Re: [PATCH V9 00/20] riscv: compat: Add COMPAT Kbuild skeletal support

Palmer Dabbelt
2022-03-22T21:00:49Z

On Tue, 22 Mar 2022 07:39:43 PDT (-0700), guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> Currently, most 64-bit architectures (x86, parisc, powerpc, arm64,
> s390, mips, sparc) have supported COMPAT mode. But they all have
> history issues and can't use standard linux unistd.h. RISC-V would
> be first standard __SYSCALL_COMPAT user of include/uapi/asm-generic
> /unistd.h.
>
> The patchset are based on v5.17-rc8, you can compare rv64-compat
> v.s. rv32-native in qemu with following steps:
>
> - Prepare rv32 rootfs & fw_jump.bin by buildroot.org
> $ git clone git://git.busybox.net/buildroot
> $ cd buildroot
> $ make qemu_riscv32_virt_defconfig O=qemu_riscv32_virt_defconfig
> $ make -C qemu_riscv32_virt_defconfig
> $ make qemu_riscv64_virt_defconfig O=qemu_riscv64_virt_defconfig
> $ make -C qemu_riscv64_virt_defconfig
> (Got fw_jump.bin & rootfs.ext2 in qemu_riscvXX_virt_defconfig/images)
>
> - Prepare Linux rv32 & rv64 Image
> $ git clone git@github.com:c-sky/csky-linux.git -b riscv_compat_v8 linux
> $ cd linux
> $ echo "CONFIG_STRICT_KERNEL_RWX=n" >> arch/riscv/configs/defconfig
> $ echo "CONFIG_STRICT_MODULE_RWX=n" >> arch/riscv/configs/defconfig
> $ make ARCH=riscv CROSS_COMPILE=riscv32-buildroot-linux-gnu- O=../build-rv32/ rv32_defconfig
> $ make ARCH=riscv CROSS_COMPILE=riscv32-buildroot-linux-gnu- O=../build-rv32/ Image
> $ make ARCH=riscv CROSS_COMPILE=riscv64-buildroot-linux-gnu- O=../build-rv64/ defconfig
> $ make ARCH=riscv CROSS_COMPILE=riscv64-buildroot-linux-gnu- O=../build-rv64/ Image
>
> - Prepare Qemu:
> $ git clone https://gitlab.com/qemu-project/qemu.git -b master linux
> $ cd qemu
> $ ./configure --target-list="riscv64-softmmu riscv32-softmmu"
> $ make
>
> Now let's compare rv64-compat with rv32-native memory footprint with almost the same
> defconfig, rootfs, opensbi in one qemu.
>
> - Run rv64 with rv32 rootfs in compat mode:
> $ ./build/qemu-system-riscv64 -cpu rv64 -M virt -m 64m -nographic -bios qemu_riscv64_virt_defconfig/images/fw_jump.bin -kernel build-rv64/Image -drive file qemu_riscv32_virt_defconfig/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -append "rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi" -netdev user,id=net0 -device virtio-net-device,netdev=net0
>
> QEMU emulator version 6.2.50 (v6.2.0-29-g196d7182c8)
> OpenSBI v0.9
> [ 0.000000] Linux version 5.16.0-rc6-00017-g750f87086bdd-dirty (guoren@guoren-Z87-HD3) (riscv64-unknown-linux-gnu-gcc (GCC) 10.2.0, GNU ld (GNU Binutils) 2.37) #96 SMP Tue Dec 28 21:01:55 CST 2021
> [ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
> [ 0.000000] Machine model: riscv-virtio,qemu
> [ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
> [ 0.000000] printk: bootconsole [sbi0] enabled
> [ 0.000000] efi: UEFI not found.
