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Message-ID: <20240906170648.323759-3-towinchenmi@gmail.com>
Date: Sat, 7 Sep 2024 00:59:39 +0800
From: Nick Chan <towinchenmi@...il.com>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: asahi@...r.kernel.org,
~postmarketos/upstreaming@...ts.sr.ht,
Nick Chan <towinchenmi@...il.com>
Subject: [PATCH 2/2] arm64: cpufeature: Pretend that Apple A10(X), T2 does not support 32-bit EL0
The Apple A10(X), T2 consists of logical cores that can switch
between P-mode and E-mode based on the frequency. However, only
P-mode supported 32-bit EL0.
Trying to support 32-bit EL0 on a CPU that can only execute it in certain
states is a bad idea. The A10(X), T2 only supports 16KB page size anyway so
many AArch32 executables won't run anyways. Pretend that it does not
support 32-bit EL0 at all.
Signed-off-by: Nick Chan <towinchenmi@...il.com>
---
arch/arm64/kernel/cpufeature.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 718728a85430..458bcbc4f328 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -3529,6 +3529,29 @@ void __init setup_boot_cpu_features(void)
setup_boot_cpu_capabilities();
}
+static void __init bad_aarch32_el0_fixup(void)
+{
+#ifdef CONFIG_ARCH_APPLE
+ static const struct midr_range bad_aarch32_el0[] = {
+ MIDR_ALL_VERSIONS(MIDR_APPLE_A10_T2_HURRICANE_ZEPHYR),
+ MIDR_ALL_VERSIONS(MIDR_APPLE_A10X_HURRICANE_ZEPHYR),
+ {}
+ };
+
+ if (is_midr_in_range_list(read_cpuid_id(), bad_aarch32_el0)) {
+ struct arm64_ftr_reg *regp;
+
+ regp = get_arm64_ftr_reg(SYS_ID_AA64PFR0_EL1);
+ if (!regp)
+ return;
+ u64 val = (regp->sys_val & ~ID_AA64PFR0_EL1_EL0_MASK)
+ | ID_AA64PFR0_EL1_EL0_IMP;
+
+ update_cpu_ftr_reg(regp, val);
+ }
+#endif
+}
+
static void __init setup_system_capabilities(void)
{
/*
@@ -3562,6 +3585,8 @@ static void __init setup_system_capabilities(void)
void __init setup_system_features(void)
{
+ bad_aarch32_el0_fixup();
+
setup_system_capabilities();
kpti_install_ng_mappings();
--
2.46.0
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