linux.git/tools/bpf/bpftool, branch v6.9 Linux kernel source tree libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVM 2024-03-15T21:24:00+00:00 Alexei Starovoitov ast@kernel.org 2024-03-15T02:18:32+00:00 10ebe835c937a11870690aa44c7c970fe906ff54 The selftests use to tell LLVM about special pointers. For LLVM there is nothing "arena" about them. They are simply pointers in a different address space. Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed: . macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST . global variables in __attribute__((address_space(N))) are now placed in section named ".addr_space.N" instead of ".arena.N". Adjust libbpf, bpftool, and selftests to match LLVM. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/bpf/20240315021834.62988-3-alexei.starovoitov@gmail.com 
The selftests use
to tell LLVM about special pointers. For LLVM there is nothing "arena"
about them. They are simply pointers in a different address space.
Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed:
. macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST
. global variables in __attribute__((address_space(N))) are now
  placed in section named ".addr_space.N" instead of ".arena.N".

Adjust libbpf, bpftool, and selftests to match LLVM.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20240315021834.62988-3-alexei.starovoitov@gmail.com
libbpf: Recognize __arena global variables. 2024-03-11T22:43:35+00:00 Andrii Nakryiko andrii@kernel.org 2024-03-08T01:08:08+00:00 2e7ba4f8fd1fa879b37db0b738c23ba2af8292ee LLVM automatically places __arena variables into ".arena.1" ELF section. In order to use such global variables bpf program must include definition of arena map in ".maps" section, like: struct { __uint(type, BPF_MAP_TYPE_ARENA); __uint(map_flags, BPF_F_MMAPABLE); __uint(max_entries, 1000); /* number of pages */ __ulong(map_extra, 2ull << 44); /* start of mmap() region */ } arena SEC(".maps"); libbpf recognizes both uses of arena and creates single `struct bpf_map *` instance in libbpf APIs. ".arena.1" ELF section data is used as initial data image, which is exposed through skeleton and bpf_map__initial_value() to the user, if they need to tune it before the load phase. During load phase, this initial image is copied over into mmap()'ed region corresponding to arena, and discarded. Few small checks here and there had to be added to make sure this approach works with bpf_map__initial_value(), mostly due to hard-coded assumption that map->mmaped is set up with mmap() syscall and should be munmap()'ed. For arena, .arena.1 can be (much) smaller than maximum arena size, so this smaller data size has to be tracked separately. Given it is enforced that there is only one arena for entire bpf_object instance, we just keep it in a separate field. This can be generalized if necessary later. All global variables from ".arena.1" section are accessible from user space via skel->arena->name_of_var. For bss/data/rodata the skeleton/libbpf perform the following sequence: 1. addr = mmap(MAP_ANONYMOUS) 2. user space optionally modifies global vars 3. map_fd = bpf_create_map() 4. bpf_update_map_elem(map_fd, addr) // to store values into the kernel 5. mmap(addr, MAP_FIXED, map_fd) after step 5 user spaces see the values it wrote at step 2 at the same addresses arena doesn't support update_map_elem. Hence skeleton/libbpf do: 1. addr = malloc(sizeof SEC ".arena.1") 2. user space optionally modifies global vars 3. map_fd = bpf_create_map(MAP_TYPE_ARENA) 4. real_addr = mmap(map->map_extra, MAP_SHARED | MAP_FIXED, map_fd) 5. memcpy(real_addr, addr) // this will fault-in and allocate pages At the end look and feel of global data vs __arena global data is the same from bpf prog pov. Another complication is: struct { __uint(type, BPF_MAP_TYPE_ARENA); } arena SEC(".maps"); int __arena foo; int bar; ptr1 = &foo; // relocation against ".arena.1" section ptr2 = &arena; // relocation against ".maps" section ptr3 = &bar; // relocation against ".bss" section Fo the kernel ptr1 and ptr2 has point to the same arena's map_fd while ptr3 points to a different global array's map_fd. For the verifier: ptr1->type == unknown_scalar ptr2->type == const_ptr_to_map ptr3->type == ptr_to_map_value After verification, from JIT pov all 3 ptr-s are normal ld_imm64 insns. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240308010812.89848-11-alexei.starovoitov@gmail.com 
LLVM automatically places __arena variables into ".arena.1" ELF section.
In order to use such global variables bpf program must include definition
of arena map in ".maps" section, like:
struct {
       __uint(type, BPF_MAP_TYPE_ARENA);
       __uint(map_flags, BPF_F_MMAPABLE);
       __uint(max_entries, 1000);         /* number of pages */
       __ulong(map_extra, 2ull << 44);    /* start of mmap() region */
} arena SEC(".maps");

libbpf recognizes both uses of arena and creates single `struct bpf_map *`
instance in libbpf APIs.
".arena.1" ELF section data is used as initial data image, which is exposed
through skeleton and bpf_map__initial_value() to the user, if they need to tune
it before the load phase. During load phase, this initial image is copied over
into mmap()'ed region corresponding to arena, and discarded.

