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835f14ed53
Currently, any kernel built with CONFIG_PREEMPTION=y also gets CONFIG_TASKS_RCU=y, which is not helpful to people trying to build preemptible kernels of minimal size. Because CONFIG_TASKS_RCU=y is needed only in kernels doing tracing of one form or another, this commit moves from TASKS_RCU deciding when it should be enabled to the tracing Kconfig options explicitly selecting it. This allows building preemptible kernels without TASKS_RCU, if desired. This commit also updates the SRCU-N and TREE09 rcutorture scenarios in order to avoid Kconfig errors that would otherwise result from CONFIG_TASKS_RCU being selected without its CONFIG_RCU_EXPERT dependency being met. [ paulmck: Apply BPF_SYSCALL feedback from Andrii Nakryiko. ] Reported-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
103 lines
3.0 KiB
Plaintext
103 lines
3.0 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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# BPF interpreter that, for example, classic socket filters depend on.
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config BPF
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bool
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# Used by archs to tell that they support BPF JIT compiler plus which
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# flavour. Only one of the two can be selected for a specific arch since
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# eBPF JIT supersedes the cBPF JIT.
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# Classic BPF JIT (cBPF)
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config HAVE_CBPF_JIT
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bool
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# Extended BPF JIT (eBPF)
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config HAVE_EBPF_JIT
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bool
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# Used by archs to tell that they want the BPF JIT compiler enabled by
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# default for kernels that were compiled with BPF JIT support.
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config ARCH_WANT_DEFAULT_BPF_JIT
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bool
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menu "BPF subsystem"
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config BPF_SYSCALL
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bool "Enable bpf() system call"
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select BPF
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select IRQ_WORK
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select TASKS_RCU if PREEMPTION
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select TASKS_TRACE_RCU
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select BINARY_PRINTF
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select NET_SOCK_MSG if NET
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select PAGE_POOL if NET
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default n
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help
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Enable the bpf() system call that allows to manipulate BPF programs
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and maps via file descriptors.
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config BPF_JIT
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bool "Enable BPF Just In Time compiler"
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depends on BPF
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depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
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depends on MODULES
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help
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BPF programs are normally handled by a BPF interpreter. This option
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allows the kernel to generate native code when a program is loaded
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into the kernel. This will significantly speed-up processing of BPF
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programs.
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Note, an admin should enable this feature changing:
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/proc/sys/net/core/bpf_jit_enable
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/proc/sys/net/core/bpf_jit_harden (optional)
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/proc/sys/net/core/bpf_jit_kallsyms (optional)
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config BPF_JIT_ALWAYS_ON
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bool "Permanently enable BPF JIT and remove BPF interpreter"
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depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
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help
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Enables BPF JIT and removes BPF interpreter to avoid speculative
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execution of BPF instructions by the interpreter.
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When CONFIG_BPF_JIT_ALWAYS_ON is enabled, /proc/sys/net/core/bpf_jit_enable
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is permanently set to 1 and setting any other value than that will
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return failure.
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config BPF_JIT_DEFAULT_ON
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def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
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depends on HAVE_EBPF_JIT && BPF_JIT
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config BPF_UNPRIV_DEFAULT_OFF
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bool "Disable unprivileged BPF by default"
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default y
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depends on BPF_SYSCALL
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help
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Disables unprivileged BPF by default by setting the corresponding
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/proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
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still reenable it by setting it to 0 later on, or permanently
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disable it by setting it to 1 (from which no other transition to
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0 is possible anymore).
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Unprivileged BPF could be used to exploit certain potential
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speculative execution side-channel vulnerabilities on unmitigated
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affected hardware.
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If you are unsure how to answer this question, answer Y.
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source "kernel/bpf/preload/Kconfig"
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config BPF_LSM
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bool "Enable BPF LSM Instrumentation"
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depends on BPF_EVENTS
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depends on BPF_SYSCALL
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depends on SECURITY
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depends on BPF_JIT
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help
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Enables instrumentation of the security hooks with BPF programs for
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implementing dynamic MAC and Audit Policies.
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If you are unsure how to answer this question, answer N.
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endmenu # "BPF subsystem"
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