> [ 0.000000] Zone ranges:
> [ 0.000000] DMA32 [mem 0x0000000080200000-0x0000000083ffffff]
> [ 0.000000] Normal empty
> [ 0.000000] Movable zone start for each node
> [ 0.000000] Early memory node ranges
> [ 0.000000] node 0: [mem 0x0000000080200000-0x0000000083ffffff]
> [ 0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x0000000083ffffff]
> [ 0.000000] SBI specification v0.2 detected
> [ 0.000000] SBI implementation ID=0x1 Version=0x9
> [ 0.000000] SBI TIME extension detected
> [ 0.000000] SBI IPI extension detected
> [ 0.000000] SBI RFENCE extension detected
> [ 0.000000] SBI v0.2 HSM extension detected
> [ 0.000000] riscv: ISA extensions acdfhimsu
> [ 0.000000] riscv: ELF capabilities acdfim
> [ 0.000000] percpu: Embedded 17 pages/cpu s30696 r8192 d30744 u69632
> [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 15655
> [ 0.000000] Kernel command line: rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi
> [ 0.000000] Dentry cache hash table entries: 8192 (order: 4, 65536 bytes, linear)
> [ 0.000000] Inode-cache hash table entries: 4096 (order: 3, 32768 bytes, linear)
> [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
> [ 0.000000] Virtual kernel memory layout:
> [ 0.000000] fixmap : 0xffffffcefee00000 - 0xffffffceff000000 (2048 kB)
> [ 0.000000] pci io : 0xffffffceff000000 - 0xffffffcf00000000 ( 16 MB)
> [ 0.000000] vmemmap : 0xffffffcf00000000 - 0xffffffcfffffffff (4095 MB)
> [ 0.000000] vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff (65535 MB)
> [ 0.000000] lowmem : 0xffffffe000000000 - 0xffffffe003e00000 ( 62 MB)
> [ 0.000000] kernel : 0xffffffff80000000 - 0xffffffffffffffff (2047 MB)
> [ 0.000000] Memory: 52788K/63488K available (6184K kernel code, 888K rwdata, 1917K rodata, 294K init, 297K bss, 10700K reserved, 0K cma-reserved)
> [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
> [ 0.000000] rcu: Hierarchical RCU implementation.
> [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
> [ 0.000000] rcu: RCU debug extended QS entry/exit.
> [ 0.000000] Tracing variant of Tasks RCU enabled.
> [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
> [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
> [ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
> [ 0.000000] riscv-intc: 64 local interrupts mapped
> [ 0.000000] plic: plic@c000000: mapped 53 interrupts with 1 handlers for 2 contexts.
> ...
> Welcome to Buildroot
> buildroot login: root
> # cat /proc/cpuinfo
> processor : 0
> hart : 0
> isa : rv64imafdcsuh
> mmu : sv48
>
> # file /bin/busybox
> /bin/busybox: setuid ELF 32-bit LSB shared object, UCB RISC-V, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-riscv32-ilp32d.so.1, for GNU/Linux 5.15.0, stripped
> # ca[ 78.386630] random: fast init done
> # cat /proc/meminfo
> MemTotal: 53076 kB
> MemFree: 40264 kB
> MemAvailable: 40244 kB
> Buffers: 236 kB
> Cached: 1560 kB
> SwapCached: 0 kB
> Active: 1700 kB
> Inactive: 516 kB
> Active(anon): 40 kB
> Inactive(anon): 424 kB
> Active(file): 1660 kB
> Inactive(file): 92 kB
> Unevictable: 0 kB
> Mlocked: 0 kB
> SwapTotal: 0 kB
> SwapFree: 0 kB
> Dirty: 0 kB
> Writeback: 0 kB
> AnonPages: 444 kB
> Mapped: 1188 kB
> Shmem: 44 kB
> KReclaimable: 952 kB
> Slab: 5744 kB
> SReclaimable: 952 kB
> SUnreclaim: 4792 kB
> KernelStack: 624 kB
> PageTables: 156 kB
> NFS_Unstable: 0 kB
