| /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ |
| #ifndef __BPF_CORE_READ_H__ |
| #define __BPF_CORE_READ_H__ |
| |
| #include <bpf/bpf_helpers.h> |
| |
| /* |
| * enum bpf_field_info_kind is passed as a second argument into |
| * __builtin_preserve_field_info() built-in to get a specific aspect of |
| * a field, captured as a first argument. __builtin_preserve_field_info(field, |
| * info_kind) returns __u32 integer and produces BTF field relocation, which |
| * is understood and processed by libbpf during BPF object loading. See |
| * selftests/bpf for examples. |
| */ |
| enum bpf_field_info_kind { |
| BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */ |
| BPF_FIELD_BYTE_SIZE = 1, |
| BPF_FIELD_EXISTS = 2, /* field existence in target kernel */ |
| BPF_FIELD_SIGNED = 3, |
| BPF_FIELD_LSHIFT_U64 = 4, |
| BPF_FIELD_RSHIFT_U64 = 5, |
| }; |
| |
| /* second argument to __builtin_btf_type_id() built-in */ |
| enum bpf_type_id_kind { |
| BPF_TYPE_ID_LOCAL = 0, /* BTF type ID in local program */ |
| BPF_TYPE_ID_TARGET = 1, /* BTF type ID in target kernel */ |
| }; |
| |
| /* second argument to __builtin_preserve_type_info() built-in */ |
| enum bpf_type_info_kind { |
| BPF_TYPE_EXISTS = 0, /* type existence in target kernel */ |
| BPF_TYPE_SIZE = 1, /* type size in target kernel */ |
| BPF_TYPE_MATCHES = 2, /* type match in target kernel */ |
| }; |
| |
| /* second argument to __builtin_preserve_enum_value() built-in */ |
| enum bpf_enum_value_kind { |
| BPF_ENUMVAL_EXISTS = 0, /* enum value existence in kernel */ |
| BPF_ENUMVAL_VALUE = 1, /* enum value value relocation */ |
| }; |
| |
| #define __CORE_RELO(src, field, info) \ |
| __builtin_preserve_field_info((src)->field, BPF_FIELD_##info) |
| |
| #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ |
| #define __CORE_BITFIELD_PROBE_READ(dst, src, fld) \ |
| bpf_probe_read_kernel( \ |
| (void *)dst, \ |
| __CORE_RELO(src, fld, BYTE_SIZE), \ |
| (const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET)) |
| #else |
| /* semantics of LSHIFT_64 assumes loading values into low-ordered bytes, so |
| * for big-endian we need to adjust destination pointer accordingly, based on |
| * field byte size |
| */ |
| #define __CORE_BITFIELD_PROBE_READ(dst, src, fld) \ |
| bpf_probe_read_kernel( \ |
| (void *)dst + (8 - __CORE_RELO(src, fld, BYTE_SIZE)), \ |
| __CORE_RELO(src, fld, BYTE_SIZE), \ |
| (const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET)) |
| #endif |
| |
| /* |
| * Extract bitfield, identified by s->field, and return its value as u64. |
| * All this is done in relocatable manner, so bitfield changes such as |
| * signedness, bit size, offset changes, this will be handled automatically. |
| * This version of macro is using bpf_probe_read_kernel() to read underlying |
| * integer storage. Macro functions as an expression and its return type is |
| * bpf_probe_read_kernel()'s return value: 0, on success, <0 on error. |
| */ |
| #define BPF_CORE_READ_BITFIELD_PROBED(s, field) ({ \ |
| unsigned long long val = 0; \ |
| \ |
| __CORE_BITFIELD_PROBE_READ(&val, s, field); \ |
| val <<= __CORE_RELO(s, field, LSHIFT_U64); \ |
| if (__CORE_RELO(s, field, SIGNED)) \ |
| val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64); \ |
| else \ |
| val = val >> __CORE_RELO(s, field, RSHIFT_U64); \ |
| val; \ |
| }) |
| |
| /* |
| * Extract bitfield, identified by s->field, and return its value as u64. |
| * This version of macro is using direct memory reads and should be used from |
| * BPF program types that support such functionality (e.g., typed raw |
| * tracepoints). |
| */ |
