From 05460849c3b51180d5ada3373d0449aea19075e4 Mon Sep 17 00:00:00 2001 From: James Morse Date: Thu, 17 Oct 2019 18:42:58 +0100 Subject: [PATCH 1/4] arm64: errata: Hide CTR_EL0.DIC on systems affected by Neoverse-N1 #1542419 Cores affected by Neoverse-N1 #1542419 could execute a stale instruction when a branch is updated to point to freshly generated instructions. To workaround this issue we need user-space to issue unnecessary icache maintenance that we can trap. Start by hiding CTR_EL0.DIC. Reviewed-by: Suzuki K Poulose Signed-off-by: James Morse Signed-off-by: Catalin Marinas --- Documentation/arm64/silicon-errata.rst | 2 ++ arch/arm64/Kconfig | 16 +++++++++++++ arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/kernel/cpu_errata.c | 32 +++++++++++++++++++++++++- arch/arm64/kernel/traps.c | 3 +++ 5 files changed, 54 insertions(+), 2 deletions(-) diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 17ea3fecddaa..d0d480dac361 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -88,6 +88,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-N1 | #1542419 | ARM64_ERRATUM_1542419 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ +----------------+-----------------+-----------------+-----------------------------+ diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 950a56b71ff0..7c3e3e334421 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -558,6 +558,22 @@ config ARM64_ERRATUM_1463225 If unsure, say Y. +config ARM64_ERRATUM_1542419 + bool "Neoverse-N1: workaround mis-ordering of instruction fetches" + default y + help + This option adds a workaround for ARM Neoverse-N1 erratum + 1542419. + + Affected Neoverse-N1 cores could execute a stale instruction when + modified by another CPU. The workaround depends on a firmware + counterpart. + + Workaround the issue by hiding the DIC feature from EL0. This + forces user-space to perform cache maintenance. + + If unsure, say Y. + config CAVIUM_ERRATUM_22375 bool "Cavium erratum 22375, 24313" default y diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index f19fe4b9acc4..f05afaec18cd 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -52,7 +52,8 @@ #define ARM64_HAS_IRQ_PRIO_MASKING 42 #define ARM64_HAS_DCPODP 43 #define ARM64_WORKAROUND_1463225 44 +#define ARM64_WORKAROUND_1542419 45 -#define ARM64_NCAPS 45 +#define ARM64_NCAPS 46 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index f593f4cffc0d..3ae9b78b6d94 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -87,13 +87,21 @@ has_mismatched_cache_type(const struct arm64_cpu_capabilities *entry, } static void -cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *__unused) +cpu_enable_trap_ctr_access(const struct arm64_cpu_capabilities *cap) { u64 mask = arm64_ftr_reg_ctrel0.strict_mask; + bool enable_uct_trap = false; /* Trap CTR_EL0 access on this CPU, only if it has a mismatch */ if ((read_cpuid_cachetype() & mask) != (arm64_ftr_reg_ctrel0.sys_val & mask)) + enable_uct_trap = true; + + /* ... or if the system is affected by an erratum */ + if (cap->capability == ARM64_WORKAROUND_1542419) + enable_uct_trap = true; + + if (enable_uct_trap) sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCT, 0); } @@ -623,6 +631,18 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope) return (need_wa > 0); } +static bool __maybe_unused +has_neoverse_n1_erratum_1542419(const struct arm64_cpu_capabilities *entry, + int scope) +{ + u32 midr = read_cpuid_id(); + bool has_dic = read_cpuid_cachetype() & BIT(CTR_DIC_SHIFT); + const struct midr_range range = MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1); + + WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible()); + return is_midr_in_range(midr, &range) && has_dic; +} + #ifdef CONFIG_HARDEN_EL2_VECTORS static const struct midr_range arm64_harden_el2_vectors[] = { @@ -851,6 +871,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, .matches = has_cortex_a76_erratum_1463225, }, +#endif +#ifdef CONFIG_ARM64_ERRATUM_1542419 + { + /* we depend on the firmware portion for correctness */ + .desc = "ARM erratum 1542419 (kernel portion)", + .capability = ARM64_WORKAROUND_1542419, + .