[PATCH kernel 0/3] powerpc/llvm/lto: Enable CONFIG_LTO_CLANG_THIN=y

[PATCH kernel 0/3] powerpc/llvm/lto: Enable CONFIG_LTO_CLANG_THIN=y

[Alexey Kardashevskiy]

This is based on sha1
1b43a74f255c Michael Ellerman "Automatic merge of 'master' into merge (2022-02-01 10:41)".

Please comment. Thanks.



Alexey Kardashevskiy (3):
  powerpc/64: Allow LLVM LTO builds
  powerpc/llvm: Sample config for LLVM LTO
  powerpc/llvm/lto: Workaround conditional branches in FTR_SECTION_ELSE

 arch/powerpc/Makefile                    |   4 +
 arch/powerpc/Kconfig                     |   2 +
 arch/powerpc/configs/ppc64_lto_defconfig | 381 +++++++++++++++++++++++
 arch/powerpc/kernel/exceptions-64s.S     |   6 +-
 arch/powerpc/lib/copyuser_64.S           |   3 +-
 arch/powerpc/lib/memcpy_64.S             |   3 +-
 6 files changed, 396 insertions(+), 3 deletions(-)
 create mode 100644 arch/powerpc/configs/ppc64_lto_defconfig

-- 
2.30.2

[PATCH kernel 0/3] powerpc/llvm/lto: Enable CONFIG_LTO_CLANG_THIN=y

[Alexey Kardashevskiy]

This is based on sha1
1b43a74f255c Michael Ellerman "Automatic merge of 'master' into merge (2022-02-01 10:41)".

Please comment. Thanks.



Alexey Kardashevskiy (3):
  powerpc/64: Allow LLVM LTO builds
  powerpc/llvm: Sample config for LLVM LTO
  powerpc/llvm/lto: Workaround conditional branches in FTR_SECTION_ELSE

 arch/powerpc/Makefile                    |   4 +
 arch/powerpc/Kconfig                     |   2 +
 arch/powerpc/configs/ppc64_lto_defconfig | 381 +++++++++++++++++++++++
 arch/powerpc/kernel/exceptions-64s.S     |   6 +-
 arch/powerpc/lib/copyuser_64.S           |   3 +-
 arch/powerpc/lib/memcpy_64.S             |   3 +-
 6 files changed, 396 insertions(+), 3 deletions(-)
 create mode 100644 arch/powerpc/configs/ppc64_lto_defconfig

-- 
2.30.2

[PATCH kernel 1/3] powerpc/64: Allow LLVM LTO builds

[Alexey Kardashevskiy]

The upstream LLVM supports now LTO on PPC, enable it.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b779603978e1..91c122224f83 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -153,6 +153,8 @@ config PPC
 	select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select ARCH_WEAK_RELEASE_ACQUIRE
+	select ARCH_SUPPORTS_LTO_CLANG		if PPC64
+	select ARCH_SUPPORTS_LTO_CLANG_THIN	if PPC64
 	select BINFMT_ELF
 	select BUILDTIME_TABLE_SORT
 	select CLONE_BACKWARDS
-- 
2.30.2

[PATCH kernel 1/3] powerpc/64: Allow LLVM LTO builds

[Alexey Kardashevskiy]

The upstream LLVM supports now LTO on PPC, enable it.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b779603978e1..91c122224f83 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -153,6 +153,8 @@ config PPC
 	select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select ARCH_WEAK_RELEASE_ACQUIRE
+	select ARCH_SUPPORTS_LTO_CLANG		if PPC64
+	select ARCH_SUPPORTS_LTO_CLANG_THIN	if PPC64
 	select BINFMT_ELF
 	select BUILDTIME_TABLE_SORT
 	select CLONE_BACKWARDS
-- 
2.30.2

[PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Alexey Kardashevskiy]

The config is a copy of ppc64_defconfig with a few tweaks. This could be
a smaller config to merge into ppc64_defconfig but unfortunately
merger does not allow disabling already enabled options.

This is a command line to compile the kernel using the upstream llvm:

make -j64 O=/home/aik/pbuild/kernels-llvm/ \
 "KCFLAGS=-Wmissing-braces -Wno-array-bounds" \
 ARCH=powerpc LLVM_IAS=1 ppc64le_lto_defconfig CC=clang LLVM=1

Forces CONFIG_BTRFS_FS=y to make CONFIG_ZSTD_COMPRESS=y to fix:
ld.lld: error: linking module flags 'Code Model': IDs have conflicting values in 'lib/built-in.a(entropy_common.o at 5332)' and 'ld-temp.o'

because modules are linked with -mcmodel=large but the kernel uses -mcmodel=medium

Enables CONFIG_USERFAULTFD=y as otherwise vm_userfaultfd_ctx becomes
0 bytes long and clang sanitizer crashes as
https://bugs.llvm.org/show_bug.cgi?id=500375

Disables CONFIG_FTR_FIXUP_SELFTEST as it uses FTR_SECTION_ELSE with
conditional branches. There are other places like this and the following
patches address that.

Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
depends on it being disabled. In order to avoid disabling way too many
options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.

Note that even with this config there is a good chance that LTO
is going to fail linking vmlinux because of the "bc" problem.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/Makefile                    |   4 +
 arch/powerpc/configs/ppc64_lto_defconfig | 381 +++++++++++++++++++++++
 2 files changed, 385 insertions(+)
 create mode 100644 arch/powerpc/configs/ppc64_lto_defconfig

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 5f16ac1583c5..23f1ade8abc9 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -308,6 +308,10 @@ PHONY += ppc64le_defconfig
 ppc64le_defconfig:
 	$(call merge_into_defconfig,ppc64_defconfig,le)
 
