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Fri, 25 Aug 2023 01:49:18 +0000 (GMT) Received: from bgray-lenovo-p15.fritz.box (unknown [9.43.162.68]) (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 0FF516010C; Fri, 25 Aug 2023 11:49:14 +1000 (AEST) From: Benjamin Gray To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH] powerpc/dexcr: Move HASHCHK trap handler Date: Fri, 25 Aug 2023 11:49:10 +1000 Message-ID: <20230825014910.488822-1-bgray@linux.ibm.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: ddkzjoV1RNg5AqQawWkkx9fUe_-SDhTC X-Proofpoint-ORIG-GUID: ddkzjoV1RNg5AqQawWkkx9fUe_-SDhTC X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-08-25_01,2023-08-24_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 clxscore=1011 adultscore=0 spamscore=0 priorityscore=1501 mlxscore=0 malwarescore=0 phishscore=0 suspectscore=0 mlxlogscore=742 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2308100000 definitions=main-2308250012 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: Benjamin Gray , ruscur@russell.cc Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" To determine if a trap was caused by a HASHCHK instruction, we inspect the user instruction that triggered the trap. However this may sleep if the page needs to be faulted in. Move the HASHCHK handler logic to after we allow IRQs, which is fine because we are only interested in HASHCHK if it's a user space trap. Fixes: 5bcba4e6c13f ("powerpc/dexcr: Handle hashchk exception") Signed-off-by: Benjamin Gray --- arch/powerpc/kernel/traps.c | 56 ++++++++++++++++++++++++------------- 1 file changed, 36 insertions(+), 20 deletions(-) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index f5ce282dc4b8..32b5e841ea97 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -1512,23 +1512,11 @@ static void do_program_check(struct pt_regs *regs) return; } - if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE) && user_mode(regs)) { - ppc_inst_t insn; - - if (get_user_instr(insn, (void __user *)regs->nip)) { - _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip); - return; - } - - if (ppc_inst_primary_opcode(insn) == 31 && - get_xop(ppc_inst_val(insn)) == OP_31_XOP_HASHCHK) { - _exception(SIGILL, regs, ILL_ILLOPN, regs->nip); - return; - } + /* User mode considers other cases after enabling IRQs */ + if (!user_mode(regs)) { + _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip); + return; } - - _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip); - return; } #ifdef CONFIG_PPC_TRANSACTIONAL_MEM if (reason & REASON_TM) { @@ -1561,16 +1549,44 @@ static void do_program_check(struct pt_regs *regs) /* * If we took the program check in the kernel skip down to sending a - * SIGILL. The subsequent cases all relate to emulating instructions - * which we should only do for userspace. We also do not want to enable - * interrupts for kernel faults because that might lead to further - * faults, and loose the context of the original exception. + * SIGILL. The subsequent cases all relate to user space, such as + * emulating instructions which we should only do for user space. We + * also do not want to enable interrupts for kernel faults because that + * might lead to further faults, and loose the context of the original + * exception. */ if (!user_mode(regs)) goto sigill; interrupt_cond_local_irq_enable(regs); + /* + * (reason & REASON_TRAP) is mostly handled before enabling IRQs, + * except get_user_instr() can sleep so we cannot reliably inspect the + * current instruction in that context. Now that we know we are + * handling a user space trap and can sleep, we can check if the trap + * was a hashchk failure. + */ + if (reason & REASON_TRAP) { + if (cpu_has_feature(CPU_FTR_DEXCR_NPHIE)) { + ppc_inst_t insn; + + if (get_user_instr(insn, (void __user *)regs->nip)) { + _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip); + return; + } + + if (ppc_inst_primary_opcode(insn) == 31 && + get_xop(ppc_inst_val(insn)) == OP_31_XOP_HASHCHK) { + _exception(SIGILL, regs, ILL_ILLOPN, regs->nip); + return; + } + } + + _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip); + return; + } + /* (reason & REASON_ILLEGAL) would be the obvious thing here, * but there seems to be a hardware bug on the 405GP (RevD) * that means ESR is sometimes set incorrectly - either to