arm64: Generate cpucaps.h

PATCH Applied Mark Brown 7 participants 13 messages Apr 28, 2021 – Sep 22, 2021 arm64

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Mark Brown

author

2021-04-28 12:18 UTC #0 lore raw

PATCH 1/1 arm64: Generate cpucaps.h

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.

As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.

This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing. Due to the UAO cpucap having been removed in the past we end up with ARM64_NCAPS being 1 smaller than it was before.

Signed-off-by Mark Brown <[email protected]>

---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++
 6 files changed, 132 insertions(+), 74 deletions(-)
 delete mode 100644 arch/arm64/include/asm/cpucaps.h
 create mode 100644 arch/arm64/tools/Makefile
 create mode 100644 arch/arm64/tools/cpucaps
 create mode 100755 arch/arm64/tools/gen-cpucaps.awk

arch/arm64/Makefile +3 -0

index 7ef44478560d..b52481f0605d 100644
@@ -175,6 +175,9 @@ vdso_install:
 	$(if $(CONFIG_COMPAT_VDSO), \
 		$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
 
+archprepare:
+	$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
+
 # We use MRPROPER_FILES and CLEAN_FILES now
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)

arch/arm64/include/asm/Kbuild +2 -0

index 73aa25843f65..64202010b700 100644
@@ -4,3 +4,5 @@ generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
 generic-y += user.h
+
+generated-y += cpucaps.h

arch/arm64/include/asm/cpucaps.h deleted +0 ~~-74~~

74 lines not on this page · raw message

arch/arm64/tools/Makefile new file +22 -0

new file mode 100644
index 000000000000..932b4fe5c768
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+
+gen := arch/$(ARCH)/include/generated
+kapi := $(gen)/asm
+
+kapi-hdrs-y := $(kapi)/cpucaps.h
+
+targets += $(addprefix ../../../,$(gen-y) $(kapi-hdrs-y))
+
+PHONY += kapi
+
+kapi:   $(kapi-hdrs-y) $(gen-y)
+
+# Create output directory if not already present
+_dummy := $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)')
+
+quiet_cmd_gen_cpucaps = GEN     $@
+      cmd_gen_cpucaps = mkdir -p $(dir $@) && \
+                     $(AWK) -f $(filter-out $(PHONY),$^) > $@
+
+$(kapi)/cpucaps.h: $(src)/gen-cpucaps.awk $(src)/cpucaps FORCE
+	$(call if_changed,gen_cpucaps)

arch/arm64/tools/cpucaps new file +65 -0

65 lines not on this page · raw message

arch/arm64/tools/gen-cpucaps.awk new file +40 -0

new file mode 100755
index 000000000000..18737a1ce044
@@ -0,0 +1,40 @@
+#!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+# gen-cpucaps.awk: arm64 cpucaps header generator
+#
+# Usage: awk -f gen-cpucaps.awk cpucaps.txt
+
+# Log an error and terminate
+function fatal(msg) {
+	print "Error at line " NR ": " msg > "/dev/stderr"
+	exit 1
+}
+
+# skip blank lines and comment lines
+/^$/ { next }
+/^#/ { next }
+
+BEGIN {
+	print "#ifndef __ASM_CPUCAPS_H"
+	print "#define __ASM_CPUCAPS_H"
+	print ""
+	print "/* Generated file - do not edit */"
+	cap_num = 0
+	print ""
+}
+
+/^[vA-Z0-9_]+$/ {
+	printf("#define ARM64_%-30s\t%d\n", $0, cap_num++)
+	next
+}
+
+END {
+	printf("#define ARM64_NCAPS\t\t\t\t%d\n", cap_num)
+	print ""
+	print "#endif"
+}
+
+# Any lines not handled by previous rules are unexpected
+{
+	fatal("unhandled statement")
+}

Signature · 7 lines

2.20.1


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Catalin Marinas

maintainer

2021-04-29 12:34 UTC #1 lore raw

Quoted 18 lines · Mark Brown

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.
As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing. Due to the UAO cpucap having been removed in the past we end up with ARM64_NCAPS being 1 smaller than it was before.
Signed-off-by Mark Brown <[email protected]>

Quoted 12 lines

---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++
 6 files changed, 132 insertions(+), 74 deletions(-)
 delete mode 100644 arch/arm64/include/asm/cpucaps.h
 create mode 100644 arch/arm64/tools/Makefile
 create mode 100644 arch/arm64/tools/cpucaps
 create mode 100755 arch/arm64/tools/gen-cpucaps.awk

It's a good cleanup, it saves us from always sorting out conflicts around ARM64_NCAPS. I'll either take it during the merging window with the for-next/fixes folded in or push it at -rc1 as there's a change in cpucaps.h not currently in for-next/core.

Thanks.

Signature · 6 lines

Catalin

_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Mark Rutland

reviewer Reviewed-by Tested-by on v1 1/1

2021-05-04 11:45 UTC #2 lore raw

In reply to Mark Brown

Quoted 10 lines · Mark Brown

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.
As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.

Quoted 8 lines

This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing. Due to the UAO cpucap having been removed in the past we end up with ARM64_NCAPS being 1 smaller than it was before.
Signed-off-by Mark Brown <[email protected]>

Neat! This looks good to me per my understanding of awk.

I have this s quick spin, and tested and out-of-tree build and common awk implementations (gawk, mawk, nawk), and everything worked as expected. So FWIW:

Reviewed-by Mark Rutland <[email protected]>

Tested-by Mark Rutland <[email protected]>

Thanks,
Mark.

Quoted 270 lines

---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++
 6 files changed, 132 insertions(+), 74 deletions(-)
 delete mode 100644 arch/arm64/include/asm/cpucaps.h
 create mode 100644 arch/arm64/tools/Makefile
 create mode 100644 arch/arm64/tools/cpucaps
 create mode 100755 arch/arm64/tools/gen-cpucaps.awk

arch/arm64/Makefile +3 -0

index 7ef44478560d..b52481f0605d 100644
@@ -175,6 +175,9 @@ vdso_install:
 	$(if $(CONFIG_COMPAT_VDSO), \
 		$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
 
+archprepare:
+	$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
+
 # We use MRPROPER_FILES and CLEAN_FILES now
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)

arch/arm64/include/asm/Kbuild +2 -0

index 73aa25843f65..64202010b700 100644
@@ -4,3 +4,5 @@ generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
 generic-y += user.h
+
+generated-y += cpucaps.h

arch/arm64/include/asm/cpucaps.h deleted +0 ~~-74~~

deleted file mode 100644
index b0c5eda0498f..000000000000
@@ -1,74 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * arch/arm64/include/asm/cpucaps.h
- *
- * Copyright (C) 2016 ARM Ltd.
- */
-#ifndef __ASM_CPUCAPS_H
-#define __ASM_CPUCAPS_H
-
-#define ARM64_WORKAROUND_CLEAN_CACHE		0
-#define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE	1
-#define ARM64_WORKAROUND_845719			2
-#define ARM64_HAS_SYSREG_GIC_CPUIF		3
-#define ARM64_HAS_PAN				4
-#define ARM64_HAS_LSE_ATOMICS			5
-#define ARM64_WORKAROUND_CAVIUM_23154		6
-#define ARM64_WORKAROUND_834220			7
-#define ARM64_HAS_NO_HW_PREFETCH		8
-#define ARM64_HAS_VIRT_HOST_EXTN		11
-#define ARM64_WORKAROUND_CAVIUM_27456		12
-#define ARM64_HAS_32BIT_EL0			13
-#define ARM64_SPECTRE_V3A			14
-#define ARM64_HAS_CNP				15
-#define ARM64_HAS_NO_FPSIMD			16
-#define ARM64_WORKAROUND_REPEAT_TLBI		17
-#define ARM64_WORKAROUND_QCOM_FALKOR_E1003	18
-#define ARM64_WORKAROUND_858921			19
-#define ARM64_WORKAROUND_CAVIUM_30115		20
-#define ARM64_HAS_DCPOP				21
-#define ARM64_SVE				22
-#define ARM64_UNMAP_KERNEL_AT_EL0		23
-#define ARM64_SPECTRE_V2			24
-#define ARM64_HAS_RAS_EXTN			25
-#define ARM64_WORKAROUND_843419			26
-#define ARM64_HAS_CACHE_IDC			27
-#define ARM64_HAS_CACHE_DIC			28
-#define ARM64_HW_DBM				29
-#define ARM64_SPECTRE_V4			30
-#define ARM64_MISMATCHED_CACHE_TYPE		31
-#define ARM64_HAS_STAGE2_FWB			32
-#define ARM64_HAS_CRC32				33
-#define ARM64_SSBS				34
-#define ARM64_WORKAROUND_1418040		35
-#define ARM64_HAS_SB				36
-#define ARM64_WORKAROUND_SPECULATIVE_AT		37
-#define ARM64_HAS_ADDRESS_AUTH_ARCH		38
-#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_HAS_IRQ_PRIO_MASKING		42
-#define ARM64_HAS_DCPODP			43
-#define ARM64_WORKAROUND_1463225		44
-#define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM	45
-#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
-#define ARM64_WORKAROUND_1542419		47
-#define ARM64_HAS_E0PD				48
-#define ARM64_HAS_RNG				49
-#define ARM64_HAS_AMU_EXTN			50
-#define ARM64_HAS_ADDRESS_AUTH			51
-#define ARM64_HAS_GENERIC_AUTH			52
-#define ARM64_HAS_32BIT_EL1			53
-#define ARM64_BTI				54
-#define ARM64_HAS_ARMv8_4_TTL			55
-#define ARM64_HAS_TLB_RANGE			56
-#define ARM64_MTE				57
-#define ARM64_WORKAROUND_1508412		58
-#define ARM64_HAS_LDAPR				59
-#define ARM64_KVM_PROTECTED_MODE		60
-#define ARM64_WORKAROUND_NVIDIA_CARMEL_CNP	61
-#define ARM64_HAS_EPAN				62
-
-#define ARM64_NCAPS				63
-
-#endif /* __ASM_CPUCAPS_H */

arch/arm64/tools/Makefile new file +22 -0

new file mode 100644
index 000000000000..932b4fe5c768
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+
+gen := arch/$(ARCH)/include/generated
+kapi := $(gen)/asm
+
+kapi-hdrs-y := $(kapi)/cpucaps.h
+
+targets += $(addprefix ../../../,$(gen-y) $(kapi-hdrs-y))
+
+PHONY += kapi
+
+kapi:   $(kapi-hdrs-y) $(gen-y)
+
+# Create output directory if not already present
+_dummy := $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)')
+
+quiet_cmd_gen_cpucaps = GEN     $@
+      cmd_gen_cpucaps = mkdir -p $(dir $@) && \
+                     $(AWK) -f $(filter-out $(PHONY),$^) > $@
+
+$(kapi)/cpucaps.h: $(src)/gen-cpucaps.awk $(src)/cpucaps FORCE
+	$(call if_changed,gen_cpucaps)

arch/arm64/tools/cpucaps new file +65 -0

new file mode 100644
index 000000000000..21fbdda7086e
@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Internal CPU capabilities constants, keep this list sorted
+
+BTI
+HAS_32BIT_EL0
+HAS_32BIT_EL1
+HAS_ADDRESS_AUTH
+HAS_ADDRESS_AUTH_ARCH
+HAS_ADDRESS_AUTH_IMP_DEF
+HAS_AMU_EXTN
+HAS_ARMv8_4_TTL
+HAS_CACHE_DIC
+HAS_CACHE_IDC
+HAS_CNP
+HAS_CRC32
+HAS_DCPODP
+HAS_DCPOP
+HAS_E0PD
+HAS_EPAN
+HAS_GENERIC_AUTH
+HAS_GENERIC_AUTH_ARCH
+HAS_GENERIC_AUTH_IMP_DEF
+HAS_IRQ_PRIO_MASKING
+HAS_LDAPR
+HAS_LSE_ATOMICS
+HAS_NO_FPSIMD
+HAS_NO_HW_PREFETCH
+HAS_PAN
+HAS_RAS_EXTN
+HAS_RNG
+HAS_SB
+HAS_STAGE2_FWB
+HAS_SYSREG_GIC_CPUIF
+HAS_TLB_RANGE
+HAS_VIRT_HOST_EXTN
+HW_DBM
+KVM_PROTECTED_MODE
+MISMATCHED_CACHE_TYPE
+MTE
+SPECTRE_V2
+SPECTRE_V3A
+SPECTRE_V4
+SSBS
+SVE
+UNMAP_KERNEL_AT_EL0
+WORKAROUND_834220
+WORKAROUND_843419
+WORKAROUND_845719
+WORKAROUND_858921
+WORKAROUND_1418040
+WORKAROUND_1463225
+WORKAROUND_1508412
+WORKAROUND_1542419
+WORKAROUND_CAVIUM_23154
+WORKAROUND_CAVIUM_27456
+WORKAROUND_CAVIUM_30115
+WORKAROUND_CAVIUM_TX2_219_PRFM
+WORKAROUND_CAVIUM_TX2_219_TVM
+WORKAROUND_CLEAN_CACHE
+WORKAROUND_DEVICE_LOAD_ACQUIRE
+WORKAROUND_NVIDIA_CARMEL_CNP
+WORKAROUND_QCOM_FALKOR_E1003
+WORKAROUND_REPEAT_TLBI
+WORKAROUND_SPECULATIVE_AT

arch/arm64/tools/gen-cpucaps.awk new file +40 -0

new file mode 100755
index 000000000000..18737a1ce044
@@ -0,0 +1,40 @@
+#!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+# gen-cpucaps.awk: arm64 cpucaps header generator
+#
+# Usage: awk -f gen-cpucaps.awk cpucaps.txt
+
+# Log an error and terminate
+function fatal(msg) {
+	print "Error at line " NR ": " msg > "/dev/stderr"
+	exit 1
+}
+
+# skip blank lines and comment lines
+/^$/ { next }
+/^#/ { next }
+
+BEGIN {
+	print "#ifndef __ASM_CPUCAPS_H"
+	print "#define __ASM_CPUCAPS_H"
+	print ""
+	print "/* Generated file - do not edit */"
+	cap_num = 0
+	print ""
+}
+
+/^[vA-Z0-9_]+$/ {
+	printf("#define ARM64_%-30s\t%d\n", $0, cap_num++)
+	next
+}
+
+END {
+	printf("#define ARM64_NCAPS\t\t\t\t%d\n", cap_num)
+	print ""
+	print "#endif"
+}
+
+# Any lines not handled by previous rules are unexpected
+{
+	fatal("unhandled statement")
+}

Signature · 7 lines

2.20.1


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Catalin Marinas

maintainer Applied

2021-05-10 12:57 UTC #3 lore raw

In reply to Mark Brown

Quoted 8 lines · Mark Brown

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.
[...]

Applied to arm64 (for-next/fixes), thanks! While not actually a fix, I'm merging it at -rc1 to avoid conflicts with changes to cpucaps.h during the merging window.

[1/1] arm64: Generate cpucaps.h

      https://git.kernel.org/arm64/c/0c6c2d3615ef

Signature · 7 lines

Catalin


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Anshuman Khandual

Reviewed-by Tested-by on v1 1/1

2021-05-13 05:06 UTC #4 lore raw

In reply to Mark Brown

Quoted 36 lines · Mark Brown

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.
As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing. Due to the UAO cpucap having been removed in the past we end up with ARM64_NCAPS being 1 smaller than it was before.
Signed-off-by Mark Brown <[email protected]>
---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++
 6 files changed, 132 insertions(+), 74 deletions(-)
 delete mode 100644 arch/arm64/include/asm/cpucaps.h
 create mode 100644 arch/arm64/tools/Makefile
 create mode 100644 arch/arm64/tools/cpucaps
 create mode 100755 arch/arm64/tools/gen-cpucaps.awk
arch/arm64/Makefile +0 -0
index 7ef44478560d..b52481f0605d 100644

arch/arm64/Makefile vdso_install: · line 179

Quoted 5 lines

arch/arm64/Makefile +2 -0

@@ -175,6 +175,9 @@ vdso_install:
 	$(if $(CONFIG_COMPAT_VDSO), \
 		$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
 
+archprepare:
+	$(Q)$(MAKE) $(build)=arch/arm64/tools kapi

Small nit. So going forward this new directory (arch/arm64/tools/), will be used to hold similar scripts that generate header or similar things ? At first the directory name 'tool' was bit confusing but seems like other archs (arm, m68k, mips, powerpc, s390, sh) have this directory as well.

Quoted 215 lines

arch/arm64/Makefile +1 -0

+
 # We use MRPROPER_FILES and CLEAN_FILES now
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)

arch/arm64/include/asm/Kbuild +2 -0

index 73aa25843f65..64202010b700 100644
@@ -4,3 +4,5 @@ generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
 generic-y += user.h
+
+generated-y += cpucaps.h

arch/arm64/include/asm/cpucaps.h deleted +0 ~~-74~~

deleted file mode 100644
index b0c5eda0498f..000000000000
@@ -1,74 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * arch/arm64/include/asm/cpucaps.h
- *
- * Copyright (C) 2016 ARM Ltd.
- */
-#ifndef __ASM_CPUCAPS_H
-#define __ASM_CPUCAPS_H
-
-#define ARM64_WORKAROUND_CLEAN_CACHE		0
-#define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE	1
-#define ARM64_WORKAROUND_845719			2
-#define ARM64_HAS_SYSREG_GIC_CPUIF		3
-#define ARM64_HAS_PAN				4
-#define ARM64_HAS_LSE_ATOMICS			5
-#define ARM64_WORKAROUND_CAVIUM_23154		6
-#define ARM64_WORKAROUND_834220			7
-#define ARM64_HAS_NO_HW_PREFETCH		8
-#define ARM64_HAS_VIRT_HOST_EXTN		11
-#define ARM64_WORKAROUND_CAVIUM_27456		12
-#define ARM64_HAS_32BIT_EL0			13
-#define ARM64_SPECTRE_V3A			14
-#define ARM64_HAS_CNP				15
-#define ARM64_HAS_NO_FPSIMD			16
-#define ARM64_WORKAROUND_REPEAT_TLBI		17
-#define ARM64_WORKAROUND_QCOM_FALKOR_E1003	18
-#define ARM64_WORKAROUND_858921			19
-#define ARM64_WORKAROUND_CAVIUM_30115		20
-#define ARM64_HAS_DCPOP				21
-#define ARM64_SVE				22
-#define ARM64_UNMAP_KERNEL_AT_EL0		23
-#define ARM64_SPECTRE_V2			24
-#define ARM64_HAS_RAS_EXTN			25
-#define ARM64_WORKAROUND_843419			26
-#define ARM64_HAS_CACHE_IDC			27
-#define ARM64_HAS_CACHE_DIC			28
-#define ARM64_HW_DBM				29
-#define ARM64_SPECTRE_V4			30
-#define ARM64_MISMATCHED_CACHE_TYPE		31
-#define ARM64_HAS_STAGE2_FWB			32
-#define ARM64_HAS_CRC32				33
-#define ARM64_SSBS				34
-#define ARM64_WORKAROUND_1418040		35
-#define ARM64_HAS_SB				36
-#define ARM64_WORKAROUND_SPECULATIVE_AT		37
-#define ARM64_HAS_ADDRESS_AUTH_ARCH		38
-#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_HAS_IRQ_PRIO_MASKING		42
-#define ARM64_HAS_DCPODP			43
-#define ARM64_WORKAROUND_1463225		44
-#define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM	45
-#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
-#define ARM64_WORKAROUND_1542419		47
-#define ARM64_HAS_E0PD				48
-#define ARM64_HAS_RNG				49
-#define ARM64_HAS_AMU_EXTN			50
-#define ARM64_HAS_ADDRESS_AUTH			51
-#define ARM64_HAS_GENERIC_AUTH			52
-#define ARM64_HAS_32BIT_EL1			53
-#define ARM64_BTI				54
-#define ARM64_HAS_ARMv8_4_TTL			55
-#define ARM64_HAS_TLB_RANGE			56
-#define ARM64_MTE				57
-#define ARM64_WORKAROUND_1508412		58
-#define ARM64_HAS_LDAPR				59
-#define ARM64_KVM_PROTECTED_MODE		60
-#define ARM64_WORKAROUND_NVIDIA_CARMEL_CNP	61
-#define ARM64_HAS_EPAN				62
-
-#define ARM64_NCAPS				63
-
-#endif /* __ASM_CPUCAPS_H */

arch/arm64/tools/Makefile new file +22 -0

new file mode 100644
index 000000000000..932b4fe5c768
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+
+gen := arch/$(ARCH)/include/generated
+kapi := $(gen)/asm
+
+kapi-hdrs-y := $(kapi)/cpucaps.h
+
+targets += $(addprefix ../../../,$(gen-y) $(kapi-hdrs-y))
+
+PHONY += kapi
+
+kapi:   $(kapi-hdrs-y) $(gen-y)
+
+# Create output directory if not already present
+_dummy := $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)')
+
+quiet_cmd_gen_cpucaps = GEN     $@
+      cmd_gen_cpucaps = mkdir -p $(dir $@) && \
+                     $(AWK) -f $(filter-out $(PHONY),$^) > $@
+
+$(kapi)/cpucaps.h: $(src)/gen-cpucaps.awk $(src)/cpucaps FORCE
+	$(call if_changed,gen_cpucaps)

arch/arm64/tools/cpucaps new file +65 -0

new file mode 100644
index 000000000000..21fbdda7086e
@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Internal CPU capabilities constants, keep this list sorted
+
+BTI
+HAS_32BIT_EL0
+HAS_32BIT_EL1
+HAS_ADDRESS_AUTH
+HAS_ADDRESS_AUTH_ARCH
+HAS_ADDRESS_AUTH_IMP_DEF
+HAS_AMU_EXTN
+HAS_ARMv8_4_TTL
+HAS_CACHE_DIC
+HAS_CACHE_IDC
+HAS_CNP
+HAS_CRC32
+HAS_DCPODP
+HAS_DCPOP
+HAS_E0PD
+HAS_EPAN
+HAS_GENERIC_AUTH
+HAS_GENERIC_AUTH_ARCH
+HAS_GENERIC_AUTH_IMP_DEF
+HAS_IRQ_PRIO_MASKING
+HAS_LDAPR
+HAS_LSE_ATOMICS
+HAS_NO_FPSIMD
+HAS_NO_HW_PREFETCH
+HAS_PAN
+HAS_RAS_EXTN
+HAS_RNG
+HAS_SB
+HAS_STAGE2_FWB
+HAS_SYSREG_GIC_CPUIF
+HAS_TLB_RANGE
+HAS_VIRT_HOST_EXTN
+HW_DBM
+KVM_PROTECTED_MODE
+MISMATCHED_CACHE_TYPE
+MTE
+SPECTRE_V2
+SPECTRE_V3A
+SPECTRE_V4
+SSBS
+SVE
+UNMAP_KERNEL_AT_EL0
+WORKAROUND_834220
+WORKAROUND_843419
+WORKAROUND_845719
+WORKAROUND_858921
+WORKAROUND_1418040
+WORKAROUND_1463225
+WORKAROUND_1508412
+WORKAROUND_1542419
+WORKAROUND_CAVIUM_23154
+WORKAROUND_CAVIUM_27456
+WORKAROUND_CAVIUM_30115
+WORKAROUND_CAVIUM_TX2_219_PRFM
+WORKAROUND_CAVIUM_TX2_219_TVM
+WORKAROUND_CLEAN_CACHE
+WORKAROUND_DEVICE_LOAD_ACQUIRE
+WORKAROUND_NVIDIA_CARMEL_CNP
+WORKAROUND_QCOM_FALKOR_E1003
+WORKAROUND_REPEAT_TLBI
+WORKAROUND_SPECULATIVE_AT

arch/arm64/tools/gen-cpucaps.awk new file +16 -0

new file mode 100755
index 000000000000..18737a1ce044
@@ -0,0 +1,40 @@
+#!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+# gen-cpucaps.awk: arm64 cpucaps header generator
+#
+# Usage: awk -f gen-cpucaps.awk cpucaps.txt
+
+# Log an error and terminate
+function fatal(msg) {
+	print "Error at line " NR ": " msg > "/dev/stderr"
+	exit 1
+}
+
+# skip blank lines and comment lines
+/^$/ { next }
+/^#/ { next }
+

arch/arm64/tools/gen-cpucaps.awk line 26

Quoted 10 lines

arch/arm64/tools/gen-cpucaps.awk new file +10 -0

+BEGIN {
+	print "#ifndef __ASM_CPUCAPS_H"
+	print "#define __ASM_CPUCAPS_H"
+	print ""
+	print "/* Generated file - do not edit */"
+	cap_num = 0
+	print ""
+}
+
+/^[vA-Z0-9_]+$/ {

Small nit. Should this be length restricted at the least ? Like each CAP entries should not exceed a certain length.

arch/arm64/tools/gen-cpucaps.awk line 34

Quoted 8 lines

arch/arm64/tools/gen-cpucaps.awk new file +8 -0

+	printf("#define ARM64_%-30s\t%d\n", $0, cap_num++)
+	next
+}
+
+END {
+	printf("#define ARM64_NCAPS\t\t\t\t%d\n", cap_num)
+	print ""
+	print "#endif"

Small nit. Should it be print "#endif /* __ASM_CPUCAPS_H */" instead in order to be complete.

arch/arm64/tools/gen-cpucaps.awk line 40

Quoted 7 lines

arch/arm64/tools/gen-cpucaps.awk new file +6 -0

+}
+
+# Any lines not handled by previous rules are unexpected
+{
+	fatal("unhandled statement")
+}

Did not see any problem with the patch after using it with multiple 'awk' implementations. FWIW, with/without changes requested earlier.

Reviewed-by Anshuman Khandual <[email protected]>

Tested-by Anshuman Khandual <[email protected]>

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Mark Rutland

reviewer

2021-05-13 11:53 UTC #5 lore raw

Quoted 41 lines · Anshuman Khandual

Quoted 39 lines · Mark Brown
The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.
As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing. Due to the UAO cpucap having been removed in the past we end up with ARM64_NCAPS being 1 smaller than it was before.
Signed-off-by Mark Brown <[email protected]>
---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++
 6 files changed, 132 insertions(+), 74 deletions(-)
 delete mode 100644 arch/arm64/include/asm/cpucaps.h
 create mode 100644 arch/arm64/tools/Makefile
 create mode 100644 arch/arm64/tools/cpucaps
 create mode 100755 arch/arm64/tools/gen-cpucaps.awk
arch/arm64/Makefile +0 -0
index 7ef44478560d..b52481f0605d 100644
@@ -175,6 +175,9 @@ vdso_install:
 	$(if $(CONFIG_COMPAT_VDSO), \
 		$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
 

Quoted 7 lines

arch/arm64/Makefile vdso_install: · line 179
Quoted 2 lines
arch/arm64/Makefile +2 -0
+archprepare:
+	$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
Small nit. So going forward this new directory (arch/arm64/tools/), will be used to hold similar scripts that generate header or similar things ? At first the directory name 'tool' was bit confusing but seems like other archs (arm, m68k, mips, powerpc, s390, sh) have this directory as well.

Yup; there's more stuff we might want to put here in future, e.g.

* Generation of (or consistency-checks) for the kernel HWCAP glue
* Generation of the sysreg headers
* Generation of the insn code
* Generation of metadata (or consistency checks) for RELIABLE_STACKTRACE, LIVEPATCH, etc

[...]

Quoted 5 lines

arch/arm64/Makefile +5 -0

+BEGIN {
+	print "#ifndef __ASM_CPUCAPS_H"
+	print "#define __ASM_CPUCAPS_H"
+	print ""
+	print "/* Generated file - do not edit */"

Quoted 8 lines

arch/arm64/Makefile
Quoted 5 lines
arch/arm64/Makefile +5 -0
+	cap_num = 0
+	print ""
+}
+
+/^[vA-Z0-9_]+$/ {
Small nit. Should this be length restricted at the least ? Like each CAP entries should not exceed a certain length.

I don't think we should enforce a length limit in the script, as we'd have to select an arbitrary limit, and given we should catch exceedingly long names during review, I think it's more likely to be a hindrance than a help (e.g. if we ever bump up against that limit).

Quoted 11 lines

arch/arm64/Makefile
Quoted 8 lines
arch/arm64/Makefile +8 -0
+	printf("#define ARM64_%-30s\t%d\n", $0, cap_num++)
+	next
+}
+
+END {
+	printf("#define ARM64_NCAPS\t\t\t\t%d\n", cap_num)
+	print ""
+	print "#endif"
Small nit. Should it be print "#endif /* __ASM_CPUCAPS_H */" instead in order to be complete.

Agreed; that would be nice.

Thanks,
Mark.

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Mark Brown

author

2021-05-13 12:48 UTC #6 lore raw

In reply to Anshuman Khandual

Quoted 2 lines · Anshuman Khandual

Small nit. So going forward this new directory (arch/arm64/tools/), will be used to hold similar scripts that generate header or similar things ?

Yes, anything we need to run in the build process. Some of the other architectures have some tools to verify generated binaries have particular properties as well for example.

Quoted 2 lines

At first the directory name 'tool' was bit confusing but seems like other archs (arm, m68k, mips, powerpc, s390, sh) have this directory as well.

Yes, it's the standard pattern.

Quoted 4 lines

Quoted 1 line
+/^[vA-Z0-9_]+$/ {
Small nit. Should this be length restricted at the least ? Like each CAP entries should not exceed a certain length.

If you want to send a patch by all means, I don't think it's useful though - it doesn't matter to the software and the main issue is taste which is going to get considered regardless of what software says, if people are happy with an identifer that hits some limit they're just going to raise the limit.

Quoted 2 lines

Small nit. Should it be print "#endif /* __ASM_CPUCAPS_H */" instead in order to be complete.

I guess. Given that this is merged that'd need to be an incremental patch.

Please delete unneeded context from mails when replying. Doing this makes it much easier to find your reply in the message, helping ensure it won't be missed by people scrolling through the irrelevant quoted material.

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Geert Uytterhoeven

2021-05-13 11:33 UTC #7 lore raw

In reply to Mark Brown

Hi Mark,

Quoted 17 lines · Mark Brown

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.
As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing. Due to the UAO cpucap having been removed in the past we end up with ARM64_NCAPS being 1 smaller than it was before.

Quoted 8 lines

Signed-off-by Mark Brown <[email protected]>

---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++

I guess the reason you're doing it like this, and not using a simple C enum, is that some of these definitions are used from asm files? Do we use similar mechanisms in other places?
Would introducing a generic way to generate headers with definitions from a C enum be worthwhile?

Gr{oetje,eeting}s,

Geert

Signature · 10 lines

Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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Mark Brown

author

2021-05-13 13:06 UTC #8 lore raw

Quoted 2 lines · Geert Uytterhoeven

I guess the reason you're doing it like this, and not using a simple C enum, is that some of these definitions are used from asm files?

Yes, there's references in asm files.

Quoted 1 line

Do we use similar mechanisms in other places?

I'd be surprised if we weren't, though off the top of my head the other examples in arm64 are the sysregs and the hwcaps which are both ABI and don't really benefit in the same way.

Quoted 2 lines

Would introducing a generic way to generate headers with definitions from a C enum be worthwhile?

There must be some other arch which could use one at least.

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dann frazier

2021-09-21 18:10 UTC #9 lore raw

In reply to Mark Brown

Quoted 6 lines · Mark Brown

The arm64 code allocates an internal constant to every CPU feature it can detect, distinct from the public hwcap numbers we use to expose some features to userspace. Currently this is maintained manually which is an irritating source of conflicts when working on new features, to avoid this replace the header with a simple text file listing the names we've assigned and sort it to minimise conflicts.

Thanks for doing this Mark, speaking as someone who has had to backport a lot of these patches to a distro kernel :)

Quoted 8 lines

As part of doing this we also do the Kbuild hookup required to hook up an arch tools directory and to generate header files in there.
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing.

Unfortunately I believe I've hit a regression[*] due to such an ordering dependency. UNMAP_KERNEL_AT_EL0 currently needs to be processed after WORKAROUND_CAVIUM_27456. ThunderX systems are incompatible with KPTI, so unmap_kernel_at_el0() bails if WORKAROUND_CAVIUM_27456 is set. Because of the sorting, WORKAROUND_CAVIUM_27456 will not yet have been considered when unmap_kernel_at_el0() checks for it, so the kernel tries to run w/ KPTI - and quickly falls over.

I've verified that reordering cpucaps to move WORKAROUND_CAVIUM_27456 just above UNMAP_KERNEL_AT_EL0 restores the old behavior. I'm not sure of the right way to address this - perhaps unmap_kernel_at_el0() could check cavium_erratum_27456_cpus[] directly instead of keying on the ARM64_WORKAROUND_CAVIUM_27456 cap?

-dann

[*] https://bugs.launchpad.net/bugs/1942633

Quoted 256 lines

Due to the UAO cpucap having been removed in
the past we end up with ARM64_NCAPS being 1 smaller than it was before.

Signed-off-by Mark Brown <[email protected]>

---
 arch/arm64/Makefile              |  3 ++
 arch/arm64/include/asm/Kbuild    |  2 +
 arch/arm64/include/asm/cpucaps.h | 74 --------------------------------
 arch/arm64/tools/Makefile        | 22 ++++++++++
 arch/arm64/tools/cpucaps         | 65 ++++++++++++++++++++++++++++
 arch/arm64/tools/gen-cpucaps.awk | 40 +++++++++++++++++
 6 files changed, 132 insertions(+), 74 deletions(-)
 delete mode 100644 arch/arm64/include/asm/cpucaps.h
 create mode 100644 arch/arm64/tools/Makefile
 create mode 100644 arch/arm64/tools/cpucaps
 create mode 100755 arch/arm64/tools/gen-cpucaps.awk

arch/arm64/Makefile +3 -0

index 7ef44478560d..b52481f0605d 100644
@@ -175,6 +175,9 @@ vdso_install:
 	$(if $(CONFIG_COMPAT_VDSO), \
 		$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
 
+archprepare:
+	$(Q)$(MAKE) $(build)=arch/arm64/tools kapi
+
 # We use MRPROPER_FILES and CLEAN_FILES now
 archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)

arch/arm64/include/asm/Kbuild +2 -0

index 73aa25843f65..64202010b700 100644
@@ -4,3 +4,5 @@ generic-y += mcs_spinlock.h
 generic-y += qrwlock.h
 generic-y += qspinlock.h
 generic-y += user.h
+
+generated-y += cpucaps.h

arch/arm64/include/asm/cpucaps.h deleted +0 ~~-74~~

deleted file mode 100644
index b0c5eda0498f..000000000000
@@ -1,74 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * arch/arm64/include/asm/cpucaps.h
- *
- * Copyright (C) 2016 ARM Ltd.
- */
-#ifndef __ASM_CPUCAPS_H
-#define __ASM_CPUCAPS_H
-
-#define ARM64_WORKAROUND_CLEAN_CACHE		0
-#define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE	1
-#define ARM64_WORKAROUND_845719			2
-#define ARM64_HAS_SYSREG_GIC_CPUIF		3
-#define ARM64_HAS_PAN				4
-#define ARM64_HAS_LSE_ATOMICS			5
-#define ARM64_WORKAROUND_CAVIUM_23154		6
-#define ARM64_WORKAROUND_834220			7
-#define ARM64_HAS_NO_HW_PREFETCH		8
-#define ARM64_HAS_VIRT_HOST_EXTN		11
-#define ARM64_WORKAROUND_CAVIUM_27456		12
-#define ARM64_HAS_32BIT_EL0			13
-#define ARM64_SPECTRE_V3A			14
-#define ARM64_HAS_CNP				15
-#define ARM64_HAS_NO_FPSIMD			16
-#define ARM64_WORKAROUND_REPEAT_TLBI		17
-#define ARM64_WORKAROUND_QCOM_FALKOR_E1003	18
-#define ARM64_WORKAROUND_858921			19
-#define ARM64_WORKAROUND_CAVIUM_30115		20
-#define ARM64_HAS_DCPOP				21
-#define ARM64_SVE				22
-#define ARM64_UNMAP_KERNEL_AT_EL0		23
-#define ARM64_SPECTRE_V2			24
-#define ARM64_HAS_RAS_EXTN			25
-#define ARM64_WORKAROUND_843419			26
-#define ARM64_HAS_CACHE_IDC			27
-#define ARM64_HAS_CACHE_DIC			28
-#define ARM64_HW_DBM				29
-#define ARM64_SPECTRE_V4			30
-#define ARM64_MISMATCHED_CACHE_TYPE		31
-#define ARM64_HAS_STAGE2_FWB			32
-#define ARM64_HAS_CRC32				33
-#define ARM64_SSBS				34
-#define ARM64_WORKAROUND_1418040		35
-#define ARM64_HAS_SB				36
-#define ARM64_WORKAROUND_SPECULATIVE_AT		37
-#define ARM64_HAS_ADDRESS_AUTH_ARCH		38
-#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_HAS_IRQ_PRIO_MASKING		42
-#define ARM64_HAS_DCPODP			43
-#define ARM64_WORKAROUND_1463225		44
-#define ARM64_WORKAROUND_CAVIUM_TX2_219_TVM	45
-#define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
-#define ARM64_WORKAROUND_1542419		47
-#define ARM64_HAS_E0PD				48
-#define ARM64_HAS_RNG				49
-#define ARM64_HAS_AMU_EXTN			50
-#define ARM64_HAS_ADDRESS_AUTH			51
-#define ARM64_HAS_GENERIC_AUTH			52
-#define ARM64_HAS_32BIT_EL1			53
-#define ARM64_BTI				54
-#define ARM64_HAS_ARMv8_4_TTL			55
-#define ARM64_HAS_TLB_RANGE			56
-#define ARM64_MTE				57
-#define ARM64_WORKAROUND_1508412		58
-#define ARM64_HAS_LDAPR				59
-#define ARM64_KVM_PROTECTED_MODE		60
-#define ARM64_WORKAROUND_NVIDIA_CARMEL_CNP	61
-#define ARM64_HAS_EPAN				62
-
-#define ARM64_NCAPS				63
-
-#endif /* __ASM_CPUCAPS_H */

arch/arm64/tools/Makefile new file +22 -0

new file mode 100644
index 000000000000..932b4fe5c768
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+
+gen := arch/$(ARCH)/include/generated
+kapi := $(gen)/asm
+
+kapi-hdrs-y := $(kapi)/cpucaps.h
+
+targets += $(addprefix ../../../,$(gen-y) $(kapi-hdrs-y))
+
+PHONY += kapi
+
+kapi:   $(kapi-hdrs-y) $(gen-y)
+
+# Create output directory if not already present
+_dummy := $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)')
+
+quiet_cmd_gen_cpucaps = GEN     $@
+      cmd_gen_cpucaps = mkdir -p $(dir $@) && \
+                     $(AWK) -f $(filter-out $(PHONY),$^) > $@
+
+$(kapi)/cpucaps.h: $(src)/gen-cpucaps.awk $(src)/cpucaps FORCE
+	$(call if_changed,gen_cpucaps)

arch/arm64/tools/cpucaps new file +65 -0

new file mode 100644
index 000000000000..21fbdda7086e
@@ -0,0 +1,65 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Internal CPU capabilities constants, keep this list sorted
+
+BTI
+HAS_32BIT_EL0
+HAS_32BIT_EL1
+HAS_ADDRESS_AUTH
+HAS_ADDRESS_AUTH_ARCH
+HAS_ADDRESS_AUTH_IMP_DEF
+HAS_AMU_EXTN
+HAS_ARMv8_4_TTL
+HAS_CACHE_DIC
+HAS_CACHE_IDC
+HAS_CNP
+HAS_CRC32
+HAS_DCPODP
+HAS_DCPOP
+HAS_E0PD
+HAS_EPAN
+HAS_GENERIC_AUTH
+HAS_GENERIC_AUTH_ARCH
+HAS_GENERIC_AUTH_IMP_DEF
+HAS_IRQ_PRIO_MASKING
+HAS_LDAPR
+HAS_LSE_ATOMICS
+HAS_NO_FPSIMD
+HAS_NO_HW_PREFETCH
+HAS_PAN
+HAS_RAS_EXTN
+HAS_RNG
+HAS_SB
+HAS_STAGE2_FWB
+HAS_SYSREG_GIC_CPUIF
+HAS_TLB_RANGE
+HAS_VIRT_HOST_EXTN
+HW_DBM
+KVM_PROTECTED_MODE
+MISMATCHED_CACHE_TYPE
+MTE
+SPECTRE_V2
+SPECTRE_V3A
+SPECTRE_V4
+SSBS
+SVE
+UNMAP_KERNEL_AT_EL0
+WORKAROUND_834220
+WORKAROUND_843419
+WORKAROUND_845719
+WORKAROUND_858921
+WORKAROUND_1418040
+WORKAROUND_1463225
+WORKAROUND_1508412
+WORKAROUND_1542419
+WORKAROUND_CAVIUM_23154
+WORKAROUND_CAVIUM_27456
+WORKAROUND_CAVIUM_30115
+WORKAROUND_CAVIUM_TX2_219_PRFM
+WORKAROUND_CAVIUM_TX2_219_TVM
+WORKAROUND_CLEAN_CACHE
+WORKAROUND_DEVICE_LOAD_ACQUIRE
+WORKAROUND_NVIDIA_CARMEL_CNP
+WORKAROUND_QCOM_FALKOR_E1003
+WORKAROUND_REPEAT_TLBI
+WORKAROUND_SPECULATIVE_AT

arch/arm64/tools/gen-cpucaps.awk new file +30 -0

new file mode 100755
index 000000000000..18737a1ce044
@@ -0,0 +1,40 @@
+#!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+# gen-cpucaps.awk: arm64 cpucaps header generator
+#
+# Usage: awk -f gen-cpucaps.awk cpucaps.txt
+
+# Log an error and terminate
+function fatal(msg) {
+	print "Error at line " NR ": " msg > "/dev/stderr"
+	exit 1
+}
+
+# skip blank lines and comment lines
+/^$/ { next }
+/^#/ { next }
+
+BEGIN {
+	print "#ifndef __ASM_CPUCAPS_H"
+	print "#define __ASM_CPUCAPS_H"
+	print ""
+	print "/* Generated file - do not edit */"
+	cap_num = 0
+	print ""
+}
+
+/^[vA-Z0-9_]+$/ {
+	printf("#define ARM64_%-30s\t%d\n", $0, cap_num++)
+	next
+}
+

arch/arm64/tools/gen-cpucaps.awk line 40

Quoted 10 lines

arch/arm64/tools/gen-cpucaps.awk new file +10 -0

+END {
+	printf("#define ARM64_NCAPS\t\t\t\t%d\n", cap_num)
+	print ""
+	print "#endif"
+}
+
+# Any lines not handled by previous rules are unexpected
+{
+	fatal("unhandled statement")
+}

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Mark Brown

author

2021-09-21 18:38 UTC #10 lore raw

Quoted 17 lines · dann frazier

Quoted 5 lines · Mark Brown
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing.
Unfortunately I believe I've hit a regression[*] due to such an ordering dependency. UNMAP_KERNEL_AT_EL0 currently needs to be processed after WORKAROUND_CAVIUM_27456. ThunderX systems are incompatible with KPTI, so unmap_kernel_at_el0() bails if WORKAROUND_CAVIUM_27456 is set. Because of the sorting, WORKAROUND_CAVIUM_27456 will not yet have been considered when unmap_kernel_at_el0() checks for it, so the kernel tries to run w/ KPTI - and quickly falls over.

Quoted 5 lines

I've verified that reordering cpucaps to move WORKAROUND_CAVIUM_27456 just above UNMAP_KERNEL_AT_EL0 restores the old behavior. I'm not sure of the right way to address this - perhaps unmap_kernel_at_el0() could check cavium_erratum_27456_cpus[] directly instead of keying on the ARM64_WORKAROUND_CAVIUM_27456 cap?

Ugh, right. Another option would be to do something like rename to CAVIUM_WORKAROUND_27456 which would be inconsistent naming and but would sort things in a way that gets the checks to run in the order we're relying on but either works for me. Neither is great.

It'd be really good to get more coverage of the enterprise systems in KernelCI or similar so we can catch issues like this more easily.

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Suzuki K Poulose

2021-09-21 21:11 UTC #11 lore raw

Quoted 18 lines · Mark Brown

Quoted 16 lines · dann frazier
Quoted 5 lines · Mark Brown
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing.
Unfortunately I believe I've hit a regression[*] due to such an ordering dependency. UNMAP_KERNEL_AT_EL0 currently needs to be processed after WORKAROUND_CAVIUM_27456. ThunderX systems are incompatible with KPTI, so unmap_kernel_at_el0() bails if WORKAROUND_CAVIUM_27456 is set. Because of the sorting, WORKAROUND_CAVIUM_27456 will not yet have been considered when unmap_kernel_at_el0() checks for it, so the kernel tries to run w/ KPTI - and quickly falls over.

Quoted 5 lines

Quoted 5 lines
I've verified that reordering cpucaps to move WORKAROUND_CAVIUM_27456 just above UNMAP_KERNEL_AT_EL0 restores the old behavior. I'm not sure of the right way to address this - perhaps unmap_kernel_at_el0() could check cavium_erratum_27456_cpus[] directly instead of keying on the ARM64_WORKAROUND_CAVIUM_27456 cap?

Given that these capabilities are LOCAL_CPU scope, and the systems in question never have heterogeneous CPUs, you could replace

cpus_have_const_cap() => this_cpu_has_cap()

in unmap_kernel_at_el0().

If they were heterogeneous, we would fail anyway, no matter what the order was.

Suzuki

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dann frazier

2021-09-22 13:48 UTC #12 lore raw

Quoted 28 lines · Suzuki K Poulose

Quoted 18 lines · Mark Brown
Quoted 16 lines · dann frazier
Quoted 5 lines · Mark Brown
This will result in a renumbering and reordering of the existing constants, since they are all internal only the values should not be important. The reordering will impact the order in which some steps in enumeration handle features but the algorithm is not intended to depend on this and I haven't seen any issues when testing.
Unfortunately I believe I've hit a regression[*] due to such an ordering dependency. UNMAP_KERNEL_AT_EL0 currently needs to be processed after WORKAROUND_CAVIUM_27456. ThunderX systems are incompatible with KPTI, so unmap_kernel_at_el0() bails if WORKAROUND_CAVIUM_27456 is set. Because of the sorting, WORKAROUND_CAVIUM_27456 will not yet have been considered when unmap_kernel_at_el0() checks for it, so the kernel tries to run w/ KPTI - and quickly falls over.
Quoted 5 lines
Quoted 5 lines
I've verified that reordering cpucaps to move WORKAROUND_CAVIUM_27456 just above UNMAP_KERNEL_AT_EL0 restores the old behavior. I'm not sure of the right way to address this - perhaps unmap_kernel_at_el0() could check cavium_erratum_27456_cpus[] directly instead of keying on the ARM64_WORKAROUND_CAVIUM_27456 cap?
Given that these capabilities are LOCAL_CPU scope, and the systems in question never have heterogeneous CPUs, you could replace

Quoted 6 lines

cpus_have_const_cap() => this_cpu_has_cap()
in unmap_kernel_at_el0().
If they were heterogeneous, we would fail anyway, no matter what the order was.

That seems to me to be the simplest approach, and I've verified it addresses the problem. I'll prepare a patch. Thanks Suzuki.

-dann

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