338d4f49d6
'Privileged Access Never' is a new arm8.1 feature which prevents
privileged code from accessing any virtual address where read or write
access is also permitted at EL0.
This patch enables the PAN feature on all CPUs, and modifies {get,put}_user
helpers temporarily to permit access.
This will catch kernel bugs where user memory is accessed directly.
'Unprivileged loads and stores' using ldtrb et al are unaffected by PAN.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
[will: use ALTERNATIVE in asm and tidy up pan_enable check]
Signed-off-by: Will Deacon <will.deacon@arm.com>
92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
/*
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* Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_CPUFEATURE_H
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#define __ASM_CPUFEATURE_H
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#include <asm/hwcap.h>
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/*
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* In the arm64 world (as in the ARM world), elf_hwcap is used both internally
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* in the kernel and for user space to keep track of which optional features
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* are supported by the current system. So let's map feature 'x' to HWCAP_x.
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* Note that HWCAP_x constants are bit fields so we need to take the log.
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*/
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#define MAX_CPU_FEATURES (8 * sizeof(elf_hwcap))
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#define cpu_feature(x) ilog2(HWCAP_ ## x)
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#define ARM64_WORKAROUND_CLEAN_CACHE 0
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#define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE 1
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#define ARM64_WORKAROUND_845719 2
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#define ARM64_HAS_SYSREG_GIC_CPUIF 3
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#define ARM64_HAS_PAN 4
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#define ARM64_NCAPS 5
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#ifndef __ASSEMBLY__
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struct arm64_cpu_capabilities {
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const char *desc;
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u16 capability;
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bool (*matches)(const struct arm64_cpu_capabilities *);
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void (*enable)(void);
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union {
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struct { /* To be used for erratum handling only */
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u32 midr_model;
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u32 midr_range_min, midr_range_max;
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};
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struct { /* Feature register checking */
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int field_pos;
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int min_field_value;
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};
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};
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};
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extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
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static inline bool cpu_have_feature(unsigned int num)
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{
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return elf_hwcap & (1UL << num);
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}
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static inline bool cpus_have_cap(unsigned int num)
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{
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if (num >= ARM64_NCAPS)
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return false;
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return test_bit(num, cpu_hwcaps);
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}
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static inline void cpus_set_cap(unsigned int num)
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{
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if (num >= ARM64_NCAPS)
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pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n",
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num, ARM64_NCAPS);
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else
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__set_bit(num, cpu_hwcaps);
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}
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static inline int __attribute_const__ cpuid_feature_extract_field(u64 features,
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int field)
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{
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return (s64)(features << (64 - 4 - field)) >> (64 - 4);
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}
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void check_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
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const char *info);
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void check_local_cpu_errata(void);
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void check_local_cpu_features(void);
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bool cpu_supports_mixed_endian_el0(void);
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bool system_supports_mixed_endian_el0(void);
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#endif /* __ASSEMBLY__ */
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#endif
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