> Bounce: 0 kB
> WritebackTmp: 0 kB
> CommitLimit: 26536 kB
> Committed_AS: 1748 kB
> VmallocTotal: 67108863 kB
> VmallocUsed: 652 kB
> VmallocChunk: 0 kB
> Percpu: 80 kB
> #
>
> - Run rv32 with rv32 rootfs:
> $ ./build/qemu-system-riscv32 -cpu rv32 -M virt -m 64m -nographic -bios qemu_riscv32_virt_defconfig/images/fw_jump.bin -kernel build-rv32/Image -drive file qemu_riscv32_virt_defconfig/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -append "rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi" -netdev user,id=net0 -device virtio-net-device,netdev=net0
>
> QEMU emulator version 6.2.50 (v6.2.0-29-g196d7182c8)
> OpenSBI v0.9
> [ 0.000000] Linux version 5.16.0-rc6-00017-g750f87086bdd-dirty (guoren@guoren-Z87-HD3) (riscv32-buildroot-linux-gnu-gcc.br_real (Buildroot 2021.11-201-g7600ca7960-dirty) 10.3.0, GNU ld (GNU Binutils) 2.36.1) #7 SMP Tue Dec 28 21:02:21 CST 2021
> [ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80400000
> [ 0.000000] Machine model: riscv-virtio,qemu
> [ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
> [ 0.000000] printk: bootconsole [sbi0] enabled
> [ 0.000000] efi: UEFI not found.
> [ 0.000000] Zone ranges:
> [ 0.000000] Normal [mem 0x0000000080400000-0x0000000083ffffff]
> [ 0.000000] Movable zone start for each node
> [ 0.000000] Early memory node ranges
> [ 0.000000] node 0: [mem 0x0000000080400000-0x0000000083ffffff]
> [ 0.000000] Initmem setup node 0 [mem 0x0000000080400000-0x0000000083ffffff]
> [ 0.000000] SBI specification v0.2 detected
> [ 0.000000] SBI implementation ID=0x1 Version=0x9
> [ 0.000000] SBI TIME extension detected
> [ 0.000000] SBI IPI extension detected
> [ 0.000000] SBI RFENCE extension detected
> [ 0.000000] SBI v0.2 HSM extension detected
> [ 0.000000] riscv: ISA extensions acdfhimsu
> [ 0.000000] riscv: ELF capabilities acdfim
> [ 0.000000] percpu: Embedded 12 pages/cpu s16600 r8192 d24360 u49152
> [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 15240
> [ 0.000000] Kernel command line: rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi
> [ 0.000000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes, linear)
> [ 0.000000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes, linear)
> [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
> [ 0.000000] Virtual kernel memory layout:
> [ 0.000000] fixmap : 0x9dc00000 - 0x9e000000 (4096 kB)
> [ 0.000000] pci io : 0x9e000000 - 0x9f000000 ( 16 MB)
> [ 0.000000] vmemmap : 0x9f000000 - 0x9fffffff ( 15 MB)
> [ 0.000000] vmalloc : 0xa0000000 - 0xbfffffff ( 511 MB)
> [ 0.000000] lowmem : 0xc0000000 - 0xc3c00000 ( 60 MB)
> [ 0.000000] Memory: 51924K/61440K available (6117K kernel code, 695K rwdata, 1594K rodata, 255K init, 241K bss, 9516K reserved, 0K cma-reserved)
> [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
> [ 0.000000] rcu: Hierarchical RCU implementation.
> [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
> [ 0.000000] rcu: RCU debug extended QS entry/exit.
> [ 0.000000] Tracing variant of Tasks RCU enabled.
> [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
> [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
> [ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
> [ 0.000000] riscv-intc: 32 local interrupts mapped
> [ 0.000000] plic: plic@c000000: mapped 53 interrupts with 1 handlers for 2 contexts.
> ...
