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Subject[PATCH v4] arm64: Add workaround for Fujitsu A64FX erratum 010001
Date
Hi guys,

Thanks for your comments.
I am sending the revised patch, version 4, which includes a whole
description of the patch.

This patch adds a workaround for Fujitsu A64FX erratum 010001

There are some discussions on former versions, as follows:

[PATCH] arm64 memory accesses may cause undefined fault on Fujitsu-A64FX
https://lkml.org/lkml/2019/1/18/403

[PATCH v2 0/1] arm64: Add workaround for Fujitsu A64FX erratum 010001
https://lkml.org/lkml/2019/1/22/137

[PATCH v2 1/1] arm64: Add workaround for Fujitsu A64FX erratum 010001
https://lkml.org/lkml/2019/1/22/138

[PATCH v3 0/1] arm64: Add workaround for Fujitsu A64FX erratum 010001
https://www.spinics.net/lists/arm-kernel/msg703111.html

[v3,1/1] Arm64: Add workaround for Fujitsu A64FX erratum 010001
https://patchwork.kernel.org/patch/10786139/

Please merge this patch.

Note that this patch is for the linux-5.0-rc2 which set TCR_ELx.NFD1 to '1'
only once in the boot sequence and does not set TCR_ELx.NFD0.
If the newer kernel handles TCR_ELx.{NFD0,NFD1} in different way,
I will update the patch as soon as possible.


Changes since [v3]

* Add description of the patch.
* Add dependency to Kconfig.
- Set default value of FUJITSU_ERRATUM_010001 depends on RANDOMIZE_BASE.

Changes since [v2]

* Change TCR_ELx.NFD1.
- Set TCR_ELx.NFD1 to 0 when entry kernel.
- Set TCR_ELx.NFD1 to 1 when exit kernel.

Changes since [v1]

* Use the errata framework to work around for Fujitsu A64FX erratum 010001.



On the Fujitsu-A64FX cores ver(1.0, 1.1), memory access may
cause an undefined fault (Data abort, DFSC=0b111111).
This fault occurs under a specific hardware condition when a
load/store instruction performs an address translation.
Any load/store instruction, except non-fault access
including Armv8 and SVE might cause this undefined fault.

Since this erratum occurs only when TCR_ELx.NFD1=1,
I keep TCR_ELx.NFD1=0 during EL1/EL2.

By doing above, the erratum occurs only in EL0.
I deal with this erratum in EL0 by a new fault handler
which ignores this undefined fault.

Signed-off-by: Zhang Lei <zhang.lei@jp.fujitsu.com>
---
Documentation/arm64/silicon-errata.txt | 1 +
arch/arm64/Kconfig | 23 +++++++++++++++++++++++
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/include/asm/cputype.h | 4 ++++
arch/arm64/kernel/cpu_errata.c | 8 ++++++++
arch/arm64/kernel/entry.S | 16 ++++++++++++++++
arch/arm64/mm/fault.c | 16 +++++++++++++++-
arch/arm64/mm/proc.S | 20 ++++++++++++++++++++
8 files changed, 89 insertions(+), 2 deletions(-)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 1f09d04..26d64e9 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -80,3 +80,4 @@ stable kernels.
| Qualcomm Tech. | Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 |
| Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 |
| Qualcomm Tech. | Falkor v{1,2} | E1041 | QCOM_FALKOR_ERRATUM_1041 |
+| Fujitsu | A64FX | E#010001 | FUJITSU_ERRATUM_010001 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a4168d3..7c76c66 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -643,6 +643,29 @@ config QCOM_FALKOR_ERRATUM_E1041

If unsure, say Y.

