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(unknown [9.177.18.116]) (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 E2DDA60151; Wed, 24 Aug 2022 12:07:19 +1000 (AEST) From: Rohan McLure To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v4 20/20] powerpc/64e: Clear gprs on interrupt routine entry Date: Wed, 24 Aug 2022 12:05:48 +1000 Message-Id: <20220824020548.62625-21-rmclure@linux.ibm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220824020548.62625-1-rmclure@linux.ibm.com> References: <20220824020548.62625-1-rmclure@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: GsY2svRfVJgNzIzQzeQEbIGuBYxsChJA X-Proofpoint-ORIG-GUID: GsY2svRfVJgNzIzQzeQEbIGuBYxsChJA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-23_10,2022-08-22_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 spamscore=0 malwarescore=0 mlxlogscore=556 suspectscore=0 mlxscore=0 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2208240005 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: Rohan McLure Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Zero GPRS r14-r31 on entry into the kernel for interrupt sources to limit influence of user-space values in potential speculation gadgets. Prior to this commit, all other GPRS are reassigned during the common prologue to interrupt handlers and so need not be zeroised explicitly. This may be done safely, without loss of register state prior to the interrupt, as the common prologue saves the initial values of non-volatiles, which are unconditionally restored in interrupt_64.S. Signed-off-by: Rohan McLure --- V3 -> V4: New patch. --- arch/powerpc/kernel/exceptions-64e.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S index 48c640ca425d..296b3bf6b2a6 100644 --- a/arch/powerpc/kernel/exceptions-64e.S +++ b/arch/powerpc/kernel/exceptions-64e.S @@ -401,7 +401,8 @@ exc_##n##_common: \ std r12,STACK_FRAME_OVERHEAD-16(r1); /* mark the frame */ \ std r3,_TRAP(r1); /* set trap number */ \ std r0,RESULT(r1); /* clear regs->result */ \ - SAVE_NVGPRS(r1); + SAVE_NVGPRS(r1); \ + ZEROIZE_NVGPRS(); /* minimise speculation influence */ #define EXCEPTION_COMMON(n) \ EXCEPTION_COMMON_LVL(n, SPRN_SPRG_GEN_SCRATCH, PACA_EXGEN) @@ -1068,6 +1069,7 @@ bad_stack_book3e: std r11,_CTR(r1) std r12,_XER(r1) SAVE_NVGPRS(r1) + ZEROIZE_NVGPRS() lhz r12,PACA_TRAP_SAVE(r13) std r12,_TRAP(r1) addi r11,r1,INT_FRAME_SIZE