> Welcome to Buildroot
> buildroot login: root
> # cat /proc/cpuinfo
> processor : 0
> hart : 0
> isa : rv32imafdcsuh
> mmu : sv32
>
> # file /bin/busybox
> /bin/busybox: setuid ELF 32-bit LSB shared object, UCB RISC-V, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-riscv32-ilp32d.so.1, for GNU/Linux 5.15.0, stripped
> [ 79.320589] random: fast init done
> # cat /proc/meminfo
> MemTotal: 52176 kB
> MemFree: 41012 kB
> MemAvailable: 42176 kB
> Buffers: 644 kB
> Cached: 2724 kB
> SwapCached: 0 kB
> Active: 3128 kB
> Inactive: 752 kB
> Active(anon): 40 kB
> Inactive(anon): 516 kB
> Active(file): 3088 kB
> Inactive(file): 236 kB
> Unevictable: 0 kB
> Mlocked: 0 kB
> SwapTotal: 0 kB
> SwapFree: 0 kB
> Dirty: 4 kB
> Writeback: 0 kB
> AnonPages: 556 kB
> Mapped: 2172 kB
> Shmem: 44 kB
> KReclaimable: 656 kB
> Slab: 3684 kB
> SReclaimable: 656 kB
> SUnreclaim: 3028 kB
> KernelStack: 312 kB
> PageTables: 88 kB
> NFS_Unstable: 0 kB
> Bounce: 0 kB
> WritebackTmp: 0 kB
> CommitLimit: 26088 kB
> Committed_AS: 2088 kB
> VmallocTotal: 524287 kB
> VmallocUsed: 12 kB
> VmallocChunk: 0 kB
> Percpu: 60 kB
> #
>
> Some conclusions:
> - kernel statics:
> 64: Memory: 52788K/63488K available (6184K kernel code, 888K rwdata, 1917K rodata, 294K init, 297K bss, 10700K reserved)
> 32: Memory: 51924K/61440K available (6117K kernel code, 695K rwdata, 1594K rodata, 255K init, 241K bss, 9516K reserved)
> rv32 better than rv64: 1% 22% 17% 13% 19% 11%
> The code size is very similar, but data size rv32 would be better.
>
> - rv32 kernel runtime KernelStack, Slab... are smaller,
> rv64: MemTotal: 53076 kB, MemFree: 40264 kB
> rv32: MemTotal: 52176 + 2048 kB, MemFree: 41012 + 2048 kB
> rv32 better than rv64: 2% 6%
>
> (Because opensbi problem, we could add another 2MB for rv32.)
> Overall in 64MB memory situation, rv64-compat is 6% worse than rv32-native
> at memory footprint. If the userspace memory usage increases, I think
> the gap will be further reduced.
>
> Changes in v9:
> - Fixup rv32 call rv64 segment fault
> - Ready for 5.18

Thanks. I'd also seen some arm64 autobuilder failures, not sure if
those got fixed as I don't see anything specificlly listed in here
(sorry if I just missed it).

I've gone ahead and put this on palmer/riscv-compat, I'm going to let it
sit at least overnight before putting it on for-next proper. It's a
big one and the autobuilders seem to find stuff over there, I don't want
to break any of the other ports. IIRC you were getting CC'd on the
build failures I was seeing.

If it's clean I'll merge it into for-next propely. It's passing my
staging merge tests, but I don't yet have anything specifically for
compat -- at least it's not causing any regressions, though.

>
> Changes in v8:
> - Enhanced elf_check_arch with EI_CLASS
> - Fixup SR_UXL doesn't exist in CONFIG_32BIT
> - Add Tested-by with Heiko
> - Update qemu compile tips with upstream repo
>
> Changes in v7:
> - Re-construct compat_vdso/Makefile
> - Fixup disable COMPAT compile error by csr.h's macro.
