diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/lib/bpf/bpf_helpers.h | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/lib/bpf/bpf_helpers.h')
-rw-r--r-- | tools/lib/bpf/bpf_helpers.h | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h new file mode 100644 index 000000000..1c389b0f5 --- /dev/null +++ b/tools/lib/bpf/bpf_helpers.h @@ -0,0 +1,136 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ +#ifndef __BPF_HELPERS__ +#define __BPF_HELPERS__ + +/* + * Note that bpf programs need to include either + * vmlinux.h (auto-generated from BTF) or linux/types.h + * in advance since bpf_helper_defs.h uses such types + * as __u64. + */ +#include "bpf_helper_defs.h" + +#define __uint(name, val) int (*name)[val] +#define __type(name, val) typeof(val) *name +#define __array(name, val) typeof(val) *name[] + +/* Helper macro to print out debug messages */ +#define bpf_printk(fmt, ...) \ +({ \ + char ____fmt[] = fmt; \ + bpf_trace_printk(____fmt, sizeof(____fmt), \ + ##__VA_ARGS__); \ +}) + +/* + * Helper macro to place programs, maps, license in + * different sections in elf_bpf file. Section names + * are interpreted by elf_bpf loader + */ +#define SEC(NAME) __attribute__((section(NAME), used)) + +#ifndef __always_inline +#define __always_inline __attribute__((always_inline)) +#endif +#ifndef __noinline +#define __noinline __attribute__((noinline)) +#endif +#ifndef __weak +#define __weak __attribute__((weak)) +#endif + +/* + * Helper macro to manipulate data structures + */ + +/* offsetof() definition that uses __builtin_offset() might not preserve field + * offset CO-RE relocation properly, so force-redefine offsetof() using + * old-school approach which works with CO-RE correctly + */ +#undef offsetof +#define offsetof(type, member) ((unsigned long)&((type *)0)->member) + +/* redefined container_of() to ensure we use the above offsetof() macro */ +#undef container_of +#define container_of(ptr, type, member) \ + ({ \ + void *__mptr = (void *)(ptr); \ + ((type *)(__mptr - offsetof(type, member))); \ + }) + +/* + * Helper macro to throw a compilation error if __bpf_unreachable() gets + * built into the resulting code. This works given BPF back end does not + * implement __builtin_trap(). This is useful to assert that certain paths + * of the program code are never used and hence eliminated by the compiler. + * + * For example, consider a switch statement that covers known cases used by + * the program. __bpf_unreachable() can then reside in the default case. If + * the program gets extended such that a case is not covered in the switch + * statement, then it will throw a build error due to the default case not + * being compiled out. + */ +#ifndef __bpf_unreachable +# define __bpf_unreachable() __builtin_trap() +#endif + +/* + * Helper function to perform a tail call with a constant/immediate map slot. + */ +#if __clang_major__ >= 8 && defined(__bpf__) +static __always_inline void +bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) +{ + if (!__builtin_constant_p(slot)) + __bpf_unreachable(); + + /* + * Provide a hard guarantee that LLVM won't optimize setting r2 (map + * pointer) and r3 (constant map index) from _different paths_ ending + * up at the _same_ call insn as otherwise we won't be able to use the + * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel + * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key + * tracking for prog array pokes") for details on verifier tracking. + * + * Note on clobber list: we need to stay in-line with BPF calling + * convention, so even if we don't end up using r0, r4, r5, we need + * to mark them as clobber so that LLVM doesn't end up using them + * before / after the call. + */ + asm volatile("r1 = %[ctx]\n\t" + "r2 = %[map]\n\t" + "r3 = %[slot]\n\t" + "call 12" + :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) + : "r0", "r1", "r2", "r3", "r4", "r5"); +} +#endif + +/* + * Helper structure used by eBPF C program + * to describe BPF map attributes to libbpf loader + */ +struct bpf_map_def { + unsigned int type; + unsigned int key_size; + unsigned int value_size; + unsigned int max_entries; + unsigned int map_flags; +}; + +enum libbpf_pin_type { + LIBBPF_PIN_NONE, + /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */ + LIBBPF_PIN_BY_NAME, +}; + +enum libbpf_tristate { + TRI_NO = 0, + TRI_YES = 1, + TRI_MODULE = 2, +}; + +#define __kconfig __attribute__((section(".kconfig"))) +#define __ksym __attribute__((section(".ksyms"))) + +#endif |