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5b0c308a05
In order to integrate rseq into user-space applications, expose a
__rseq_handled symbol so many rseq users can be linked into the same
application (e.g. librseq and glibc).
The __rseq_refcount TLS variable is static to the librseq library. It
ensures that rseq syscall registration/unregistration happens only for
the most early/late caller to rseq_{,un}register_current_thread for each
thread, thus ensuring that rseq is registered across the lifetime of all
rseq users for a given thread.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Shuah Khan <shuah@kernel.org>
CC: Carlos O'Donell <carlos@redhat.com>
CC: Florian Weimer <fweimer@redhat.com>
CC: Joseph Myers <joseph@codesourcery.com>
CC: Szabolcs Nagy <szabolcs.nagy@arm.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ben Maurer <bmaurer@fb.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Dave Watson <davejwatson@fb.com>
CC: Paul Turner <pjt@google.com>
CC: linux-api@vger.kernel.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
164 lines
4.1 KiB
C
164 lines
4.1 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* rseq.h
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*
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* (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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*/
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#ifndef RSEQ_H
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#define RSEQ_H
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#include <stdint.h>
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#include <stdbool.h>
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#include <pthread.h>
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#include <signal.h>
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#include <sched.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <linux/rseq.h>
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/*
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* Empty code injection macros, override when testing.
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* It is important to consider that the ASM injection macros need to be
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* fully reentrant (e.g. do not modify the stack).
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*/
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#ifndef RSEQ_INJECT_ASM
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#define RSEQ_INJECT_ASM(n)
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#endif
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#ifndef RSEQ_INJECT_C
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#define RSEQ_INJECT_C(n)
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#endif
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#ifndef RSEQ_INJECT_INPUT
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#define RSEQ_INJECT_INPUT
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#endif
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#ifndef RSEQ_INJECT_CLOBBER
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#define RSEQ_INJECT_CLOBBER
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#endif
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#ifndef RSEQ_INJECT_FAILED
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#define RSEQ_INJECT_FAILED
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#endif
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extern __thread volatile struct rseq __rseq_abi;
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extern int __rseq_handled;
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#define rseq_likely(x) __builtin_expect(!!(x), 1)
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#define rseq_unlikely(x) __builtin_expect(!!(x), 0)
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#define rseq_barrier() __asm__ __volatile__("" : : : "memory")
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#define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x))
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#define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
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#define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x)
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#define __rseq_str_1(x) #x
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#define __rseq_str(x) __rseq_str_1(x)
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#define rseq_log(fmt, args...) \
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fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
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## args, __func__)
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#define rseq_bug(fmt, args...) \
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do { \
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rseq_log(fmt, ##args); \
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abort(); \
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} while (0)
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#if defined(__x86_64__) || defined(__i386__)
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#include <rseq-x86.h>
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#elif defined(__ARMEL__)
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#include <rseq-arm.h>
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#elif defined (__AARCH64EL__)
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#include <rseq-arm64.h>
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#elif defined(__PPC__)
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#include <rseq-ppc.h>
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#elif defined(__mips__)
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#include <rseq-mips.h>
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#elif defined(__s390__)
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#include <rseq-s390.h>
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#else
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#error unsupported target
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#endif
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/*
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* Register rseq for the current thread. This needs to be called once
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* by any thread which uses restartable sequences, before they start
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* using restartable sequences, to ensure restartable sequences
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* succeed. A restartable sequence executed from a non-registered
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* thread will always fail.
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*/
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int rseq_register_current_thread(void);
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/*
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* Unregister rseq for current thread.
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*/
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int rseq_unregister_current_thread(void);
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/*
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* Restartable sequence fallback for reading the current CPU number.
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*/
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int32_t rseq_fallback_current_cpu(void);
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/*
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* Values returned can be either the current CPU number, -1 (rseq is
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* uninitialized), or -2 (rseq initialization has failed).
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*/
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static inline int32_t rseq_current_cpu_raw(void)
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{
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return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id);
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}
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/*
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* Returns a possible CPU number, which is typically the current CPU.
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* The returned CPU number can be used to prepare for an rseq critical
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* section, which will confirm whether the cpu number is indeed the
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* current one, and whether rseq is initialized.
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*
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* The CPU number returned by rseq_cpu_start should always be validated
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* by passing it to a rseq asm sequence, or by comparing it to the
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* return value of rseq_current_cpu_raw() if the rseq asm sequence
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* does not need to be invoked.
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*/
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static inline uint32_t rseq_cpu_start(void)
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{
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return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start);
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}
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static inline uint32_t rseq_current_cpu(void)
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{
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int32_t cpu;
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cpu = rseq_current_cpu_raw();
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if (rseq_unlikely(cpu < 0))
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cpu = rseq_fallback_current_cpu();
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return cpu;
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}
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static inline void rseq_clear_rseq_cs(void)
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{
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#ifdef __LP64__
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__rseq_abi.rseq_cs.ptr = 0;
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#else
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__rseq_abi.rseq_cs.ptr.ptr32 = 0;
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#endif
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}
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/*
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* rseq_prepare_unload() should be invoked by each thread executing a rseq
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* critical section at least once between their last critical section and
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* library unload of the library defining the rseq critical section
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* (struct rseq_cs). This also applies to use of rseq in code generated by
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* JIT: rseq_prepare_unload() should be invoked at least once by each
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* thread executing a rseq critical section before reclaim of the memory
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* holding the struct rseq_cs.
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*/
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static inline void rseq_prepare_unload(void)
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{
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rseq_clear_rseq_cs();
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}
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#endif /* RSEQ_H_ */
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