Few small checks here and there had to be added to make sure this
approach works with bpf_map__initial_value(), mostly due to hard-coded
assumption that map->mmaped is set up with mmap() syscall and should be
munmap()'ed. For arena, .arena.1 can be (much) smaller than maximum
arena size, so this smaller data size has to be tracked separately.
Given it is enforced that there is only one arena for entire bpf_object
instance, we just keep it in a separate field. This can be generalized
if necessary later.

All global variables from ".arena.1" section are accessible from user space
via skel->arena->name_of_var.

For bss/data/rodata the skeleton/libbpf perform the following sequence:
1. addr = mmap(MAP_ANONYMOUS)
2. user space optionally modifies global vars
3. map_fd = bpf_create_map()
4. bpf_update_map_elem(map_fd, addr) // to store values into the kernel
5. mmap(addr, MAP_FIXED, map_fd)
after step 5 user spaces see the values it wrote at step 2 at the same addresses

arena doesn't support update_map_elem. Hence skeleton/libbpf do:
1. addr = malloc(sizeof SEC ".arena.1")
2. user space optionally modifies global vars
3. map_fd = bpf_create_map(MAP_TYPE_ARENA)
4. real_addr = mmap(map->map_extra, MAP_SHARED | MAP_FIXED, map_fd)
5. memcpy(real_addr, addr) // this will fault-in and allocate pages

At the end look and feel of global data vs __arena global data is the same from
bpf prog pov.

Another complication is:
struct {
  __uint(type, BPF_MAP_TYPE_ARENA);
} arena SEC(".maps");

int __arena foo;
int bar;

  ptr1 = &foo;   // relocation against ".arena.1" section
  ptr2 = &arena; // relocation against ".maps" section
  ptr3 = &bar;   // relocation against ".bss" section

Fo the kernel ptr1 and ptr2 has point to the same arena's map_fd
while ptr3 points to a different global array's map_fd.
For the verifier:
ptr1->type == unknown_scalar
ptr2->type == const_ptr_to_map
ptr3->type == ptr_to_map_value

After verification, from JIT pov all 3 ptr-s are normal ld_imm64 insns.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20240308010812.89848-11-alexei.starovoitov@gmail.com
bpftool: Recognize arena map type 2024-03-11T22:37:24+00:00 Alexei Starovoitov ast@kernel.org 2024-03-08T01:08:07+00:00 eed512e8ac64339cfc69da1a6a4b60982cb502ca Teach bpftool to recognize arena map type. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240308010812.89848-10-alexei.starovoitov@gmail.com 
Teach bpftool to recognize arena map type.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20240308010812.89848-10-alexei.starovoitov@gmail.com
bpftool: rename is_internal_mmapable_map into is_mmapable_map 2024-03-07T22:58:48+00:00 Andrii Nakryiko andrii@kernel.org 2024-03-07T03:12:27+00:00 1576b07961971d4eeb0e269c7133e9a6d430daf8 It's not restricted to working with "internal" maps, it cares about any map that can be mmap'ed. Reflect that in more succinct and generic name. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/r/20240307031228.42896-6-alexei.starovoitov@gmail.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
It's not restricted to working with "internal" maps, it cares about any
map that can be mmap'ed. Reflect that in more succinct and generic name.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20240307031228.42896-6-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
bpftool: Add an example for struct_ops map and shadow type. 2024-02-29T22:23:53+00:00 Kui-Feng Lee thinker.li@gmail.com 2024-02-29T06:45:22+00:00 f2e81192e07e87897ff1296c96775eceea8f582a The example in bpftool-gen.8 explains how to use the pointer of the shadow type to change the value of a field of a struct_ops map. Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240229064523.2091270-5-thinker.li@gmail.com 
The example in bpftool-gen.8 explains how to use the pointer of the shadow
type to change the value of a field of a struct_ops map.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20240229064523.2091270-5-thinker.li@gmail.com
bpftool: Generated shadow variables for struct_ops maps. 2024-02-29T22:23:53+00:00 Kui-Feng Lee thinker.li@gmail.com 2024-02-29T06:45:21+00:00 a7b0fa352eafef95bd0d736ca94965d3f884ad18 Declares and defines a pointer of the shadow type for each struct_ops map. The code generator will create an anonymous struct type as the shadow type for each struct_ops map. The shadow type is translated from the original struct type of the map. The user of the skeleton use pointers of them to access the values of struct_ops maps. However, shadow types only supports certain types of fields, including scalar types and function pointers. Any fields of unsupported types are translated into an array of characters to occupy the space of the original field. Function pointers are translated into pointers of the struct bpf_program. Additionally, padding fields are generated to occupy the space between two consecutive fields. The pointers of shadow types of struct_osp maps are initialized when *__open_opts() in skeletons are called. For a map called FOO, the user can access it through the pointer at skel->struct_ops.FOO. Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240229064523.2091270-4-thinker.li@gmail.com 
Declares and defines a pointer of the shadow type for each struct_ops map.

