2019-08-16 05:45:43 +00:00
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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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selftests/bpf: add bpf-gcc support
Now that binutils and gcc support for BPF is upstream, make use of it in
BPF selftests using alu32-like approach. Share as much as possible of
CFLAGS calculation with clang.
Fixes only obvious issues, leaving more complex ones for later:
- Use gcc-provided bpf-helpers.h instead of manually defining the
helpers, change bpf_helpers.h include guard to avoid conflict.
- Include <linux/stddef.h> for __always_inline.
- Add $(OUTPUT)/../usr/include to include path in order to use local
kernel headers instead of system kernel headers when building with O=.
In order to activate the bpf-gcc support, one needs to configure
binutils and gcc with --target=bpf and make them available in $PATH. In
particular, gcc must be installed as `bpf-gcc`, which is the default.
Right now with binutils 25a2915e8dba and gcc r275589 only a handful of
tests work:
# ./test_progs_bpf_gcc
# Summary: 7/39 PASSED, 1 SKIPPED, 98 FAILED
The reason for those failures are as follows:
- Build errors:
- `error: too many function arguments for eBPF` for __always_inline
functions read_str_var and read_map_var - must be inlining issue,
and for process_l3_headers_v6, which relies on optimizing away
function arguments.
- `error: indirect call in function, which are not supported by eBPF`
where there are no obvious indirect calls in the source calls, e.g.
in __encap_ipip_none.
- `error: field 'lock' has incomplete type` for fields of `struct
bpf_spin_lock` type - bpf_spin_lock is re#defined by bpf-helpers.h,
so its usage is sensitive to order of #includes.
- `error: eBPF stack limit exceeded` in sysctl_tcp_mem.
- Load errors:
- Missing object files due to above build errors.
- `libbpf: failed to create map (name: 'test_ver.bss')`.
- `libbpf: object file doesn't contain bpf program`.
- `libbpf: Program '.text' contains unrecognized relo data pointing to
section 0`.
- `libbpf: BTF is required, but is missing or corrupted` - no BTF
support in gcc yet.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Jose E. Marchesi <jose.marchesi@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-09-12 16:05:43 +00:00
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#ifndef __BPF_HELPERS__
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#define __BPF_HELPERS__
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2014-12-01 23:06:37 +00:00
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2020-04-21 00:05:27 +00:00
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/*
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* Note that bpf programs need to include either
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* vmlinux.h (auto-generated from BTF) or linux/types.h
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* in advance since bpf_helper_defs.h uses such types
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* as __u64.
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*/
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2019-10-07 03:07:38 +00:00
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#include "bpf_helper_defs.h"
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2019-07-05 15:50:10 +00:00
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#define __uint(name, val) int (*name)[val]
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2019-10-04 04:02:11 +00:00
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#define __type(name, val) typeof(val) *name
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2019-07-05 15:50:10 +00:00
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2019-10-08 17:59:41 +00:00
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/* Helper macro to print out debug messages */
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2019-05-23 12:53:54 +00:00
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#define bpf_printk(fmt, ...) \
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({ \
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char ____fmt[] = fmt; \
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bpf_trace_printk(____fmt, sizeof(____fmt), \
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##__VA_ARGS__); \
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})
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2019-10-08 17:59:41 +00:00
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/*
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* Helper macro to place programs, maps, license in
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selftests/bpf: add bpf-gcc support
Now that binutils and gcc support for BPF is upstream, make use of it in
BPF selftests using alu32-like approach. Share as much as possible of
CFLAGS calculation with clang.
Fixes only obvious issues, leaving more complex ones for later:
- Use gcc-provided bpf-helpers.h instead of manually defining the
helpers, change bpf_helpers.h include guard to avoid conflict.
- Include <linux/stddef.h> for __always_inline.
- Add $(OUTPUT)/../usr/include to include path in order to use local
kernel headers instead of system kernel headers when building with O=.
In order to activate the bpf-gcc support, one needs to configure
binutils and gcc with --target=bpf and make them available in $PATH. In
particular, gcc must be installed as `bpf-gcc`, which is the default.
