From 82ff0c022d19c2ad69a472692bb7ee01ac07a40b Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Wed, 8 Dec 2021 14:11:21 -0600 Subject: perf: Add a counter for number of user access events in context On arm64, user space counter access will be controlled differently compared to x86. On x86, access in the strictest mode is enabled for all tasks in an MM when any event is mmap'ed. For arm64, access is explicitly requested for an event and only enabled when the event's context is active. This avoids hooks into the arch context switch code and gives better control of when access is enabled. In order to configure user space access when the PMU is enabled, it is necessary to know if any event (currently active or not) in the current context has user space accessed enabled. Add a counter similar to other counters in the context to avoid walking the event list every time. Reviewed-by: Mark Rutland Reviewed-by: Thomas Gleixner Signed-off-by: Rob Herring Link: https://lore.kernel.org/r/20211208201124.310740-3-robh@kernel.org Signed-off-by: Will Deacon --- kernel/events/core.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 30d94f68c5bd..1362b9b770d8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1808,6 +1808,8 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx) list_add_rcu(&event->event_entry, &ctx->event_list); ctx->nr_events++; + if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT) + ctx->nr_user++; if (event->attr.inherit_stat) ctx->nr_stat++; @@ -1999,6 +2001,8 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) event->attach_state &= ~PERF_ATTACH_CONTEXT; ctx->nr_events--; + if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT) + ctx->nr_user--; if (event->attr.inherit_stat) ctx->nr_stat--; -- cgit v1.2.3 From dd03762ab608e058c8f390ad9cf667e490089796 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Sat, 11 Dec 2021 21:17:34 +0800 Subject: arm64: Enable KCSAN This patch enables KCSAN for arm64, with updates to build rules to not use KCSAN for several incompatible compilation units. Recent GCC version(at least GCC10) made outline-atomics as the default option(unlike Clang), which will cause linker errors for kernel/kcsan/core.o. Disables the out-of-line atomics by no-outline-atomics to fix the linker errors. Meanwhile, as Mark said[1], some latent issues are needed to be fixed which isn't just a KCSAN problem, we make the KCSAN depends on EXPERT for now. Tested selftest and kcsan_test(built with GCC11 and Clang 13), and all passed. [1] https://lkml.kernel.org/r/YadiUPpJ0gADbiHQ@FVFF77S0Q05N Acked-by: Marco Elver # kernel/kcsan Tested-by: Joey Gouly Signed-off-by: Kefeng Wang Link: https://lore.kernel.org/r/20211211131734.126874-1-wangkefeng.wang@huawei.com [catalin.marinas@arm.com: added comment to justify EXPERT] Signed-off-by: Catalin Marinas --- arch/arm64/Kconfig | 2 ++ arch/arm64/kernel/vdso/Makefile | 1 + arch/arm64/kvm/hyp/nvhe/Makefile | 1 + kernel/kcsan/Makefile | 1 + 4 files changed, 5 insertions(+) (limited to 'kernel') diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c4207cf9bb17..1d98e935c4d6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -150,6 +150,8 @@ config ARM64 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_HW_TAGS if (HAVE_ARCH_KASAN && ARM64_MTE) + # Some instrumentation may be unsound, hence EXPERT + select HAVE_ARCH_KCSAN if EXPERT select HAVE_ARCH_KFENCE select HAVE_ARCH_KGDB select HAVE_ARCH_MMAP_RND_BITS diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index 700767dfd221..60813497a381 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -32,6 +32,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS) \ $(CC_FLAGS_LTO) KASAN_SANITIZE := n +KCSAN_SANITIZE := n UBSAN_SANITIZE := n OBJECT_FILES_NON_STANDARD := y KCOV_INSTRUMENT := n diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index c3c11974fa3b..24b2c2425b38 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -89,6 +89,7 @@ KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_CFI) # cause crashes. Just disable it. GCOV_PROFILE := n KASAN_SANITIZE := n +KCSAN_SANITIZE := n UBSAN_SANITIZE := n KCOV_INSTRUMENT := n diff --git a/kernel/kcsan/Makefile b/kernel/kcsan/Makefile index c2bb07f5bcc7..e893b0e1d62a 100644 --- a/kernel/kcsan/Makefile +++ b/kernel/kcsan/Makefile @@ -8,6 +8,7 @@ CFLAGS_REMOVE_debugfs.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE) CFLAGS_core.o := $(call cc-option,-fno-conserve-stack) \ + $(call cc-option,-mno-outline-atomics) \ -fno-stack-protector -DDISABLE_BRANCH_PROFILING obj-y := core.o debugfs.o report.o -- cgit v1.2.3