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[193.116.82.75]) by smtp.gmail.com with ESMTPSA id z9sm17258805pfh.219.2022.01.24.19.04.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jan 2022 19:04:13 -0800 (PST) Date: Tue, 25 Jan 2022 13:04:07 +1000 From: Nicholas Piggin Subject: Re: [PATCH 0/2] powerpc: Disable syscall emulation and stepping To: Christophe Leroy , "linuxppc-dev@lists.ozlabs.org" References: <20220124055741.3686496-1-npiggin@gmail.com> In-Reply-To: MIME-Version: 1.0 Message-Id: <1643079479.32j7nee5j0.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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: "Naveen N. Rao" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" +Naveen (sorry missed cc'ing you at first) Excerpts from Christophe Leroy's message of January 24, 2022 4:39 pm: >=20 >=20 > Le 24/01/2022 =C3=A0 06:57, Nicholas Piggin a =C3=A9crit=C2=A0: >> As discussed previously >>=20 >> https://lists.ozlabs.org/pipermail/linuxppc-dev/2022-January/238946.html >>=20 >> I'm wondering whether PPC32 should be returning -1 for syscall >> instructions too here? That could be done in another patch anyway. >>=20 >=20 > The 'Programming Environments Manual for 32-Bit Implementations of the=20 > PowerPC=E2=84=A2 Architecture' says: >=20 > The following are not traced: > =E2=80=A2 rfi instruction > =E2=80=A2 sc and trap instructions that trap > =E2=80=A2 Other instructions that cause interrupts (other than trace inte= rrupts) > =E2=80=A2 The first instruction of any interrupt handler > =E2=80=A2 Instructions that are emulated by software >=20 >=20 > So I think PPC32 should return -1 as well. I agree. What about the trap instructions? analyse_instr returns 0 for them which falls through to return 0 for emulate_step, should they return -1 as well or am I missing something? Thanks, Nick