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, + .matches = has_neoverse_n1_erratum_1542419, + .cpu_enable = cpu_enable_trap_ctr_access, + }, #endif { } diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 34739e80211b..465f0a0f8f0a 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -470,6 +470,9 @@ static void ctr_read_handler(unsigned int esr, struct pt_regs *regs) int rt = ESR_ELx_SYS64_ISS_RT(esr); unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0); + if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) + val &= ~BIT(CTR_DIC_SHIFT); + pt_regs_write_reg(regs, rt, val); arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); From ee9d90be9ddace01b7fb126567e4b539fbe1f82f Mon Sep 17 00:00:00 2001 From: James Morse Date: Thu, 17 Oct 2019 18:42:59 +0100 Subject: [PATCH 2/4] arm64: Fake the IminLine size on systems affected by Neoverse-N1 #1542419 Systems affected by Neoverse-N1 #1542419 support DIC so do not need to perform icache maintenance once new instructions are cleaned to the PoU. For the errata workaround, the kernel hides DIC from user-space, so that the unnecessary cache maintenance can be trapped by firmware. To reduce the number of traps, produce a fake IminLine value based on PAGE_SIZE. Signed-off-by: James Morse Reviewed-by: Suzuki K Poulose Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/cache.h | 3 ++- arch/arm64/kernel/traps.c | 8 +++++++- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h index 43da6dd29592..806e9dc2a852 100644 --- a/arch/arm64/include/asm/cache.h +++ b/arch/arm64/include/asm/cache.h @@ -11,6 +11,7 @@ #define CTR_L1IP_MASK 3 #define CTR_DMINLINE_SHIFT 16 #define CTR_IMINLINE_SHIFT 0 +#define CTR_IMINLINE_MASK 0xf #define CTR_ERG_SHIFT 20 #define CTR_CWG_SHIFT 24 #define CTR_CWG_MASK 15 @@ -18,7 +19,7 @@ #define CTR_DIC_SHIFT 29 #define CTR_CACHE_MINLINE_MASK \ - (0xf << CTR_DMINLINE_SHIFT | 0xf << CTR_IMINLINE_SHIFT) + (0xf << CTR_DMINLINE_SHIFT | CTR_IMINLINE_MASK << CTR_IMINLINE_SHIFT) #define CTR_L1IP(ctr) (((ctr) >> CTR_L1IP_SHIFT) & CTR_L1IP_MASK) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 465f0a0f8f0a..4e3e9d9c8151 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -470,9 +470,15 @@ static void ctr_read_handler(unsigned int esr, struct pt_regs *regs) int rt = ESR_ELx_SYS64_ISS_RT(esr); unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0); - if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) + if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) { + /* Hide DIC so that we can trap the unnecessary maintenance...*/ val &= ~BIT(CTR_DIC_SHIFT); + /* ... and fake IminLine to reduce the number of traps. */ + val &= ~CTR_IMINLINE_MASK; + val |= (PAGE_SHIFT - 2) & CTR_IMINLINE_MASK; + } + pt_regs_write_reg(regs, rt, val); arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); From 222fc0c8503d98cec3cb2bac2780cdd21a6e31c0 Mon Sep 17 00:00:00 2001 From: James Morse Date: Thu, 17 Oct 2019 18:43:00 +0100 Subject: [PATCH 3/4] arm64: compat: Workaround Neoverse-N1 #1542419 for compat user-space Compat user-space is unable to perform ICIMVAU instructions from user-space. Instead it uses a compat-syscall. Add the workaround for Neoverse-N1 #1542419 to this code path. Signed-off-by: James Morse Signed-off-by: Catalin Marinas --- arch/arm64/kernel/sys_compat.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c index f1cb64959427..c9fb02927d3e 100644 --- a/arch/arm64/kernel/sys_compat.c +++ b/arch/arm64/kernel/sys_compat.c @@ -8,6 +8,7 @@ */ #include +#include #include #include #include @@ -17,6 +18,7 @@ #include #include +#include #include static long @@ -30,6 +32,15 @@ __do_compat_cache_op(unsigned long start, unsigned long end) if (fatal_signal_pending(current)) return 0; + if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) { + /* + * The workaround requires an inner-shareable tlbi. + * We pick the reserved-ASID to minimise the impact. + */ + __tlbi(aside1is, 0); + dsb(ish); + } + ret = __flush_cache_user_range(start, start + chunk); if (ret) return ret; From 27a22fbdeedd6c5c451cf5f830d51782bf50c3a2 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 28 Oct 2019 09:08:34 +0000 Subject: [PATCH 4/4] arm64: Silence clang warning on mismatched value/register sizes Clang reports a warning on the __tlbi(aside1is, 0) macro expansion since the value size does not match the register size specified in the inline asm. Construct the ASID value using the __TLBI_VADDR() macro. Fixes: 222fc0c8503d ("arm64: compat: Workaround Neoverse-N1 #1542419 for compat user-space") Reported-by: Nathan Chancellor Cc: James Morse Signed-off-by: Catalin Marinas --- arch/arm64/kernel/sys_compat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c index c9fb02927d3e..3c18c2454089 100644 --- a/arch/arm64/kernel/sys_compat.c +++ b/arch/arm64/kernel/sys_compat.c @@ -37,7 +37,7 @@ __do_compat_cache_op(unsigned long start, unsigned long end) * The workaround requires an inner-shareable tlbi. * We pick the reserved-ASID to minimise the impact. */ - __tlbi(aside1is, 0); + __tlbi(aside1is, __TLBI_VADDR(0, 0)); dsb(ish); }