Hi,
Am Sonntag, 27. Februar 2022, 17:28:11 CET schrieb guoren@xxxxxxxxxx:
> 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 v5.17-rc5, you can compare rv64-compat
> v.s. rv32-native in qemu with following steps:
I've followed your great test-instructions :-) .
Starting a riscv32 userspace with a riscv64-kernel _without_ that series
fails as expected. It wants to find the binfmt module to emulate the
unavailable architecture.
Same userspace and this series applied to the kernel tree makes that
riscv32 userspace boot nicely on the riscv64 kernel.
So the series:
Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
> - 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_v6 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: (rv32 compat was made by LIU Zhiwei <zhiwei_liu@xxxxxxxxx>)
> $ git clone git@xxxxxxxxxx:alistair23/qemu.git -b riscv-to-apply.for-upstream linux
> $ cd qemu
> $ ./configure --target-list="riscv64-softmmu riscv32-softmmu"
> $ make
>
> Now let's compare rv64-compat with rv32-native memory footprint with almost the same
> defconfig, rootfs, opensbi in one qemu.
>
> - Run rv64 with rv32 rootfs in compat mode:
> $ ./build/qemu-system-riscv64 -cpu rv64 -M virt -m 64m -nographic -bios qemu_riscv64_virt_defconfig/images/fw_jump.bin -kernel build-rv64/Image -drive file qemu_riscv32_virt_defconfig/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -append "rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi" -netdev user,id=net0 -device virtio-net-device,netdev=net0
>
> QEMU emulator version 6.2.50 (v6.2.0-29-g196d7182c8)
> OpenSBI v0.9
> [ 0.000000] Linux version 5.16.0-rc6-00017-g750f87086bdd-dirty (guoren@guoren-Z87-HD3) (riscv64-unknown-linux-gnu-gcc (GCC) 10.2.0, GNU ld (GNU Binutils) 2.37) #96 SMP Tue Dec 28 21:01:55 CST 2021
> [ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
> [ 0.000000] Machine model: riscv-virtio,qemu
> [ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
> [ 0.000000] printk: bootconsole [sbi0] enabled
> [ 0.000000] efi: UEFI not found.
> [ 0.000000] Zone ranges:
> [ 0.000000] DMA32 [mem 0x0000000080200000-0x0000000083ffffff]
> [ 0.000000] Normal empty
> [ 0.000000] Movable zone start for each node
> [ 0.000000] Early memory node ranges
> [ 0.000000] node 0: [mem 0x0000000080200000-0x0000000083ffffff]
> [ 0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x0000000083ffffff]
> [ 0.000000] SBI specification v0.2 detected
> [ 0.000000] SBI implementation ID=0x1 Version=0x9
> [ 0.000000] SBI TIME extension detected
> [ 0.000000] SBI IPI extension detected
> [ 0.000000] SBI RFENCE extension detected
> [ 0.000000] SBI v0.2 HSM extension detected
> [ 0.000000] riscv: ISA extensions acdfhimsu
> [ 0.000000] riscv: ELF capabilities acdfim
> [ 0.000000] percpu: Embedded 17 pages/cpu s30696 r8192 d30744 u69632
> [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 15655
> [ 0.000000] Kernel command line: rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi
> [ 0.000000] Dentry cache hash table entries: 8192 (order: 4, 65536 bytes, linear)
> [ 0.000000] Inode-cache hash table entries: 4096 (order: 3, 32768 bytes, linear)
> [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
> [ 0.000000] Virtual kernel memory layout:
> [ 0.000000] fixmap : 0xffffffcefee00000 - 0xffffffceff000000 (2048 kB)
> [ 0.000000] pci io : 0xffffffceff000000 - 0xffffffcf00000000 ( 16 MB)
> [ 0.000000] vmemmap : 0xffffffcf00000000 - 0xffffffcfffffffff (4095 MB)
> [ 0.000000] vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff (65535 MB)
> [ 0.000000] lowmem : 0xffffffe000000000 - 0xffffffe003e00000 ( 62 MB)
> [ 0.000000] kernel : 0xffffffff80000000 - 0xffffffffffffffff (2047 MB)
> [ 0.000000] Memory: 52788K/63488K available (6184K kernel code, 888K rwdata, 1917K rodata, 294K init, 297K bss, 10700K reserved, 0K cma-reserved)
> [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
> [ 0.000000] rcu: Hierarchical RCU implementation.
