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arm64: add support for the AMU extension v1

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The activity monitors extension is an optional extension introduced
by the ARMv8.4 CPU architecture. This implements basic support for
version 1 of the activity monitors architecture, AMUv1.

This support includes:
- Extension detection on each CPU (boot, secondary, hotplugged)
- Register interface for AMU aarch64 registers

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ionela Voinescu 2020-03-05 09:06:21 +00:00 committed by Catalin Marinas
parent f8788d86ab
commit 2c9d45b43c
5 changed files with 138 additions and 1 deletions
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27
arch/arm64/Kconfig
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@ -1517,6 +1517,33 @@ config ARM64_PTR_AUTH
endmenu
menu "ARMv8.4 architectural features"
config ARM64_AMU_EXTN
bool "Enable support for the Activity Monitors Unit CPU extension"
default y
help
The activity monitors extension is an optional extension introduced
by the ARMv8.4 CPU architecture. This enables support for version 1
of the activity monitors architecture, AMUv1.
To enable the use of this extension on CPUs that implement it, say Y.
Note that for architectural reasons, firmware _must_ implement AMU
support when running on CPUs that present the activity monitors
extension. The required support is present in:
* Version 1.5 and later of the ARM Trusted Firmware
For kernels that have this configuration enabled but boot with broken
firmware, you may need to say N here until the firmware is fixed.
Otherwise you may experience firmware panics or lockups when
accessing the counter registers. Even if you are not observing these
symptoms, the values returned by the register reads might not
correctly reflect reality. Most commonly, the value read will be 0,
indicating that the counter is not enabled.
endmenu
menu "ARMv8.5 architectural features"
config ARM64_E0PD

3
arch/arm64/include/asm/cpucaps.h
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@ -58,7 +58,8 @@
#define ARM64_WORKAROUND_SPECULATIVE_AT_NVHE 48
#define ARM64_HAS_E0PD 49
#define ARM64_HAS_RNG 50
#define ARM64_HAS_AMU_EXTN 51
#define ARM64_NCAPS 51
#define ARM64_NCAPS 52
#endif /* __ASM_CPUCAPS_H */

5
arch/arm64/include/asm/cpufeature.h
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@ -678,6 +678,11 @@ static inline bool cpu_has_hw_af(void)
ID_AA64MMFR1_HADBS_SHIFT);
}
#ifdef CONFIG_ARM64_AMU_EXTN
/* Check whether the cpu supports the Activity Monitors Unit (AMU) */
extern bool cpu_has_amu_feat(int cpu);
#endif
#endif /* __ASSEMBLY__ */
#endif

38
arch/arm64/include/asm/sysreg.h
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@ -386,6 +386,42 @@
#define SYS_TPIDR_EL0 sys_reg(3, 3, 13, 0, 2)
#define SYS_TPIDRRO_EL0 sys_reg(3, 3, 13, 0, 3)
/* Definitions for system register interface to AMU for ARMv8.4 onwards */
#define SYS_AM_EL0(crm, op2) sys_reg(3, 3, 13, (crm), (op2))
#define SYS_AMCR_EL0 SYS_AM_EL0(2, 0)
#define SYS_AMCFGR_EL0 SYS_AM_EL0(2, 1)
#define SYS_AMCGCR_EL0 SYS_AM_EL0(2, 2)
#define SYS_AMUSERENR_EL0 SYS_AM_EL0(2, 3)
#define SYS_AMCNTENCLR0_EL0 SYS_AM_EL0(2, 4)
#define SYS_AMCNTENSET0_EL0 SYS_AM_EL0(2, 5)
#define SYS_AMCNTENCLR1_EL0 SYS_AM_EL0(3, 0)
#define SYS_AMCNTENSET1_EL0 SYS_AM_EL0(3, 1)
/*
* Group 0 of activity monitors (architected):
* op0 op1 CRn CRm op2
* Counter: 11 011 1101 010:n<3> n<2:0>
* Type: 11 011 1101 011:n<3> n<2:0>
* n: 0-15
*
* Group 1 of activity monitors (auxiliary):
* op0 op1 CRn CRm op2
* Counter: 11 011 1101 110:n<3> n<2:0>
* Type: 11 011 1101 111:n<3> n<2:0>
* n: 0-15
*/
#define SYS_AMEVCNTR0_EL0(n) SYS_AM_EL0(4 + ((n) >> 3), (n) & 7)
#define SYS_AMEVTYPE0_EL0(n) SYS_AM_EL0(6 + ((n) >> 3), (n) & 7)
#define SYS_AMEVCNTR1_EL0(n) SYS_AM_EL0(12 + ((n) >> 3), (n) & 7)
#define SYS_AMEVTYPE1_EL0(n) SYS_AM_EL0(14 + ((n) >> 3), (n) & 7)
/* AMU v1: Fixed (architecturally defined) activity monitors */
#define SYS_AMEVCNTR0_CORE_EL0 SYS_AMEVCNTR0_EL0(0)
#define SYS_AMEVCNTR0_CONST_EL0 SYS_AMEVCNTR0_EL0(1)
#define SYS_AMEVCNTR0_INST_RET_EL0 SYS_AMEVCNTR0_EL0(2)
#define SYS_AMEVCNTR0_MEM_STALL SYS_AMEVCNTR0_EL0(3)
#define SYS_CNTFRQ_EL0 sys_reg(3, 3, 14, 0, 0)
#define SYS_CNTP_TVAL_EL0 sys_reg(3, 3, 14, 2, 0)
@ -598,6 +634,7 @@
#define ID_AA64PFR0_CSV3_SHIFT 60
#define ID_AA64PFR0_CSV2_SHIFT 56
#define ID_AA64PFR0_DIT_SHIFT 48
#define ID_AA64PFR0_AMU_SHIFT 44
#define ID_AA64PFR0_SVE_SHIFT 32
#define ID_AA64PFR0_RAS_SHIFT 28
#define ID_AA64PFR0_GIC_SHIFT 24
@ -608,6 +645,7 @@
#define ID_AA64PFR0_EL1_SHIFT 4
#define ID_AA64PFR0_EL0_SHIFT 0
#define ID_AA64PFR0_AMU 0x1
#define ID_AA64PFR0_SVE 0x1
#define ID_AA64PFR0_RAS_V1 0x1
#define ID_AA64PFR0_FP_NI 0xf

66
arch/arm64/kernel/cpufeature.c
View File

@ -163,6 +163,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV2_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_DIT_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_AMU_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_RAS_SHIFT, 4, 0),
@ -1222,6 +1223,53 @@ static bool has_hw_dbm(const struct arm64_cpu_capabilities *cap,
#endif
#ifdef CONFIG_ARM64_AMU_EXTN
/*
* The "amu_cpus" cpumask only signals that the CPU implementation for the
* flagged CPUs supports the Activity Monitors Unit (AMU) but does not provide
* information regarding all the events that it supports. When a CPU bit is
* set in the cpumask, the user of this feature can only rely on the presence
* of the 4 fixed counters for that CPU. But this does not guarantee that the
* counters are enabled or access to these counters is enabled by code
* executed at higher exception levels (firmware).
*/
static struct cpumask amu_cpus __read_mostly;
bool cpu_has_amu_feat(int cpu)
{
return cpumask_test_cpu(cpu, &amu_cpus);
}
static void cpu_amu_enable(struct arm64_cpu_capabilities const *cap)
{
if (has_cpuid_feature(cap, SCOPE_LOCAL_CPU)) {
pr_info("detected CPU%d: Activity Monitors Unit (AMU)\n",
smp_processor_id());
cpumask_set_cpu(smp_processor_id(), &amu_cpus);
}
}
static bool has_amu(const struct arm64_cpu_capabilities *cap,
int __unused)
{
/*
* The AMU extension is a non-conflicting feature: the kernel can
* safely run a mix of CPUs with and without support for the
* activity monitors extension. Therefore, unconditionally enable
* the capability to allow any late CPU to use the feature.
*
* With this feature unconditionally enabled, the cpu_enable
* function will be called for all CPUs that match the criteria,
* including secondary and hotplugged, marking this feature as
* present on that respective CPU. The enable function will also
* print a detection message.
*/
return true;
}
#endif
#ifdef CONFIG_ARM64_VHE
static bool runs_at_el2(const struct arm64_cpu_capabilities *entry, int __unused)
{
@ -1499,6 +1547,24 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.cpu_enable = cpu_clear_disr,
},
#endif /* CONFIG_ARM64_RAS_EXTN */
#ifdef CONFIG_ARM64_AMU_EXTN
{
/*
* The feature is enabled by default if CONFIG_ARM64_AMU_EXTN=y.
* Therefore, don't provide .desc as we don't want the detection
* message to be shown until at least one CPU is detected to
* support the feature.
*/
.capability = ARM64_HAS_AMU_EXTN,
.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
.matches = has_amu,
.sys_reg = SYS_ID_AA64PFR0_EL1,
.sign = FTR_UNSIGNED,
.field_pos = ID_AA64PFR0_AMU_SHIFT,
.min_field_value = ID_AA64PFR0_AMU,
.cpu_enable = cpu_amu_enable,
},
#endif /* CONFIG_ARM64_AMU_EXTN */
{
.desc = "Data cache clean to the PoU not required for I/D coherence",
.capability = ARM64_HAS_CACHE_IDC,