From 7dd01aef055792260287c6708daf75aac3918f66 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Tue, 28 Jun 2016 18:07:32 +0100 Subject: [PATCH] arm64: trap userspace "dc cvau" cache operation on errata-affected core The ARM errata 819472, 826319, 827319 and 824069 for affected Cortex-A53 cores demand to promote "dc cvau" instructions to "dc civac". Since we allow userspace to also emit those instructions, we should make sure that "dc cvau" gets promoted there too. So lets grasp the nettle here and actually trap every userland cache maintenance instruction once we detect at least one affected core in the system. We then emulate the instruction by executing it on behalf of userland, promoting "dc cvau" to "dc civac" on the way and injecting access fault back into userspace. Signed-off-by: Andre Przywara [catalin.marinas@arm.com: s/set_segfault/arm64_notify_segfault/] Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/processor.h | 1 + arch/arm64/include/asm/sysreg.h | 2 +- arch/arm64/kernel/cpu_errata.c | 2 + arch/arm64/kernel/entry.S | 12 +++++- arch/arm64/kernel/traps.c | 60 ++++++++++++++++++++++++++++++ 5 files changed, 75 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index cef1cf398356..ace0a96e7d6e 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -192,5 +192,6 @@ static inline void spin_lock_prefetch(const void *ptr) void cpu_enable_pan(void *__unused); void cpu_enable_uao(void *__unused); +void cpu_enable_cache_maint_trap(void *__unused); #endif /* __ASM_PROCESSOR_H */ diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 751e901c8d37..cc06794b7346 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -98,11 +98,11 @@ SCTLR_ELx_SA | SCTLR_ELx_I) /* SCTLR_EL1 specific flags. */ +#define SCTLR_EL1_UCI (1 << 26) #define SCTLR_EL1_SPAN (1 << 23) #define SCTLR_EL1_SED (1 << 8) #define SCTLR_EL1_CP15BEN (1 << 5) - /* id_aa64isar0 */ #define ID_AA64ISAR0_RDM_SHIFT 28 #define ID_AA64ISAR0_ATOMICS_SHIFT 20 diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index c2261a7a316e..af647d2cee22 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -46,6 +46,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .desc = "ARM errata 826319, 827319, 824069", .capability = ARM64_WORKAROUND_CLEAN_CACHE, MIDR_RANGE(MIDR_CORTEX_A53, 0x00, 0x02), + .enable = cpu_enable_cache_maint_trap, }, #endif #ifdef CONFIG_ARM64_ERRATUM_819472 @@ -54,6 +55,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .desc = "ARM errata 819472", .capability = ARM64_WORKAROUND_CLEAN_CACHE, MIDR_RANGE(MIDR_CORTEX_A53, 0x00, 0x01), + .enable = cpu_enable_cache_maint_trap, }, #endif #ifdef CONFIG_ARM64_ERRATUM_832075 diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index eefffa81c6df..3eca5d34f7a6 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -451,7 +451,7 @@ el0_sync: cmp x24, #ESR_ELx_EC_FP_EXC64 // FP/ASIMD exception b.eq el0_fpsimd_exc cmp x24, #ESR_ELx_EC_SYS64 // configurable trap - b.eq el0_undef + b.eq el0_sys cmp x24, #ESR_ELx_EC_SP_ALIGN // stack alignment exception b.eq el0_sp_pc cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception @@ -579,6 +579,16 @@ el0_undef: mov x0, sp bl do_undefinstr b ret_to_user +el0_sys: + /* + * System instructions, for trapped cache maintenance instructions + */ + enable_dbg_and_irq + ct_user_exit + mov x0, x25 + mov x1, sp + bl do_sysinstr + b ret_to_user el0_dbg: /* * Debug exception handling diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index d8a5366dcc24..e04f83873af7 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -41,6 +41,7 @@ #include #include #include +#include static const char *handler[]= { "Synchronous Abort", @@ -427,6 +428,65 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs) force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0); } +void cpu_enable_cache_maint_trap(void *__unused) +{ + config_sctlr_el1(SCTLR_EL1_UCI, 0); +} + +#define __user_cache_maint(insn, address, res) \ + asm volatile ( \ + "1: " insn ", %1\n" \ + " mov %w0, #0\n" \ + "2:\n" \ + " .pushsection .fixup,\"ax\"\n" \ + " .align 2\n" \ + "3: mov %w0, %w2\n" \ + " b 2b\n" \ + " .popsection\n" \ + _ASM_EXTABLE(1b, 3b) \ + : "=r" (res) \ + : "r" (address), "i" (-EFAULT) ) + +asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs) +{ + unsigned long address; + int ret; + + /* if this is a write with: Op0=1, Op2=1, Op1=3, CRn=7 */ + if ((esr & 0x01fffc01) == 0x0012dc00) { + int rt = (esr >> 5) & 0x1f; + int crm = (esr >> 1) & 0x0f; + + address = (rt == 31) ? 0 : regs->regs[rt]; + + switch (crm) { + case 11: /* DC CVAU, gets promoted */ + __user_cache_maint("dc civac", address, ret); + break; + case 10: /* DC CVAC, gets promoted */ + __user_cache_maint("dc civac", address, ret); + break; + case 14: /* DC CIVAC */ + __user_cache_maint("dc civac", address, ret); + break; + case 5: /* IC IVAU */ + __user_cache_maint("ic ivau", address, ret); + break; + default: + force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0); + return; + } + } else { + force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0); + return; + } + + if (ret) + arm64_notify_segfault(regs, address); + else + regs->pc += 4; +} + long compat_arm_syscall(struct pt_regs *regs); asmlinkage long do_ni_syscall(struct pt_regs *regs) -- 2.20.1