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Add vagrant VM support and XDP_USE_NEED_WAKEUP for advanced03 #70

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Add vagrant VM support and XDP_USE_NEED_WAKEUP for advanced03 #70

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d3c1045
vagrant: add vagrant support to build latest bpf-next in VM
chaudron Sep 3, 2019
eaf1e96
advanced03: add support for the XDP_USE_NEED_WAKEUP API
chaudron Sep 3, 2019
ce93ed3
advanced03: add some basic kernel version checking for AF_XDP support
chaudron Sep 25, 2019
3f89b0e
advanced03: fix compilation of custom xdp program on older kernels
chaudron Sep 25, 2019
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12 changes: 12 additions & 0 deletions advanced03-AF_XDP/af_xdp_kern.c
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/bpf.h>
#include <linux/version.h>

#include "bpf_helpers.h"

Expand All @@ -18,6 +19,17 @@ struct bpf_map_def SEC("maps") xdp_stats_map = {
.max_entries = 64,
};

#if LINUX_VERSION_CODE < KERNEL_VERSION(5,3,0)
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It is not the right approach to check against a kernel version.
(Because distros will backport changes)

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I know, but due to the lack of any run-time checks, what would you suggest?

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Instead we have to write a bpf probe that can detect this (like bpftool does).
@tohojo have added a configure script in his XDP-tools repo.
In this case, we likely need to confine the check to the advanced03-AF_XDP/ directory, and we can likely add it as part of the Makefile.

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The configure script just sets some variables; so we can do that in the top-level and only react to them in advanced03. I've been meaning to port over some of the build stuff I did in xdp-tools to this repo anyway, so this sounds like a way forward :)


/* Kernel version before 5.3 needed an additional map */
struct bpf_map_def SEC("maps") qidconf_map = {
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I don't see this map referred to anywhere; how is it actually used on those old kernels?

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Think this is part of the older libbpf installing int

.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(int),
.max_entries = 64,
};
#endif

SEC("xdp_sock")
int xdp_sock_prog(struct xdp_md *ctx)
{
Expand Down
27 changes: 26 additions & 1 deletion advanced03-AF_XDP/af_xdp_user.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
#include <unistd.h>

#include <sys/resource.h>
#include <sys/utsname.h>

#include <bpf/bpf.h>
#include <bpf/xsk.h>
Expand Down Expand Up @@ -534,6 +535,29 @@ int main(int argc, char **argv)
struct xsk_socket_info *xsk_socket;
struct bpf_object *bpf_obj = NULL;
pthread_t stats_poll_thread;
struct utsname uname_info;
unsigned int major, minor, revision;

/* Some basic version checking for AF_XDP */
if (uname(&uname_info) == -1) {
fprintf(stderr, "ERROR: failed calling uname(): %s\n",
strerror(errno));
exit(EXIT_FAILURE);
}
if (sscanf(uname_info.release, "%u.%u.%u-",
&major, &minor, &revision) != 3) {
fprintf(stderr, "ERROR: failed to extract Kernel version\n");
exit(EXIT_FAILURE);
}
if (major < 5 || (major == 5 && minor < 2)) {
printf("WARNING: For AF_XDP you need at least an upstream "
"kernel of 5.2!\n");
}
if (major == 5 && minor == 2) {
printf("WARNING: Although AF_XDP is supported in upstream "
"kernel 5.2, due to known libbpf issues it's "
"recommended to use at least version 5.3!\n");
}

/* Global shutdown handler */
signal(SIGINT, exit_application);
Expand Down Expand Up @@ -602,7 +626,8 @@ int main(int argc, char **argv)
/* Open and configure the AF_XDP (xsk) socket */
xsk_socket = xsk_configure_socket(&cfg, umem);
if (xsk_socket == NULL) {
fprintf(stderr, "ERROR: Can't setup AF_XDP socket \"%s\"\n",
fprintf(stderr, "ERROR: Can't setup AF_XDP socket \"%s\"\n"
"Make sure Kernel is build with CONFIG_XDP_SOCKETS=y\n",
strerror(errno));
exit(EXIT_FAILURE);
}
Expand Down