+PHONY += ppc64le_lto_defconfig
+ppc64le_lto_defconfig:
+	$(call merge_into_defconfig,ppc64_lto_defconfig,le)
+
 PHONY += ppc64le_guest_defconfig
 ppc64le_guest_defconfig:
 	$(call merge_into_defconfig,ppc64_defconfig,le guest)
diff --git a/arch/powerpc/configs/ppc64_lto_defconfig b/arch/powerpc/configs/ppc64_lto_defconfig
new file mode 100644
index 000000000000..67f82b422b7d
--- /dev/null
+++ b/arch/powerpc/configs/ppc64_lto_defconfig
@@ -0,0 +1,381 @@
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_TASKSTATS=y
+CONFIG_TASK_DELAY_ACCT=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=18
+CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
+CONFIG_NUMA_BALANCING=y
+CONFIG_CGROUPS=y
+CONFIG_MEMCG=y
+CONFIG_CGROUP_SCHED=y
+CONFIG_CGROUP_FREEZER=y
+CONFIG_CPUSETS=y
+CONFIG_CGROUP_DEVICE=y
+CONFIG_CGROUP_CPUACCT=y
+CONFIG_CGROUP_PERF=y
+CONFIG_CGROUP_BPF=y
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_BPF_SYSCALL=y
+# CONFIG_COMPAT_BRK is not set
+CONFIG_PROFILING=y
+CONFIG_PPC64=y
+CONFIG_NR_CPUS=2048
+CONFIG_PPC_SPLPAR=y
+CONFIG_DTL=y
+CONFIG_PPC_SMLPAR=y
+CONFIG_IBMEBUS=y
+CONFIG_PPC_SVM=y
+CONFIG_PPC_MAPLE=y
+CONFIG_PPC_PASEMI=y
+CONFIG_PPC_PASEMI_IOMMU=y
+CONFIG_PPC_PS3=y
+CONFIG_PS3_DISK=m
+CONFIG_PS3_ROM=m
+CONFIG_PS3_FLASH=m
+CONFIG_PS3_LPM=m
+CONFIG_PPC_IBM_CELL_BLADE=y
+CONFIG_RTAS_FLASH=m
+CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
+CONFIG_CPU_FREQ_GOV_POWERSAVE=y
+CONFIG_CPU_FREQ_GOV_USERSPACE=y
+CONFIG_CPU_FREQ_GOV_CONSERVATIVE=y
+CONFIG_CPU_FREQ_PMAC64=y
+CONFIG_HZ_100=y
+CONFIG_PPC_TRANSACTIONAL_MEM=y
+CONFIG_KEXEC=y
+CONFIG_KEXEC_FILE=y
+CONFIG_CRASH_DUMP=y
+CONFIG_FA_DUMP=y
+CONFIG_IRQ_ALL_CPUS=y
+CONFIG_SCHED_SMT=y
+CONFIG_HOTPLUG_PCI=y
+CONFIG_HOTPLUG_PCI_RPA=m
+CONFIG_HOTPLUG_PCI_RPA_DLPAR=m
+CONFIG_PCCARD=y
+CONFIG_ELECTRA_CF=y
+CONFIG_VIRTUALIZATION=y
+CONFIG_KVM_BOOK3S_64=m
+CONFIG_KVM_BOOK3S_64_HV=m
+CONFIG_VHOST_NET=m
+CONFIG_KPROBES=y
+CONFIG_JUMP_LABEL=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_MODVERSIONS=y
+CONFIG_MODULE_SRCVERSION_ALL=y
+CONFIG_PARTITION_ADVANCED=y
+CONFIG_BINFMT_MISC=m
+CONFIG_MEMORY_HOTPLUG=y
+CONFIG_MEMORY_HOTREMOVE=y
+CONFIG_KSM=y
+CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_XFRM_USER=m
+CONFIG_NET_KEY=m
+CONFIG_INET=y
+CONFIG_IP_MULTICAST=y
+CONFIG_IP_PNP=y
+CONFIG_IP_PNP_DHCP=y
+CONFIG_IP_PNP_BOOTP=y
+CONFIG_NET_IPIP=y
+CONFIG_SYN_COOKIES=y
+CONFIG_INET_AH=m
+CONFIG_INET_ESP=m
+CONFIG_INET_IPCOMP=m
+CONFIG_IPV6=y
+CONFIG_NETFILTER=y
+# CONFIG_NETFILTER_ADVANCED is not set
+CONFIG_BRIDGE=m
+CONFIG_NET_SCHED=y
+CONFIG_NET_CLS_BPF=m
+CONFIG_NET_CLS_ACT=y
+CONFIG_NET_ACT_BPF=m
+CONFIG_BPF_JIT=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_BLK_DEV_FD=y
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_BLK_DEV_NBD=m
+CONFIG_BLK_DEV_RAM=y
+CONFIG_BLK_DEV_RAM_SIZE=65536
+CONFIG_VIRTIO_BLK=m
+CONFIG_BLK_DEV_SD=y
+CONFIG_CHR_DEV_ST=m
+CONFIG_BLK_DEV_SR=y
+CONFIG_CHR_DEV_SG=y
+CONFIG_SCSI_CONSTANTS=y
+CONFIG_SCSI_FC_ATTRS=y
+CONFIG_SCSI_CXGB3_ISCSI=m
+CONFIG_SCSI_CXGB4_ISCSI=m
+CONFIG_SCSI_BNX2_ISCSI=m
+CONFIG_BE2ISCSI=m
+CONFIG_SCSI_MPT2SAS=m
+CONFIG_SCSI_IBMVSCSI=y
+CONFIG_SCSI_IBMVFC=m
+CONFIG_SCSI_SYM53C8XX_2=m
+CONFIG_SCSI_SYM53C8XX_DMA_ADDRESSING_MODE=0
+CONFIG_SCSI_IPR=y
+CONFIG_SCSI_QLA_FC=m
+CONFIG_SCSI_QLA_ISCSI=m
+CONFIG_SCSI_LPFC=m
+CONFIG_SCSI_VIRTIO=m
+CONFIG_SCSI_DH=y
+CONFIG_SCSI_DH_RDAC=m
+CONFIG_SCSI_DH_ALUA=m
+CONFIG_ATA=y
+CONFIG_SATA_AHCI=y
+CONFIG_SATA_SIL24=y
+CONFIG_SATA_MV=y
+CONFIG_SATA_SVW=y
+CONFIG_PATA_AMD=y
+CONFIG_PATA_MACIO=y
+CONFIG_ATA_GENERIC=y
+CONFIG_MD=y
+CONFIG_BLK_DEV_MD=y
+CONFIG_MD_LINEAR=y
+CONFIG_MD_RAID0=y
+CONFIG_MD_RAID1=y
+CONFIG_MD_RAID10=m
+CONFIG_MD_RAID456=m
+CONFIG_MD_MULTIPATH=m
+CONFIG_MD_FAULTY=m
+CONFIG_BLK_DEV_DM=y
+CONFIG_DM_CRYPT=m
+CONFIG_DM_SNAPSHOT=m
+CONFIG_DM_MIRROR=m
+CONFIG_DM_ZERO=m
+CONFIG_DM_MULTIPATH=m
+CONFIG_DM_MULTIPATH_QL=m
+CONFIG_DM_MULTIPATH_ST=m
+CONFIG_DM_UEVENT=y
+CONFIG_ADB_PMU=y
+CONFIG_PMAC_SMU=y
+CONFIG_WINDFARM=y
+CONFIG_WINDFARM_PM81=y
+CONFIG_WINDFARM_PM91=y
+CONFIG_WINDFARM_PM112=y
+CONFIG_WINDFARM_PM121=y
+CONFIG_BONDING=m
+CONFIG_DUMMY=m
+CONFIG_NETCONSOLE=y
+CONFIG_TUN=m
+CONFIG_VIRTIO_NET=m
+CONFIG_VORTEX=m
+CONFIG_ACENIC=m
+CONFIG_ACENIC_OMIT_TIGON_I=y
+CONFIG_PCNET32=m
+CONFIG_TIGON3=y
+CONFIG_BNX2X=m
+CONFIG_CHELSIO_T1=m
+CONFIG_BE2NET=m
+CONFIG_IBMVETH=m
+CONFIG_EHEA=m
+CONFIG_IBMVNIC=m
+CONFIG_E100=y
+CONFIG_E1000=y
+CONFIG_E1000E=y
+CONFIG_IXGB=m
+CONFIG_IXGBE=m
+CONFIG_I40E=m
+CONFIG_MLX4_EN=m
+CONFIG_MYRI10GE=m
+CONFIG_S2IO=m
+CONFIG_PASEMI_MAC=y
+CONFIG_NETXEN_NIC=m
+CONFIG_SUNGEM=y
+CONFIG_GELIC_NET=m
+CONFIG_GELIC_WIRELESS=y
+CONFIG_SPIDER_NET=m
+CONFIG_BROADCOM_PHY=m
+CONFIG_MARVELL_PHY=y
+CONFIG_PPP=m
+CONFIG_PPP_BSDCOMP=m
+CONFIG_PPP_DEFLATE=m
+CONFIG_PPPOE=m
+CONFIG_PPP_ASYNC=m
+CONFIG_PPP_SYNC_TTY=m
+CONFIG_INPUT_EVDEV=m
+CONFIG_INPUT_MISC=y
+CONFIG_INPUT_PCSPKR=m
+# CONFIG_SERIO_SERPORT is not set
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_ICOM=m
+CONFIG_SERIAL_JSM=m
+CONFIG_HVC_CONSOLE=y
+CONFIG_HVC_RTAS=y
+CONFIG_HVCS=m
+CONFIG_VIRTIO_CONSOLE=m
+CONFIG_IBM_BSR=m
+CONFIG_RAW_DRIVER=y
+CONFIG_I2C_CHARDEV=y
+CONFIG_I2C_AMD8111=y
+CONFIG_I2C_PASEMI=y
+CONFIG_FB=y
+CONFIG_FIRMWARE_EDID=y
+CONFIG_FB_OF=y
+CONFIG_FB_MATROX=y
+CONFIG_FB_MATROX_MILLENIUM=y
+CONFIG_FB_MATROX_MYSTIQUE=y
+CONFIG_FB_MATROX_G=y
+CONFIG_FB_MATROX_I2C=m
+CONFIG_FB_MATROX_MAVEN=m
+CONFIG_FB_RADEON=y
+CONFIG_FB_IBM_GXT4500=y
+CONFIG_FB_PS3=m
+CONFIG_LCD_CLASS_DEVICE=y
+# CONFIG_VGA_CONSOLE is not set
+CONFIG_FRAMEBUFFER_CONSOLE=y
+CONFIG_LOGO=y
+CONFIG_SOUND=m
+CONFIG_SND=m
+CONFIG_SND_OSSEMUL=y
+CONFIG_SND_MIXER_OSS=m
+CONFIG_SND_PCM_OSS=m
+CONFIG_SND_SEQUENCER=m
+CONFIG_SND_SEQ_DUMMY=m
+CONFIG_SND_SEQUENCER_OSS=m
+CONFIG_SND_POWERMAC=m
+CONFIG_SND_AOA=m
+CONFIG_SND_AOA_FABRIC_LAYOUT=m
+CONFIG_SND_AOA_ONYX=m
+CONFIG_SND_AOA_TAS=m
+CONFIG_SND_AOA_TOONIE=m
+CONFIG_HID_GYRATION=y
+CONFIG_HID_PANTHERLORD=y
+CONFIG_HID_PETALYNX=y
+CONFIG_HID_SAMSUNG=y
+CONFIG_HID_SUNPLUS=y
+CONFIG_USB_HIDDEV=y
+CONFIG_USB=y
+CONFIG_USB_MON=m
+CONFIG_USB_EHCI_HCD=y
+# CONFIG_USB_EHCI_HCD_PPC_OF is not set
+CONFIG_USB_OHCI_HCD=y
+CONFIG_USB_STORAGE=m
+CONFIG_USB_APPLEDISPLAY=m
+CONFIG_NEW_LEDS=y
+CONFIG_LEDS_CLASS=m
+CONFIG_LEDS_POWERNV=m
+CONFIG_INFINIBAND=m
+CONFIG_INFINIBAND_USER_MAD=m
+CONFIG_INFINIBAND_USER_ACCESS=m
+CONFIG_INFINIBAND_MTHCA=m
+CONFIG_INFINIBAND_CXGB4=m
+CONFIG_MLX4_INFINIBAND=m
+CONFIG_INFINIBAND_IPOIB=m
+CONFIG_INFINIBAND_IPOIB_CM=y
+CONFIG_INFINIBAND_SRP=m
+CONFIG_INFINIBAND_ISER=m
+CONFIG_EDAC=y
+CONFIG_EDAC_PASEMI=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_DS1307=y
+CONFIG_VIRTIO_PCI=m
+CONFIG_VIRTIO_BALLOON=m
+CONFIG_LIBNVDIMM=y
+CONFIG_RAS=y
+CONFIG_EXT2_FS=y
+CONFIG_EXT2_FS_XATTR=y
+CONFIG_EXT2_FS_POSIX_ACL=y
+CONFIG_EXT2_FS_SECURITY=y
+CONFIG_EXT4_FS=y
+CONFIG_EXT4_FS_POSIX_ACL=y
+CONFIG_EXT4_FS_SECURITY=y
+CONFIG_REISERFS_FS=m
+CONFIG_REISERFS_FS_XATTR=y
+CONFIG_REISERFS_FS_POSIX_ACL=y
+CONFIG_REISERFS_FS_SECURITY=y
+CONFIG_JFS_FS=m
+CONFIG_JFS_POSIX_ACL=y
+CONFIG_JFS_SECURITY=y
+CONFIG_XFS_FS=y
+CONFIG_XFS_POSIX_ACL=y
+CONFIG_BTRFS_FS=y
+CONFIG_BTRFS_FS_POSIX_ACL=y
+CONFIG_NILFS2_FS=m
+CONFIG_FS_DAX=y
+CONFIG_AUTOFS4_FS=m
+CONFIG_FUSE_FS=m
+CONFIG_OVERLAY_FS=m
+CONFIG_ISO9660_FS=y
+CONFIG_UDF_FS=m
+CONFIG_MSDOS_FS=y
+CONFIG_VFAT_FS=m
+CONFIG_PROC_KCORE=y
+CONFIG_TMPFS=y
+CONFIG_TMPFS_POSIX_ACL=y
+CONFIG_HUGETLBFS=y
+CONFIG_HFS_FS=m
+CONFIG_HFSPLUS_FS=m
+CONFIG_CRAMFS=m
+CONFIG_SQUASHFS=m
+CONFIG_SQUASHFS_XATTR=y
+CONFIG_SQUASHFS_LZO=y
+CONFIG_SQUASHFS_XZ=y
+CONFIG_NFS_FS=y
+CONFIG_NFS_V3_ACL=y
+CONFIG_NFS_V4=y
+CONFIG_ROOT_NFS=y
+CONFIG_NFSD=m
+CONFIG_NFSD_V3_ACL=y
+CONFIG_NFSD_V4=y
+CONFIG_CIFS=m
+CONFIG_CIFS_XATTR=y
+CONFIG_CIFS_POSIX=y
+CONFIG_NLS_DEFAULT="utf8"
+CONFIG_NLS_CODEPAGE_437=y
+CONFIG_NLS_ASCII=y
+CONFIG_NLS_ISO8859_1=y
+CONFIG_NLS_UTF8=y
+CONFIG_CRYPTO_TEST=m
+CONFIG_CRYPTO_PCBC=m
+CONFIG_CRYPTO_HMAC=y
+CONFIG_CRYPTO_CRC32C_VPMSUM=m
+CONFIG_CRYPTO_MD5_PPC=m
+CONFIG_CRYPTO_MICHAEL_MIC=m
+CONFIG_CRYPTO_SHA1_PPC=m
+CONFIG_CRYPTO_SHA256=y
+CONFIG_CRYPTO_TGR192=m
+CONFIG_CRYPTO_WP512=m
+CONFIG_CRYPTO_ANUBIS=m
+CONFIG_CRYPTO_BLOWFISH=m
+CONFIG_CRYPTO_CAST6=m
+CONFIG_CRYPTO_KHAZAD=m
+CONFIG_CRYPTO_SALSA20=m
+CONFIG_CRYPTO_SERPENT=m
+CONFIG_CRYPTO_TEA=m
+CONFIG_CRYPTO_TWOFISH=m
+CONFIG_CRYPTO_LZO=m
+CONFIG_CRYPTO_DEV_NX=y
+CONFIG_CRYPTO_DEV_NX_ENCRYPT=m
+CONFIG_CRYPTO_DEV_VMX=y
+CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_CALLER=y
+CONFIG_MAGIC_SYSRQ=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DEBUG_STACK_USAGE=y
+CONFIG_DEBUG_STACKOVERFLOW=y
+CONFIG_SOFTLOCKUP_DETECTOR=y
+CONFIG_HARDLOCKUP_DETECTOR=y
+CONFIG_DEBUG_MUTEXES=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_SCHED_TRACER=y
+CONFIG_STACK_TRACER=y
+CONFIG_BLK_DEV_IO_TRACE=y
+CONFIG_CODE_PATCHING_SELFTEST=y
+CONFIG_FTR_FIXUP_SELFTEST=n
+CONFIG_MSI_BITMAP_SELFTEST=y
+CONFIG_XMON=y
+CONFIG_BOOTX_TEXT=y
+CONFIG_LTO=y
+CONFIG_LTO_CLANG_THIN=y
+CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT=n
+CONFIG_USERFAULTFD=y
-- 
2.30.2

[PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Alexey Kardashevskiy]

The config is a copy of ppc64_defconfig with a few tweaks. This could be
a smaller config to merge into ppc64_defconfig but unfortunately
merger does not allow disabling already enabled options.

This is a command line to compile the kernel using the upstream llvm:

make -j64 O=/home/aik/pbuild/kernels-llvm/ \
 "KCFLAGS=-Wmissing-braces -Wno-array-bounds" \
 ARCH=powerpc LLVM_IAS=1 ppc64le_lto_defconfig CC=clang LLVM=1

Forces CONFIG_BTRFS_FS=y to make CONFIG_ZSTD_COMPRESS=y to fix:
ld.lld: error: linking module flags 'Code Model': IDs have conflicting values in 'lib/built-in.a(entropy_common.o at 5332)' and 'ld-temp.o'

because modules are linked with -mcmodel=large but the kernel uses -mcmodel=medium

Enables CONFIG_USERFAULTFD=y as otherwise vm_userfaultfd_ctx becomes
0 bytes long and clang sanitizer crashes as
https://bugs.llvm.org/show_bug.cgi?id=500375

Disables CONFIG_FTR_FIXUP_SELFTEST as it uses FTR_SECTION_ELSE with
conditional branches. There are other places like this and the following
patches address that.

Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
depends on it being disabled. In order to avoid disabling way too many
options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.

Note that even with this config there is a good chance that LTO
is going to fail linking vmlinux because of the "bc" problem.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/Makefile                    |   4 +
 arch/powerpc/configs/ppc64_lto_defconfig | 381 +++++++++++++++++++++++
 2 files changed, 385 insertions(+)
 create mode 100644 arch/powerpc/configs/ppc64_lto_defconfig

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 5f16ac1583c5..23f1ade8abc9 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -308,6 +308,10 @@ PHONY += ppc64le_defconfig
 ppc64le_defconfig:
 	$(call merge_into_defconfig,ppc64_defconfig,le)
 
