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([2a02:85f:e63c:d500:6659:3d96:c62:a251]) by smtp.gmail.com with ESMTPSA id x16-20020a5d54d0000000b002c71703876bsm13320810wrv.14.2023.03.01.11.28.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Mar 2023 11:28:45 -0800 (PST) Message-ID: <588fb3db-887e-697a-8e0a-a428f59d1187@gmail.com> Date: Wed, 1 Mar 2023 21:28:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH] ptrace.2: Add details about usage of PTRACE_GET_SYSCALL_INFO From: =?UTF-8?B?zqbPjs+EzrfPgiDOks6xzrvOsc+DzrnOrM60zrfPgg==?= To: linux-man@vger.kernel.org Cc: alx.manpages@gmail.com, ldv@strace.io, mtk.manpages@gmail.com, lineprinter0@gmail.com, Nate Eldredge , Alejandro Colomar References: <9f4aaf34-66cc-554f-d45f-73f0bb9b4a94@gmail.com> <20230227191731.15069-1-fvalasiad@gmail.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org Hi yet again Alex! You didn't confirm so I was wondering if you received my message! Let me know if possible. -- fvalasiad -- On 27/2/23 21:19, Φώτης Βαλασιάδης wrote: > Hi Alex! > > Is that good enough? > > -- fvalasiad -- > > On 27/2/23 21:17, Fotios Valasiadis wrote: >> Document the role of PTRACE_O_TRACESYSGOOD option in connection with >> PTRACE_GET_SYSCALL_INFO. >> >> Came upon this after writing a test program using >> PTRACE_GET_SYSCALL_INFO. >> After failing to find what's wrong I posted a StackOverflow question >> which you can find right here: >> >> >> >> Nate Eldredge found out what happens by looking into the kernel's source >> code, here is a link to the relevant part >> >> >> >> In the code it can be seen that in case of system call entry or >> exit stops, the union is filled if and only if the signal matches >> "SIGTRAP | 0x80", a signal which is only sent if the >> PTRACE_O_TRACESYSGOOD >> option is set.  You can read about that in the PTRACE_O_TRACESYSGOOD >> section of ptrace(2)'s manual. >> >> Complements: fc91449cb "ptrace.2: Document PTRACE_GET_SYSCALL_INFO" >> Cowritten-by: Dmitry V. Levin >> Signed-off-by: Dmitry V. Levin >> Signed-off-by: Fotios Valasiadis >> Acked-by: Nate Eldredge >> Cc: Elvira Khabirova >> Signed-off-by: Alejandro Colomar >> --- >>   man2/ptrace.2 | 9 +++++++++ >>   1 file changed, 9 insertions(+) >> >> diff --git a/man2/ptrace.2 b/man2/ptrace.2 >> index 55d9fd36d..9737b3825 100644 >> --- a/man2/ptrace.2 >> +++ b/man2/ptrace.2 >> @@ -1111,6 +1111,15 @@ stop. >>   .B PTRACE_SYSCALL_INFO_NONE >>   No component of the union contains relevant information. >>   .RE >> +.IP >> +In case of system call entry or exit stops, >> +the data returned by >> +.B PTRACE_GET_SYSCALL_INFO >> +is limited to type >> +.B PTRACE_SYSCALL_INFO_NONE >> +unless >> +.B PTRACE_O_TRACESYSGOOD >> +option is set before the corresponding system call stop has occurred. >>   .\" >>   .SS Death under ptrace >>   When a (possibly multithreaded) process receives a killing signal