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Wed, 9 Nov 2022 04:51:31 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A9EC44C040; Wed, 9 Nov 2022 04:51:30 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 9 Nov 2022 04:51:30 +0000 (GMT) Received: from li-0d7fa1cc-2c9d-11b2-a85c-aed20764436d.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id C8993602FC; Wed, 9 Nov 2022 15:51:28 +1100 (AEDT) From: Benjamin Gray To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v10 2/9] powerpc/code-patching: Use WARN_ON and fix check in poking_init Date: Wed, 9 Nov 2022 15:51:05 +1100 Message-Id: <20221109045112.187069-3-bgray@linux.ibm.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221109045112.187069-1-bgray@linux.ibm.com> References: <20221109045112.187069-1-bgray@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: YgfbHTA8fbJv1TMU2XChynadPwDG9GmK X-Proofpoint-ORIG-GUID: sOQqZMFy9ZKBLPlrgCLWfaEL79iQ3g9U 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=2022-11-09_01,2022-11-08_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 adultscore=0 lowpriorityscore=0 malwarescore=0 spamscore=0 impostorscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211090032 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: ajd@linux.ibm.com, jniethe5@gmail.com, Benjamin Gray , npiggin@gmail.com, cmr@bluescreens.de Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" BUG_ON() when failing to initialise the code patching window is unnecessary, and use of BUG_ON is discouraged. We don't set poking_init_done in this case, so failure to init the boot CPU will result in a strict RWX error when a following patch_instruction uses raw_patch_instruction. If it only fails for later CPUs, they won't be onlined in the first place. The return value of cpuhp_setup_state() is also >= 0 on success, so check for < 0. Signed-off-by: Benjamin Gray Reviewed-by: Christophe Leroy --- v10: * Don't mention caller recovery * Don't set poking_init_done on failure * Add setup return code comment from later patch * Reviewed-by not applied because of above changes v9: * Reword commit message to explain why init failure is not fatal --- arch/powerpc/lib/code-patching.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index ad0cf3108dd0..3055eef7dcdc 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -81,16 +81,17 @@ static int text_area_cpu_down(unsigned int cpu) static __ro_after_init DEFINE_STATIC_KEY_FALSE(poking_init_done); -/* - * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and - * we judge it as being preferable to a kernel that will crash later when - * someone tries to use patch_instruction(). - */ void __init poking_init(void) { - BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, - "powerpc/text_poke:online", text_area_cpu_up, - text_area_cpu_down)); + int ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "powerpc/text_poke:online", + text_area_cpu_up, + text_area_cpu_down); + + /* cpuhp_setup_state returns >= 0 on success */ + if (WARN_ON(ret < 0)) + return; + static_branch_enable(&poking_init_done); }