From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- tools/scripts/Makefile.include | 230 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 230 insertions(+) create mode 100644 tools/scripts/Makefile.include (limited to 'tools/scripts/Makefile.include') diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include new file mode 100644 index 000000000..41971a689 --- /dev/null +++ b/tools/scripts/Makefile.include @@ -0,0 +1,230 @@ +# SPDX-License-Identifier: GPL-2.0 +ifneq ($(O),) +ifeq ($(origin O), command line) + $(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),) + ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd) + OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/) + COMMAND_O := O=$(ABSOLUTE_O) +ifeq ($(objtree),) + objtree := $(O) +endif +endif +endif + +# check that the output directory actually exists +ifneq ($(OUTPUT),) +OUTDIR := $(shell cd $(OUTPUT) && pwd) +$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist)) +endif + +# +# Include saner warnings here, which can catch bugs: +# +EXTRA_WARNINGS := -Wbad-function-cast +EXTRA_WARNINGS += -Wdeclaration-after-statement +EXTRA_WARNINGS += -Wformat-security +EXTRA_WARNINGS += -Wformat-y2k +EXTRA_WARNINGS += -Winit-self +EXTRA_WARNINGS += -Wmissing-declarations +EXTRA_WARNINGS += -Wmissing-prototypes +EXTRA_WARNINGS += -Wnested-externs +EXTRA_WARNINGS += -Wno-system-headers +EXTRA_WARNINGS += -Wold-style-definition +EXTRA_WARNINGS += -Wpacked +EXTRA_WARNINGS += -Wredundant-decls +EXTRA_WARNINGS += -Wstrict-prototypes +EXTRA_WARNINGS += -Wswitch-default +EXTRA_WARNINGS += -Wswitch-enum +EXTRA_WARNINGS += -Wundef +EXTRA_WARNINGS += -Wwrite-strings +EXTRA_WARNINGS += -Wformat +EXTRA_WARNINGS += -Wno-type-limits + +# Makefiles suck: This macro sets a default value of $(2) for the +# variable named by $(1), unless the variable has been set by +# environment or command line. This is necessary for CC and AR +# because make sets default values, so the simpler ?= approach +# won't work as expected. +define allow-override + $(if $(or $(findstring environment,$(origin $(1))),\ + $(findstring command line,$(origin $(1)))),,\ + $(eval $(1) = $(2))) +endef + +ifneq ($(LLVM),) +ifneq ($(filter %/,$(LLVM)),) +LLVM_PREFIX := $(LLVM) +else ifneq ($(filter -%,$(LLVM)),) +LLVM_SUFFIX := $(LLVM) +else ifneq ($(LLVM),1) +$(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst) +endif + +$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX)) +$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)) +$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)) +$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX)) +$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)) +else +# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. +$(call allow-override,CC,$(CROSS_COMPILE)gcc) +$(call allow-override,AR,$(CROSS_COMPILE)ar) +$(call allow-override,LD,$(CROSS_COMPILE)ld) +$(call allow-override,CXX,$(CROSS_COMPILE)g++) +$(call allow-override,STRIP,$(CROSS_COMPILE)strip) +endif + +CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) + +ifneq ($(LLVM),) +HOSTAR ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX) +HOSTCC ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX) +HOSTLD ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX) +else +HOSTAR ?= ar +HOSTCC ?= gcc +HOSTLD ?= ld +endif + +# Some tools require Clang, LLC and/or LLVM utils +CLANG ?= clang +LLC ?= llc +LLVM_CONFIG ?= llvm-config +LLVM_OBJCOPY ?= llvm-objcopy +LLVM_STRIP ?= llvm-strip + +# Some tools require bpftool +SYSTEM_BPFTOOL ?= bpftool + +RUSTC ?