| #define BPF_CORE_READ_BITFIELD(s, field) ({ \ |
| const void *p = (const void *)s + __CORE_RELO(s, field, BYTE_OFFSET); \ |
| unsigned long long val; \ |
| \ |
| /* This is a so-called barrier_var() operation that makes specified \ |
| * variable "a black box" for optimizing compiler. \ |
| * It forces compiler to perform BYTE_OFFSET relocation on p and use \ |
| * its calculated value in the switch below, instead of applying \ |
| * the same relocation 4 times for each individual memory load. \ |
| */ \ |
| asm volatile("" : "=r"(p) : "0"(p)); \ |
| \ |
| switch (__CORE_RELO(s, field, BYTE_SIZE)) { \ |
| case 1: val = *(const unsigned char *)p; break; \ |
| case 2: val = *(const unsigned short *)p; break; \ |
| case 4: val = *(const unsigned int *)p; break; \ |
| case 8: val = *(const unsigned long long *)p; break; \ |
| } \ |
| val <<= __CORE_RELO(s, field, LSHIFT_U64); \ |
| if (__CORE_RELO(s, field, SIGNED)) \ |
| val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64); \ |
| else \ |
| val = val >> __CORE_RELO(s, field, RSHIFT_U64); \ |
| val; \ |
| }) |
| |
| /* |
| * Write to a bitfield, identified by s->field. |
| * This is the inverse of BPF_CORE_WRITE_BITFIELD(). |
| */ |
| #define BPF_CORE_WRITE_BITFIELD(s, field, new_val) ({ \ |
| void *p = (void *)s + __CORE_RELO(s, field, BYTE_OFFSET); \ |
| unsigned int byte_size = __CORE_RELO(s, field, BYTE_SIZE); \ |
| unsigned int lshift = __CORE_RELO(s, field, LSHIFT_U64); \ |
| unsigned int rshift = __CORE_RELO(s, field, RSHIFT_U64); \ |
| unsigned long long mask, val, nval = new_val; \ |
| unsigned int rpad = rshift - lshift; \ |
| \ |
| asm volatile("" : "+r"(p)); \ |
| \ |
| switch (byte_size) { \ |
| case 1: val = *(unsigned char *)p; break; \ |
| case 2: val = *(unsigned short *)p; break; \ |
| case 4: val = *(unsigned int *)p; break; \ |
| case 8: val = *(unsigned long long *)p; break; \ |
| } \ |
| \ |
| mask = (~0ULL << rshift) >> lshift; \ |
| val = (val & ~mask) | ((nval << rpad) & mask); \ |
| \ |
| switch (byte_size) { \ |
| case 1: *(unsigned char *)p = val; break; \ |
| case 2: *(unsigned short *)p = val; break; \ |
| case 4: *(unsigned int *)p = val; break; \ |
| case 8: *(unsigned long long *)p = val; break; \ |
| } \ |
| }) |
| |
| /* Differentiator between compilers builtin implementations. This is a |
| * requirement due to the compiler parsing differences where GCC optimizes |
| * early in parsing those constructs of type pointers to the builtin specific |
| * type, resulting in not being possible to collect the required type |
| * information in the builtin expansion. |
| */ |
| #ifdef __clang__ |
| #define ___bpf_typeof(type) ((typeof(type) *) 0) |
| #else |
| #define ___bpf_typeof1(type, NR) ({ \ |
| extern typeof(type) *___concat(bpf_type_tmp_, NR); \ |
| ___concat(bpf_type_tmp_, NR); \ |
| }) |
| #define ___bpf_typeof(type) ___bpf_typeof1(type, __COUNTER__) |
| #endif |
| |
| #ifdef __clang__ |
| #define ___bpf_field_ref1(field) (field) |
| #define ___bpf_field_ref2(type, field) (___bpf_typeof(type)->field) |
| #else |
| #define ___bpf_field_ref1(field) (&(field)) |
| #define ___bpf_field_ref2(type, field) (&(___bpf_typeof(type)->field)) |
| #endif |
| #define ___bpf_field_ref(args...) \ |
| ___bpf_apply(___bpf_field_ref, ___bpf_narg(args))(args) |
| |
| /* |
| * Convenience macro to check that field actually exists in target kernel's. |
| * Returns: |
| * 1, if matching field is present in target kernel; |
| * 0, if no matching field found. |
| * |
| * Supports two forms: |
| * - field reference through variable access: |
| * bpf_core_field_exists(p->my_field); |
| * - field reference through type and field names: |