Right now with binutils 25a2915e8dba and gcc r275589 only a handful of
tests work:
# ./test_progs_bpf_gcc
# Summary: 7/39 PASSED, 1 SKIPPED, 98 FAILED
The reason for those failures are as follows:
- Build errors:
- `error: too many function arguments for eBPF` for __always_inline
functions read_str_var and read_map_var - must be inlining issue,
and for process_l3_headers_v6, which relies on optimizing away
function arguments.
- `error: indirect call in function, which are not supported by eBPF`
where there are no obvious indirect calls in the source calls, e.g.
in __encap_ipip_none.
- `error: field 'lock' has incomplete type` for fields of `struct
bpf_spin_lock` type - bpf_spin_lock is re#defined by bpf-helpers.h,
so its usage is sensitive to order of #includes.
- `error: eBPF stack limit exceeded` in sysctl_tcp_mem.
- Load errors:
- Missing object files due to above build errors.
- `libbpf: failed to create map (name: 'test_ver.bss')`.
- `libbpf: object file doesn't contain bpf program`.
- `libbpf: Program '.text' contains unrecognized relo data pointing to
section 0`.
- `libbpf: BTF is required, but is missing or corrupted` - no BTF
support in gcc yet.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Jose E. Marchesi <jose.marchesi@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-09-12 16:05:43 +00:00
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* different sections in elf_bpf file. Section names
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* are interpreted by elf_bpf loader
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*/
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#define SEC(NAME) __attribute__((section(NAME), used))
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2019-10-08 17:59:41 +00:00
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#ifndef __always_inline
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#define __always_inline __attribute__((always_inline))
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#endif
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libbpf: Support libbpf-provided extern variables
Add support for extern variables, provided to BPF program by libbpf. Currently
the following extern variables are supported:
- LINUX_KERNEL_VERSION; version of a kernel in which BPF program is
executing, follows KERNEL_VERSION() macro convention, can be 4- and 8-byte
long;
- CONFIG_xxx values; a set of values of actual kernel config. Tristate,
boolean, strings, and integer values are supported.
Set of possible values is determined by declared type of extern variable.
Supported types of variables are:
- Tristate values. Are represented as `enum libbpf_tristate`. Accepted values
are **strictly** 'y', 'n', or 'm', which are represented as TRI_YES, TRI_NO,
or TRI_MODULE, respectively.
- Boolean values. Are represented as bool (_Bool) types. Accepted values are
'y' and 'n' only, turning into true/false values, respectively.
- Single-character values. Can be used both as a substritute for
bool/tristate, or as a small-range integer:
- 'y'/'n'/'m' are represented as is, as characters 'y', 'n', or 'm';
- integers in a range [-128, 127] or [0, 255] (depending on signedness of
char in target architecture) are recognized and represented with
respective values of char type.
- Strings. String values are declared as fixed-length char arrays. String of
up to that length will be accepted and put in first N bytes of char array,
with the rest of bytes zeroed out. If config string value is longer than
space alloted, it will be truncated and warning message emitted. Char array
is always zero terminated. String literals in config have to be enclosed in
double quotes, just like C-style string literals.
- Integers. 8-, 16-, 32-, and 64-bit integers are supported, both signed and
unsigned variants. Libbpf enforces parsed config value to be in the
supported range of corresponding integer type. Integers values in config can
be:
- decimal integers, with optional + and - signs;
- hexadecimal integers, prefixed with 0x or 0X;
- octal integers, starting with 0.
Config file itself is searched in /boot/config-$(uname -r) location with
fallback to /proc/config.gz, unless config path is specified explicitly
through bpf_object_open_opts' kernel_config_path option. Both gzipped and
plain text formats are supported. Libbpf adds explicit dependency on zlib
because of this, but this shouldn't be a problem, given libelf already depends
on zlib.
All detected extern variables, are put into a separate .extern internal map.
It, similarly to .rodata map, is marked as read-only from BPF program side, as
well as is frozen on load. This allows BPF verifier to track extern values as
constants and perform enhanced branch prediction and dead code elimination.
