From 264410306381d4edceeb03b3a0e8db66605427be Mon Sep 17 00:00:00 2001 From: Antonio Nino Diaz Date: Mon, 19 Feb 2018 16:27:06 +0000 Subject: [PATCH] Invalidate TLB entries during warm boot During the warm boot sequence: 1. The MMU is enabled with the data cache disabled. The MMU table walker is set up to access the translation tables as in cacheable memory, but its accesses are non-cacheable because SCTLR_EL3.C controls them as well. 2. The interconnect is set up and the CPU enters coherency with the rest of the system. 3. The data cache is enabled. If the support for dynamic translation tables is enabled and another CPU makes changes to a region, the changes may only be present in the data cache, not in RAM. The CPU that is booting isn't in coherency with the rest of the system, so the table walker of that CPU isn't either. This means that it may read old entries from RAM and it may have invalid TLB entries corresponding to the dynamic mappings. This is not a problem for the boot code because the mapping is 1:1 and the regions are static. However, the code that runs after the boot sequence may need to access the dynamically mapped regions. This patch invalidates all TLBs during warm boot when the dynamic translation tables support is enabled to prevent this problem. Change-Id: I80264802dc0aa1cb3edd77d0b66b91db6961af3d Signed-off-by: Antonio Nino Diaz --- lib/psci/aarch32/psci_helpers.S | 24 +++++++++++++++++++++++- lib/psci/aarch64/psci_helpers.S | 24 +++++++++++++++++++++++- 2 files changed, 46 insertions(+), 2 deletions(-) diff --git a/lib/psci/aarch32/psci_helpers.S b/lib/psci/aarch32/psci_helpers.S index 9373d4f16..a29a29c49 100644 --- a/lib/psci/aarch32/psci_helpers.S +++ b/lib/psci/aarch32/psci_helpers.S @@ -1,5 +1,5 @@ /* - * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved. + * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved. * * SPDX-License-Identifier: BSD-3-Clause */ @@ -91,6 +91,28 @@ func psci_do_pwrup_cache_maintenance stcopr r0, SCTLR isb +#if PLAT_XLAT_TABLES_DYNAMIC + /* --------------------------------------------- + * During warm boot the MMU is enabled with data + * cache disabled, then the interconnect is set + * up and finally the data cache is enabled. + * + * During this period, if another CPU modifies + * the translation tables, the MMU table walker + * may read the old entries. This is only a + * problem for dynamic regions, the warm boot + * code isn't affected because it is static. + * + * Invalidate all TLB entries loaded while the + * CPU wasn't coherent with the rest of the + * system. + * --------------------------------------------- + */ + stcopr r0, TLBIALL + dsb ish + isb +#endif + pop {r12, pc} endfunc psci_do_pwrup_cache_maintenance diff --git a/lib/psci/aarch64/psci_helpers.S b/lib/psci/aarch64/psci_helpers.S index afe21ebe4..d37ca764a 100644 --- a/lib/psci/aarch64/psci_helpers.S +++ b/lib/psci/aarch64/psci_helpers.S @@ -1,5 +1,5 @@ /* - * Copyright (c) 2014-2016, ARM Limited and Contributors. All rights reserved. + * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved. * * SPDX-License-Identifier: BSD-3-Clause */ @@ -115,6 +115,28 @@ func psci_do_pwrup_cache_maintenance msr sctlr_el3, x0 isb +#if PLAT_XLAT_TABLES_DYNAMIC + /* --------------------------------------------- + * During warm boot the MMU is enabled with data + * cache disabled, then the interconnect is set + * up and finally the data cache is enabled. + * + * During this period, if another CPU modifies + * the translation tables, the MMU table walker + * may read the old entries. This is only a + * problem for dynamic regions, the warm boot + * code isn't affected because it is static. + * + * Invalidate all TLB entries loaded while the + * CPU wasn't coherent with the rest of the + * system. + * --------------------------------------------- + */ + tlbi alle3 + dsb ish + isb +#endif + ldp x29, x30, [sp], #16 ret endfunc psci_do_pwrup_cache_maintenance