> - Optimize coding convention for lo/hi in compat.h
>
> Changes in v6:
> - Rebase on linux-5.17-rc5
> - Optimize hw capability check for elf
> - Optimize comment in thread_info.h
> - Optimize start_thread with SR_UXL setting
> - Optimize vdso.c with direct panic
>
> Changes in v5:
> - Rebase on linux-5.17-rc2
> - Include consolidate the fcntl patches by Christoph Hellwig
> - Remove F_GETLK64/F_SETLK64/F_SETLKW64 from asm/compat.h
> - Change COMPAT_RLIM_INFINITY from 0x7fffffff to 0xffffffff
> - Bring back "Add hw-cap detect in setup_arch patch" in v1
>
> Changes in v4:
> - Rebase on linux-5.17-rc1
> - Optimize compat_sys_call_table implementation with Arnd's advice
> - Add reviewed-by for Arnd. Thx :)
> - Remove FIXME comment in elf.h
> - Optimize Cleanup duplicate definitions in compat.h with Arnd's advice
>
> Changes in v3:
> - Rebase on newest master (pre linux-5.17-rc1)
> - Using newest qemu version v7 for test
> - Remove fcntl common modification
> - Fixup SET_PERSONALITY in elf.h by Arnd
> - Fixup KVM Kconfig
> - Update Acked-by & Reviewed-by
>
> Changes in v2:
> - Add __ARCH_WANT_COMPAT_STAT suggested
> - Cleanup fcntl compatduplicate definitions
> - Cleanup compat.h
> - Move rv32_defconfig into Makefile
> - Fixup rv64 rootfs boot failed, remove hw_compat_mode_detect
> - Move SYSVIPC_COMPAT into init/Kconfig
> - Simplify compat_elf_check
>
> Christoph Hellwig (3):
> uapi: simplify __ARCH_FLOCK{,64}_PAD a little
> uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h
> compat: consolidate the compat_flock{,64} definition
>
> Guo Ren (17):
> kconfig: Add SYSVIPC_COMPAT for all architectures
> fs: stat: compat: Add __ARCH_WANT_COMPAT_STAT
> asm-generic: compat: Cleanup duplicate definitions
> syscalls: compat: Fix the missing part for __SYSCALL_COMPAT
> riscv: Fixup difference with defconfig
> riscv: compat: Add basic compat data type implementation
> riscv: compat: Re-implement TASK_SIZE for COMPAT_32BIT
> riscv: compat: syscall: Add compat_sys_call_table implementation
> riscv: compat: syscall: Add entry.S implementation
> riscv: compat: process: Add UXL_32 support in start_thread
> riscv: compat: Add elf.h implementation
> riscv: compat: Add hw capability check for elf
> riscv: compat: vdso: Add COMPAT_VDSO base code implementation
> riscv: compat: vdso: Add setup additional pages implementation
> riscv: compat: signal: Add rt_frame implementation
> riscv: compat: ptrace: Add compat_arch_ptrace implement
> riscv: compat: Add COMPAT Kbuild skeletal support
>
> arch/arm64/Kconfig | 4 -
> arch/arm64/include/asm/compat.h | 91 +------
> arch/arm64/include/asm/unistd.h | 1 +
> arch/mips/Kconfig | 5 -
> arch/mips/include/asm/compat.h | 41 +--
> arch/mips/include/asm/unistd.h | 2 +
> arch/mips/include/uapi/asm/fcntl.h | 30 +--
> arch/parisc/Kconfig | 4 -
> arch/parisc/include/asm/compat.h | 45 +---
> arch/parisc/include/asm/unistd.h | 1 +
> arch/powerpc/Kconfig | 5 -
> arch/powerpc/include/asm/compat.h | 50 +---
> arch/powerpc/include/asm/unistd.h | 1 +
> arch/riscv/Kconfig | 19 ++