The code generator will create an anonymous struct type as the shadow type
for each struct_ops map. The shadow type is translated from the original
struct type of the map. The user of the skeleton use pointers of them to
access the values of struct_ops maps.

However, shadow types only supports certain types of fields, including
scalar types and function pointers. Any fields of unsupported types are
translated into an array of characters to occupy the space of the original
field. Function pointers are translated into pointers of the struct
bpf_program. Additionally, padding fields are generated to occupy the space
between two consecutive fields.

The pointers of shadow types of struct_osp maps are initialized when
*__open_opts() in skeletons are called. For a map called FOO, the user can
access it through the pointer at skel->struct_ops.FOO.

Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20240229064523.2091270-4-thinker.li@gmail.com
bpftool: Be more portable by using POSIX's basename() 2024-01-29T15:08:46+00:00 Arnaldo Carvalho de Melo acme@kernel.org 2024-01-29T14:33:26+00:00 29788f39a4171dd48a6d19eb78cf2ab168c4349a musl libc had the basename() prototype in string.h, but this is a glibc-ism, now they removed the _GNU_SOURCE bits in their devel distro, Alpine Linux edge: https://git.musl-libc.org/cgit/musl/commit/?id=725e17ed6dff4d0cd22487bb64470881e86a92e7 So lets use the POSIX version, the whole rationale is spelled out at: https://gitlab.alpinelinux.org/alpine/aports/-/issues/15643 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jiri Olsa <olsajiri@gmail.com> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/lkml/ZZhsPs00TI75RdAr@kernel.org Link: https://lore.kernel.org/bpf/Zbe3NuOgaupvUcpF@kernel.org 
musl libc had the basename() prototype in string.h, but this is a
glibc-ism, now they removed the _GNU_SOURCE bits in their devel distro,
Alpine Linux edge:

  https://git.musl-libc.org/cgit/musl/commit/?id=725e17ed6dff4d0cd22487bb64470881e86a92e7

So lets use the POSIX version, the whole rationale is spelled out at:

  https://gitlab.alpinelinux.org/alpine/aports/-/issues/15643

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/lkml/ZZhsPs00TI75RdAr@kernel.org
Link: https://lore.kernel.org/bpf/Zbe3NuOgaupvUcpF@kernel.org
bpftool: Display cookie for kprobe multi link 2024-01-24T00:05:28+00:00 Jiri Olsa jolsa@kernel.org 2024-01-19T11:05:05+00:00 b0dc037399b19a777d569dbd9e2e9bbd62f3b3b1 Displaying cookies for kprobe multi link, in plain mode: # bpftool link ... 1397: kprobe_multi prog 47532 kretprobe.multi func_cnt 3 addr cookie func [module] ffffffff82b370c0 3 bpf_fentry_test1 ffffffff82b39780 1 bpf_fentry_test2 ffffffff82b397a0 2 bpf_fentry_test3 And in json mode: # bpftool link -j | jq ... { "id": 1397, "type": "kprobe_multi", "prog_id": 47532, "retprobe": true, "func_cnt": 3, "missed": 0, "funcs": [ { "addr": 18446744071607382208, "func": "bpf_fentry_test1", "module": null, "cookie": 3 }, { "addr": 18446744071607392128, "func": "bpf_fentry_test2", "module": null, "cookie": 1 }, { "addr": 18446744071607392160, "func": "bpf_fentry_test3", "module": null, "cookie": 2 } ] } Cookie is attached to specific address, and because we sort addresses before printing, we need to sort cookies the same way, hence adding the struct addr_cookie to keep and sort them together. Also adding missing dd.sym_count check to show_kprobe_multi_json. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20240119110505.400573-9-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Displaying cookies for kprobe multi link, in plain mode:

  # bpftool link
  ...
  1397: kprobe_multi  prog 47532
          kretprobe.multi  func_cnt 3
          addr             cookie           func [module]
          ffffffff82b370c0 3                bpf_fentry_test1
          ffffffff82b39780 1                bpf_fentry_test2
          ffffffff82b397a0 2                bpf_fentry_test3