This can be relied upon for doing kernel version/feature detection and using
potentially unsupported field relocations or BPF helpers in a CO-RE-based BPF
program, while still having a single version of BPF program running on old and
new kernels. Selftests are validating this explicitly for unexisting BPF
helper.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191214014710.3449601-3-andriin@fb.com
2019-12-14 01:47:08 +00:00
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#ifndef __weak
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#define __weak __attribute__((weak))
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#endif
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2019-10-08 17:59:41 +00:00
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/*
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* Helper structure used by eBPF C program
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2019-10-08 17:59:37 +00:00
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* to describe BPF map attributes to libbpf loader
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2014-12-01 23:06:37 +00:00
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*/
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struct bpf_map_def {
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unsigned int type;
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unsigned int key_size;
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unsigned int value_size;
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unsigned int max_entries;
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2016-03-08 05:57:20 +00:00
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unsigned int map_flags;
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2014-12-01 23:06:37 +00:00
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};
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2019-11-02 11:09:41 +00:00
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enum libbpf_pin_type {
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LIBBPF_PIN_NONE,
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/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
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LIBBPF_PIN_BY_NAME,
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};
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libbpf: Support libbpf-provided extern variables
Add support for extern variables, provided to BPF program by libbpf. Currently
the following extern variables are supported:
- LINUX_KERNEL_VERSION; version of a kernel in which BPF program is
executing, follows KERNEL_VERSION() macro convention, can be 4- and 8-byte
long;
- CONFIG_xxx values; a set of values of actual kernel config. Tristate,
boolean, strings, and integer values are supported.
Set of possible values is determined by declared type of extern variable.
Supported types of variables are:
- Tristate values. Are represented as `enum libbpf_tristate`. Accepted values
are **strictly** 'y', 'n', or 'm', which are represented as TRI_YES, TRI_NO,
or TRI_MODULE, respectively.
- Boolean values. Are represented as bool (_Bool) types. Accepted values are
'y' and 'n' only, turning into true/false values, respectively.
- Single-character values. Can be used both as a substritute for
bool/tristate, or as a small-range integer:
- 'y'/'n'/'m' are represented as is, as characters 'y', 'n', or 'm';
- integers in a range [-128, 127] or [0, 255] (depending on signedness of
char in target architecture) are recognized and represented with
respective values of char type.
- Strings. String values are declared as fixed-length char arrays. String of
up to that length will be accepted and put in first N bytes of char array,
with the rest of bytes zeroed out. If config string value is longer than
space alloted, it will be truncated and warning message emitted. Char array
is always zero terminated. String literals in config have to be enclosed in
double quotes, just like C-style string literals.
- Integers. 8-, 16-, 32-, and 64-bit integers are supported, both signed and
unsigned variants. Libbpf enforces parsed config value to be in the
supported range of corresponding integer type. Integers values in config can
be:
- decimal integers, with optional + and - signs;
- hexadecimal integers, prefixed with 0x or 0X;
- octal integers, starting with 0.
Config file itself is searched in /boot/config-$(uname -r) location with
fallback to /proc/config.gz, unless config path is specified explicitly
through bpf_object_open_opts' kernel_config_path option. Both gzipped and
plain text formats are supported. Libbpf adds explicit dependency on zlib
because of this, but this shouldn't be a problem, given libelf already depends
on zlib.
All detected extern variables, are put into a separate .extern internal map.
It, similarly to .rodata map, is marked as read-only from BPF program side, as
well as is frozen on load. This allows BPF verifier to track extern values as
constants and perform enhanced branch prediction and dead code elimination.
This can be relied upon for doing kernel version/feature detection and using
potentially unsupported field relocations or BPF helpers in a CO-RE-based BPF
program, while still having a single version of BPF program running on old and
new kernels. Selftests are validating this explicitly for unexisting BPF
helper.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191214014710.3449601-3-andriin@fb.com
2019-12-14 01:47:08 +00:00
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enum libbpf_tristate {
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TRI_NO = 0,
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TRI_YES = 1,
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TRI_MODULE = 2,
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};
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2019-12-19 00:28:34 +00:00
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#define __kconfig __attribute__((section(".kconfig")))
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2014-12-01 23:06:37 +00:00
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#endif
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