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[PATCH 3.13.y-ckt 23/48] arm64: errata: add module build workaround for erratum #843419

From Kamal Mostafa <kamal@canonical.com>
Newsgroups linux.kernel
Subject [PATCH 3.13.y-ckt 23/48] arm64: errata: add module build workaround for erratum #843419
Date 2015-10-27 22:50 +0100
Message-ID <qokhX-21H-13@gated-at.bofh.it> (permalink)
References <qok8h-1XT-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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3.13.11-ckt29 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Will Deacon <will.deacon@arm.com>

commit df057cc7b4fa59e9b55f07ffdb6c62bf02e99a00 upstream.

Cortex-A53 processors <= r0p4 are affected by erratum #843419 which can
lead to a memory access using an incorrect address in certain sequences
headed by an ADRP instruction.

There is a linker fix to generate veneers for ADRP instructions, but
this doesn't work for kernel modules which are built as unlinked ELF
objects.

This patch adds a new config option for the erratum which, when enabled,
builds kernel modules with the mcmodel=large flag. This uses absolute
addressing for all kernel symbols, thereby removing the use of ADRP as
a PC-relative form of addressing. The ADRP relocs are removed from the
module loader so that we fail to load any potentially affected modules.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 arch/arm64/Kconfig         | 16 ++++++++++++++++
 arch/arm64/Makefile        |  4 ++++
 arch/arm64/kernel/module.c |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 239635b..a29f98a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -129,6 +129,22 @@ menu "Bus support"
 config ARM_AMBA
 	bool
 
+config ARM64_ERRATUM_843419
+	bool "Cortex-A53: 843419: A load or store might access an incorrect address"
+	depends on MODULES
+	default y
+	help
+	  This option builds kernel modules using the large memory model in
+	  order to avoid the use of the ADRP instruction, which can cause
+	  a subsequent memory access to use an incorrect address on Cortex-A53
+	  parts up to r0p4.
+
+	  Note that the kernel itself must be linked with a version of ld
+	  which fixes potentially affected ADRP instructions through the
+	  use of veneers.
+
+	  If unsure, say Y.
+
 endmenu
 
 menu "Kernel Features"
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 2fceb71..0ab1a34 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -34,6 +34,10 @@ comma = ,
 
 CHECKFLAGS	+= -D__aarch64__
 
+ifeq ($(CONFIG_ARM64_ERRATUM_843419), y)
+CFLAGS_MODULE	+= -mcmodel=large
+endif
+
 # Default value
 head-y		:= arch/arm64/kernel/head.o
 
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index e2ad0d8..373c208 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -393,12 +393,14 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 			ovf = reloc_insn_imm(RELOC_OP_PREL, loc, val, 0, 21,
 					     INSN_IMM_ADR);
 			break;
+#ifndef CONFIG_ARM64_ERRATUM_843419
 		case R_AARCH64_ADR_PREL_PG_HI21_NC:
 			overflow_check = false;
 		case R_AARCH64_ADR_PREL_PG_HI21:
 			ovf = reloc_insn_imm(RELOC_OP_PAGE, loc, val, 12, 21,
 					     INSN_IMM_ADR);
 			break;
+#endif
 		case R_AARCH64_ADD_ABS_LO12_NC:
 		case R_AARCH64_LDST8_ABS_LO12_NC:
 			overflow_check = false;
-- 
1.9.1

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Thread

[3.13.y-ckt stable] Linux 3.13.11-ckt29 stable review Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:40 +0100
  [PATCH 3.13.y-ckt 27/48] usb: Use the USB_SS_MULT() macro to get the burst multiplier. Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 16/48] arm64: head.S: initialise mdcr_el2 in el2_setup Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 21/48] x86/platform: Fix Geode LX timekeeping in the generic x86 build Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 07/48] spi: Fix documentation of spi_alloc_master() Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 23/48] arm64: errata: add module build workaround for erratum #843419 Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 03/48] KEYS: Fix crash when attempt to garbage collect an uninstantiated keyring Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 15/48] btrfs: skip waiting on ordered range for special files Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 29/48] usb: xhci: Clear XHCI_STATE_DYING on start Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 24/48] arm64: KVM: Disable virtual timer even if the guest is not using it Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 28/48] xhci: give command abortion one more chance before killing xhci Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 18/48] iser-target: remove command with state ISTATE_REMOVE Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 26/48] KVM: x86: trap AMD MSRs for the TSeg base and mask Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 12/48] USB: option: add ZTE PIDs Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 05/48] [stable-only] net: add length argument to skb_copy_and_csum_datagram_iovec Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 11/48] hwmon: (nct6775) Swap STEP_UP_TIME and STEP_DOWN_TIME registers for most chips Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 14/48] Btrfs: fix read corruption of compressed and shared extents Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 04/48] KEYS: Don't permit request_key() to construct a new keyring Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 25/48] arm: KVM: Disable virtual timer even if the guest is not using it Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 06/48] spi: spi-pxa2xx: Check status register to determine if SSSR_TINT is disabled Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 20/48] powerpc/mm: Recompute hash value after a failed update Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 10/48] CIFS: fix type confusion in copy offload ioctl Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 08/48] ARM: 8429/1: disable GCC SRA optimization Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 02/48] KEYS: Fix race between key destruction and finding a keyring by name Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 09/48] powerpc/MSI: Fix race condition in tearing down MSI interrupts Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100
  [PATCH 3.13.y-ckt 13/48] x86/apic: Serialize LVTT and TSC_DEADLINE writes Kamal Mostafa <kamal@canonical.com> - 2015-10-27 22:50 +0100

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