Re: [PATCH bpf-next 1/3] libbpf: add asm/unistd.h to xsk to get __NR_mmap2
From: BjÃrn TÃpel
Date: Wed Aug 14 2019 - 09:32:40 EST
On Wed, 14 Aug 2019 at 13:57, Ivan Khoronzhuk
<ivan.khoronzhuk@xxxxxxxxxx> wrote:
>
> On Wed, Aug 14, 2019 at 12:24:05PM +0300, Ivan Khoronzhuk wrote:
> >On Tue, Aug 13, 2019 at 04:38:13PM -0700, Andrii Nakryiko wrote:
> >
> >Hi, Andrii
> >
> >>On Tue, Aug 13, 2019 at 3:24 AM Ivan Khoronzhuk
> >><ivan.khoronzhuk@xxxxxxxxxx> wrote:
> >>>
> >>>That's needed to get __NR_mmap2 when mmap2 syscall is used.
> >>>
> >>>Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
> >>>---
> >>> tools/lib/bpf/xsk.c | 1 +
> >>> 1 file changed, 1 insertion(+)
> >>>
> >>>diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
> >>>index 5007b5d4fd2c..f2fc40f9804c 100644
> >>>--- a/tools/lib/bpf/xsk.c
> >>>+++ b/tools/lib/bpf/xsk.c
> >>>@@ -12,6 +12,7 @@
> >>> #include <stdlib.h>
> >>> #include <string.h>
> >>> #include <unistd.h>
> >>>+#include <asm/unistd.h>
> >>
> >>asm/unistd.h is not present in Github libbpf projection. Is there any
> >
> >Look on includes from
> >tools/lib/bpf/libpf.c
> >tools/lib/bpf/bpf.c
> >
> >That's how it's done... Copping headers to arch/arm will not
> >solve this, it includes both of them anyway, and anyway it needs
> >asm/unistd.h inclusion here, only because xsk.c needs __NR_*
> >
> >
>
> There is one more radical solution for this I can send, but I'm not sure how it
> can impact on other syscals/arches...
>
> Looks like:
>
>
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 9312066a1ae3..8b2f8ff7ce44 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -113,6 +113,7 @@ override CFLAGS += -Werror -Wall
> override CFLAGS += -fPIC
> override CFLAGS += $(INCLUDES)
> override CFLAGS += -fvisibility=hidden
> +override CFLAGS += -D_FILE_OFFSET_BITS=64
>
Hmm, isn't this glibc-ism? Does is it work for, say, musl or bionic?
If this is portable, and works on 32-, and 64-bit archs, I'm happy
with the patch. :-)
BjÃrn
> ifeq ($(VERBOSE),1)
> Q =
> diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
> index f2fc40f9804c..ff2d03b8380d 100644
> --- a/tools/lib/bpf/xsk.c
> +++ b/tools/lib/bpf/xsk.c
> @@ -75,23 +75,6 @@ struct xsk_nl_info {
> int fd;
> };
>
> -/* For 32-bit systems, we need to use mmap2 as the offsets are 64-bit.
> - * Unfortunately, it is not part of glibc.
> - */
> -static inline void *xsk_mmap(void *addr, size_t length, int prot, int flags,
> - int fd, __u64 offset)
> -{
> -#ifdef __NR_mmap2
> - unsigned int page_shift = __builtin_ffs(getpagesize()) - 1;
> - long ret = syscall(__NR_mmap2, addr, length, prot, flags, fd,
> - (off_t)(offset >> page_shift));
> -
> - return (void *)ret;
> -#else
> - return mmap(addr, length, prot, flags, fd, offset);
> -#endif
> -}
> -
> int xsk_umem__fd(const struct xsk_umem *umem)
> {
> return umem ? umem->fd : -EINVAL;
> @@ -211,10 +194,9 @@ int xsk_umem__create(struct xsk_umem **umem_ptr, void *umem_area, __u64 size,
> goto out_socket;
> }
>
> - map = xsk_mmap(NULL, off.fr.desc +
> - umem->config.fill_size * sizeof(__u64),
> - PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
> - umem->fd, XDP_UMEM_PGOFF_FILL_RING);
> + map = mmap(NULL, off.fr.desc + umem->config.fill_size * sizeof(__u64),
> + PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, umem->fd,
> + XDP_UMEM_PGOFF_FILL_RING);
> if (map == MAP_FAILED) {
> err = -errno;
> goto out_socket;
> @@ -228,10 +210,9 @@ int xsk_umem__create(struct xsk_umem **umem_ptr, void *umem_area, __u64 size,
> fill->ring = map + off.fr.desc;
> fill->cached_cons = umem->config.fill_size;
>
> - map = xsk_mmap(NULL,
> - off.cr.desc + umem->config.comp_size * sizeof(__u64),
> - PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
> - umem->fd, XDP_UMEM_PGOFF_COMPLETION_RING);
> + map = mmap(NULL, off.cr.desc + umem->config.comp_size * sizeof(__u64),
> + PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, umem->fd,
> + XDP_UMEM_PGOFF_COMPLETION_RING);
> if (map == MAP_FAILED) {
> err = -errno;
> goto out_mmap;
> @@ -552,11 +533,10 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
> }
>
> if (rx) {
> - rx_map = xsk_mmap(NULL, off.rx.desc +
> - xsk->config.rx_size * sizeof(struct xdp_desc),
> - PROT_READ | PROT_WRITE,
> - MAP_SHARED | MAP_POPULATE,
> - xsk->fd, XDP_PGOFF_RX_RING);
> + rx_map = mmap(NULL, off.rx.desc +
> + xsk->config.rx_size * sizeof(struct xdp_desc),
> + PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
> + xsk->fd, XDP_PGOFF_RX_RING);
> if (rx_map == MAP_FAILED) {
> err = -errno;
> goto out_socket;
> @@ -571,11 +551,10 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
> xsk->rx = rx;
>
> if (tx) {
> - tx_map = xsk_mmap(NULL, off.tx.desc +
> - xsk->config.tx_size * sizeof(struct xdp_desc),
> - PROT_READ | PROT_WRITE,
> - MAP_SHARED | MAP_POPULATE,
> - xsk->fd, XDP_PGOFF_TX_RING);
> + tx_map = mmap(NULL, off.tx.desc +
> + xsk->config.tx_size * sizeof(struct xdp_desc),
> + PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
> + xsk->fd, XDP_PGOFF_TX_RING);
> if (tx_map == MAP_FAILED) {
> err = -errno;
> goto out_mmap_rx;
>
>
> If maintainers are ready to accept this I can send.
> What do you say?
>
> --
> Regards,
> Ivan Khoronzhuk