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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/arm64/mm/proc.S
parent74e248286e1d04b0d9bfdd002450ef0211f6f29f (diff)
downloadlinux-5ffdfaedfa0aba3f5db0fbb8ed4f3192be2b39b8.tar.bz2
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 'arch/arm64/mm/proc.S')
-rw-r--r--arch/arm64/mm/proc.S11
1 files changed, 8 insertions, 3 deletions
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