+PHONY += ppc64le_lto_defconfig
+ppc64le_lto_defconfig:
+	$(call merge_into_defconfig,ppc64_lto_defconfig,le)
+
 PHONY += ppc64le_guest_defconfig
 ppc64le_guest_defconfig:
 	$(call merge_into_defconfig,ppc64_defconfig,le guest)
diff --git a/arch/powerpc/configs/ppc64_lto_defconfig b/arch/powerpc/configs/ppc64_lto_defconfig
new file mode 100644
index 000000000000..67f82b422b7d
--- /dev/null
+++ b/arch/powerpc/configs/ppc64_lto_defconfig
@@ -0,0 +1,381 @@
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_TASKSTATS=y
+CONFIG_TASK_DELAY_ACCT=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=18
+CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
+CONFIG_NUMA_BALANCING=y
+CONFIG_CGROUPS=y
+CONFIG_MEMCG=y
+CONFIG_CGROUP_SCHED=y
+CONFIG_CGROUP_FREEZER=y
+CONFIG_CPUSETS=y
+CONFIG_CGROUP_DEVICE=y
+CONFIG_CGROUP_CPUACCT=y
+CONFIG_CGROUP_PERF=y
+CONFIG_CGROUP_BPF=y
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_BPF_SYSCALL=y
+# CONFIG_COMPAT_BRK is not set
+CONFIG_PROFILING=y
+CONFIG_PPC64=y
+CONFIG_NR_CPUS=2048
+CONFIG_PPC_SPLPAR=y
+CONFIG_DTL=y
+CONFIG_PPC_SMLPAR=y
+CONFIG_IBMEBUS=y
+CONFIG_PPC_SVM=y
+CONFIG_PPC_MAPLE=y
+CONFIG_PPC_PASEMI=y
+CONFIG_PPC_PASEMI_IOMMU=y
+CONFIG_PPC_PS3=y
+CONFIG_PS3_DISK=m
+CONFIG_PS3_ROM=m
+CONFIG_PS3_FLASH=m
+CONFIG_PS3_LPM=m
+CONFIG_PPC_IBM_CELL_BLADE=y
+CONFIG_RTAS_FLASH=m
+CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
+CONFIG_CPU_FREQ_GOV_POWERSAVE=y
+CONFIG_CPU_FREQ_GOV_USERSPACE=y
+CONFIG_CPU_FREQ_GOV_CONSERVATIVE=y
+CONFIG_CPU_FREQ_PMAC64=y
+CONFIG_HZ_100=y
+CONFIG_PPC_TRANSACTIONAL_MEM=y
+CONFIG_KEXEC=y
+CONFIG_KEXEC_FILE=y
+CONFIG_CRASH_DUMP=y
+CONFIG_FA_DUMP=y
+CONFIG_IRQ_ALL_CPUS=y
+CONFIG_SCHED_SMT=y
+CONFIG_HOTPLUG_PCI=y
+CONFIG_HOTPLUG_PCI_RPA=m
+CONFIG_HOTPLUG_PCI_RPA_DLPAR=m
+CONFIG_PCCARD=y
+CONFIG_ELECTRA_CF=y
+CONFIG_VIRTUALIZATION=y
+CONFIG_KVM_BOOK3S_64=m
+CONFIG_KVM_BOOK3S_64_HV=m
+CONFIG_VHOST_NET=m
+CONFIG_KPROBES=y
+CONFIG_JUMP_LABEL=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_MODVERSIONS=y
+CONFIG_MODULE_SRCVERSION_ALL=y
+CONFIG_PARTITION_ADVANCED=y
+CONFIG_BINFMT_MISC=m
+CONFIG_MEMORY_HOTPLUG=y
+CONFIG_MEMORY_HOTREMOVE=y
+CONFIG_KSM=y
+CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_XFRM_USER=m
+CONFIG_NET_KEY=m
+CONFIG_INET=y
+CONFIG_IP_MULTICAST=y
+CONFIG_IP_PNP=y
+CONFIG_IP_PNP_DHCP=y
+CONFIG_IP_PNP_BOOTP=y
+CONFIG_NET_IPIP=y
+CONFIG_SYN_COOKIES=y
+CONFIG_INET_AH=m
+CONFIG_INET_ESP=m
+CONFIG_INET_IPCOMP=m
+CONFIG_IPV6=y
+CONFIG_NETFILTER=y
+# CONFIG_NETFILTER_ADVANCED is not set
+CONFIG_BRIDGE=m
+CONFIG_NET_SCHED=y
+CONFIG_NET_CLS_BPF=m
+CONFIG_NET_CLS_ACT=y
+CONFIG_NET_ACT_BPF=m
+CONFIG_BPF_JIT=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_BLK_DEV_FD=y
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_BLK_DEV_NBD=m
+CONFIG_BLK_DEV_RAM=y
+CONFIG_BLK_DEV_RAM_SIZE=65536
+CONFIG_VIRTIO_BLK=m
+CONFIG_BLK_DEV_SD=y
+CONFIG_CHR_DEV_ST=m
+CONFIG_BLK_DEV_SR=y
+CONFIG_CHR_DEV_SG=y
+CONFIG_SCSI_CONSTANTS=y
+CONFIG_SCSI_FC_ATTRS=y
+CONFIG_SCSI_CXGB3_ISCSI=m
+CONFIG_SCSI_CXGB4_ISCSI=m
+CONFIG_SCSI_BNX2_ISCSI=m
+CONFIG_BE2ISCSI=m
+CONFIG_SCSI_MPT2SAS=m
+CONFIG_SCSI_IBMVSCSI=y
+CONFIG_SCSI_IBMVFC=m
+CONFIG_SCSI_SYM53C8XX_2=m
+CONFIG_SCSI_SYM53C8XX_DMA_ADDRESSING_MODE=0
+CONFIG_SCSI_IPR=y
+CONFIG_SCSI_QLA_FC=m
+CONFIG_SCSI_QLA_ISCSI=m
+CONFIG_SCSI_LPFC=m
+CONFIG_SCSI_VIRTIO=m
+CONFIG_SCSI_DH=y
+CONFIG_SCSI_DH_RDAC=m
+CONFIG_SCSI_DH_ALUA=m
+CONFIG_ATA=y
+CONFIG_SATA_AHCI=y
+CONFIG_SATA_SIL24=y
+CONFIG_SATA_MV=y
+CONFIG_SATA_SVW=y
+CONFIG_PATA_AMD=y
+CONFIG_PATA_MACIO=y
+CONFIG_ATA_GENERIC=y
+CONFIG_MD=y
+CONFIG_BLK_DEV_MD=y
+CONFIG_MD_LINEAR=y
+CONFIG_MD_RAID0=y
+CONFIG_MD_RAID1=y
+CONFIG_MD_RAID10=m
+CONFIG_MD_RAID456=m
+CONFIG_MD_MULTIPATH=m
+CONFIG_MD_FAULTY=m
+CONFIG_BLK_DEV_DM=y
+CONFIG_DM_CRYPT=m
+CONFIG_DM_SNAPSHOT=m
+CONFIG_DM_MIRROR=m
+CONFIG_DM_ZERO=m
+CONFIG_DM_MULTIPATH=m
+CONFIG_DM_MULTIPATH_QL=m
+CONFIG_DM_MULTIPATH_ST=m
+CONFIG_DM_UEVENT=y
+CONFIG_ADB_PMU=y
+CONFIG_PMAC_SMU=y
+CONFIG_WINDFARM=y
+CONFIG_WINDFARM_PM81=y
+CONFIG_WINDFARM_PM91=y
+CONFIG_WINDFARM_PM112=y
+CONFIG_WINDFARM_PM121=y
+CONFIG_BONDING=m
+CONFIG_DUMMY=m
+CONFIG_NETCONSOLE=y
+CONFIG_TUN=m
+CONFIG_VIRTIO_NET=m
+CONFIG_VORTEX=m
+CONFIG_ACENIC=m
+CONFIG_ACENIC_OMIT_TIGON_I=y
+CONFIG_PCNET32=m
+CONFIG_TIGON3=y
+CONFIG_BNX2X=m
+CONFIG_CHELSIO_T1=m
+CONFIG_BE2NET=m
+CONFIG_IBMVETH=m
+CONFIG_EHEA=m
+CONFIG_IBMVNIC=m
+CONFIG_E100=y
+CONFIG_E1000=y
+CONFIG_E1000E=y
+CONFIG_IXGB=m
+CONFIG_IXGBE=m
+CONFIG_I40E=m
+CONFIG_MLX4_EN=m