= rustc + +ifeq ($(CC_NO_CLANG), 1) +EXTRA_WARNINGS += -Wstrict-aliasing=3 + +else ifneq ($(CROSS_COMPILE),) +# Allow userspace to override CLANG_CROSS_FLAGS to specify their own +# sysroots and flags or to avoid the GCC call in pure Clang builds. +ifeq ($(CLANG_CROSS_FLAGS),) +CLANG_TARGET := $(notdir $(CROSS_COMPILE:%-=%)) +CLANG_TARGET := $(subst s390-linux,s390x-linux,$(CLANG_TARGET)) +CLANG_CROSS_FLAGS := --target=$(CLANG_TARGET) +GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null)) +ifneq ($(GCC_TOOLCHAIN_DIR),) +CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) +CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot) +CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..) +endif # GCC_TOOLCHAIN_DIR +endif # CLANG_CROSS_FLAGS +CFLAGS += $(CLANG_CROSS_FLAGS) +AFLAGS += $(CLANG_CROSS_FLAGS) +else +CLANG_CROSS_FLAGS := +endif # CROSS_COMPILE + +# Hack to avoid type-punned warnings on old systems such as RHEL5: +# We should be changing CFLAGS and checking gcc version, but this +# will do for now and keep the above -Wstrict-aliasing=3 in place +# in newer systems. +# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h +# +# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/ +# and https://gcc.gnu.org/gcc-4.8/changes.html, +# that takes into account Linus's comments (search for Wshadow) for the reasoning about +# -Wshadow not being interesting before gcc 4.8. + +ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 +EXTRA_WARNINGS += -fno-strict-aliasing +EXTRA_WARNINGS += -Wno-shadow +else +EXTRA_WARNINGS += -Wshadow +endif + +ifneq ($(findstring $(MAKEFLAGS), w),w) +PRINT_DIR = --no-print-directory +else +NO_SUBDIR = : +endif + +# Beautify output +# --------------------------------------------------------------------------- +# +# Most of build commands in Kbuild start with "cmd_". You can optionally define +# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from +# that command is printed by default. +# +# e.g.) +# quiet_cmd_depmod = DEPMOD $(MODLIB) +# cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE) +# +# A simple variant is to prefix commands with $(Q) - that's useful +# for commands that shall be hidden in non-verbose mode. +# +# $(Q)$(MAKE) $(build)=scripts/basic +# +# To put more focus on warnings, be less verbose as default +# Use 'make V=1' to see the full commands + +ifeq ($(V),1) + quiet = + Q = +else + quiet = quiet_ + Q = @ +endif + +# If the user is running make -s (silent mode), suppress echoing of commands +# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS. +ifeq ($(filter 3.%,$(MAKE_VERSION)),) +short-opts := $(firstword -$(MAKEFLAGS)) +else +short-opts := $(filter-out --%,$(MAKEFLAGS)) +endif + +ifneq ($(findstring s,$(short-opts)),) + silent=1 + quiet=silent_ +endif + +export quiet Q + +# +# Define a callable command for descending to a new directory +# +# Call by doing: $(call descend,directory[,target]) +# +descend = \ + +mkdir -p $(OUTPUT)$(1) && \ + $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) + +QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir +QUIET_SUBDIR1 = + +ifneq ($(silent),1) + ifneq ($(V),1) + QUIET_CC = @echo ' CC '$@; + QUIET_CC_FPIC = @echo ' CC FPIC '$@; + QUIET_CLANG = @echo ' CLANG '$@; + QUIET_AR = @echo ' AR '$@; + QUIET_LINK = @echo ' LINK '$@; + QUIET_MKDIR = @echo ' MKDIR '$@; + QUIET_GEN = @echo ' GEN '$@; + QUIET_SUBDIR0 = +@subdir= + QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ + echo ' SUBDIR '$$subdir; \ + $(MAKE) $(PRINT_DIR) -C $$subdir + QUIET_FLEX = @echo ' FLEX '$@; + QUIET_BISON = @echo ' BISON '$@; + QUIET_GENSKEL = @echo ' GENSKEL '$@; + + descend = \ + +@echo ' DESCEND '$(1); \ + mkdir -p $(OUTPUT)$(1) && \ + $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) + + QUIET_CLEAN = @printf ' CLEAN %s\n' $1; + QUIET_INSTALL = @printf ' INSTALL %s\n' $1; + QUIET_UNINST = @printf ' UNINST %s\n' $1; + endif +endif + +pound := \# -- cgit v1.3.1