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Mon, 28 Nov 2022 23:44:34 GMT Received: from smtpav04.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2459D58045; Mon, 28 Nov 2022 23:44:34 +0000 (GMT) Received: from smtpav04.wdc07v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EDDDB58050; Mon, 28 Nov 2022 23:44:33 +0000 (GMT) Received: from localhost (unknown [9.211.69.164]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 28 Nov 2022 23:44:33 +0000 (GMT) From: Nathan Lynch To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 13/13] powerpc/rtas: place tracepoints in do_enter_rtas() In-Reply-To: References: <20221118150751.469393-1-nathanl@linux.ibm.com> <20221118150751.469393-14-nathanl@linux.ibm.com> Date: Mon, 28 Nov 2022 17:44:33 -0600 Message-ID: <87tu2i8x0e.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: f25eNuxxwIJD_hRr_EsLCeLaDI98za9f X-Proofpoint-ORIG-GUID: wgjbaes2FL6KG03OUty7-9BHKTdhvlpv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-28_17,2022-11-28_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 bulkscore=0 priorityscore=1501 mlxscore=0 clxscore=1015 phishscore=0 impostorscore=0 spamscore=0 mlxlogscore=558 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211280169 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: tyreld@linux.ibm.com, nnac123@linux.ibm.com, ldufour@linux.ibm.com, ajd@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" "Nicholas Piggin" writes: > On Sat Nov 19, 2022 at 1:07 AM AEST, Nathan Lynch wrote: >> Call the just-added rtas tracepoints in do_enter_rtas(), taking care >> to avoid function name lookups in the CPU offline path. >> >> Signed-off-by: Nathan Lynch >> --- >> arch/powerpc/kernel/rtas.c | 23 +++++++++++++++++++++++ >> 1 file changed, 23 insertions(+) >> >> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c >> index 198366d641d0..3487b42cfbf7 100644 >> --- a/arch/powerpc/kernel/rtas.c >> +++ b/arch/powerpc/kernel/rtas.c >> @@ -38,6 +38,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> enum rtas_function_flags { >> @@ -525,6 +526,7 @@ void enter_rtas(unsigned long); >> static void do_enter_rtas(struct rtas_args *args) >> { >> unsigned long msr; >> + const char *name = NULL; >> >> /* >> * Make sure MSR[RI] is currently enabled as it will be forced later >> @@ -537,9 +539,30 @@ static void do_enter_rtas(struct rtas_args *args) >> >> hard_irq_disable(); /* Ensure MSR[EE] is disabled on PPC64 */ >> >> + if ((trace_rtas_input_enabled() || trace_rtas_output_enabled())) { >> + /* >> + * rtas_token_to_function() uses xarray which uses RCU, >> + * but this code can run in the CPU offline path >> + * (e.g. stop-self), after it's become invalid to call >> + * RCU APIs. >> + */ > > We can call this in real-mode via pseries_machine_check_realmode > -> fwnmi_release_errinfo, so tracing should be disabled for that > case too... Does this_cpu_set_ftrace_enabled(0) in the early > machine check handler cover that sufficiently? I suspect so, but I'd like to verify. Do you know how I could exercise this path in qemu or LPAR?