| Message ID | 20220201150545.1512822-1-guoren@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | riscv: compat: Add COMPAT mode support for rv64 | expand |
On Tue, Feb 1, 2022 at 11:06 PM <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-rc2, 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 git@github.com:c-sky/csky-linux.git -b riscv_compat_v5 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 <zhiwei_liu@c-sky.com>) > $ git clone git@github.com:alistair23/qemu.git -b riscv-to-apply.for-upstream linux > $ cd qemu > $ ./configure --target-list="riscv64-softmmu riscv32-softmmu" > $ make > > Now let's compare rv32-compat with rv32-native memory footprint. Kernel with rv32 = rv64 > defconfig, rootfs, opensbi, Qemu are the same. > > - 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 Fixup qemu cmdline (Remove x-h=true): $ ./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,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 Fixup qemu cmdline (Remove x-h=true): $ ./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-full > at memory footprint. If the user space memory usage increases, I think > the gap will be further reduced. > > 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 (18): > 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 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 | 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 | 52 +++- > 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 | 36 +++ > 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 | 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 +- > virt/kvm/Kconfig | 2 +- > 68 files changed, 1198 insertions(+), 691 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 >
On Tue, 01 Feb 2022 07:05:24 PST (-0800), 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. TBH, I'd always sort of hoped we wouldn't have to do this: it's a lot of ABI surface to keep around for a use case I'm not really sure is ever going to get any traction (it's not like we have legacy 32-bit userspaces floating around, the 32-bit userspace is newer than the 64-bit userspace). My assumption is that users who actually wanted the memory savings (likely a very small number) would be better served with rv64/ilp32, as that'll allow the larger registers that the hardware supports. From some earlier discussions it looks like rv64/ilp32 isn't going to be allowed, though, so this seems like the only way to go. I've left some minor comments, and I saw some unresolved ones as well. I'm going to assume there'll be a v6, but LMK if you want me to deal with cleaning things up. I'm OK targeting this for 5.18, assuming the cleanups can be resolved in the next week or two: generally with a lot of ABI surface I'd prefer to let things sit on for-next for a whole cycle, but I don't think it's a stretch to say that the actual ABI here is the rv32 port and that rv64/COMPAT=y is just our best attempt at matching it. It's probably worth running at least the glibc test suite, just to see if there's anything obvious that's failing. > The patchset are based on v5.17-rc2, 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 git@github.com:c-sky/csky-linux.git -b riscv_compat_v5 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 <zhiwei_liu@c-sky.com>) > $ git clone git@github.com:alistair23/qemu.git -b riscv-to-apply.for-upstream linux > $ cd qemu > $ ./configure --target-list="riscv64-softmmu riscv32-softmmu" > $ make > > Now let's compare rv32-compat with rv32-native memory footprint. Kernel with rv32 = rv64 > defconfig, rootfs, opensbi, Qemu are the same. > > - 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 in 64MB memory situation, rv64-compat is 6% worse than rv32-full > at memory footprint. If the user space memory usage increases, I think > the gap will be further reduced. > > 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 (18): > 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 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 | 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 | 52 +++- > 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 | 36 +++ > 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 | 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 +- > virt/kvm/Kconfig | 2 +- > 68 files changed, 1198 insertions(+), 691 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
On Wed, Feb 23, 2022 at 2:43 AM Palmer Dabbelt <palmer@dabbelt.com> wrote: > > On Tue, 01 Feb 2022 07:05:24 PST (-0800), 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. > > TBH, I'd always sort of hoped we wouldn't have to do this: it's a lot of > ABI surface to keep around for a use case I'm not really sure is ever > going to get any traction (it's not like we have legacy 32-bit > userspaces floating around, the 32-bit userspace is newer than the > 64-bit userspace). The low-end embedded market isn't usually that newsworthy, but the machines ship in huge quantities, and they all run 32-bit user space for good reasons: The cheapest Linux systems at the moment use a low-end MIPS or Arm core with a single DDR2 (32MB to 128MB) or DDR3 (128MB to 512MB) memory chip that for now is a bit cheaper than a larger LP-DDR4 (256MB+). The smaller configurations will go away over time as they get outpriced by systems with LP-DDR4, but a 32-bit system with 256MB will keep beating a 64-bit-only system with 512MB on price, and will run most workloads better than a 64-bit system with the same amount of RAM. On the Arm side, I hope that these systems will migrate to Armv8 based designs (Cortex-A53/A35 or newer) running 64-bit kernel with 32-bit user space to replace the currently dominant but aging 32-bit Cortex-A7 cores. As you say, RISC-V is at a disadvantage here because there is no existing 32-bit ecosystem, but it may take a chunk of that market anyway based on licensing cost. Between doing this using pure 32-bit cores or on mixed 32/64-bit cores, I found Guo Ren's explanation very sensible, it lets you use the same chip both as a low-end embedded version with SiP memory, or using an external DDR3/LPDDR4 chip with enough capacity to run a generic 64-bit distro. > My assumption is that users who actually wanted the > memory savings (likely a very small number) would be better served with > rv64/ilp32, as that'll allow the larger registers that the hardware > supports. From some earlier discussions it looks like rv64/ilp32 isn't > going to be allowed, though, so this seems like the only way to go. Right, between rv32 user space and a hypothetical rv64-ilp32 target, I think it's clear that the former is better because it means introducing only one fringe ABI rather than two incompatible ones with minor performance differences. Arnd
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-rc2, 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 git@github.com:c-sky/csky-linux.git -b riscv_compat_v5 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 <zhiwei_liu@c-sky.com>) $ git clone git@github.com:alistair23/qemu.git -b riscv-to-apply.for-upstream linux $ cd qemu $ ./configure --target-list="riscv64-softmmu riscv32-softmmu" $ make Now let's compare rv32-compat with rv32-native memory footprint. Kernel with rv32 = rv64 defconfig, rootfs, opensbi, Qemu are the same. - 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 in 64MB memory situation, rv64-compat is 6% worse than rv32-full at memory footprint. If the user space memory usage increases, I think the gap will be further reduced. 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 (18): 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 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 | 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 | 52 +++- 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 | 36 +++ 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 | 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 +- virt/kvm/Kconfig | 2 +- 68 files changed, 1198 insertions(+), 691 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