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Mon, 2 Nov 2026 11:31:22 +0000 (UTC) Received: from onestero-thinkpadp1gen7.tpbc.csb (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 499BD410; Mon, 2 Nov 2026 11:31:19 +0000 (UTC) Received: by onestero-thinkpadp1gen7.tpbc.csb (nbSMTP-1.00) for uid 13628 oleg@redhat.com; Mon, 2 Nov 2026 12:31:22 +0100 (CET) Date: Mon, 2 Nov 2026 12:31:18 +0100 From: Oleg Nesterov To: Zhao Gongyi Cc: Jinjie Ruan , Catalin Marinas , will@kernel.org, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] arm64: ptrace: don't warn on missing siginfo in a group-stop Message-ID: References: <20261023110710.10145-1-zhaogongyi@bytedance.com> <8028d335-c304-49de-81fa-07fd446cf9d0@bytedance.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8028d335-c304-49de-81fa-07fd446cf9d0@bytedance.com> X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 On 11/02, Zhao Gongyi wrote: > > Hi Jinjie, > > > On 11/2/26 3:54 PM, Jinjie Ruan wrote: > > > > I think maybe we can refer to ptrace_get_syscall_info_op()? > > > > Thanks for the suggestion. > > I checked ptrace_get_syscall_info_op(). It is currently static to > kernel/ptrace.c and identifies a syscall stop only when > last_siginfo->si_code is SIGTRAP | 0x80. > > The arm64 path here also needs to handle a syscall-exit-stop when the > tracer has not enabled PTRACE_O_TRACESYSGOOD. In that case, the tested Yes, PTRACE_GET_SYSCALL_INFO/etc depends on PTRACE_O_TRACESYSGOOD by design, this is even documented in man 2 ptrace. > For this patch, I think > the local check of last_siginfo, with bit 0x80 masked and ptrace_message > checked for PTRACE_EVENTMSG_SYSCALL_EXIT, is the smaller and safer change. Agreed. Oleg.