From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> 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 v5.16-rc6, 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@xxxxxxxxxx:c-sky/csky-linux.git -b riscv_compat_v3 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@xxxxxxxxx>) $ git clone https://github.com/romanheros/qemu.git -b riscv-upstream-uxl-v7 $ 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 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 arch/arm64/Kconfig | 4 - arch/arm64/include/asm/compat.h | 108 +------- arch/arm64/include/asm/unistd.h | 1 + arch/mips/Kconfig | 5 - arch/mips/include/asm/compat.h | 24 +- arch/mips/include/asm/unistd.h | 2 + arch/parisc/Kconfig | 4 - arch/parisc/include/asm/compat.h | 47 +--- arch/parisc/include/asm/unistd.h | 1 + arch/powerpc/Kconfig | 5 - arch/powerpc/include/asm/compat.h | 47 +--- 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 | 136 ++++++++++ arch/riscv/include/asm/csr.h | 7 + arch/riscv/include/asm/elf.h | 56 +++- arch/riscv/include/asm/mmu.h | 1 + arch/riscv/include/asm/pgtable.h | 11 +- arch/riscv/include/asm/processor.h | 6 + arch/riscv/include/asm/syscall.h | 3 + arch/riscv/include/asm/thread_info.h | 1 + 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 | 72 ++++++ 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 | 109 +------- arch/s390/include/asm/unistd.h | 1 + arch/sparc/Kconfig | 5 - arch/sparc/include/asm/compat.h | 39 ++- arch/sparc/include/asm/unistd.h | 1 + arch/x86/Kconfig | 4 - arch/x86/include/asm/compat.h | 114 +------- arch/x86/include/asm/unistd.h | 1 + drivers/firmware/efi/libstub/efi-stub.c | 2 +- fs/stat.c | 2 +- include/asm-generic/compat.h | 122 +++++++++ include/uapi/asm-generic/unistd.h | 4 +- init/Kconfig | 4 + tools/include/uapi/asm-generic/unistd.h | 4 +- virt/kvm/Kconfig | 2 +- 60 files changed, 1082 insertions(+), 634 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
