On Sun, Jan 24, 2021 at 8:07 PM Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 1/22/21 4:44 PM, KP Singh wrote:
> > The script runs the BPF selftests locally on the same kernel image
> > as they would run post submit in the BPF continuous integration
> > framework.
> >
> > The goal of the script is to allow contributors to run selftests locally
> > in the same environment to check if their changes would end up breaking
> > the BPF CI and reduce the back-and-forth between the maintainers and the
> > developers.
> >
> > Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
>
> Thanks! I tried the script, and it works great.
>
> Tested-by: Yonghong Song <yhs@xxxxxx>
Thanks!
>
> When I tried to apply the patch locally, I see the following warnings:
> -bash-4.4$ git apply ~/p1.txt
> /home/yhs/p1.txt:306: space before tab in indent.
> : )
> /home/yhs/p1.txt:307: space before tab in indent.
> echo "Invalid Option: -$OPTARG requires an
> argument"
> warning: 2 lines add whitespace errors.
>
> Maybe you want to fix them.
Sorry about that, fixed in the next revision.
>
> One issue I found with the following script,
> KBUILD_OUTPUT=/home/yhs/work/linux-bld/
> tools/testing/selftests/bpf/run_in_vm.sh -- cat /sys/fs/bpf/progs.debug
> I see the following warning:
>
> [ 1.081000] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid:
> 101, name: cat
> [ 1.081684] 3 locks held by cat/101:
>
> [ 1.082032] #0: ffff8880047770a0 (&p->lock){+.+.}-{3:3}, at:
> bpf_seq_read+0x3a/0x3d0
> [ 1.082734] #1: ffffffff82d69800 (rcu_read_lock){....}-{1:2}, at:
> bpf_iter_run_prog+0x5/0x160
> [ 1.083521] #2: ffff88800618c148 (&mm->mmap_lock#2){++++}-{3:3}, at:
> exc_page_fault+0x1a1/0x640
> [ 1.084344] Preemption disabled at:
>
> [ 1.084346] [<ffffffff8108f913>] migrate_disable+0x33/0x80
>
> [ 1.085207] CPU: 2 PID: 101 Comm: cat Not tainted
> 5.11.0-rc4-00524-g6e66fbb10597-dirty #1257
> [ 1.085933] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.9.3-1.el7.centos 04/01
> /2014
>
> [ 1.086747] Call Trace:
>
> [ 1.086961] dump_stack+0x77/0x97
>
> [ 1.087294] ___might_sleep.cold.119+0xf2/0x106
>
> [ 1.087702] exc_page_fault+0x1c1/0x640
>
> [ 1.088056] asm_exc_page_fault+0x1e/0x30
>
> [ 1.088413] RIP:
> 0010:bpf_prog_0a182df2d34af188_dump_bpf_prog+0xf5/0xbc8
>
> [ 1.089009] Code: 00 00 8b 7d f4 41 8b 76 44 48 39 f7 73 06 48 01 fb
> 49 89 df 4c 89 7d d8 49 8b
> bd 20 01 00 00 48 89 7d e0 49 8b bd e0 00 00 00 <48> 8b 7f 20 48 01 d7
> 48 89 7d e8 48 89 e9 48 83 c
> 1 d0 48 8b 7d c8
>
> [ 1.090635] RSP: 0018:ffffc90000197dc8 EFLAGS: 00010282
>
> [ 1.091100] RAX: 0000000000000000 RBX: ffff888005a60458 RCX:
> 0000000000000024
> [ 1.091727] RDX: 00000000000002f0 RSI: 0000000000000509 RDI:
> 0000000000000000
> [ 1.092384] RBP: ffffc90000197e20 R08: 0000000000000001 R09:
> 0000000000000000
> [ 1.093014] R10: 0000000000000002 R11: 0000000000000000 R12:
> 0000000000020000
> [ 1.093660] R13: ffff888006199800 R14: ffff88800474c480 R15:
> ffff888005a60458
> [ 1.094314] ? bpf_prog_0a182df2d34af188_dump_bpf_prog+0xc8/0xbc8
> [ 1.094871] bpf_iter_run_prog+0x75/0x160
> [ 1.095231] __bpf_prog_seq_show+0x39/0x40
> [ 1.095602] bpf_seq_read+0xf6/0x3d0
> [ 1.095915] vfs_read+0xa3/0x1b0
> [ 1.096226] ksys_read+0x4f/0xc0
> [ 1.096527] do_syscall_64+0x2d/0x40
> [ 1.096831] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 1.097287] RIP: 0033:0x7f13a43e3ec2
> [ 1.097625] Code: c0 e9 b2 fe ff ff 50 48 8d 3d aa 36 0a 00 e8 65 eb
> 01 00 0f 1f 44 00 00 f3 0f
> 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77
> 56 c3 0f 1f 44 00 00 48 83 e
> c 28 48 89 54 24
> [ 1.099232] RSP: 002b:00007fffed256bb8 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000000
> [ 1.099922] RAX: ffffffffffffffda RBX: 0000000000020000 RCX:
> 00007f13a43e3ec2
> [ 1.100576] RDX: 0000000000020000 RSI: 00007f13a42d0000 RDI:
> 0000000000000003
> [ 1.101197] RBP: 00007f13a42d0000 R08: 00007f13a42cf010 R09:
> 0000000000000000
> [ 1.101868] R10: 0000000000000022 R11: 0000000000000246 R12:
> 0000561599794c00
> [ 1.102486] R13: 0000000000000003 R14: 0000000000020000 R15:
> 0000000000020000
>
> Note that above `cat` is called during /sbin/init init process.