+config FUJITSU_ERRATUM_010001
+ bool "Fujitsu-A64FX erratum E#010001: Undefined fault may occur wrongly"
+ depends on RANDOMIZE_BASE
+ default RANDOMIZE_BASE
+ help
+ This option adds workaround for Fujitsu-A64FX erratum E#010001.
+ On some variants of the Fujitsu-A64FX cores ver(1.0, 1.1), memory accesses
+ may cause undefined fault (Data abort, DFSC=0b111111).
+ This fault occurs under a specific hardware condition when a load/store
+ instruction performs an address translation using:
+ case-1 TTBR0_EL1 with TCR_EL1.NFD0 == 1.
+ case-2 TTBR0_EL2 with TCR_EL2.NFD0 == 1.
+ case-3 TTBR1_EL1 with TCR_EL1.NFD1 == 1.
+ case-4 TTBR1_EL2 with TCR_EL2.NFD1 == 1.
+
+ The workaround is to set '0' to TCR_ELx.NFD1 at kernel-entry,
+ to set '1' at kernel-exit. And also replace the fault handler
+ for Data abort DFSC=0b111111 with a new fault handler to ignore this
+ undefined fault.
+ The workaround only affect the Fujitsu-A64FX.
+
+ If unsure, say Y.
+
endmenu


diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 82e9099..3a0b375 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -60,7 +60,8 @@
#define ARM64_HAS_ADDRESS_AUTH_IMP_DEF 39
#define ARM64_HAS_GENERIC_AUTH_ARCH 40
#define ARM64_HAS_GENERIC_AUTH_IMP_DEF 41
+#define ARM64_WORKAROUND_FUJITSU_A64FX_0100001 42

-#define ARM64_NCAPS 42
+#define ARM64_NCAPS 43

#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
index 951ed1a..70203f9 100644
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -76,6 +76,7 @@
#define ARM_CPU_IMP_BRCM 0x42
#define ARM_CPU_IMP_QCOM 0x51
#define ARM_CPU_IMP_NVIDIA 0x4E
+#define ARM_CPU_IMP_FUJITSU 0x46

#define ARM_CPU_PART_AEM_V8 0xD0F
#define ARM_CPU_PART_FOUNDATION 0xD00
@@ -104,6 +105,8 @@
#define NVIDIA_CPU_PART_DENVER 0x003
#define NVIDIA_CPU_PART_CARMEL 0x004

+#define FUJITSU_CPU_PART_A64FX 0x001
+
#define MIDR_CORTEX_A53 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A53)
#define MIDR_CORTEX_A57 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A57)
#define MIDR_CORTEX_A72 MIDR_CPU_MODEL(ARM_CPU_IMP_ARM, ARM_CPU_PART_CORTEX_A72)
@@ -122,6 +125,7 @@
#define MIDR_QCOM_KRYO MIDR_CPU_MODEL(ARM_CPU_IMP_QCOM, QCOM_CPU_PART_KRYO)
#define MIDR_NVIDIA_DENVER MIDR_CPU_MODEL(ARM_CPU_IMP_NVIDIA, NVIDIA_CPU_PART_DENVER)
#define MIDR_NVIDIA_CARMEL MIDR_CPU_MODEL(ARM_CPU_IMP_NVIDIA, NVIDIA_CPU_PART_CARMEL)
+#define MIDR_FUJITSU_A64FX MIDR_CPU_MODEL(ARM_CPU_IMP_FUJITSU, FUJITSU_CPU_PART_A64FX)