And in json mode:

  # bpftool link -j | jq
  ...
    {
      "id": 1397,
      "type": "kprobe_multi",
      "prog_id": 47532,
      "retprobe": true,
      "func_cnt": 3,
      "missed": 0,
      "funcs": [
        {
          "addr": 18446744071607382208,
          "func": "bpf_fentry_test1",
          "module": null,
          "cookie": 3
        },
        {
          "addr": 18446744071607392128,
          "func": "bpf_fentry_test2",
          "module": null,
          "cookie": 1
        },
        {
          "addr": 18446744071607392160,
          "func": "bpf_fentry_test3",
          "module": null,
          "cookie": 2
        }
      ]
    }

Cookie is attached to specific address, and because we sort addresses
before printing, we need to sort cookies the same way, hence adding
the struct addr_cookie to keep and sort them together.

Also adding missing dd.sym_count check to show_kprobe_multi_json.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-9-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Display cookie for perf event link probes 2024-01-24T00:05:28+00:00 Jiri Olsa jolsa@kernel.org 2024-01-19T11:05:04+00:00 54258324b934aa8552c239c443272ec7aea55285 Displaying cookie for perf event link probes, in plain mode: # bpftool link 17: perf_event prog 90 kprobe ffffffff82b1c2b0 bpf_fentry_test1 cookie 3735928559 18: perf_event prog 90 kretprobe ffffffff82b1c2b0 bpf_fentry_test1 cookie 3735928559 20: perf_event prog 92 tracepoint sched_switch cookie 3735928559 21: perf_event prog 93 event software:page-faults cookie 3735928559 22: perf_event prog 91 uprobe /proc/self/exe+0xd703c cookie 3735928559 And in json mode: # bpftool link -j | jq { "id": 30, "type": "perf_event", "prog_id": 160, "retprobe": false, "addr": 18446744071607272112, "func": "bpf_fentry_test1", "offset": 0, "missed": 0, "cookie": 3735928559 } { "id": 33, "type": "perf_event", "prog_id": 162, "tracepoint": "sched_switch", "cookie": 3735928559 } { "id": 34, "type": "perf_event", "prog_id": 163, "event_type": "software", "event_config": "page-faults", "cookie": 3735928559 } { "id": 35, "type": "perf_event", "prog_id": 161, "retprobe": false, "file": "/proc/self/exe", "offset": 880700, "cookie": 3735928559 } Reviewed-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20240119110505.400573-8-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Displaying cookie for perf event link probes, in plain mode:

  # bpftool link
  17: perf_event  prog 90
          kprobe ffffffff82b1c2b0 bpf_fentry_test1  cookie 3735928559
  18: perf_event  prog 90
          kretprobe ffffffff82b1c2b0 bpf_fentry_test1  cookie 3735928559
  20: perf_event  prog 92
          tracepoint sched_switch  cookie 3735928559
  21: perf_event  prog 93
          event software:page-faults  cookie 3735928559
  22: perf_event  prog 91
          uprobe /proc/self/exe+0xd703c  cookie 3735928559

And in json mode:

  # bpftool link -j | jq

  {
    "id": 30,
    "type": "perf_event",
    "prog_id": 160,
    "retprobe": false,
    "addr": 18446744071607272112,
    "func": "bpf_fentry_test1",
    "offset": 0,
    "missed": 0,
    "cookie": 3735928559
  }

  {
    "id": 33,
    "type": "perf_event",
    "prog_id": 162,
    "tracepoint": "sched_switch",
    "cookie": 3735928559
  }

  {
    "id": 34,
    "type": "perf_event",
    "prog_id": 163,
    "event_type": "software",
    "event_config": "page-faults",
    "cookie": 3735928559
  }

  {
    "id": 35,
    "type": "perf_event",
    "prog_id": 161,
    "retprobe": false,
    "file": "/proc/self/exe",
    "offset": 880700,
    "cookie": 3735928559
  }

Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-8-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Fix wrong free call in do_show_link 2024-01-24T00:05:27+00:00 Jiri Olsa jolsa@kernel.org 2024-01-19T11:05:00+00:00 2adb2e0fcdf3c6d8e28a5a9c33e458e1037ae5ad The error path frees wrong array, it should be ref_ctr_offsets. Acked-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Fixes: a7795698f8b6 ("bpftool: Add support to display uprobe_multi links") Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20240119110505.400573-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
The error path frees wrong array, it should be ref_ctr_offsets.

Acked-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Fixes: a7795698f8b6 ("bpftool: Add support to display uprobe_multi links")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-4-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>