
--- a/arch/arm64/include/asm/futex.h
+++ b/arch/arm64/include/asm/futex.h
@@ -20,6 +20,7 @@
 
 #include <linux/futex.h>
 #include <linux/uaccess.h>
+#include <linux/compiler.h>
 
 #include <asm/errno.h>
 
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 760c851439b1..df57d48e2ab5 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1024,9 +1024,8 @@ static bool __this_cpu_has_cap(const struct arm64_cpu_capabilities *cap_array,
 	if (WARN_ON(preemptible()))
 		return false;
 
-	for (caps = cap_array; caps->desc; caps++)
+	for (caps = cap_array; caps->matches; caps++)
 		if (caps->capability == cap &&
-		    caps->matches &&
 		    caps->matches(caps, SCOPE_LOCAL_CPU))
 			return true;
 	return false;