* [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
@ 2017-12-11 2:03 ` Shanker Donthineni
0 siblings, 0 replies; 11+ messages in thread
From: Shanker Donthineni @ 2017-12-11 2:03 UTC (permalink / raw)
To: linux-arm-kernel
The ARM architecture defines the memory locations that are permitted
to be accessed as the result of a speculative instruction fetch from
an exception level for which all stages of translation are disabled.
Specifically, the core is permitted to speculatively fetch from the
4KB region containing the current program counter 4K and next 4K.
When translation is changed from enabled to disabled for the running
exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the
Falkor core may errantly speculatively access memory locations outside
of the 4KB region permitted by the architecture. The errant memory
access may lead to one of the following unexpected behaviors.
1) A System Error Interrupt (SEI) being raised by the Falkor core due
to the errant memory access attempting to access a region of memory
that is protected by a slave-side memory protection unit.
2) Unpredictable device behavior due to a speculative read from device
memory. This behavior may only occur if the instruction cache is
disabled prior to or coincident with translation being changed from
enabled to disabled.
The conditions leading to this erratum will not occur when either of the
following occur:
1) A higher exception level disables translation of a lower exception level
(e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0).
2) An exception level disabling its stage-1 translation if its stage-2
translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1
to 0 when HCR_EL2[VM] has a value of 1).
To avoid the errant behavior, software must execute an ISB immediately
prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0.
Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
---
Changes since v3:
Rebased to kernel v4.15-rc1.
Changes since v2:
Repost the corrected patches.
Changes since v1:
Apply the workaround where it's required.
Documentation/arm64/silicon-errata.txt | 1 +
arch/arm64/Kconfig | 12 +++++++++++-
arch/arm64/include/asm/assembler.h | 19 +++++++++++++++++++
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/kernel/cpu-reset.S | 1 +
arch/arm64/kernel/cpu_errata.c | 16 ++++++++++++++++
arch/arm64/kernel/efi-entry.S | 2 ++
arch/arm64/kernel/head.S | 1 +
arch/arm64/kernel/relocate_kernel.S | 1 +
arch/arm64/kvm/hyp-init.S | 1 +
10 files changed, 55 insertions(+), 2 deletions(-)
diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 304bf22..fc1c884 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -75,3 +75,4 @@ stable kernels.
| Qualcomm Tech. | Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
| 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 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a93339f..c9a7e9e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -557,7 +557,6 @@ config QCOM_QDF2400_ERRATUM_0065
If unsure, say Y.
-
config SOCIONEXT_SYNQUACER_PREITS
bool "Socionext Synquacer: Workaround for GICv3 pre-ITS"
default y
@@ -576,6 +575,17 @@ config HISILICON_ERRATUM_161600802
a 128kB offset to be applied to the target address in this commands.
If unsure, say Y.
+
+config QCOM_FALKOR_ERRATUM_E1041
+ bool "Falkor E1041: Speculative instruction fetches might cause errant memory access"
+ default y
+ help
+ Falkor CPU may speculatively fetch instructions from an improper
+ memory location when MMU translation is changed from SCTLR_ELn[M]=1
+ to SCTLR_ELn[M]=0. Prefix an ISB instruction to fix the problem.
+
+ If unsure, say Y.
+
endmenu
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index aef72d8..c77742a 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -31,6 +31,7 @@
#include <asm/pgtable-hwdef.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
+#include <asm/alternative.h>
.macro save_and_disable_daif, flags
mrs \flags, daif
@@ -512,4 +513,22 @@
#endif
.endm
+/**
+ * Errata workaround prior to disable MMU. Insert an ISB immediately prior
+ * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
+ */
+ .macro pre_disable_mmu_workaround
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
+ isb
+alternative_else_nop_endif
+#endif
+ .endm
+
+ .macro pre_disable_mmu_early_workaround
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+ isb
+#endif
+ .endm
+
#endif /* __ASM_ASSEMBLER_H */
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 2ff7c5e..b884268 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -41,7 +41,8 @@
#define ARM64_WORKAROUND_CAVIUM_30115 20
#define ARM64_HAS_DCPOP 21
#define ARM64_SVE 22
+#define ARM64_WORKAROUND_QCOM_FALKOR_E1041 23
-#define ARM64_NCAPS 23
+#define ARM64_NCAPS 24
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 65f42d2..2a752cb 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -37,6 +37,7 @@ ENTRY(__cpu_soft_restart)
mrs x12, sctlr_el1
ldr x13, =SCTLR_ELx_FLAGS
bic x12, x12, x13
+ pre_disable_mmu_workaround
msr sctlr_el1, x12
isb
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 0e27f86..2fd1938 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -179,6 +179,22 @@ static int cpu_enable_trap_ctr_access(void *__unused)
MIDR_CPU_VAR_REV(0, 0)),
},
#endif
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+ {
+ .desc = "Qualcomm Technologies Falkor erratum 1041",
+ .capability = ARM64_WORKAROUND_QCOM_FALKOR_E1041,
+ MIDR_RANGE(MIDR_QCOM_FALKOR_V1,
+ MIDR_CPU_VAR_REV(0, 0),
+ MIDR_CPU_VAR_REV(0, 0)),
+ },
+ {
+ .desc = "Qualcomm Technologies Falkor erratum 1041",
+ .capability = ARM64_WORKAROUND_QCOM_FALKOR_E1041,
+ MIDR_RANGE(MIDR_QCOM_FALKOR,
+ MIDR_CPU_VAR_REV(0, 1),
+ MIDR_CPU_VAR_REV(0, 2)),
+ },
+#endif
#ifdef CONFIG_ARM64_ERRATUM_858921
{
/* Cortex-A73 all versions */
diff --git a/arch/arm64/kernel/efi-entry.S b/arch/arm64/kernel/efi-entry.S
index 4e6ad35..dc675ba 100644
--- a/arch/arm64/kernel/efi-entry.S
+++ b/arch/arm64/kernel/efi-entry.S
@@ -96,6 +96,7 @@ ENTRY(entry)
mrs x0, sctlr_el2
bic x0, x0, #1 << 0 // clear SCTLR.M
bic x0, x0, #1 << 2 // clear SCTLR.C
+ pre_disable_mmu_early_workaround
msr sctlr_el2, x0
isb
b 2f
@@ -103,6 +104,7 @@ ENTRY(entry)
mrs x0, sctlr_el1
bic x0, x0, #1 << 0 // clear SCTLR.M
bic x0, x0, #1 << 2 // clear SCTLR.C
+ pre_disable_mmu_early_workaround
msr sctlr_el1, x0
isb
2:
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 67e86a0..a0d737d 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -750,6 +750,7 @@ __primary_switch:
* to take into account by discarding the current kernel mapping and
* creating a new one.
*/
+ pre_disable_mmu_early_workaround
msr sctlr_el1, x20 // disable the MMU
isb
bl __create_page_tables // recreate kernel mapping
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index ce704a4..f407e42 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -45,6 +45,7 @@ ENTRY(arm64_relocate_new_kernel)
mrs x0, sctlr_el2
ldr x1, =SCTLR_ELx_FLAGS
bic x0, x0, x1
+ pre_disable_mmu_workaround
msr sctlr_el2, x0
isb
1:
diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
index 3f96155..870828c 100644
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -151,6 +151,7 @@ reset:
mrs x5, sctlr_el2
ldr x6, =SCTLR_ELx_FLAGS
bic x5, x5, x6 // Clear SCTL_M and etc
+ pre_disable_mmu_workaround
msr sctlr_el2, x5
isb
--
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 11+ messages in thread* [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
@ 2017-12-11 2:03 ` Shanker Donthineni
0 siblings, 0 replies; 11+ messages in thread
From: Shanker Donthineni @ 2017-12-11 2:03 UTC (permalink / raw)
To: Will Deacon, Marc Zyngier, linux-arm-kernel
Cc: linux-efi, Ard Biesheuvel, Matt Fleming, Catalin Marinas,
linux-kernel, Robin Murphy, kvmarm
The ARM architecture defines the memory locations that are permitted
to be accessed as the result of a speculative instruction fetch from
an exception level for which all stages of translation are disabled.
Specifically, the core is permitted to speculatively fetch from the
4KB region containing the current program counter 4K and next 4K.
When translation is changed from enabled to disabled for the running
exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the
Falkor core may errantly speculatively access memory locations outside
of the 4KB region permitted by the architecture. The errant memory
access may lead to one of the following unexpected behaviors.
1) A System Error Interrupt (SEI) being raised by the Falkor core due
to the errant memory access attempting to access a region of memory
that is protected by a slave-side memory protection unit.
2) Unpredictable device behavior due to a speculative read from device
memory. This behavior may only occur if the instruction cache is
disabled prior to or coincident with translation being changed from
enabled to disabled.
The conditions leading to this erratum will not occur when either of the
following occur:
1) A higher exception level disables translation of a lower exception level
(e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0).
2) An exception level disabling its stage-1 translation if its stage-2
translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1
to 0 when HCR_EL2[VM] has a value of 1).
To avoid the errant behavior, software must execute an ISB immediately
prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0.
Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
---
Changes since v3:
Rebased to kernel v4.15-rc1.
Changes since v2:
Repost the corrected patches.
Changes since v1:
Apply the workaround where it's required.
Documentation/arm64/silicon-errata.txt | 1 +
arch/arm64/Kconfig | 12 +++++++++++-
arch/arm64/include/asm/assembler.h | 19 +++++++++++++++++++
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/kernel/cpu-reset.S | 1 +
arch/arm64/kernel/cpu_errata.c | 16 ++++++++++++++++
arch/arm64/kernel/efi-entry.S | 2 ++
arch/arm64/kernel/head.S | 1 +
arch/arm64/kernel/relocate_kernel.S | 1 +
arch/arm64/kvm/hyp-init.S | 1 +
10 files changed, 55 insertions(+), 2 deletions(-)
diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 304bf22..fc1c884 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -75,3 +75,4 @@ stable kernels.
| Qualcomm Tech. | Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
| 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 |
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a93339f..c9a7e9e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -557,7 +557,6 @@ config QCOM_QDF2400_ERRATUM_0065
If unsure, say Y.
-
config SOCIONEXT_SYNQUACER_PREITS
bool "Socionext Synquacer: Workaround for GICv3 pre-ITS"
default y
@@ -576,6 +575,17 @@ config HISILICON_ERRATUM_161600802
a 128kB offset to be applied to the target address in this commands.
If unsure, say Y.
+
+config QCOM_FALKOR_ERRATUM_E1041
+ bool "Falkor E1041: Speculative instruction fetches might cause errant memory access"
+ default y
+ help
+ Falkor CPU may speculatively fetch instructions from an improper
+ memory location when MMU translation is changed from SCTLR_ELn[M]=1
+ to SCTLR_ELn[M]=0. Prefix an ISB instruction to fix the problem.
+
+ If unsure, say Y.
+
endmenu
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index aef72d8..c77742a 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -31,6 +31,7 @@
#include <asm/pgtable-hwdef.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
+#include <asm/alternative.h>
.macro save_and_disable_daif, flags
mrs \flags, daif
@@ -512,4 +513,22 @@
#endif
.endm
+/**
+ * Errata workaround prior to disable MMU. Insert an ISB immediately prior
+ * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
+ */
+ .macro pre_disable_mmu_workaround
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
+ isb
+alternative_else_nop_endif
+#endif
+ .endm
+
+ .macro pre_disable_mmu_early_workaround
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+ isb
+#endif
+ .endm
+
#endif /* __ASM_ASSEMBLER_H */
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 2ff7c5e..b884268 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -41,7 +41,8 @@
#define ARM64_WORKAROUND_CAVIUM_30115 20
#define ARM64_HAS_DCPOP 21
#define ARM64_SVE 22
+#define ARM64_WORKAROUND_QCOM_FALKOR_E1041 23
-#define ARM64_NCAPS 23
+#define ARM64_NCAPS 24
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 65f42d2..2a752cb 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -37,6 +37,7 @@ ENTRY(__cpu_soft_restart)
mrs x12, sctlr_el1
ldr x13, =SCTLR_ELx_FLAGS
bic x12, x12, x13
+ pre_disable_mmu_workaround
msr sctlr_el1, x12
isb
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 0e27f86..2fd1938 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -179,6 +179,22 @@ static int cpu_enable_trap_ctr_access(void *__unused)
MIDR_CPU_VAR_REV(0, 0)),
},
#endif
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+ {
+ .desc = "Qualcomm Technologies Falkor erratum 1041",
+ .capability = ARM64_WORKAROUND_QCOM_FALKOR_E1041,
+ MIDR_RANGE(MIDR_QCOM_FALKOR_V1,
+ MIDR_CPU_VAR_REV(0, 0),
+ MIDR_CPU_VAR_REV(0, 0)),
+ },
+ {
+ .desc = "Qualcomm Technologies Falkor erratum 1041",
+ .capability = ARM64_WORKAROUND_QCOM_FALKOR_E1041,
+ MIDR_RANGE(MIDR_QCOM_FALKOR,
+ MIDR_CPU_VAR_REV(0, 1),
+ MIDR_CPU_VAR_REV(0, 2)),
+ },
+#endif
#ifdef CONFIG_ARM64_ERRATUM_858921
{
/* Cortex-A73 all versions */
diff --git a/arch/arm64/kernel/efi-entry.S b/arch/arm64/kernel/efi-entry.S
index 4e6ad35..dc675ba 100644
--- a/arch/arm64/kernel/efi-entry.S
+++ b/arch/arm64/kernel/efi-entry.S
@@ -96,6 +96,7 @@ ENTRY(entry)
mrs x0, sctlr_el2
bic x0, x0, #1 << 0 // clear SCTLR.M
bic x0, x0, #1 << 2 // clear SCTLR.C
+ pre_disable_mmu_early_workaround
msr sctlr_el2, x0
isb
b 2f
@@ -103,6 +104,7 @@ ENTRY(entry)
mrs x0, sctlr_el1
bic x0, x0, #1 << 0 // clear SCTLR.M
bic x0, x0, #1 << 2 // clear SCTLR.C
+ pre_disable_mmu_early_workaround
msr sctlr_el1, x0
isb
2:
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 67e86a0..a0d737d 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -750,6 +750,7 @@ __primary_switch:
* to take into account by discarding the current kernel mapping and
* creating a new one.
*/
+ pre_disable_mmu_early_workaround
msr sctlr_el1, x20 // disable the MMU
isb
bl __create_page_tables // recreate kernel mapping
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index ce704a4..f407e42 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -45,6 +45,7 @@ ENTRY(arm64_relocate_new_kernel)
mrs x0, sctlr_el2
ldr x1, =SCTLR_ELx_FLAGS
bic x0, x0, x1
+ pre_disable_mmu_workaround
msr sctlr_el2, x0
isb
1:
diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
index 3f96155..870828c 100644
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -151,6 +151,7 @@ reset:
mrs x5, sctlr_el2
ldr x6, =SCTLR_ELx_FLAGS
bic x5, x5, x6 // Clear SCTL_M and etc
+ pre_disable_mmu_workaround
msr sctlr_el2, x5
isb
--
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 11+ messages in thread* Re: [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
2017-12-11 2:03 ` Shanker Donthineni
@ 2017-12-11 10:45 ` Mark Rutland
-1 siblings, 0 replies; 11+ messages in thread
From: Mark Rutland @ 2017-12-11 10:45 UTC (permalink / raw)
To: Shanker Donthineni
Cc: Will Deacon, Marc Zyngier, linux-arm-kernel, linux-efi,
Ard Biesheuvel, Matt Fleming, Catalin Marinas, linux-kernel,
Robin Murphy, kvmarm
Hi,
On Sun, Dec 10, 2017 at 08:03:43PM -0600, Shanker Donthineni wrote:
> +/**
> + * Errata workaround prior to disable MMU. Insert an ISB immediately prior
> + * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
> + */
> + .macro pre_disable_mmu_workaround
> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
> +alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
> + isb
> +alternative_else_nop_endif
> +#endif
> + .endm
There's really no need for this to be an alternative. It makes the
kernel larger and more complex due to all the altinstr data and probing
code.
As Will suggested last time [1], please just use the ifdef, and always
compile-in the extra ISB if CONFIG_QCOM_FALKOR_ERRATUM_E1041 is
selected. Get rid of the alternatives and probing code.
All you need here is:
/*
* Some Falkor parts make errant speculative instruction fetches
* when SCTLR_ELx.M is cleared. An ISB before the write to
* SCTLR_ELx prevents this.
*/
.macro pre_disable_mmu_workaround
#ifdef
isb
#endif
.endm
> +
> + .macro pre_disable_mmu_early_workaround
> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
> + isb
> +#endif
> + .endm
> +
... and we don't need a special early variant.
Thanks,
Mark.
[1] https://lkml.kernel.org/r/20171201112457.GE18083@arm.com
^ permalink raw reply [flat|nested] 11+ messages in thread
* [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
@ 2017-12-11 10:45 ` Mark Rutland
0 siblings, 0 replies; 11+ messages in thread
From: Mark Rutland @ 2017-12-11 10:45 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
On Sun, Dec 10, 2017 at 08:03:43PM -0600, Shanker Donthineni wrote:
> +/**
> + * Errata workaround prior to disable MMU. Insert an ISB immediately prior
> + * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
> + */
> + .macro pre_disable_mmu_workaround
> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
> +alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
> + isb
> +alternative_else_nop_endif
> +#endif
> + .endm
There's really no need for this to be an alternative. It makes the
kernel larger and more complex due to all the altinstr data and probing
code.
As Will suggested last time [1], please just use the ifdef, and always
compile-in the extra ISB if CONFIG_QCOM_FALKOR_ERRATUM_E1041 is
selected. Get rid of the alternatives and probing code.
All you need here is:
/*
* Some Falkor parts make errant speculative instruction fetches
* when SCTLR_ELx.M is cleared. An ISB before the write to
* SCTLR_ELx prevents this.
*/
.macro pre_disable_mmu_workaround
#ifdef
isb
#endif
.endm
> +
> + .macro pre_disable_mmu_early_workaround
> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
> + isb
> +#endif
> + .endm
> +
... and we don't need a special early variant.
Thanks,
Mark.
[1] https://lkml.kernel.org/r/20171201112457.GE18083 at arm.com
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
@ 2017-12-11 22:26 ` Shanker Donthineni
0 siblings, 0 replies; 11+ messages in thread
From: Shanker Donthineni @ 2017-12-11 22:26 UTC (permalink / raw)
To: Mark Rutland
Cc: linux-efi, Ard Biesheuvel, Marc Zyngier, Catalin Marinas,
Will Deacon, linux-kernel, Matt Fleming, Robin Murphy, kvmarm,
linux-arm-kernel
Thanks Mark, I'll post v5 patch without alternatives.
On 12/11/2017 04:45 AM, Mark Rutland wrote:
> Hi,
>
> On Sun, Dec 10, 2017 at 08:03:43PM -0600, Shanker Donthineni wrote:
>> +/**
>> + * Errata workaround prior to disable MMU. Insert an ISB immediately prior
>> + * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
>> + */
>> + .macro pre_disable_mmu_workaround
>> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
>> +alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
>> + isb
>> +alternative_else_nop_endif
>> +#endif
>> + .endm
>
> There's really no need for this to be an alternative. It makes the
> kernel larger and more complex due to all the altinstr data and probing
> code.
>
> As Will suggested last time [1], please just use the ifdef, and always
> compile-in the extra ISB if CONFIG_QCOM_FALKOR_ERRATUM_E1041 is
> selected. Get rid of the alternatives and probing code.
>
> All you need here is:
>
> /*
> * Some Falkor parts make errant speculative instruction fetches
> * when SCTLR_ELx.M is cleared. An ISB before the write to
> * SCTLR_ELx prevents this.
> */
> .macro pre_disable_mmu_workaround
> #ifdef
> isb
> #endif
> .endm
>
>> +
>> + .macro pre_disable_mmu_early_workaround
>> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
>> + isb
>> +#endif
>> + .endm
>> +
>
> ... and we don't need a special early variant.
>
> Thanks,
> Mark.
>
> [1] https://lkml.kernel.org/r/20171201112457.GE18083@arm.com
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply [flat|nested] 11+ messages in thread
* [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
@ 2017-12-11 22:26 ` Shanker Donthineni
0 siblings, 0 replies; 11+ messages in thread
From: Shanker Donthineni @ 2017-12-11 22:26 UTC (permalink / raw)
To: linux-arm-kernel
Thanks Mark, I'll post v5 patch without alternatives.
On 12/11/2017 04:45 AM, Mark Rutland wrote:
> Hi,
>
> On Sun, Dec 10, 2017 at 08:03:43PM -0600, Shanker Donthineni wrote:
>> +/**
>> + * Errata workaround prior to disable MMU. Insert an ISB immediately prior
>> + * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
>> + */
>> + .macro pre_disable_mmu_workaround
>> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
>> +alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
>> + isb
>> +alternative_else_nop_endif
>> +#endif
>> + .endm
>
> There's really no need for this to be an alternative. It makes the
> kernel larger and more complex due to all the altinstr data and probing
> code.
>
> As Will suggested last time [1], please just use the ifdef, and always
> compile-in the extra ISB if CONFIG_QCOM_FALKOR_ERRATUM_E1041 is
> selected. Get rid of the alternatives and probing code.
>
> All you need here is:
>
> /*
> * Some Falkor parts make errant speculative instruction fetches
> * when SCTLR_ELx.M is cleared. An ISB before the write to
> * SCTLR_ELx prevents this.
> */
> .macro pre_disable_mmu_workaround
> #ifdef
> isb
> #endif
> .endm
>
>> +
>> + .macro pre_disable_mmu_early_workaround
>> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
>> + isb
>> +#endif
>> + .endm
>> +
>
> ... and we don't need a special early variant.
>
> Thanks,
> Mark.
>
> [1] https://lkml.kernel.org/r/20171201112457.GE18083 at arm.com
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [RESEND PATCH v4 2/2] arm64: Add software workaround for Falkor erratum 1041
@ 2017-12-11 22:26 ` Shanker Donthineni
0 siblings, 0 replies; 11+ messages in thread
From: Shanker Donthineni @ 2017-12-11 22:26 UTC (permalink / raw)
To: Mark Rutland
Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA, Ard Biesheuvel, Marc Zyngier,
Catalin Marinas, Will Deacon,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Matt Fleming, Robin Murphy,
kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
Thanks Mark, I'll post v5 patch without alternatives.
On 12/11/2017 04:45 AM, Mark Rutland wrote:
> Hi,
>
> On Sun, Dec 10, 2017 at 08:03:43PM -0600, Shanker Donthineni wrote:
>> +/**
>> + * Errata workaround prior to disable MMU. Insert an ISB immediately prior
>> + * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
>> + */
>> + .macro pre_disable_mmu_workaround
>> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
>> +alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1041
>> + isb
>> +alternative_else_nop_endif
>> +#endif
>> + .endm
>
> There's really no need for this to be an alternative. It makes the
> kernel larger and more complex due to all the altinstr data and probing
> code.
>
> As Will suggested last time [1], please just use the ifdef, and always
> compile-in the extra ISB if CONFIG_QCOM_FALKOR_ERRATUM_E1041 is
> selected. Get rid of the alternatives and probing code.
>
> All you need here is:
>
> /*
> * Some Falkor parts make errant speculative instruction fetches
> * when SCTLR_ELx.M is cleared. An ISB before the write to
> * SCTLR_ELx prevents this.
> */
> .macro pre_disable_mmu_workaround
> #ifdef
> isb
> #endif
> .endm
>
>> +
>> + .macro pre_disable_mmu_early_workaround
>> +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
>> + isb
>> +#endif
>> + .endm
>> +
>
> ... and we don't need a special early variant.
>
> Thanks,
> Mark.
>
> [1] https://lkml.kernel.org/r/20171201112457.GE18083-5wv7dgnIgG8@public.gmane.org
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply [flat|nested] 11+ messages in thread