+CONFIG_MYRI10GE=m
+CONFIG_S2IO=m
+CONFIG_PASEMI_MAC=y
+CONFIG_NETXEN_NIC=m
+CONFIG_SUNGEM=y
+CONFIG_GELIC_NET=m
+CONFIG_GELIC_WIRELESS=y
+CONFIG_SPIDER_NET=m
+CONFIG_BROADCOM_PHY=m
+CONFIG_MARVELL_PHY=y
+CONFIG_PPP=m
+CONFIG_PPP_BSDCOMP=m
+CONFIG_PPP_DEFLATE=m
+CONFIG_PPPOE=m
+CONFIG_PPP_ASYNC=m
+CONFIG_PPP_SYNC_TTY=m
+CONFIG_INPUT_EVDEV=m
+CONFIG_INPUT_MISC=y
+CONFIG_INPUT_PCSPKR=m
+# CONFIG_SERIO_SERPORT is not set
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_ICOM=m
+CONFIG_SERIAL_JSM=m
+CONFIG_HVC_CONSOLE=y
+CONFIG_HVC_RTAS=y
+CONFIG_HVCS=m
+CONFIG_VIRTIO_CONSOLE=m
+CONFIG_IBM_BSR=m
+CONFIG_RAW_DRIVER=y
+CONFIG_I2C_CHARDEV=y
+CONFIG_I2C_AMD8111=y
+CONFIG_I2C_PASEMI=y
+CONFIG_FB=y
+CONFIG_FIRMWARE_EDID=y
+CONFIG_FB_OF=y
+CONFIG_FB_MATROX=y
+CONFIG_FB_MATROX_MILLENIUM=y
+CONFIG_FB_MATROX_MYSTIQUE=y
+CONFIG_FB_MATROX_G=y
+CONFIG_FB_MATROX_I2C=m
+CONFIG_FB_MATROX_MAVEN=m
+CONFIG_FB_RADEON=y
+CONFIG_FB_IBM_GXT4500=y
+CONFIG_FB_PS3=m
+CONFIG_LCD_CLASS_DEVICE=y
+# CONFIG_VGA_CONSOLE is not set
+CONFIG_FRAMEBUFFER_CONSOLE=y
+CONFIG_LOGO=y
+CONFIG_SOUND=m
+CONFIG_SND=m
+CONFIG_SND_OSSEMUL=y
+CONFIG_SND_MIXER_OSS=m
+CONFIG_SND_PCM_OSS=m
+CONFIG_SND_SEQUENCER=m
+CONFIG_SND_SEQ_DUMMY=m
+CONFIG_SND_SEQUENCER_OSS=m
+CONFIG_SND_POWERMAC=m
+CONFIG_SND_AOA=m
+CONFIG_SND_AOA_FABRIC_LAYOUT=m
+CONFIG_SND_AOA_ONYX=m
+CONFIG_SND_AOA_TAS=m
+CONFIG_SND_AOA_TOONIE=m
+CONFIG_HID_GYRATION=y
+CONFIG_HID_PANTHERLORD=y
+CONFIG_HID_PETALYNX=y
+CONFIG_HID_SAMSUNG=y
+CONFIG_HID_SUNPLUS=y
+CONFIG_USB_HIDDEV=y
+CONFIG_USB=y
+CONFIG_USB_MON=m
+CONFIG_USB_EHCI_HCD=y
+# CONFIG_USB_EHCI_HCD_PPC_OF is not set
+CONFIG_USB_OHCI_HCD=y
+CONFIG_USB_STORAGE=m
+CONFIG_USB_APPLEDISPLAY=m
+CONFIG_NEW_LEDS=y
+CONFIG_LEDS_CLASS=m
+CONFIG_LEDS_POWERNV=m
+CONFIG_INFINIBAND=m
+CONFIG_INFINIBAND_USER_MAD=m
+CONFIG_INFINIBAND_USER_ACCESS=m
+CONFIG_INFINIBAND_MTHCA=m
+CONFIG_INFINIBAND_CXGB4=m
+CONFIG_MLX4_INFINIBAND=m
+CONFIG_INFINIBAND_IPOIB=m
+CONFIG_INFINIBAND_IPOIB_CM=y
+CONFIG_INFINIBAND_SRP=m
+CONFIG_INFINIBAND_ISER=m
+CONFIG_EDAC=y
+CONFIG_EDAC_PASEMI=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_DS1307=y
+CONFIG_VIRTIO_PCI=m
+CONFIG_VIRTIO_BALLOON=m
+CONFIG_LIBNVDIMM=y
+CONFIG_RAS=y
+CONFIG_EXT2_FS=y
+CONFIG_EXT2_FS_XATTR=y
+CONFIG_EXT2_FS_POSIX_ACL=y
+CONFIG_EXT2_FS_SECURITY=y
+CONFIG_EXT4_FS=y
+CONFIG_EXT4_FS_POSIX_ACL=y
+CONFIG_EXT4_FS_SECURITY=y
+CONFIG_REISERFS_FS=m
+CONFIG_REISERFS_FS_XATTR=y
+CONFIG_REISERFS_FS_POSIX_ACL=y
+CONFIG_REISERFS_FS_SECURITY=y
+CONFIG_JFS_FS=m
+CONFIG_JFS_POSIX_ACL=y
+CONFIG_JFS_SECURITY=y
+CONFIG_XFS_FS=y
+CONFIG_XFS_POSIX_ACL=y
+CONFIG_BTRFS_FS=y
+CONFIG_BTRFS_FS_POSIX_ACL=y
+CONFIG_NILFS2_FS=m
+CONFIG_FS_DAX=y
+CONFIG_AUTOFS4_FS=m
+CONFIG_FUSE_FS=m
+CONFIG_OVERLAY_FS=m
+CONFIG_ISO9660_FS=y
+CONFIG_UDF_FS=m
+CONFIG_MSDOS_FS=y
+CONFIG_VFAT_FS=m
+CONFIG_PROC_KCORE=y
+CONFIG_TMPFS=y
+CONFIG_TMPFS_POSIX_ACL=y
+CONFIG_HUGETLBFS=y
+CONFIG_HFS_FS=m
+CONFIG_HFSPLUS_FS=m
+CONFIG_CRAMFS=m
+CONFIG_SQUASHFS=m
+CONFIG_SQUASHFS_XATTR=y
+CONFIG_SQUASHFS_LZO=y
+CONFIG_SQUASHFS_XZ=y
+CONFIG_NFS_FS=y
+CONFIG_NFS_V3_ACL=y
+CONFIG_NFS_V4=y
+CONFIG_ROOT_NFS=y
+CONFIG_NFSD=m
+CONFIG_NFSD_V3_ACL=y
+CONFIG_NFSD_V4=y
+CONFIG_CIFS=m
+CONFIG_CIFS_XATTR=y
+CONFIG_CIFS_POSIX=y
+CONFIG_NLS_DEFAULT="utf8"
+CONFIG_NLS_CODEPAGE_437=y
+CONFIG_NLS_ASCII=y
+CONFIG_NLS_ISO8859_1=y
+CONFIG_NLS_UTF8=y
+CONFIG_CRYPTO_TEST=m
+CONFIG_CRYPTO_PCBC=m
+CONFIG_CRYPTO_HMAC=y
+CONFIG_CRYPTO_CRC32C_VPMSUM=m
+CONFIG_CRYPTO_MD5_PPC=m
+CONFIG_CRYPTO_MICHAEL_MIC=m
+CONFIG_CRYPTO_SHA1_PPC=m
+CONFIG_CRYPTO_SHA256=y
+CONFIG_CRYPTO_TGR192=m
+CONFIG_CRYPTO_WP512=m
+CONFIG_CRYPTO_ANUBIS=m
+CONFIG_CRYPTO_BLOWFISH=m
+CONFIG_CRYPTO_CAST6=m
+CONFIG_CRYPTO_KHAZAD=m
+CONFIG_CRYPTO_SALSA20=m
+CONFIG_CRYPTO_SERPENT=m
+CONFIG_CRYPTO_TEA=m
+CONFIG_CRYPTO_TWOFISH=m
+CONFIG_CRYPTO_LZO=m
+CONFIG_CRYPTO_DEV_NX=y
+CONFIG_CRYPTO_DEV_NX_ENCRYPT=m
+CONFIG_CRYPTO_DEV_VMX=y
+CONFIG_PRINTK_TIME=y
+CONFIG_PRINTK_CALLER=y
+CONFIG_MAGIC_SYSRQ=y
+CONFIG_DEBUG_KERNEL=y
+CONFIG_DEBUG_STACK_USAGE=y
+CONFIG_DEBUG_STACKOVERFLOW=y
+CONFIG_SOFTLOCKUP_DETECTOR=y
+CONFIG_HARDLOCKUP_DETECTOR=y
+CONFIG_DEBUG_MUTEXES=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_SCHED_TRACER=y
+CONFIG_STACK_TRACER=y
+CONFIG_BLK_DEV_IO_TRACE=y
+CONFIG_CODE_PATCHING_SELFTEST=y
+CONFIG_FTR_FIXUP_SELFTEST=n
+CONFIG_MSI_BITMAP_SELFTEST=y
+CONFIG_XMON=y
+CONFIG_BOOTX_TEXT=y
+CONFIG_LTO=y
+CONFIG_LTO_CLANG_THIN=y
+CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT=n
+CONFIG_USERFAULTFD=y
-- 
2.30.2