#ifndef __ASSEMBLY__

diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 9950bb0..fc0737f 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -739,6 +739,14 @@ static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry,
ERRATA_MIDR_RANGE(MIDR_CORTEX_A76, 0, 0, 2, 0),
},
#endif
+#ifdef CONFIG_FUJITSU_ERRATUM_010001
+ {
+ .desc = "Fujitsu erratum 010001",
+ .capability = ARM64_WORKAROUND_FUJITSU_A64FX_0100001,
+ ERRATA_MIDR_RANGE(MIDR_FUJITSU_A64FX, 0, 0, 1, 0),
+ },
+#endif
+
{
}
};
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 0ec0c46..34a4f44 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -940,6 +940,14 @@ alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003
dsb nsh
alternative_else_nop_endif
#endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */
+#ifdef CONFIG_FUJITSU_CPU_PART_A64FX
+alternative_if ARM64_WORKAROUND_FUJITSU_A64FX_0100001
+ mrs \tmp, tcr_el1
+ and \tmp, \tmp, #0xffbfffffffffffff
+ msr tcr_el1,\tmp
+ isb
+alternative_else_nop_endif
+#endif /* CONFIG_FUJITSU_CPU_PART_A64FX */
.endm

.macro tramp_unmap_kernel, tmp
@@ -952,6 +960,14 @@ alternative_else_nop_endif
* it's only needed by Cavium ThunderX, which requires KPTI to be
* disabled.
*/
+#ifdef CONFIG_FUJITSU_CPU_PART_A64FX
+alternative_if ARM64_WORKAROUND_FUJITSU_A64FX_0100001
+ mrs \tmp, tcr_el1
+ orr \tmp, \tmp, #0x40000000000000
+ msr tcr_el1,\tmp
+ isb
+alternative_else_nop_endif
+#endif /* CONFIG_FUJITSU_CPU_PART_A64FX */
.endm

.macro tramp_ventry, regsize = 64
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index efb7b2c..1bf0377 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -666,6 +666,20 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
return 0;
}

+static int do_bad_unknown_63(unsigned long addr, unsigned int esr, struct pt_regs *regs)
+{
+ /*
+ * On some variants of the Fujitsu-A64FX cores ver(1.0, 1.1),
+ * memory accesses may spuriously trigger data aborts with
+ * DFSC=0b111111.
+ */
+ if (IS_ENABLED(CONFIG_FUJITSU_ERRATUM_010001) &&
+ cpus_have_cap(ARM64_WORKAROUND_FUJITSU_A64FX_0100001))
+ return 0;
+ return do_bad(addr, esr, regs);
+}
+
+
static const struct fault_info fault_info[] = {
{ do_bad, SIGKILL, SI_KERNEL, "ttbr address size fault" },
{ do_bad, SIGKILL, SI_KERNEL, "level 1 address size fault" },
@@ -730,7 +744,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{ do_bad, SIGKILL, SI_KERNEL, "unknown 60" },
{ do_bad, SIGKILL, SI_KERNEL, "section domain fault" },
{ do_bad, SIGKILL, SI_KERNEL, "page domain fault" },
- { do_bad, SIGKILL, SI_KERNEL, "unknown 63" },
+ { do_bad_unknown_63, SIGKILL, SI_KERNEL, "unknown 63" },
};

int handle_guest_sea(phys_addr_t addr, unsigned int esr)
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 73886a5..75f7d99 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -453,9 +453,29 @@ ENTRY(__cpu_setup)
* Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
* both user and kernel.
*/
+#ifdef CONFIG_FUJITSU_ERRATUM_010001
ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
+ /* Can use x19/x20/x5 */
+ mrs x19, midr_el1
+ /* ERRATA_MIDR_RANGE(MIDR_FUJITSU_A64FX, 0, 0, 1, 0) */
+ mov w20, #0x10 //#16
+ movk w20, #0x460f, lsl #16
+ mov w5, #0xffefffff
+ and w19, w5, w19
+ /* cmp midr_el1 with ERRATA_MIDR_RANGE(MIDR_FUJITSU_A64FX, 0, 0, 1, 0) */
+ cmp w19, w20
+ b.ne 2f
+ ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
+ TCR_TG_FLAGS | TCR_ASID16 | \
+ TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
+2: nop
+#else
+ ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
+ TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
+ TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
+#endif

#ifdef CONFIG_ARM64_USER_VA_BITS_52
ldr_l x9, vabits_user
--
1.8.3.1

Best Regards,
Zhang Lei
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