Subject: [PATCH V4 00/17] riscv: compat: Add COMPAT mode support for rv64

From: [email-masked]
Date: Sat, 29 Jan 2022 20:17:11 +0800

From: Guo Ren <[email-masked]>

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-rc1, you can compare rv64-compat32
v.s. rv32-whole in qemu with following step:

 - 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 [email-masked]:c-sky/csky-linux.git -b riscv_compat_v4 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: (made by LIU Zhiwei <[email-masked]>)
   $ git clone [email-masked]:alistair23/qemu.git -b riscv-to-apply.for-upstream linux
   $ cd qemu
   $ ./configure --target-list="riscv64-softmmu riscv32-softmmu"
   $ make

 - Run rv64 with rv32 rootfs in compat mode:
   $ ./build/qemu-system-riscv64 -cpu rv64,x-h=true -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,x-h=true -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, rv64-compat is 6% worse than rv32-full at memory footprint.
   If the user space memory usage increases, the gap will be further
   reduced.

 - Qemu, kernel, rv32 = rv64 defconfig, rootfs, opensbi
   are the same in this comparison.

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

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 date 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: Add elf.h implementation
  riscv: compat: vdso: Add rv32 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 UXL_32 support in start_thread
  riscv: compat: Add COMPAT Kbuild skeletal support
  KVM: compat: riscv: Prevent KVM_COMPAT from being selected

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 date 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: vdso: Add rv32 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
  KVM: compat: riscv: Prevent KVM_COMPAT from being selected

 arch/arm64/Kconfig                            |   4 -
 arch/arm64/include/asm/compat.h               | 106 +-------
 arch/arm64/include/asm/unistd.h               |   1 +
 arch/mips/Kconfig                             |   5 -
 arch/mips/include/asm/compat.h                |  27 +-
 arch/mips/include/asm/unistd.h                |   2 +
 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             |  46 +---
 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               | 135 ++++++++++
 arch/riscv/include/asm/csr.h                  |   7 +
 arch/riscv/include/asm/elf.h                  |  53 +++-
 arch/riscv/include/asm/mmu.h                  |   1 +
 arch/riscv/include/asm/pgtable.h              |  13 +-
 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        |  68 +++++
 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                   |   5 +
 arch/riscv/kernel/ptrace.c                    |  87 ++++++-
 arch/riscv/kernel/signal.c                    |  13 +-
 arch/riscv/kernel/sys_riscv.c                 |   6 +-
 arch/riscv/kernel/vdso.c                      | 104 +++++---
 arch/riscv/kernel/vdso/vdso.S                 |   6 +-
 arch/s390/Kconfig                             |   3 -
 arch/s390/include/asm/compat.h                |  95 +------
 arch/s390/include/asm/unistd.h                |   1 +
 arch/sparc/Kconfig                            |   5 -
 arch/sparc/include/asm/compat.h               |  42 ++-
 arch/sparc/include/asm/unistd.h               |   1 +
 arch/x86/Kconfig                              |   4 -
 arch/x86/include/asm/compat.h                 |  89 +------
 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                  | 133 ++++++++++
 include/linux/compat.h                        |  37 +++
 include/uapi/asm-generic/unistd.h             |   4 +-
 init/Kconfig                                  |   4 +
 mm/fadvise.c                                  |  11 +
 mm/readahead.c                                |   7 +
 tools/include/uapi/asm-generic/unistd.h       |   4 +-
 virt/kvm/Kconfig                              |   2 +-
 65 files changed, 1141 insertions(+), 598 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

-- 
2.25.1