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Fri, 18 Nov 2022 15:07:52 GMT Received: from smtpav03.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1939558061; Fri, 18 Nov 2022 15:07:53 +0000 (GMT) Received: from smtpav03.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E537758056; Fri, 18 Nov 2022 15:07:52 +0000 (GMT) Received: from localhost (unknown [9.211.69.164]) by smtpav03.dal12v.mail.ibm.com (Postfix) with ESMTP; Fri, 18 Nov 2022 15:07:52 +0000 (GMT) From: Nathan Lynch To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH 03/13] powerpc/rtas: avoid device tree lookups in rtas_os_term() Date: Fri, 18 Nov 2022 09:07:41 -0600 Message-Id: <20221118150751.469393-4-nathanl@linux.ibm.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221118150751.469393-1-nathanl@linux.ibm.com> References: <20221118150751.469393-1-nathanl@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: tn08NBkwIr__vgtJypIU8ahW2E5IyOzG X-Proofpoint-GUID: cYrOAr3hB3M36aw91SJmc4kV6gqjN4U7 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=2022-11-18_02,2022-11-18_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 priorityscore=1501 mlxlogscore=999 suspectscore=0 bulkscore=0 clxscore=1015 impostorscore=0 mlxscore=0 spamscore=0 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211180084 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, npiggin@gmail.com Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" rtas_os_term() is called during panic. Its behavior depends on a couple of conditions in the /rtas node of the device tree, the traversal of which entails locking and local IRQ state changes. If the kernel panics while devtree_lock is held, rtas_os_term() as currently written could hang. Instead of discovering the relevant characteristics at panic time, cache them in file-static variables at boot. Note the lookup for "ibm,extended-os-term" is converted to of_property_read_bool() since it is a boolean property, not a RTAS function token. Signed-off-by: Nathan Lynch Reviewed-by: Andrew Donnellan Reviewed-by: Nicholas Piggin --- arch/powerpc/kernel/rtas.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index c12dd5ed5e00..81e4996012b7 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -947,6 +947,8 @@ void __noreturn rtas_halt(void) /* Must be in the RMO region, so we place it here */ static char rtas_os_term_buf[2048]; +static s32 ibm_os_term_token = RTAS_UNKNOWN_SERVICE; +static bool ibm_extended_os_term; void rtas_os_term(char *str) { @@ -958,14 +960,13 @@ void rtas_os_term(char *str) * this property may terminate the partition which we want to avoid * since it interferes with panic_timeout. */ - if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term") || - RTAS_UNKNOWN_SERVICE == rtas_token("ibm,extended-os-term")) + if (ibm_os_term_token == RTAS_UNKNOWN_SERVICE || !ibm_extended_os_term) return; snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str); do { - status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL, + status = rtas_call(ibm_os_term_token, 1, 1, NULL, __pa(rtas_os_term_buf)); } while (rtas_busy_delay(status)); @@ -1335,6 +1336,13 @@ void __init rtas_initialize(void) no_entry = of_property_read_u32(rtas.dev, "linux,rtas-entry", &entry); rtas.entry = no_entry ? rtas.base : entry; + /* + * Discover these now to avoid device tree lookups in the + * panic path. + */ + ibm_os_term_token = rtas_token("ibm,os-term"); + ibm_extended_os_term = of_property_read_bool(rtas.dev, "ibm,extended-os-term"); + /* If RTAS was found, allocate the RMO buffer for it and look for * the stop-self token if any */