> [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
> [ 0.000000] rcu: RCU debug extended QS entry/exit.
> [ 0.000000] Tracing variant of Tasks RCU enabled.
> [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
> [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
> [ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
> [ 0.000000] riscv-intc: 64 local interrupts mapped
> [ 0.000000] plic: plic@c000000: mapped 53 interrupts with 1 handlers for 2 contexts.
> ...
> Welcome to Buildroot
> buildroot login: root
> # cat /proc/cpuinfo
> processor : 0
> hart : 0
> isa : rv64imafdcsuh
> mmu : sv48
>
> # file /bin/busybox
> /bin/busybox: setuid ELF 32-bit LSB shared object, UCB RISC-V, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-riscv32-ilp32d.so.1, for GNU/Linux 5.15.0, stripped
> # ca[ 78.386630] random: fast init done
> # cat /proc/meminfo
> MemTotal: 53076 kB
> MemFree: 40264 kB
> MemAvailable: 40244 kB
> Buffers: 236 kB
> Cached: 1560 kB
> SwapCached: 0 kB
> Active: 1700 kB
> Inactive: 516 kB
> Active(anon): 40 kB
> Inactive(anon): 424 kB
> Active(file): 1660 kB
> Inactive(file): 92 kB
> Unevictable: 0 kB
> Mlocked: 0 kB
> SwapTotal: 0 kB
> SwapFree: 0 kB
> Dirty: 0 kB
> Writeback: 0 kB
> AnonPages: 444 kB
> Mapped: 1188 kB
> Shmem: 44 kB
> KReclaimable: 952 kB
> Slab: 5744 kB
> SReclaimable: 952 kB
> SUnreclaim: 4792 kB
> KernelStack: 624 kB
> PageTables: 156 kB
> NFS_Unstable: 0 kB
> Bounce: 0 kB
> WritebackTmp: 0 kB
> CommitLimit: 26536 kB
> Committed_AS: 1748 kB
> VmallocTotal: 67108863 kB
> VmallocUsed: 652 kB
> VmallocChunk: 0 kB
> Percpu: 80 kB
> #
>
> - Run rv32 with rv32 rootfs:
> $ ./build/qemu-system-riscv32 -cpu rv32 -M virt -m 64m -nographic -bios qemu_riscv32_virt_defconfig/images/fw_jump.bin -kernel build-rv32/Image -drive file qemu_riscv32_virt_defconfig/images/rootfs.ext2,format=raw,id=hd0 -device virtio-blk-device,drive=hd0 -append "rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi" -netdev user,id=net0 -device virtio-net-device,netdev=net0
>
> QEMU emulator version 6.2.50 (v6.2.0-29-g196d7182c8)
> OpenSBI v0.9
> [ 0.000000] Linux version 5.16.0-rc6-00017-g750f87086bdd-dirty (guoren@guoren-Z87-HD3) (riscv32-buildroot-linux-gnu-gcc.br_real (Buildroot 2021.11-201-g7600ca7960-dirty) 10.3.0, GNU ld (GNU Binutils) 2.36.1) #7 SMP Tue Dec 28 21:02:21 CST 2021
> [ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80400000
> [ 0.000000] Machine model: riscv-virtio,qemu
> [ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
> [ 0.000000] printk: bootconsole [sbi0] enabled
> [ 0.000000] efi: UEFI not found.
