From c52195d25825abc749c5187f4c18834eabe4bfee Mon Sep 17 00:00:00 2001 From: Nicolas Lacasse Date: Sun, 10 May 2020 17:51:01 -0700 Subject: Stop avoiding preadv2 and pwritev2, and add them to the filters. Some code paths needed these syscalls anyways, so they should be included in the filters. Given that we depend on these syscalls in some cases, there's no real reason to avoid them any more. PiperOrigin-RevId: 310829126 --- pkg/sentry/hostfd/hostfd_unsafe.go | 46 ++++++++++---------------------------- 1 file changed, 12 insertions(+), 34 deletions(-) (limited to 'pkg/sentry/hostfd') diff --git a/pkg/sentry/hostfd/hostfd_unsafe.go b/pkg/sentry/hostfd/hostfd_unsafe.go index 5e9e60fc4..cd4dc67fb 100644 --- a/pkg/sentry/hostfd/hostfd_unsafe.go +++ b/pkg/sentry/hostfd/hostfd_unsafe.go @@ -34,24 +34,13 @@ func Preadv2(fd int32, dsts safemem.BlockSeq, offset int64, flags uint32) (uint6 n uintptr e syscall.Errno ) - // Avoid preadv2(2) if possible, since it's relatively new and thus least - // likely to be supported by the host kernel. - if flags == 0 { - if dsts.NumBlocks() == 1 { - // Use read() or pread() to avoid iovec allocation and copying. - dst := dsts.Head() - if offset == -1 { - n, _, e = syscall.Syscall(unix.SYS_READ, uintptr(fd), dst.Addr(), uintptr(dst.Len())) - } else { - n, _, e = syscall.Syscall6(unix.SYS_PREAD64, uintptr(fd), dst.Addr(), uintptr(dst.Len()), uintptr(offset), 0 /* pos_h */, 0 /* unused */) - } + if flags == 0 && dsts.NumBlocks() == 1 { + // Use read() or pread() to avoid iovec allocation and copying. + dst := dsts.Head() + if offset == -1 { + n, _, e = syscall.Syscall(unix.SYS_READ, uintptr(fd), dst.Addr(), uintptr(dst.Len())) } else { - iovs := safemem.IovecsFromBlockSeq(dsts) - if offset == -1 { - n, _, e = syscall.Syscall(unix.SYS_READV, uintptr(fd), uintptr((unsafe.Pointer)(&iovs[0])), uintptr(len(iovs))) - } else { - n, _, e = syscall.Syscall6(unix.SYS_PREADV, uintptr(fd), uintptr((unsafe.Pointer)(&iovs[0])), uintptr(len(iovs)), uintptr(offset), 0 /* pos_h */, 0 /* unused */) - } + n, _, e = syscall.Syscall6(unix.SYS_PREAD64, uintptr(fd), dst.Addr(), uintptr(dst.Len()), uintptr(offset), 0 /* pos_h */, 0 /* unused */) } } else { iovs := safemem.IovecsFromBlockSeq(dsts) @@ -77,24 +66,13 @@ func Pwritev2(fd int32, srcs safemem.BlockSeq, offset int64, flags uint32) (uint n uintptr e syscall.Errno ) - // Avoid pwritev2(2) if possible, since it's relatively new and thus least - // likely to be supported by the host kernel. - if flags == 0 { - if srcs.NumBlocks() == 1 { - // Use write() or pwrite() to avoid iovec allocation and copying. - src := srcs.Head() - if offset == -1 { - n, _, e = syscall.Syscall(unix.SYS_WRITE, uintptr(fd), src.Addr(), uintptr(src.Len())) - } else { - n, _, e = syscall.Syscall6(unix.SYS_PWRITE64, uintptr(fd), src.Addr(), uintptr(src.Len()), uintptr(offset), 0 /* pos_h */, 0 /* unused */) - } + if flags == 0 && srcs.NumBlocks() == 1 { + // Use write() or pwrite() to avoid iovec allocation and copying. + src := srcs.Head() + if offset == -1 { + n, _, e = syscall.Syscall(unix.SYS_WRITE, uintptr(fd), src.Addr(), uintptr(src.Len())) } else { - iovs := safemem.IovecsFromBlockSeq(srcs) - if offset == -1 { - n, _, e = syscall.Syscall(unix.SYS_WRITEV, uintptr(fd), uintptr((unsafe.Pointer)(&iovs[0])), uintptr(len(iovs))) - } else { - n, _, e = syscall.Syscall6(unix.SYS_PWRITEV, uintptr(fd), uintptr((unsafe.Pointer)(&iovs[0])), uintptr(len(iovs)), uintptr(offset), 0 /* pos_h */, 0 /* unused */) - } + n, _, e = syscall.Syscall6(unix.SYS_PWRITE64, uintptr(fd), src.Addr(), uintptr(src.Len()), uintptr(offset), 0 /* pos_h */, 0 /* unused */) } } else { iovs := safemem.IovecsFromBlockSeq(srcs) -- cgit v1.2.3