| * bpf_core_field_exists(struct my_type, my_field). |
| */ |
| #define bpf_core_field_exists(field...) \ |
| __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_EXISTS) |
| |
| /* |
| * Convenience macro to get the byte size of a field. Works for integers, |
| * struct/unions, pointers, arrays, and enums. |
| * |
| * Supports two forms: |
| * - field reference through variable access: |
| * bpf_core_field_size(p->my_field); |
| * - field reference through type and field names: |
| * bpf_core_field_size(struct my_type, my_field). |
| */ |
| #define bpf_core_field_size(field...) \ |
| __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_SIZE) |
| |
| /* |
| * Convenience macro to get field's byte offset. |
| * |
| * Supports two forms: |
| * - field reference through variable access: |
| * bpf_core_field_offset(p->my_field); |
| * - field reference through type and field names: |
| * bpf_core_field_offset(struct my_type, my_field). |
| */ |
| #define bpf_core_field_offset(field...) \ |
| __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_OFFSET) |
| |
| /* |
| * Convenience macro to get BTF type ID of a specified type, using a local BTF |
| * information. Return 32-bit unsigned integer with type ID from program's own |
| * BTF. Always succeeds. |
| */ |
| #define bpf_core_type_id_local(type) \ |
| __builtin_btf_type_id(*___bpf_typeof(type), BPF_TYPE_ID_LOCAL) |
| |
| /* |
| * Convenience macro to get BTF type ID of a target kernel's type that matches |
| * specified local type. |
| * Returns: |
| * - valid 32-bit unsigned type ID in kernel BTF; |
| * - 0, if no matching type was found in a target kernel BTF. |
| */ |
| #define bpf_core_type_id_kernel(type) \ |
| __builtin_btf_type_id(*___bpf_typeof(type), BPF_TYPE_ID_TARGET) |
| |
| /* |
| * Convenience macro to check that provided named type |
| * (struct/union/enum/typedef) exists in a target kernel. |
| * Returns: |
| * 1, if such type is present in target kernel's BTF; |
| * 0, if no matching type is found. |
| */ |
| #define bpf_core_type_exists(type) \ |
| __builtin_preserve_type_info(*___bpf_typeof(type), BPF_TYPE_EXISTS) |
| |
| /* |
| * Convenience macro to check that provided named type |
| * (struct/union/enum/typedef) "matches" that in a target kernel. |
| * Returns: |
| * 1, if the type matches in the target kernel's BTF; |
| * 0, if the type does not match any in the target kernel |
| */ |
| #define bpf_core_type_matches(type) \ |
| __builtin_preserve_type_info(*___bpf_typeof(type), BPF_TYPE_MATCHES) |
| |
| /* |
| * Convenience macro to get the byte size of a provided named type |
| * (struct/union/enum/typedef) in a target kernel. |
| * Returns: |
| * >= 0 size (in bytes), if type is present in target kernel's BTF; |
| * 0, if no matching type is found. |
| */ |
| #define bpf_core_type_size(type) \ |
| __builtin_preserve_type_info(*___bpf_typeof(type), BPF_TYPE_SIZE) |
| |
| /* |
| * Convenience macro to check that provided enumerator value is defined in |
| * a target kernel. |
| * Returns: |
| * 1, if specified enum type and its enumerator value are present in target |
| * kernel's BTF; |
| * 0, if no matching enum and/or enum value within that enum is found. |
| */ |
| #ifdef __clang__ |
| #define bpf_core_enum_value_exists(enum_type, enum_value) \ |
| __builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_EXISTS) |
| #else |
| #define bpf_core_enum_value_exists(enum_type, enum_value) \ |
| __builtin_preserve_enum_value(___bpf_typeof(enum_type), enum_value, BPF_ENUMVAL_EXISTS) |
| #endif |
| |
| /* |
| * Convenience macro to get the integer value of an enumerator value in |