[PATCH kernel 3/3] powerpc/llvm/lto: Workaround conditional branches in FTR_SECTION_ELSE

[Alexey Kardashevskiy]

LTO invites ld/lld to optimize the output binary and this may affect
the FTP alternative section if alt branches use "bc" (Branch Conditional)
which only allows 16 bit offsets. This manifests in errors like:

ld.lld: error: InputSection too large for range extension thunk vmlinux.o:(__ftr_alt_97+0xF0)

This works around the problem by replacing "bc" and its alias(es) in
FTR_SECTION_ELSE with "b" which allows 26 bit offsets.

This catches the problem instructions in vmlinux.o before it LTO'ed:

$ objdump -d -M raw -j __ftr_alt_97 vmlinux.o | egrep '\S+\s*\<bc\>'
  30:   00 00 82 40     bc      4,eq,30 <__ftr_alt_97+0x30>
  f0:   00 00 82 40     bc      4,eq,f0 <__ftr_alt_97+0xf0>

The change in copyuser_64.S is needed even when building default
configs, the other two changes are needed if the kernel config grows.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/kernel/exceptions-64s.S | 6 +++++-
 arch/powerpc/lib/copyuser_64.S       | 3 ++-
 arch/powerpc/lib/memcpy_64.S         | 3 ++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 55caeee37c08..b8d9a2f5f3a5 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -476,9 +476,13 @@ DEFINE_FIXED_SYMBOL(\name\()_common_real, text)
 		.if IHSRR_IF_HVMODE
 		BEGIN_FTR_SECTION
 		bne	masked_Hinterrupt
+		b	4f
 		FTR_SECTION_ELSE
-		bne	masked_interrupt
+		nop
+		nop
 		ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
+		bne	masked_interrupt
+4:
 		.elseif IHSRR
 		bne	masked_Hinterrupt
 		.else
diff --git a/arch/powerpc/lib/copyuser_64.S b/arch/powerpc/lib/copyuser_64.S
index db8719a14846..d07f95eebc65 100644
--- a/arch/powerpc/lib/copyuser_64.S
+++ b/arch/powerpc/lib/copyuser_64.S
@@ -75,10 +75,11 @@ _GLOBAL(__copy_tofrom_user_base)
  * set is Power6.
  */
 test_feature = (SELFTEST_CASE == 1)
+	beq	.Ldst_aligned
 BEGIN_FTR_SECTION
 	nop
 FTR_SECTION_ELSE
-	bne	.Ldst_unaligned
+	b	.Ldst_unaligned
 ALT_FTR_SECTION_END(CPU_FTR_UNALIGNED_LD_STD | CPU_FTR_CP_USE_DCBTZ, \
 		    CPU_FTR_UNALIGNED_LD_STD)
 .Ldst_aligned:
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index 016c91e958d8..286c7e2d0883 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -50,10 +50,11 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY)
    At the time of writing the only CPU that has this combination of bits
    set is Power6. */
 test_feature = (SELFTEST_CASE == 1)
+	beq      .ldst_aligned
 BEGIN_FTR_SECTION
 	nop
 FTR_SECTION_ELSE
-	bne	.Ldst_unaligned
+	b	.Ldst_unaligned
 ALT_FTR_SECTION_END(CPU_FTR_UNALIGNED_LD_STD | CPU_FTR_CP_USE_DCBTZ, \
                     CPU_FTR_UNALIGNED_LD_STD)
 .Ldst_aligned:
-- 
2.30.2

[PATCH kernel 3/3] powerpc/llvm/lto: Workaround conditional branches in FTR_SECTION_ELSE

[Alexey Kardashevskiy]

LTO invites ld/lld to optimize the output binary and this may affect
the FTP alternative section if alt branches use "bc" (Branch Conditional)
which only allows 16 bit offsets. This manifests in errors like:

ld.lld: error: InputSection too large for range extension thunk vmlinux.o:(__ftr_alt_97+0xF0)

This works around the problem by replacing "bc" and its alias(es) in
FTR_SECTION_ELSE with "b" which allows 26 bit offsets.

