linux-kernel - [PATCH 21/29] arm64: capabilities: Handle duplicate entries for a capability

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Date:   Wed, 28 Feb 2018 11:56:43 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        stable@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Suzuki K Poulose <suzuki.poulose@....com>,
        Mark Rutland <mark.rutland@....com>,
        Alex Shi <alex.shi@...aro.org>
Subject: [PATCH 21/29] arm64: capabilities: Handle duplicate entries for a capability

From: Suzuki K Poulose <suzuki.poulose@....com>

commit 67948af41f2e upstream.

Sometimes a single capability could be listed multiple times with
differing matches(), e.g, CPU errata for different MIDR versions.
This breaks verify_local_cpu_feature() and this_cpu_has_cap() as
we stop checking for a capability on a CPU with the first
entry in the given table, which is not sufficient. Make sure we
run the checks for all entries of the same capability. We do
this by fixing __this_cpu_has_cap() to run through all the
entries in the given table for a match and reuse it for
verify_local_cpu_feature().

Cc: Mark Rutland <mark.rutland@....com>
Cc: Will Deacon <will.deacon@....com>
Acked-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Alex Shi <alex.shi@...aro.org>

Conflicts:
	arch/arm64/kernel/cpufeature.c
---
 arch/arm64/kernel/cpufeature.c | 44 ++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4e5dff1..6200b81 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -969,6 +969,26 @@ static void __init setup_elf_hwcaps(const struct arm64_cpu_capabilities *hwcaps)
 			cap_set_elf_hwcap(hwcaps);
 }
 
+/*
+ * Check if the current CPU has a given feature capability.
+ * Should be called from non-preemptible context.
+ */
+static bool __this_cpu_has_cap(const struct arm64_cpu_capabilities *cap_array,
+			       unsigned int cap)
+{
+	const struct arm64_cpu_capabilities *caps;
+
+	if (WARN_ON(preemptible()))
+		return false;
+
+	for (caps = cap_array; caps->desc; caps++)
+		if (caps->capability == cap &&
+		    caps->matches &&
+		    caps->matches(caps, SCOPE_LOCAL_CPU))
+			return true;
+	return false;
+}
+
 void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
 			    const char *info)
 {
@@ -1037,8 +1057,9 @@ verify_local_elf_hwcaps(const struct arm64_cpu_capabilities *caps)
 }
 
 static void
-verify_local_cpu_features(const struct arm64_cpu_capabilities *caps)
+verify_local_cpu_features(const struct arm64_cpu_capabilities *caps_list)
 {
+	const struct arm64_cpu_capabilities *caps = caps_list;
 	for (; caps->matches; caps++) {
 		if (!cpus_have_cap(caps->capability))
 			continue;
@@ -1046,7 +1067,7 @@ verify_local_cpu_features(const struct arm64_cpu_capabilities *caps)
 		 * If the new CPU misses an advertised feature, we cannot proceed
 		 * further, park the cpu.
 		 */
-		if (!caps->matches(caps, SCOPE_LOCAL_CPU)) {
+		if (!__this_cpu_has_cap(caps_list, caps->capability)) {
 			pr_crit("CPU%d: missing feature: %s\n",
 					smp_processor_id(), caps->desc);
 			cpu_die_early();
@@ -1099,25 +1120,6 @@ static void __init setup_feature_capabilities(void)
 	enable_cpu_capabilities(arm64_features);
 }
 
-/*
- * Check if the current CPU has a given feature capability.
- * Should be called from non-preemptible context.
- */
-static bool __this_cpu_has_cap(const struct arm64_cpu_capabilities *cap_array,
-			       unsigned int cap)
-{
-	const struct arm64_cpu_capabilities *caps;
-
-	if (WARN_ON(preemptible()))
-		return false;
-
-	for (caps = cap_array; caps->desc; caps++)
-		if (caps->capability == cap && caps->matches)
-			return caps->matches(caps, SCOPE_LOCAL_CPU);
-
-	return false;
-}
-
 extern const struct arm64_cpu_capabilities arm64_errata[];
 
 bool this_cpu_has_cap(unsigned int cap)
-- 
2.7.4