> ......
> [ 0.964879] Run /sbin/init as init process
>
> starting pid 84, tty '': '/etc/init.d/rcS'
> ......
>
> I checked the assembly code and the above error info and the reason
> is due to an exception (address 0) happens in bpf_prog iterator.
>
> SEC("iter/bpf_prog")
> int dump_bpf_prog(struct bpf_iter__bpf_prog *ctx)
> {
> struct seq_file *seq = ctx->meta->seq;
> __u64 seq_num = ctx->meta->seq_num;
> struct bpf_prog *prog = ctx->prog;
> struct bpf_prog_aux *aux;
>
> if (!prog)
> return 0;
>
> aux = prog->aux;
> if (seq_num == 0)
> BPF_SEQ_PRINTF(seq, " id name attached\n");
>
> BPF_SEQ_PRINTF(seq, "%4u %-16s %s %s\n", aux->id,
> get_name(aux->btf, aux->func_info[0].type_id,
> aux->name),
> aux->attach_func_name, aux->dst_prog->aux->name);
> return 0;
> }
>
> In the above, aux->dst_prog == 0 and exception does not get caught
> properly and kernel complains. This might be due to
> ths `cat /sys/fs/bpf/progs.debug` is called too early (in init process)
> and something is not set up properly yet.
>
> In a different rootfs, I called `cat /sys/fs/bpf/progs.debug` after
> login prompt, and I did not see the error.
>
> If somebody knows what is the possible reason, that will be great.
> Otherwise, I will continue to debug this later.
>
> > ---
> > tools/testing/selftests/bpf/run_in_vm.sh | 353 +++++++++++++++++++++++
> > 1 file changed, 353 insertions(+)
> > create mode 100755 tools/testing/selftests/bpf/run_in_vm.sh
> >
> > diff --git a/tools/testing/selftests/bpf/run_in_vm.sh b/tools/testing/selftests/bpf/run_in_vm.sh
> > new file mode 100755
> > index 000000000000..09bb9705acb3
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/run_in_vm.sh
> > @@ -0,0 +1,353 @@
> > +#!/bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +set -u
> > +set -e
> > +
> > +QEMU_BINARY="${QEMU_BINARY:="qemu-system-x86_64"}"
> > +X86_BZIMAGE="arch/x86/boot/bzImage"
> > +DEFAULT_COMMAND="./test_progs"
> > +MOUNT_DIR="mnt"
> > +ROOTFS_IMAGE="root.img"
> > +OUTPUT_DIR="$HOME/.bpf_selftests"
> > +KCONFIG_URL="https://raw.githubusercontent.com/libbpf/libbpf/master/travis-ci/vmtest/configs/latest.config "
> > +INDEX_URL="https://raw.githubusercontent.com/libbpf/libbpf/master/travis-ci/vmtest/configs/INDEX "
> > +NUM_COMPILE_JOBS="$(nproc)"
> > +
> > +usage()
> > +{
> > + cat <<EOF
> > +Usage: $0 [-k] [-i] [-d <output_dir>] -- [<command>]
> > +
> > +<command> is the command you would normally run when you are in
> > +tools/testing/selftests/bpf. e.g:
> > +
> > + $0 -- ./test_progs -t test_lsm
> > +
> > +If no command is specified, "${DEFAULT_COMMAND}" will be run by
> > +default.
> > +
> > +If you build your kernel using KBUILD_OUTPUT= or O= options, these
> > +can be passed as environment variables to the script:
> > +
> > + O=<path_relative_to_cwd> $0 -- ./test_progs -t test_lsm
> > +
> > +or
> > +
> > + KBUILD_OUTPUT=<path_relative_to_cwd> $0 -- ./test_progs -t test_lsm
> > +
> > +Options:
> > +
> > + -k) "Keep the kernel", i.e. don't recompile the kernel if it exists.
> > + -i) Update the rootfs image with a newer version.
> > + -d) Update the output directory (default: ${OUTPUT_DIR})
> > + -j) Number of jobs for compilation, similar to -j in make
> > + (default: ${NUM_COMPILE_JOBS})
> > +EOF
> > +}
> > +
> [...]
