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Fri, 06 Dec 2024 15:35:32 -0800 (PST) Received: from archie.me ([103.124.138.155]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-215f8e5f265sm33841085ad.70.2024.12.06.15.35.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Dec 2024 15:35:31 -0800 (PST) Received: by archie.me (Postfix, from userid 1000) id 5B40542806FA; Sat, 07 Dec 2024 06:35:27 +0700 (WIB) Date: Sat, 7 Dec 2024 06:35:27 +0700 From: Bagas Sanjaya To: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , Andy Chiu , Steven Rostedt , Masami Hiramatsu , Mark Rutland , Paul Walmsley , Palmer Dabbelt , Albert Ou , Robbin Ehn Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, bjorn@rivosinc.com, puranjay12@gmail.com, alexghiti@rivosinc.com, yongxuan.wang@sifive.com, greentime.hu@sifive.com, nick.hu@sifive.com, nylon.chen@sifive.com, tommy.wu@sifive.com, eric.lin@sifive.com, viccent.chen@sifive.com, zong.li@sifive.com, samuel.holland@sifive.com Subject: Re: [PATCH v3 3/7] riscv: ftrace: prepare ftrace for atomic code patching Message-ID: References: <20241127172908.17149-1-andybnac@gmail.com> <20241127172908.17149-4-andybnac@gmail.com> <87v7vxf7t6.fsf@all.your.base.are.belong.to.us> MIME-Version: 1.0 In-Reply-To: <87v7vxf7t6.fsf@all.your.base.are.belong.to.us> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241206_153534_676158_76676FD3 X-CRM114-Status: GOOD ( 11.05 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============8286598528974407869==" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org --===============8286598528974407869== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="fdN/cFbE4b73Mn/0" Content-Disposition: inline --fdN/cFbE4b73Mn/0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Dec 06, 2024 at 11:02:29AM +0100, Bj=C3=B6rn T=C3=B6pel wrote: > Adding Robbin for input, who's doing much more crazy text patching in > JVM, than what we do in the kernel. ;-) >=20 > Let's say we're tracing "f". Previously w/ stop_machine() it was > something like: >=20 > f: > 1: nop > nop > ... > ... >=20 > ftrace_caller: > ... > auipc a2, function_trace_op > ld a2, function_trace_op(a2) > ... > 2: auipc ra, ftrace_stub > jalr ftrace_stub(ra) >=20 > The text was patched by ftrace in 1 and 2. >=20 > ...and now: > f: > auipc t0, ftrace_caller > A: nop > ... > ... >=20 > ftrace_caller: > ... > auipc a2, function_trace_op > ld a2, function_trace_op(a2) > ... > auipc ra, ftrace_call_dest > ld ra, ftrace_call_dest(ra) > jalr ra=20 >=20 > The text is only patched in A, and the tracer func is loaded via > ftrace_call_dest. Previously the operation was no-op, right? Confused... --=20 An old man doll... just what I always wanted! - Clara --fdN/cFbE4b73Mn/0 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQSSYQ6Cy7oyFNCHrUH2uYlJVVFOowUCZ1OKOgAKCRD2uYlJVVFO o6Y+AQCiT8k5GCk4aLvmXeShXl/pfnz5HC+PJM+m4E8quF6IJQD+My2mpICqvpg/ Bn0rGqOqUEb+abAgVYRVjE8IIuPdPwE= =ruu5 -----END PGP SIGNATURE----- --fdN/cFbE4b73Mn/0-- --===============8286598528974407869== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv --===============8286598528974407869==--