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Levin" To: Michael Ellerman , Oleg Nesterov Subject: [PATCH] powerpc/ptrace: cleanup do_syscall_trace_enter Message-ID: <20181216172828.GA25359@altlinux.org> References: <20181119210139.GA8360@altlinux.org> <87efbe166y.fsf@concordia.ellerman.id.au> <20181203031823.GE11573@altlinux.org> <20181207011946.GA18558@altlinux.org> <87y391k2tq.fsf@concordia.ellerman.id.au> <20181207154255.GA28964@altlinux.org> <20181207155605.GB28964@altlinux.org> <20181207185226.GB31278@altlinux.org> <20181210132806.GA4177@redhat.com> <20181210133655.GH11942@altlinux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181210133655.GH11942@altlinux.org> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Invoke tracehook_report_syscall_entry once. Signed-off-by: Dmitry V. Levin --- arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 23 deletions(-) diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 714c3480c52d..8794d32c2d9e 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -3263,32 +3263,40 @@ static inline int do_seccomp(struct pt_regs *regs) { return 0; } */ long do_syscall_trace_enter(struct pt_regs *regs) { + u32 cached_flags; + user_exit(); - if (test_thread_flag(TIF_SYSCALL_EMU)) { - /* - * A nonzero return code from tracehook_report_syscall_entry() - * tells us to prevent the syscall execution, but we are not - * going to execute it anyway. - * - * Returning -1 will skip the syscall execution. We want to - * avoid clobbering any register also, thus, not 'gotoing' - * skip label. - */ - if (tracehook_report_syscall_entry(regs)) - ; - return -1; - } + cached_flags = READ_ONCE(current_thread_info()->flags) & + (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE); - /* - * The tracer may decide to abort the syscall, if so tracehook - * will return !0. Note that the tracer may also just change - * regs->gpr[0] to an invalid syscall number, that is handled - * below on the exit path. - */ - if (test_thread_flag(TIF_SYSCALL_TRACE) && - tracehook_report_syscall_entry(regs)) - goto skip; + if (cached_flags) { + int rc = tracehook_report_syscall_entry(regs); + + if (unlikely(cached_flags & _TIF_SYSCALL_EMU)) { + /* + * A nonzero return code from + * tracehook_report_syscall_entry() tells us + * to prevent the syscall execution, but + * we are not going to execute it anyway. + * + * Returning -1 will skip the syscall execution. + * We want to avoid clobbering any register also, + * thus, not 'gotoing' skip label. + */ + return -1; + } + + if (rc) { + /* + * The tracer decided to abort the syscall. + * Note that the tracer may also just change + * regs->gpr[0] to an invalid syscall number, + * that is handled below on the exit path. + */ + goto skip; + } + } /* Run seccomp after ptrace; allow it to set gpr[3]. */ if (do_seccomp(regs)) -- ldv