> [ 0.000000] Zone ranges:
> [ 0.000000] Normal [mem 0x0000000080400000-0x0000000083ffffff]
> [ 0.000000] Movable zone start for each node
> [ 0.000000] Early memory node ranges
> [ 0.000000] node 0: [mem 0x0000000080400000-0x0000000083ffffff]
> [ 0.000000] Initmem setup node 0 [mem 0x0000000080400000-0x0000000083ffffff]
> [ 0.000000] SBI specification v0.2 detected
> [ 0.000000] SBI implementation ID=0x1 Version=0x9
> [ 0.000000] SBI TIME extension detected
> [ 0.000000] SBI IPI extension detected
> [ 0.000000] SBI RFENCE extension detected
> [ 0.000000] SBI v0.2 HSM extension detected
> [ 0.000000] riscv: ISA extensions acdfhimsu
> [ 0.000000] riscv: ELF capabilities acdfim
> [ 0.000000] percpu: Embedded 12 pages/cpu s16600 r8192 d24360 u49152
> [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 15240
> [ 0.000000] Kernel command line: rootwait root=/dev/vda ro console=ttyS0 earlycon=sbi
> [ 0.000000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes, linear)
> [ 0.000000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes, linear)
> [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
> [ 0.000000] Virtual kernel memory layout:
> [ 0.000000] fixmap : 0x9dc00000 - 0x9e000000 (4096 kB)
> [ 0.000000] pci io : 0x9e000000 - 0x9f000000 ( 16 MB)
> [ 0.000000] vmemmap : 0x9f000000 - 0x9fffffff ( 15 MB)
> [ 0.000000] vmalloc : 0xa0000000 - 0xbfffffff ( 511 MB)
> [ 0.000000] lowmem : 0xc0000000 - 0xc3c00000 ( 60 MB)
> [ 0.000000] Memory: 51924K/61440K available (6117K kernel code, 695K rwdata, 1594K rodata, 255K init, 241K bss, 9516K reserved, 0K cma-reserved)
> [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
> [ 0.000000] rcu: Hierarchical RCU implementation.
> [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
> [ 0.000000] rcu: RCU debug extended QS entry/exit.
> [ 0.000000] Tracing variant of Tasks RCU enabled.
> [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
> [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
> [ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
> [ 0.000000] riscv-intc: 32 local interrupts mapped
> [ 0.000000] plic: plic@c000000: mapped 53 interrupts with 1 handlers for 2 contexts.
> ...
> Welcome to Buildroot
> buildroot login: root
> # cat /proc/cpuinfo
> processor : 0
> hart : 0
> isa : rv32imafdcsuh
> mmu : sv32
>
> # file /bin/busybox
> /bin/busybox: setuid ELF 32-bit LSB shared object, UCB RISC-V, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-riscv32-ilp32d.so.1, for GNU/Linux 5.15.0, stripped
> [ 79.320589] random: fast init done
> # cat /proc/meminfo
> MemTotal: 52176 kB
> MemFree: 41012 kB
> MemAvailable: 42176 kB
> Buffers: 644 kB
> Cached: 2724 kB
> SwapCached: 0 kB
> Active: 3128 kB
> Inactive: 752 kB
> Active(anon): 40 kB
> Inactive(anon): 516 kB
> Active(file): 3088 kB
> Inactive(file): 236 kB
> Unevictable: 0 kB
> Mlocked: 0 kB
> SwapTotal: 0 kB
> SwapFree: 0 kB
> Dirty: 4 kB
> Writeback: 0 kB
> AnonPages: 556 kB
> Mapped: 2172 kB
> Shmem: 44 kB
> KReclaimable: 656 kB
> Slab: 3684 kB
> SReclaimable: 656 kB
> SUnreclaim: 3028 kB
> KernelStack: 312 kB
> PageTables: 88 kB
> NFS_Unstable: 0 kB
> Bounce: 0 kB
> WritebackTmp: 0 kB
> CommitLimit: 26088 kB
> Committed_AS: 2088 kB
> VmallocTotal: 524287 kB
> VmallocUsed: 12 kB
> VmallocChunk: 0 kB
> Percpu: 60 kB
> #
>
> Some conclusions:
> - kernel statics:
> 64: Memory: 52788K/63488K available (6184K kernel code, 888K rwdata, 1917K rodata, 294K init, 297K bss, 10700K reserved)
> 32: Memory: 51924K/61440K available (6117K kernel code, 695K rwdata, 1594K rodata, 255K init, 241K bss, 9516K reserved)
> rv32 better than rv64: 1% 22% 17% 13% 19% 11%
> The code size is very similar, but data size rv32 would be better.