This catches the problem instructions in vmlinux.o before it LTO'ed:

$ objdump -d -M raw -j __ftr_alt_97 vmlinux.o | egrep '\S+\s*\<bc\>'
  30:   00 00 82 40     bc      4,eq,30 <__ftr_alt_97+0x30>
  f0:   00 00 82 40     bc      4,eq,f0 <__ftr_alt_97+0xf0>

The change in copyuser_64.S is needed even when building default
configs, the other two changes are needed if the kernel config grows.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/kernel/exceptions-64s.S | 6 +++++-
 arch/powerpc/lib/copyuser_64.S       | 3 ++-
 arch/powerpc/lib/memcpy_64.S         | 3 ++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 55caeee37c08..b8d9a2f5f3a5 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -476,9 +476,13 @@ DEFINE_FIXED_SYMBOL(\name\()_common_real, text)
 		.if IHSRR_IF_HVMODE
 		BEGIN_FTR_SECTION
 		bne	masked_Hinterrupt
+		b	4f
 		FTR_SECTION_ELSE
-		bne	masked_interrupt
+		nop
+		nop
 		ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
+		bne	masked_interrupt
+4:
 		.elseif IHSRR
 		bne	masked_Hinterrupt
 		.else
diff --git a/arch/powerpc/lib/copyuser_64.S b/arch/powerpc/lib/copyuser_64.S
index db8719a14846..d07f95eebc65 100644
--- a/arch/powerpc/lib/copyuser_64.S
+++ b/arch/powerpc/lib/copyuser_64.S
@@ -75,10 +75,11 @@ _GLOBAL(__copy_tofrom_user_base)
  * set is Power6.
  */
 test_feature = (SELFTEST_CASE == 1)
+	beq	.Ldst_aligned
 BEGIN_FTR_SECTION
 	nop
 FTR_SECTION_ELSE
-	bne	.Ldst_unaligned
+	b	.Ldst_unaligned
 ALT_FTR_SECTION_END(CPU_FTR_UNALIGNED_LD_STD | CPU_FTR_CP_USE_DCBTZ, \
 		    CPU_FTR_UNALIGNED_LD_STD)
 .Ldst_aligned:
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index 016c91e958d8..286c7e2d0883 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -50,10 +50,11 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY)
    At the time of writing the only CPU that has this combination of bits
    set is Power6. */
 test_feature = (SELFTEST_CASE == 1)
+	beq      .ldst_aligned
 BEGIN_FTR_SECTION
 	nop
 FTR_SECTION_ELSE
-	bne	.Ldst_unaligned
+	b	.Ldst_unaligned
 ALT_FTR_SECTION_END(CPU_FTR_UNALIGNED_LD_STD | CPU_FTR_CP_USE_DCBTZ, \
                     CPU_FTR_UNALIGNED_LD_STD)
 .Ldst_aligned:
-- 
2.30.2

Re: [PATCH kernel 3/3] powerpc/llvm/lto: Workaround conditional branches in FTR_SECTION_ELSE

[Russell Currey]

On Fri, 2022-02-11 at 13:31 +1100, Alexey Kardashevskiy wrote:
> diff --git a/arch/powerpc/lib/memcpy_64.S
> b/arch/powerpc/lib/memcpy_64.S
> index 016c91e958d8..286c7e2d0883 100644
> --- a/arch/powerpc/lib/memcpy_64.S
> +++ b/arch/powerpc/lib/memcpy_64.S
> @@ -50,10 +50,11 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY)
>     At the time of writing the only CPU that has this combination of
> bits
>     set is Power6. */
>  test_feature = (SELFTEST_CASE == 1)
> +       beq      .ldst_aligned

Hey Alexey, typo here (should be .Ldst_aligned) that breaks the build
for BE.

>  BEGIN_FTR_SECTION
>         nop

Re: [PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Naveen N. Rao]

Alexey Kardashevskiy wrote:
> 
> Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
> depends on it being disabled. In order to avoid disabling way too many
> options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
> FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.

<snip>

> +CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT=n

I don't think that will work since we have no other ways of generating 
mcount locations on powerpc. And since we decided to only support 
DYNAMIC_FTRACE, I guess we will need to disable FUNCTION_TRACER to get 
this working, for now.

I am looking into ways to get ftrace working in this scenario.


- Naveen

Re: [PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Naveen N. Rao]

Alexey Kardashevskiy wrote:
> 
> Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
> depends on it being disabled. In order to avoid disabling way too many
> options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
> FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.

<snip>

> +CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT=n

I don't think that will work since we have no other ways of generating 
mcount locations on powerpc. And since we decided to only support 
DYNAMIC_FTRACE, I guess we will need to disable FUNCTION_TRACER to get 
this working, for now.

I am looking into ways to get ftrace working in this scenario.


- Naveen

Re: [PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Nick Desaulniers]

On Thu, Feb 10, 2022 at 6:31 PM Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>
> The config is a copy of ppc64_defconfig with a few tweaks. This could be
> a smaller config to merge into ppc64_defconfig but unfortunately
> merger does not allow disabling already enabled options.

Cool series!

>
> This is a command line to compile the kernel using the upstream llvm:
>
> make -j64 O=/home/aik/pbuild/kernels-llvm/ \
>  "KCFLAGS=-Wmissing-braces -Wno-array-bounds" \
>  ARCH=powerpc LLVM_IAS=1 ppc64le_lto_defconfig CC=clang LLVM=1

That command line invocation is kind of a mess, and many things
shouldn't be necessary.

O= is just noise; if folks are doing in tree builds then that doesn't
add anything meaningful.
KCFLAGS= why? I know -Warray-bounds is being worked on actively, but
do we have instances of -Wmissing-braces at the moment? Let's get
those fixed up.
LLVM_IAS=1 is implied by LLVM=1.
CC=clang is implied by LLVM=1

why add a new config? I think it would be simpler to just show command
line invocations of `./scripts/config -e` and `make`. No new config
required.

>
> Forces CONFIG_BTRFS_FS=y to make CONFIG_ZSTD_COMPRESS=y to fix:
> ld.lld: error: linking module flags 'Code Model': IDs have conflicting values in 'lib/built-in.a(entropy_common.o at 5332)' and 'ld-temp.o'
>
> because modules are linked with -mcmodel=large but the kernel uses -mcmodel=medium

Please file a bug about this.
https://github.com/ClangBuiltLinux/linux/issues

>
> Enables CONFIG_USERFAULTFD=y as otherwise vm_userfaultfd_ctx becomes
> 0 bytes long and clang sanitizer crashes as
> https://bugs.llvm.org/show_bug.cgi?id=500375

The above hyperlink doesn't work for me. Upstream llvm just moved from
bugzilla to github issue tracker.

https://github.com/llvm/llvm-project/issues

>
> Disables CONFIG_FTR_FIXUP_SELFTEST as it uses FTR_SECTION_ELSE with
> conditional branches. There are other places like this and the following
> patches address that.
>
> Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
> depends on it being disabled. In order to avoid disabling way too many
> options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
> FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.
>
> Note that even with this config there is a good chance that LTO
> is going to fail linking vmlinux because of the "bc" problem.

I think rather than adding a new config with LTO enabled and a few
things turned off, it would be better to not allow LTO to be
selectable if those things are turned on, until the combination of the
two are fixed.

-- 
Thanks,
~Nick Desaulniers

Re: [PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Nick Desaulniers]

On Thu, Feb 10, 2022 at 6:31 PM Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>
> The config is a copy of ppc64_defconfig with a few tweaks. This could be
> a smaller config to merge into ppc64_defconfig but unfortunately
> merger does not allow disabling already enabled options.

Cool series!

>
> This is a command line to compile the kernel using the upstream llvm:
>
> make -j64 O=/home/aik/pbuild/kernels-llvm/ \
>  "KCFLAGS=-Wmissing-braces -Wno-array-bounds" \
>  ARCH=powerpc LLVM_IAS=1 ppc64le_lto_defconfig CC=clang LLVM=1

That command line invocation is kind of a mess, and many things
shouldn't be necessary.

O= is just noise; if folks are doing in tree builds then that doesn't
add anything meaningful.
KCFLAGS= why? I know -Warray-bounds is being worked on actively, but
do we have instances of -Wmissing-braces at the moment? Let's get
those fixed up.
LLVM_IAS=1 is implied by LLVM=1.
CC=clang is implied by LLVM=1

why add a new config? I think it would be simpler to just show command
line invocations of `./scripts/config -e` and `make`. No new config
required.

