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Mon, 27 Apr 2020 08:06:00 +0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp07028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 03R85xqk46334238 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 27 Apr 2020 08:05:59 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 680E1C6057; Mon, 27 Apr 2020 08:05:59 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 67059C6059; Mon, 27 Apr 2020 08:05:57 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.85.72.10]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 27 Apr 2020 08:05:57 +0000 (GMT) From: "Aneesh Kumar K.V" To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au Subject: [RFC PATCH 14/25] powerpc/book3s64/kuep: Store/restore userspace IAMR correctly on entry and exit from kernel Date: Mon, 27 Apr 2020 13:34:55 +0530 Message-Id: <20200427080507.1626327-15-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.25.3 In-Reply-To: <20200427080507.1626327-1-aneesh.kumar@linux.ibm.com> References: <20200427080507.1626327-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-27_03:2020-04-24, 2020-04-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 spamscore=0 malwarescore=0 adultscore=0 suspectscore=0 mlxlogscore=999 impostorscore=0 lowpriorityscore=0 mlxscore=0 phishscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004270067 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: "Aneesh Kumar K.V" , linuxram@us.ibm.com, npiggin@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" This prepare kernel to operate with a different value than userspace IAMR. For this, IAMR needs to be saved and restored on entry and return from the kernel. If MMU_FTR_KEY is enabled we always use the key mechanism to implement KUEP feature. If MMU_FTR_KEY is not supported and if we support MMU_FTR_KUEP (radix translation on POWER9), we can skip restoring IAMR on return to userspace. Userspace won't be using IAMR in that specific config. We don't need to save/restore IAMR on reentry into the kernel due to interrupt because the kernel doesn't modify IAMR internally. Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/include/asm/book3s/64/kup.h | 51 +++++++++++++++++++++++- arch/powerpc/include/asm/ptrace.h | 6 ++- arch/powerpc/kernel/asm-offsets.c | 4 ++ arch/powerpc/kernel/syscall_64.c | 5 ++- 4 files changed, 62 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h index 85645d1b7102..717c2c4d3681 100644 --- a/arch/powerpc/include/asm/book3s/64/kup.h +++ b/arch/powerpc/include/asm/book3s/64/kup.h @@ -25,6 +25,13 @@ b 100f // skip_restore_amr ALT_MMU_FTR_SECTION_END_NESTED_IFSET(MMU_FTR_KUAP, 68) + /* + * We don't check KUEP feature here, because if FTR_PKEY + * is not enabled we don't need to restore IAMR on + * return to usespace. That is handled by either + * handle_kuap_restore_amr or skip_restore_amr + */ + 99: // handle_kuap_restore_amr /* * No key support, don't bother to restore AMR @@ -37,7 +44,17 @@ ld \gpr, STACK_REGS_KUAP(r1) isync mtspr SPRN_AMR, \gpr - /* No isync here because we will return to a different context */ + + /* + * Restore IAMR only when returning to userspace + */ + .ifnb \to_user + ld \gpr, STACK_REGS_KUEP(r1) + mtspr SPRN_IAMR, \gpr + .endif + /* + * No isync here because we will return to a different context + */ 100: // skip_restore_amr #endif .endm @@ -75,6 +92,12 @@ b 100f // skip_save_amr ALT_MMU_FTR_SECTION_END_NESTED_IFSET(MMU_FTR_KUAP, 68) + /* + * We don't check KUEP feature here, because if FTR_PKEY + * is not enabled we don't need to save IAMR on + * entry from usespace. That is handled by either + * handle_kuap_save_amr or skip_save_amr + */ 99: // handle_kuap_save_amr .ifnb \msr_pr_cr @@ -103,7 +126,26 @@ mtspr SPRN_AMR, \gpr2 isync 102: - END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_KUAP, 69) + END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_KUAP, 69) + + .ifnb \msr_pr_cr + beq \msr_pr_cr, 103f // from kernel space + mfspr \gpr1, SPRN_IAMR + std \gpr1, STACK_REGS_KUEP(r1) + + /* + * update kernel IAMR with AMR_KUEP_BLOCKED only + * if KUAP feature is enabled + */ + BEGIN_MMU_FTR_SECTION_NESTED(70) + LOAD_REG_IMMEDIATE(\gpr2, AMR_KUEP_BLOCKED) + cmpd \use_cr, \gpr1, \gpr2 + beq \use_cr, 103f + mtspr SPRN_IAMR, \gpr2 + isync +103: + END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_KUEP, 70) + .endif 100: // skip_save_amr #endif @@ -129,6 +171,11 @@ static inline void kuap_restore_amr(struct pt_regs *regs, bool to_user) * returning to a different context using rfid */ } + /* + * We do support FTR_PKEY, restore IAMR when returning to user + */ + if (to_user) + mtspr(SPRN_IAMR, regs->kuep); } static inline void kuap_check_amr(void) diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h index e0195e6b892b..2bfd2b6a72ab 100644 --- a/arch/powerpc/include/asm/ptrace.h +++ b/arch/powerpc/include/asm/ptrace.h @@ -56,8 +56,12 @@ struct pt_regs #ifdef CONFIG_PPC_KUAP unsigned long kuap; #endif +#ifdef CONFIG_PPC_KUEP + unsigned long kuep; +#endif + }; - unsigned long __pad[2]; /* Maintain 16 byte interrupt stack alignment */ + unsigned long __pad[4]; /* Maintain 16 byte interrupt stack alignment */ }; }; #endif diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index fcf24a365fc0..6c7326fc73b9 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -353,6 +353,10 @@ int main(void) #ifdef CONFIG_PPC_KUAP STACK_PT_REGS_OFFSET(STACK_REGS_KUAP, kuap); #endif +#ifdef CONFIG_PPC_KUEP + STACK_PT_REGS_OFFSET(STACK_REGS_KUEP, kuep); +#endif + #if defined(CONFIG_PPC32) #if defined(CONFIG_BOOKE) || defined(CONFIG_40x) diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c index f69b4774f3b3..458f2bb80c6d 100644 --- a/arch/powerpc/kernel/syscall_64.c +++ b/arch/powerpc/kernel/syscall_64.c @@ -36,11 +36,14 @@ notrace long system_call_exception(long r3, long r4, long r5, BUG_ON(regs->softe != IRQS_ENABLED); if (mmu_has_feature(MMU_FTR_PKEY)) { - unsigned long amr; + unsigned long amr, iamr; amr = mfspr(SPRN_AMR); + iamr = mfspr(SPRN_IAMR); regs->kuap = amr; + regs->kuep = iamr; mtspr(SPRN_AMR, AMR_KUAP_BLOCKED); + mtspr(SPRN_IAMR, AMR_KUEP_BLOCKED); isync(); } else kuap_check_amr(); -- 2.25.3