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Patch "[Variant 3/Meltdown] arm64: capabilities: Handle duplicate entries for a capability" has been added to the 4.15-stable tree

PATCH [email protected] 1 participant 1 message Feb 13, 2018

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This is a note to let you know that I've just added the patch titled

[Variant 3/Meltdown] arm64: capabilities: Handle duplicate entries for a capability

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-capabilities-handle-duplicate-entries-for-a-capability.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Tue Feb 13 17:25:10 CET 2018

From: Suzuki K Poulose <[email protected]>
Date: Tue, 9 Jan 2018 16:12:18 +0000
Subject: [Variant 3/Meltdown] arm64: capabilities: Handle duplicate entries for a capability

From: Suzuki K Poulose <[email protected]>

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 <[email protected]>
Cc Will Deacon <[email protected]>
Acked-by Marc Zyngier <[email protected]>
Signed-off-by Suzuki K Poulose <[email protected]>
Signed-off-by Catalin Marinas <[email protected]>
Signed-off-by Will Deacon <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/arm64/kernel/cpufeature.c |   44 +++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 21 deletions(-)
arch/arm64/kernel/cpufeature.c +23 -21
@@ -1118,6 +1118,26 @@ static void __init setup_elf_hwcaps(cons
 			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)
 {

@@ -1181,8 +1201,9 @@ verify_local_elf_hwcaps(const struct arm
 }
 
 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;

@@ -1190,7 +1211,7 @@ verify_local_cpu_features(const struct a
 		 * 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();

@@ -1272,25 +1293,6 @@ static void __init mark_const_caps_ready
 	static_branch_enable(&arm64_const_caps_ready);
 }
 
-/*
- * 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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/arm64-cpufeature-pass-capability-structure-to-enable-callback.patch queue-4.15/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch queue-4.15/arm64-take-into-account-id_aa64pfr0_el1.csv3.patch queue-4.15/arm64-run-enable-method-for-errata-work-arounds-on-late-cpus.patch queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch