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authorVladimir Murzin <vladimir.murzin@arm.com>2018-07-31 14:08:56 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2018-09-18 12:02:27 +0100
commit5ffdfaedfa0aba3f5db0fbb8ed4f3192be2b39b8 (patch)
tree4bb4a2ef29171186d317ed6396ce89572ce03d11 /arch
parentarm64: sysreg: Clean up instructions for modifying PSTATE fields (diff)
downloadlinux-dev-5ffdfaedfa0aba3f5db0fbb8ed4f3192be2b39b8.tar.xz
linux-dev-5ffdfaedfa0aba3f5db0fbb8ed4f3192be2b39b8.zip
arm64: mm: Support Common Not Private translations
Common Not Private (CNP) is a feature of ARMv8.2 extension which allows translation table entries to be shared between different PEs in the same inner shareable domain, so the hardware can use this fact to optimise the caching of such entries in the TLB. CNP occupies one bit in TTBRx_ELy and VTTBR_EL2, which advertises to the hardware that the translation table entries pointed to by this TTBR are the same as every PE in the same inner shareable domain for which the equivalent TTBR also has CNP bit set. In case CNP bit is set but TTBR does not point at the same translation table entries for a given ASID and VMID, then the system is mis-configured, so the results of translations are UNPREDICTABLE. For kernel we postpone setting CNP till all cpus are up and rely on cpufeature framework to 1) patch the code which is sensitive to CNP and 2) update TTBR1_EL1 with CNP bit set. TTBR1_EL1 can be reprogrammed as result of hibernation or cpuidle (via __enable_mmu). For these two cases we restore CnP bit via __cpu_suspend_exit(). There are a few cases we need to care of changes in TTBR0_EL1: - a switch to idmap - software emulated PAN we rule out latter via Kconfig options and for the former we make sure that CNP is set for non-zero ASIDs only. Reviewed-by: James Morse <james.morse@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com> [catalin.marinas@arm.com: default y for CONFIG_ARM64_CNP] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to '')
-rw-r--r--arch/arm64/Kconfig14
-rw-r--r--arch/arm64/include/asm/cpucaps.h3
-rw-r--r--arch/arm64/include/asm/cpufeature.h6
-rw-r--r--arch/arm64/include/asm/mmu_context.h17
-rw-r--r--arch/arm64/include/asm/pgtable-hwdef.h2
-rw-r--r--arch/arm64/kernel/cpufeature.c34
-rw-r--r--arch/arm64/kernel/suspend.c4
-rw-r--r--arch/arm64/mm/context.c3
-rw-r--r--arch/arm64/mm/proc.S11
9 files changed, 88 insertions, 6 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 58eb02796b16..fabac617d605 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1134,6 +1134,20 @@ config ARM64_RAS_EXTN
and access the new registers if the system supports the extension.
Platform RAS features may additionally depend on firmware support.
+config ARM64_CNP
+ bool "Enable support for Common Not Private (CNP) translations"
+ default y
+ depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN
+ help
+ Common Not Private (CNP) allows translation table entries to
+ be shared between different PEs in the same inner shareable
+ domain, so the hardware can use this fact to optimise the
+ caching of such entries in the TLB.
+
+ Selecting this option allows the CNP feature to be detected
+ at runtime, and does not affect PEs that do not implement
+ this feature.
+
endmenu
config ARM64_SVE
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 38eec9cf30f2..c51d7e868f3f 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -53,7 +53,8 @@
#define ARM64_HAS_STAGE2_FWB 32
#define ARM64_HAS_CRC32 33
#define ARM64_SSBS 34
+#define ARM64_HAS_CNP 35
-#define ARM64_NCAPS 35
+#define ARM64_NCAPS 36
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 9079715794af..bb9fbf6f910a 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -508,6 +508,12 @@ static inline bool system_supports_sve(void)
cpus_have_const_cap(ARM64_SVE);
}
+static inline bool system_supports_cnp(void)
+{
+ return IS_ENABLED(CONFIG_ARM64_CNP) &&
+ cpus_have_const_cap(ARM64_HAS_CNP);
+}
+
#define ARM64_SSBD_UNKNOWN -1
#define ARM64_SSBD_FORCE_DISABLE 0
#define ARM64_SSBD_KERNEL 1
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 39ec0b8a689e..1e58bf58c22b 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -147,12 +147,25 @@ static inline void cpu_replace_ttbr1(pgd_t *pgdp)
extern ttbr_replace_func idmap_cpu_replace_ttbr1;
ttbr_replace_func *replace_phys;
- phys_addr_t pgd_phys = virt_to_phys(pgdp);
+ /* phys_to_ttbr() zeros lower 2 bits of ttbr with 52-bit PA */
+ phys_addr_t ttbr1 = phys_to_ttbr(virt_to_phys(pgdp));
+
+ if (system_supports_cnp() && !WARN_ON(pgdp != lm_alias(swapper_pg_dir))) {
+ /*
+ * cpu_replace_ttbr1() is used when there's a boot CPU
+ * up (i.e. cpufeature framework is not up yet) and
+ * latter only when we enable CNP via cpufeature's
+ * enable() callback.
+ * Also we rely on the cpu_hwcap bit being set before
+ * calling the enable() function.
+ */
+ ttbr1 |= TTBR_CNP_BIT;
+ }
replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);
cpu_install_idmap();
- replace_phys(pgd_phys);
+ replace_phys(ttbr1);
cpu_uninstall_idmap();
}
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index fd208eac9f2a..1d7d8da2ef9b 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -211,6 +211,8 @@
#define PHYS_MASK_SHIFT (CONFIG_ARM64_PA_BITS)
#define PHYS_MASK ((UL(1) << PHYS_MASK_SHIFT) - 1)
+#define TTBR_CNP_BIT (UL(1) << 0)
+
/*
* TCR flags.
*/
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index f15e2fb97011..237f8822a391 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -20,6 +20,7 @@
#include <linux/bsearch.h>
#include <linux/cpumask.h>
+#include <linux/crash_dump.h>
#include <linux/sort.h>
#include <linux/stop_machine.h>
#include <linux/types.h>
@@ -117,6 +118,7 @@ EXPORT_SYMBOL(cpu_hwcap_keys);
static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused);
+static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap);
/*
* NOTE: Any changes to the visibility of features should be kept in
@@ -863,6 +865,20 @@ static bool has_cache_dic(const struct arm64_cpu_capabilities *entry,
return read_sanitised_ftr_reg(SYS_CTR_EL0) & BIT(CTR_DIC_SHIFT);
}
+static bool __maybe_unused
+has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
+{
+ /*
+ * Kdump isn't guaranteed to power-off all secondary CPUs, CNP
+ * may share TLB entries with a CPU stuck in the crashed
+ * kernel.
+ */
+ if (is_kdump_kernel())
+ return false;
+
+ return has_cpuid_feature(entry, scope);
+}
+
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */
@@ -1312,6 +1328,19 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.cpu_enable = cpu_enable_ssbs,
},
#endif
+#ifdef CONFIG_ARM64_CNP
+ {
+ .desc = "Common not Private translations",
+ .capability = ARM64_HAS_CNP,
+ .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .matches = has_useable_cnp,
+ .sys_reg = SYS_ID_AA64MMFR2_EL1,
+ .sign = FTR_UNSIGNED,
+ .field_pos = ID_AA64MMFR2_CNP_SHIFT,
+ .min_field_value = 1,
+ .cpu_enable = cpu_enable_cnp,
+ },
+#endif
{},
};
@@ -1749,6 +1778,11 @@ cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused)
return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO));
}
+static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap)
+{
+ cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+}
+
/*
* We emulate only the following system register space.
* Op0 = 0x3, CRn = 0x0, Op1 = 0x0, CRm = [0, 4 - 7]
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index 70c283368b64..9405d1b7f4b0 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -48,6 +48,10 @@ void notrace __cpu_suspend_exit(void)
*/
cpu_uninstall_idmap();
+ /* Restore CnP bit in TTBR1_EL1 */
+ if (system_supports_cnp())
+ cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+
/*
* PSTATE was not saved over suspend/resume, re-enable any detected
* features that might not have been set correctly.
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index c127f94da8e2..a65af49e12e7 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -196,6 +196,9 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
unsigned long flags;
u64 asid, old_active_asid;
+ if (system_supports_cnp())
+ cpu_set_reserved_ttbr0();
+
asid = atomic64_read(&mm->context.id);
/*
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 03646e6a2ef4..2c75b0b903ae 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -160,6 +160,12 @@ ENTRY(cpu_do_switch_mm)
mrs x2, ttbr1_el1
mmid x1, x1 // get mm->context.id
phys_to_ttbr x3, x0
+
+alternative_if ARM64_HAS_CNP
+ cbz x1, 1f // skip CNP for reserved ASID
+ orr x3, x3, #TTBR_CNP_BIT
+1:
+alternative_else_nop_endif
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
bfi x3, x1, #48, #16 // set the ASID field in TTBR0
#endif
@@ -184,7 +190,7 @@ ENDPROC(cpu_do_switch_mm)
.endm
/*
- * void idmap_cpu_replace_ttbr1(phys_addr_t new_pgd)
+ * void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
*
* This is the low-level counterpart to cpu_replace_ttbr1, and should not be
* called by anything else. It can only be executed from a TTBR0 mapping.
@@ -194,8 +200,7 @@ ENTRY(idmap_cpu_replace_ttbr1)
__idmap_cpu_set_reserved_ttbr1 x1, x3
- phys_to_ttbr x3, x0
- msr ttbr1_el1, x3
+ msr ttbr1_el1, x0
isb
restore_daif x2