>
> - rv32 kernel runtime KernelStack, Slab... are smaller,
> rv64: MemTotal: 53076 kB, MemFree: 40264 kB
> rv32: MemTotal: 52176 + 2048 kB, MemFree: 41012 + 2048 kB
> rv32 better than rv64: 2% 6%
>
> (Because opensbi problem, we could add another 2MB for rv32.)
> Overall in 64MB memory situation, rv64-compat is 6% worse than rv32-full
> at memory footprint. If the user space memory usage increases, I think
> the gap will be further reduced.
>
> Changes in v7:
> - Re-construct compat_vdso/Makefile
> - Fixup disable COMPAT compile error by csr.h's macro.
> - Optimize coding convention for lo/hi in compat.h
>
> Changes in v6:
> - Rebase on linux-5.17-rc5
> - Optimize hw capability check for elf
> - Optimize comment in thread_info.h
> - Optimize start_thread with SR_UXL setting
> - Optimize vdso.c with direct panic
>
> Changes in v5:
> - Rebase on linux-5.17-rc2
> - Include consolidate the fcntl patches by Christoph Hellwig
> - Remove F_GETLK64/F_SETLK64/F_SETLKW64 from asm/compat.h
> - Change COMPAT_RLIM_INFINITY from 0x7fffffff to 0xffffffff
> - Bring back "Add hw-cap detect in setup_arch patch" in v1
>
> Changes in v4:
> - Rebase on linux-5.17-rc1
> - Optimize compat_sys_call_table implementation with Arnd's advice
> - Add reviewed-by for Arnd. Thx :)
> - Remove FIXME comment in elf.h
> - Optimize Cleanup duplicate definitions in compat.h with Arnd's advice
>
> Changes in v3:
> - Rebase on newest master (pre linux-5.17-rc1)
> - Using newest qemu version v7 for test
> - Remove fcntl common modification
> - Fixup SET_PERSONALITY in elf.h by Arnd
> - Fixup KVM Kconfig
> - Update Acked-by & Reviewed-by
>
> Changes in v2:
> - Add __ARCH_WANT_COMPAT_STAT suggested
> - Cleanup fcntl compatduplicate definitions
> - Cleanup compat.h
> - Move rv32_defconfig into Makefile
> - Fixup rv64 rootfs boot failed, remove hw_compat_mode_detect
> - Move SYSVIPC_COMPAT into init/Kconfig
> - Simplify compat_elf_check
>
> Christoph Hellwig (3):
> uapi: simplify __ARCH_FLOCK{,64}_PAD a little
> uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.h
> compat: consolidate the compat_flock{,64} definition
>
> Guo Ren (17):
> kconfig: Add SYSVIPC_COMPAT for all architectures
> fs: stat: compat: Add __ARCH_WANT_COMPAT_STAT
> asm-generic: compat: Cleanup duplicate definitions
> syscalls: compat: Fix the missing part for __SYSCALL_COMPAT
> riscv: Fixup difference with defconfig
> riscv: compat: Add basic compat data type implementation
> riscv: compat: Re-implement TASK_SIZE for COMPAT_32BIT
> riscv: compat: syscall: Add compat_sys_call_table implementation
> riscv: compat: syscall: Add entry.S implementation
> riscv: compat: process: Add UXL_32 support in start_thread
