From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 993A41F16B; Sat, 17 Oct 2026 17:08:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792256895; cv=none; b=UQTBakSzIf5GM7DvUrmO5KmhmDQAeGX+TBxuAnTniyP3AIZMWqtqKskI12fIbCCAt2bl9yuKe7xI6k/zmP9C/tSHnwOCLk5DfW3yS37MbZnvtSBEzLfHqMBc9mq6RjFvY2hDKlvF9o/Ug7EP4p+H3MjmwFQwVy9J9KcCuleF3zU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792256895; c=relaxed/simple; bh=FbOwD0EV1OBasAXWSbvRO6Lzl9ZoHE//TRLXu10G/XU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C9v1CEgr6pNmn5s4K4SP+5+3Crj6TaOEZGyER2DjQ/Y30h06HoFImAymQVlS7pRE397SHGW4G6K9wXiym9PbaprIylD8ODpsQKyYYJ9Qi3nNZLn2tlZmDZZdRta1se5mo6MEmjRSSBdvZZTYumB0jh9V2ljSTMUQjtm4FJz7BE0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=USPvRTFn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="USPvRTFn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E76F51F000C4; Sat, 17 Oct 2026 17:08:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792256894; bh=Dmo7Y6VRPbVViTYS8TBRY+kWEJw5tJwdyGrZfoqQiD8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=USPvRTFnnyPJou53uWazZpN5z7iRtnnaKh1kesNeq0Wmp2IsM0KD6lPuCgOdFDKjV pseI+yZm7DQq96C/7nht0pC9uR11exTx9KKqw/JsRw/JkNefHvMC7luEk3MabL0R3B jPkrfsKypHWv4xdtJpnu0eYzOpOWCIAQ/rSTP6Tg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Beata Michalska , Vladimir Murzin , Will Deacon , Sasha Levin Subject: [PATCH 6.6 0384/1674] arm64: errata: Factor out broken AMU const counter cap Date: Sat, 17 Oct 2026 17:44:16 +0200 Message-ID: <20261017160440.970878070@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160431.119607952@linuxfoundation.org> References: <20261017160431.119607952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Beata Michalska [ Upstream commit 573371caf7aea8582212da81dcead2c3f48fac4b ] Move the workaround from the erratum 2457168-specific cpucap to a generic broken AMU constant-counter one. This keeps the existing Cortex-A510 handling unchanged while allowing other errata with similar AMU constant counter issue to share the capability bit and call sites. Signed-off-by: Beata Michalska Reviewed-by: Vladimir Murzin Signed-off-by: Will Deacon [ Beata: Skipped comment updated on amu_read_core_const_ctrs, as that functionality is not available here. Otherwise unmodified. ] Signed-off-by: Beata Michalska Signed-off-by: Sasha Levin --- arch/arm64/Kconfig | 8 ++++++++ arch/arm64/kernel/cpu_errata.c | 20 ++++++++++++++------ arch/arm64/kernel/cpufeature.c | 2 +- arch/arm64/kernel/topology.c | 2 +- arch/arm64/tools/cpucaps | 2 +- 5 files changed, 25 insertions(+), 9 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 723e73042c1a2..27fe95b9aac73 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1004,9 +1004,17 @@ config ARM64_ERRATUM_1902691 If unsure, say Y. +config ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT + bool + # Targeting errata affecting AMEVCNTR01, the AMU constant counter. + # On affected CPUs the counter may not increment at the expected rate, + # making it unreliable. As a result, AMU users should treat it as + # unavailable rather than relying on misleading counter values. + config ARM64_ERRATUM_2457168 bool "Cortex-A510: 2457168: workaround for AMEVCNTR01 incrementing incorrectly" depends on ARM64_AMU_EXTN + select ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT default y help This option adds the workaround for ARM Cortex-A510 erratum 2457168. diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 03a4382799091..699eb5a820a89 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -275,6 +275,16 @@ static const struct arm64_cpu_capabilities arm64_repeat_tlbi_list[] = { }; #endif +#ifdef CONFIG_ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT +static const struct midr_range workaround_amu_constcnt_list[] = { +#ifdef CONFIG_ARM64_ERRATUM_2457168 + /* Cortex-A510 r0p0-r1p1 */ + MIDR_RANGE(MIDR_CORTEX_A510, 0, 0, 1, 1), +#endif + {} +}; +#endif /* CONFIG_ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT */ + #ifdef CONFIG_CAVIUM_ERRATUM_23154 static const struct midr_range cavium_erratum_23154_cpus[] = { MIDR_ALL_VERSIONS(MIDR_THUNDERX), @@ -766,14 +776,12 @@ const struct arm64_cpu_capabilities arm64_errata[] = { ERRATA_MIDR_REV_RANGE(MIDR_CORTEX_A510, 0, 0, 2) }, #endif -#ifdef CONFIG_ARM64_ERRATUM_2457168 +#ifdef CONFIG_ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT { - .desc = "ARM erratum 2457168", - .capability = ARM64_WORKAROUND_2457168, + .desc = "Broken AMU AMEVCNTR01 (const counter)", + .capability = ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT, .type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE, - - /* Cortex-A510 r0p0-r1p1 */ - CAP_MIDR_RANGE(MIDR_CORTEX_A510, 0, 0, 1, 1) + CAP_MIDR_RANGE_LIST(workaround_amu_constcnt_list) }, #endif #ifdef CONFIG_ARM64_ERRATUM_2038923 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 5db25bfb854ff..b85d6058a347f 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1950,7 +1950,7 @@ static void cpu_amu_enable(struct arm64_cpu_capabilities const *cap) cpumask_set_cpu(smp_processor_id(), &amu_cpus); /* 0 reference values signal broken/disabled counters */ - if (!this_cpu_has_cap(ARM64_WORKAROUND_2457168)) + if (!this_cpu_has_cap(ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT)) update_freq_counters_refs(); } } diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 1a2c72f3e7f80..33a834e8aeebd 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -273,7 +273,7 @@ static void cpu_read_constcnt(void *val) * the counter is disabled. A return value of 0 at counter read is * properly handled as an error case by the users of the counter. */ - *(u64 *)val = this_cpu_has_cap(ARM64_WORKAROUND_2457168) ? + *(u64 *)val = this_cpu_has_cap(ARM64_WORKAROUND_BROKEN_AMU_CONSTCNT) ? 0UL : read_constcnt(); } diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index c251ef3caae56..1d3e0e178514d 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -81,7 +81,6 @@ WORKAROUND_1902691 WORKAROUND_2038923 WORKAROUND_2064142 WORKAROUND_2077057 -WORKAROUND_2457168 WORKAROUND_2645198 WORKAROUND_2658417 WORKAROUND_AMPERE_AC03_CPU_38 @@ -101,3 +100,4 @@ WORKAROUND_REPEAT_TLBI WORKAROUND_SPECULATIVE_AT WORKAROUND_SPECULATIVE_SSBS WORKAROUND_SPECULATIVE_UNPRIV_LOAD +WORKAROUND_BROKEN_AMU_CONSTCNT -- 2.53.0