>
> Forces CONFIG_BTRFS_FS=y to make CONFIG_ZSTD_COMPRESS=y to fix:
> ld.lld: error: linking module flags 'Code Model': IDs have conflicting values in 'lib/built-in.a(entropy_common.o at 5332)' and 'ld-temp.o'
>
> because modules are linked with -mcmodel=large but the kernel uses -mcmodel=medium

Please file a bug about this.
https://github.com/ClangBuiltLinux/linux/issues

>
> Enables CONFIG_USERFAULTFD=y as otherwise vm_userfaultfd_ctx becomes
> 0 bytes long and clang sanitizer crashes as
> https://bugs.llvm.org/show_bug.cgi?id=500375

The above hyperlink doesn't work for me. Upstream llvm just moved from
bugzilla to github issue tracker.

https://github.com/llvm/llvm-project/issues

>
> Disables CONFIG_FTR_FIXUP_SELFTEST as it uses FTR_SECTION_ELSE with
> conditional branches. There are other places like this and the following
> patches address that.
>
> Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
> depends on it being disabled. In order to avoid disabling way too many
> options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
> FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.
>
> Note that even with this config there is a good chance that LTO
> is going to fail linking vmlinux because of the "bc" problem.

I think rather than adding a new config with LTO enabled and a few
things turned off, it would be better to not allow LTO to be
selectable if those things are turned on, until the combination of the
two are fixed.

-- 
Thanks,
~Nick Desaulniers

Re: [PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Alexey Kardashevskiy]

On 2/12/22 11:05, Nick Desaulniers wrote:
> On Thu, Feb 10, 2022 at 6:31 PM Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>>
>> The config is a copy of ppc64_defconfig with a few tweaks. This could be
>> a smaller config to merge into ppc64_defconfig but unfortunately
>> merger does not allow disabling already enabled options.
> 
> Cool series!
> 
>>
>> This is a command line to compile the kernel using the upstream llvm:
>>
>> make -j64 O=/home/aik/pbuild/kernels-llvm/ \
>>   "KCFLAGS=-Wmissing-braces -Wno-array-bounds" \
>>   ARCH=powerpc LLVM_IAS=1 ppc64le_lto_defconfig CC=clang LLVM=1
> 
> That command line invocation is kind of a mess, and many things
> shouldn't be necessary.
> 
> O= is just noise; if folks are doing in tree builds then that doesn't
> add anything meaningful.
> KCFLAGS= why? I know -Warray-bounds is being worked on actively, but
> do we have instances of -Wmissing-braces at the moment? Let's get
> those fixed up.
> LLVM_IAS=1 is implied by LLVM=1.
> CC=clang is implied by LLVM=1
> 
> why add a new config? I think it would be simpler to just show command
> line invocations of `./scripts/config -e` and `make`. No new config
> required.



I should have added "RFC" in this one as the purpose of the patch is to 
show what works right now and not for actual submission.


>>
>> Forces CONFIG_BTRFS_FS=y to make CONFIG_ZSTD_COMPRESS=y to fix:
>> ld.lld: error: linking module flags 'Code Model': IDs have conflicting values in 'lib/built-in.a(entropy_common.o at 5332)' and 'ld-temp.o'
>>
>> because modules are linked with -mcmodel=large but the kernel uses -mcmodel=medium
> 
> Please file a bug about this.
> https://github.com/ClangBuiltLinux/linux/issues
> 
>>
>> Enables CONFIG_USERFAULTFD=y as otherwise vm_userfaultfd_ctx becomes
>> 0 bytes long and clang sanitizer crashes as
>> https://bugs.llvm.org/show_bug.cgi?id=500375

> 
> The above hyperlink doesn't work for me. Upstream llvm just moved from
> bugzilla to github issue tracker.


aah this is the correct one:
https://bugs.llvm.org/show_bug.cgi?id=50037

> 
> https://github.com/llvm/llvm-project/issues

oh ok.

>>
>> Disables CONFIG_FTR_FIXUP_SELFTEST as it uses FTR_SECTION_ELSE with
>> conditional branches. There are other places like this and the following
>> patches address that.
>>
>> Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
>> depends on it being disabled. In order to avoid disabling way too many
>> options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
>> FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.
>>
>> Note that even with this config there is a good chance that LTO
>> is going to fail linking vmlinux because of the "bc" problem.
> 
> I think rather than adding a new config with LTO enabled and a few
> things turned off, it would be better to not allow LTO to be
> selectable if those things are turned on, until the combination of the
> two are fixed.

Well, if I want people to try this thing, I kinda need to provide an 
easy way to allow LTO. The new config seemed the easiest (== the 
shortest) :)

Re: [PATCH kernel 2/3] powerpc/llvm: Sample config for LLVM LTO

[Alexey Kardashevskiy]

On 2/12/22 11:05, Nick Desaulniers wrote:
> On Thu, Feb 10, 2022 at 6:31 PM Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
>>
>> The config is a copy of ppc64_defconfig with a few tweaks. This could be
>> a smaller config to merge into ppc64_defconfig but unfortunately
>> merger does not allow disabling already enabled options.
> 
> Cool series!
> 
>>
>> This is a command line to compile the kernel using the upstream llvm:
>>
>> make -j64 O=/home/aik/pbuild/kernels-llvm/ \
>>   "KCFLAGS=-Wmissing-braces -Wno-array-bounds" \
>>   ARCH=powerpc LLVM_IAS=1 ppc64le_lto_defconfig CC=clang LLVM=1
> 
> That command line invocation is kind of a mess, and many things
> shouldn't be necessary.
> 
> O= is just noise; if folks are doing in tree builds then that doesn't
> add anything meaningful.
> KCFLAGS= why? I know -Warray-bounds is being worked on actively, but
> do we have instances of -Wmissing-braces at the moment? Let's get
> those fixed up.
> LLVM_IAS=1 is implied by LLVM=1.
> CC=clang is implied by LLVM=1
> 
> why add a new config? I think it would be simpler to just show command
> line invocations of `./scripts/config -e` and `make`. No new config
> required.



I should have added "RFC" in this one as the purpose of the patch is to 
show what works right now and not for actual submission.


>>
>> Forces CONFIG_BTRFS_FS=y to make CONFIG_ZSTD_COMPRESS=y to fix:
>> ld.lld: error: linking module flags 'Code Model': IDs have conflicting values in 'lib/built-in.a(entropy_common.o at 5332)' and 'ld-temp.o'
>>
>> because modules are linked with -mcmodel=large but the kernel uses -mcmodel=medium
> 
> Please file a bug about this.
> https://github.com/ClangBuiltLinux/linux/issues
> 
>>
>> Enables CONFIG_USERFAULTFD=y as otherwise vm_userfaultfd_ctx becomes
>> 0 bytes long and clang sanitizer crashes as
>> https://bugs.llvm.org/show_bug.cgi?id=500375

> 
> The above hyperlink doesn't work for me. Upstream llvm just moved from
> bugzilla to github issue tracker.


aah this is the correct one:
https://bugs.llvm.org/show_bug.cgi?id=50037

> 
> https://github.com/llvm/llvm-project/issues

oh ok.

>>
>> Disables CONFIG_FTR_FIXUP_SELFTEST as it uses FTR_SECTION_ELSE with
>> conditional branches. There are other places like this and the following
>> patches address that.
>>
>> Disables CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT as CONFIG_HAS_LTO_CLANG
>> depends on it being disabled. In order to avoid disabling way too many
>> options (like DYNAMIC_FTRACE/FUNCTION_TRACER), this converts
>> FTRACE_MCOUNT_USE_RECORDMCOUNT from def_bool to bool.
>>
>> Note that even with this config there is a good chance that LTO
>> is going to fail linking vmlinux because of the "bc" problem.
> 
> I think rather than adding a new config with LTO enabled and a few
> things turned off, it would be better to not allow LTO to be
> selectable if those things are turned on, until the combination of the
> two are fixed.

Well, if I want people to try this thing, I kinda need to provide an 
easy way to allow LTO. The new config seemed the easiest (== the 
shortest) :)