> riscv: compat: Add elf.h implementation
> riscv: compat: Add hw capability check for elf
> riscv: compat: vdso: Add COMPAT_VDSO base code implementation
> riscv: compat: vdso: Add setup additional pages implementation
> riscv: compat: signal: Add rt_frame implementation
> riscv: compat: ptrace: Add compat_arch_ptrace implement
> riscv: compat: Add COMPAT Kbuild skeletal support
>
> arch/arm64/Kconfig | 4 -
> arch/arm64/include/asm/compat.h | 91 +------
> arch/arm64/include/asm/unistd.h | 1 +
> arch/mips/Kconfig | 5 -
> arch/mips/include/asm/compat.h | 41 +--
> arch/mips/include/asm/unistd.h | 2 +
> arch/mips/include/uapi/asm/fcntl.h | 30 +--
> arch/parisc/Kconfig | 4 -
> arch/parisc/include/asm/compat.h | 45 +---
> arch/parisc/include/asm/unistd.h | 1 +
> arch/powerpc/Kconfig | 5 -
> arch/powerpc/include/asm/compat.h | 50 +---
> arch/powerpc/include/asm/unistd.h | 1 +
> arch/riscv/Kconfig | 19 ++
> arch/riscv/Makefile | 9 +
> arch/riscv/configs/rv32_defconfig | 135 ----------
> arch/riscv/include/asm/compat.h | 129 ++++++++++
> arch/riscv/include/asm/csr.h | 7 +
> arch/riscv/include/asm/elf.h | 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 | 78 ++++++
> arch/riscv/kernel/compat_vdso/compat_vdso.S | 8 +
> .../kernel/compat_vdso/compat_vdso.lds.S | 3 +
> arch/riscv/kernel/compat_vdso/flush_icache.S | 3 +
> .../compat_vdso/gen_compat_vdso_offsets.sh | 5 +
> arch/riscv/kernel/compat_vdso/getcpu.S | 3 +
> arch/riscv/kernel/compat_vdso/note.S | 3 +
> arch/riscv/kernel/compat_vdso/rt_sigreturn.S | 3 +
> arch/riscv/kernel/entry.S | 18 +-
> arch/riscv/kernel/process.c | 31 +++
> arch/riscv/kernel/ptrace.c | 87 ++++++-
> arch/riscv/kernel/signal.c | 13 +-
> arch/riscv/kernel/sys_riscv.c | 6 +-
> arch/riscv/kernel/vdso.c | 105 +++++---
> arch/riscv/kernel/vdso/vdso.S | 6 +-
> arch/s390/Kconfig | 3 -
> arch/s390/include/asm/compat.h | 99 +------
> arch/s390/include/asm/unistd.h | 1 +
> arch/sparc/Kconfig | 5 -
> arch/sparc/include/asm/compat.h | 61 ++---
> arch/sparc/include/asm/unistd.h | 1 +
> arch/x86/Kconfig | 4 -
> arch/x86/include/asm/compat.h | 104 ++------
> arch/x86/include/asm/unistd.h | 1 +
> fs/open.c | 24 ++
> fs/read_write.c | 16 ++
> fs/stat.c | 2 +-
> fs/sync.c | 9 +
> include/asm-generic/compat.h | 113 ++++++++
> include/linux/compat.h | 68 +++++
> include/uapi/asm-generic/fcntl.h | 23 +-
> include/uapi/asm-generic/unistd.h | 4 +-
> init/Kconfig | 4 +
> mm/fadvise.c | 11 +
> mm/readahead.c | 7 +
> tools/include/uapi/asm-generic/fcntl.h | 21 +-
> tools/include/uapi/asm-generic/unistd.h | 4 +-
> 67 files changed, 1197 insertions(+), 696 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
>
>
