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9667305c63
When CONFIG_BPF_SYSCALL is not set, but CONFIG_BPF_JIT=y
the kernel build fails:
In file included from ../kernel/bpf/trampoline.c:11:
../kernel/bpf/trampoline.c: In function ‘bpf_trampoline_update’:
../kernel/bpf/trampoline.c:220:39: error: ‘call_rcu_tasks_trace’ undeclared
../kernel/bpf/trampoline.c: In function ‘__bpf_prog_enter_sleepable’:
../kernel/bpf/trampoline.c:411:2: error: implicit declaration of function ‘rcu_read_lock_trace’
../kernel/bpf/trampoline.c: In function ‘__bpf_prog_exit_sleepable’:
../kernel/bpf/trampoline.c:416:2: error: implicit declaration of function ‘rcu_read_unlock_trace’
This is due to:
obj-$(CONFIG_BPF_JIT) += trampoline.o
obj-$(CONFIG_BPF_JIT) += dispatcher.o
There is a number of functions that arch/x86/net/bpf_jit_comp.c is
using from these two files, but none of them will be used when
only cBPF is on (which is the case for BPF_SYSCALL=n BPF_JIT=y).
Add rcu_trace functions to rcupdate_trace.h. The JITed code won't execute them
and BPF trampoline logic won't be used without BPF_SYSCALL.
Fixes: 1e6c62a882 ("bpf: Introduce sleepable BPF programs")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/bpf/20200831155155.62754-1-alexei.starovoitov@gmail.com
95 lines
2.9 KiB
C
95 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Read-Copy Update mechanism for mutual exclusion, adapted for tracing.
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*
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* Copyright (C) 2020 Paul E. McKenney.
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*/
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#ifndef __LINUX_RCUPDATE_TRACE_H
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#define __LINUX_RCUPDATE_TRACE_H
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#include <linux/sched.h>
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#include <linux/rcupdate.h>
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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extern struct lockdep_map rcu_trace_lock_map;
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static inline int rcu_read_lock_trace_held(void)
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{
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return lock_is_held(&rcu_trace_lock_map);
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}
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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static inline int rcu_read_lock_trace_held(void)
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{
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return 1;
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}
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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#ifdef CONFIG_TASKS_TRACE_RCU
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void rcu_read_unlock_trace_special(struct task_struct *t, int nesting);
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/**
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* rcu_read_lock_trace - mark beginning of RCU-trace read-side critical section
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*
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* When synchronize_rcu_tasks_trace() is invoked by one task, then that
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* task is guaranteed to block until all other tasks exit their read-side
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* critical sections. Similarly, if call_rcu_trace() is invoked on one
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* task while other tasks are within RCU read-side critical sections,
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* invocation of the corresponding RCU callback is deferred until after
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* the all the other tasks exit their critical sections.
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*
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* For more details, please see the documentation for rcu_read_lock().
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*/
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static inline void rcu_read_lock_trace(void)
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{
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struct task_struct *t = current;
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WRITE_ONCE(t->trc_reader_nesting, READ_ONCE(t->trc_reader_nesting) + 1);
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if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB) &&
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t->trc_reader_special.b.need_mb)
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smp_mb(); // Pairs with update-side barriers
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rcu_lock_acquire(&rcu_trace_lock_map);
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}
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/**
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* rcu_read_unlock_trace - mark end of RCU-trace read-side critical section
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*
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* Pairs with a preceding call to rcu_read_lock_trace(), and nesting is
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* allowed. Invoking a rcu_read_unlock_trace() when there is no matching
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* rcu_read_lock_trace() is verboten, and will result in lockdep complaints.
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*
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* For more details, please see the documentation for rcu_read_unlock().
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*/
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static inline void rcu_read_unlock_trace(void)
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{
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int nesting;
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struct task_struct *t = current;
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rcu_lock_release(&rcu_trace_lock_map);
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nesting = READ_ONCE(t->trc_reader_nesting) - 1;
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if (likely(!READ_ONCE(t->trc_reader_special.s)) || nesting) {
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WRITE_ONCE(t->trc_reader_nesting, nesting);
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return; // We assume shallow reader nesting.
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}
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rcu_read_unlock_trace_special(t, nesting);
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}
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void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func);
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void synchronize_rcu_tasks_trace(void);
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void rcu_barrier_tasks_trace(void);
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#else
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/*
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* The BPF JIT forms these addresses even when it doesn't call these
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* functions, so provide definitions that result in runtime errors.
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*/
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static inline void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func) { BUG(); }
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static inline void rcu_read_lock_trace(void) { BUG(); }
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static inline void rcu_read_unlock_trace(void) { BUG(); }
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#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
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#endif /* __LINUX_RCUPDATE_TRACE_H */
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