> arch/riscv/Makefile | 9 +
> arch/riscv/configs/rv32_defconfig | 135 ----------
> arch/riscv/include/asm/compat.h | 129 ++++++++++
> arch/riscv/include/asm/csr.h | 7 +
> arch/riscv/include/asm/elf.h | 50 +++-
> arch/riscv/include/asm/mmu.h | 1 +
> arch/riscv/include/asm/pgtable.h | 13 +-
> arch/riscv/include/asm/processor.h | 6 +-
> arch/riscv/include/asm/syscall.h | 1 +
> arch/riscv/include/asm/thread_info.h | 1 +
> arch/riscv/include/asm/unistd.h | 11 +
> arch/riscv/include/asm/vdso.h | 9 +
> arch/riscv/include/uapi/asm/unistd.h | 2 +-
> arch/riscv/kernel/Makefile | 3 +
> arch/riscv/kernel/compat_signal.c | 243 ++++++++++++++++++
> arch/riscv/kernel/compat_syscall_table.c | 19 ++
> arch/riscv/kernel/compat_vdso/.gitignore | 2 +
> arch/riscv/kernel/compat_vdso/Makefile | 78 ++++++
> arch/riscv/kernel/compat_vdso/compat_vdso.S | 8 +
> .../kernel/compat_vdso/compat_vdso.lds.S | 3 +
> arch/riscv/kernel/compat_vdso/flush_icache.S | 3 +
> .../compat_vdso/gen_compat_vdso_offsets.sh | 5 +
> arch/riscv/kernel/compat_vdso/getcpu.S | 3 +
> arch/riscv/kernel/compat_vdso/note.S | 3 +
> arch/riscv/kernel/compat_vdso/rt_sigreturn.S | 3 +
> arch/riscv/kernel/entry.S | 18 +-
> arch/riscv/kernel/process.c | 37 +++
> arch/riscv/kernel/ptrace.c | 87 ++++++-
> arch/riscv/kernel/signal.c | 13 +-
> arch/riscv/kernel/sys_riscv.c | 6 +-
> arch/riscv/kernel/vdso.c | 105 +++++---
> arch/riscv/kernel/vdso/vdso.S | 6 +-
> arch/s390/Kconfig | 3 -
> arch/s390/include/asm/compat.h | 99 +------
> arch/s390/include/asm/unistd.h | 1 +
> arch/sparc/Kconfig | 5 -
> arch/sparc/include/asm/compat.h | 61 ++---
> arch/sparc/include/asm/unistd.h | 1 +
> arch/x86/Kconfig | 4 -
> arch/x86/include/asm/compat.h | 104 ++------
> arch/x86/include/asm/unistd.h | 1 +
> fs/open.c | 24 ++
> fs/read_write.c | 16 ++
> fs/stat.c | 2 +-
> fs/sync.c | 9 +
> include/asm-generic/compat.h | 113 ++++++++
> include/linux/compat.h | 68 +++++
> include/uapi/asm-generic/fcntl.h | 23 +-
> include/uapi/asm-generic/unistd.h | 4 +-
> init/Kconfig | 4 +
> mm/fadvise.c | 11 +
> mm/readahead.c | 7 +
> tools/include/uapi/asm-generic/fcntl.h | 21 +-
> tools/include/uapi/asm-generic/unistd.h | 4 +-
> 68 files changed, 1205 insertions(+), 698 deletions(-)
> delete mode 100644 arch/riscv/configs/rv32_defconfig
> create mode 100644 arch/riscv/include/asm/compat.h
> create mode 100644 arch/riscv/kernel/compat_signal.c
> create mode 100644 arch/riscv/kernel/compat_syscall_table.c
> create mode 100644 arch/riscv/kernel/compat_vdso/.gitignore
> create mode 100644 arch/riscv/kernel/compat_vdso/Makefile
> create mode 100644 arch/riscv/kernel/compat_vdso/compat_vdso.S
> create mode 100644 arch/riscv/kernel/compat_vdso/compat_vdso.lds.S
> create mode 100644 arch/riscv/kernel/compat_vdso/flush_icache.S
> create mode 100755 arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh
> create mode 100644 arch/riscv/kernel/compat_vdso/getcpu.S
> create mode 100644 arch/riscv/kernel/compat_vdso/note.S
> create mode 100644 arch/riscv/kernel/compat_vdso/rt_sigreturn.S