| * a target kernel. |
| * Returns: |
| * 64-bit value, if specified enum type and its enumerator value are |
| * present in target kernel's BTF; |
| * 0, if no matching enum and/or enum value within that enum is found. |
| */ |
| #ifdef __clang__ |
| #define bpf_core_enum_value(enum_type, enum_value) \ |
| __builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_VALUE) |
| #else |
| #define bpf_core_enum_value(enum_type, enum_value) \ |
| __builtin_preserve_enum_value(___bpf_typeof(enum_type), enum_value, BPF_ENUMVAL_VALUE) |
| #endif |
| |
| /* |
| * bpf_core_read() abstracts away bpf_probe_read_kernel() call and captures |
| * offset relocation for source address using __builtin_preserve_access_index() |
| * built-in, provided by Clang. |
| * |
| * __builtin_preserve_access_index() takes as an argument an expression of |
| * taking an address of a field within struct/union. It makes compiler emit |
| * a relocation, which records BTF type ID describing root struct/union and an |
| * accessor string which describes exact embedded field that was used to take |
| * an address. See detailed description of this relocation format and |
| * semantics in comments to struct bpf_core_relo in include/uapi/linux/bpf.h. |
| * |
| * This relocation allows libbpf to adjust BPF instruction to use correct |
| * actual field offset, based on target kernel BTF type that matches original |
| * (local) BTF, used to record relocation. |
| */ |
| #define bpf_core_read(dst, sz, src) \ |
| bpf_probe_read_kernel(dst, sz, (const void *)__builtin_preserve_access_index(src)) |
| |
| /* NOTE: see comments for BPF_CORE_READ_USER() about the proper types use. */ |
| #define bpf_core_read_user(dst, sz, src) \ |
| bpf_probe_read_user(dst, sz, (const void *)__builtin_preserve_access_index(src)) |
| /* |
| * bpf_core_read_str() is a thin wrapper around bpf_probe_read_str() |
| * additionally emitting BPF CO-RE field relocation for specified source |
| * argument. |
| */ |
| #define bpf_core_read_str(dst, sz, src) \ |
| bpf_probe_read_kernel_str(dst, sz, (const void *)__builtin_preserve_access_index(src)) |
| |
| /* NOTE: see comments for BPF_CORE_READ_USER() about the proper types use. */ |
| #define bpf_core_read_user_str(dst, sz, src) \ |
| bpf_probe_read_user_str(dst, sz, (const void *)__builtin_preserve_access_index(src)) |
| |
| extern void *bpf_rdonly_cast(const void *obj, __u32 btf_id) __ksym __weak; |
| |
| /* |
| * Cast provided pointer *ptr* into a pointer to a specified *type* in such |
| * a way that BPF verifier will become aware of associated kernel-side BTF |
| * type. This allows to access members of kernel types directly without the |
| * need to use BPF_CORE_READ() macros. |
| */ |
| #define bpf_core_cast(ptr, type) \ |
| ((typeof(type) *)bpf_rdonly_cast((ptr), bpf_core_type_id_kernel(type))) |
| |
| #define ___concat(a, b) a ## b |
| #define ___apply(fn, n) ___concat(fn, n) |
| #define ___nth(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, __11, N, ...) N |
| |
| /* |
| * return number of provided arguments; used for switch-based variadic macro |
| * definitions (see ___last, ___arrow, etc below) |
| */ |
| #define ___narg(...) ___nth(_, ##__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) |
| /* |
| * return 0 if no arguments are passed, N - otherwise; used for |
| * recursively-defined macros to specify termination (0) case, and generic |
| * (N) case (e.g., ___read_ptrs, ___core_read) |
| */ |
| #define ___empty(...) ___nth(_, ##__VA_ARGS__, N, N, N, N, N, N, N, N, N, N, 0) |
| |
| #define ___last1(x) x |
| #define ___last2(a, x) x |
| #define ___last3(a, b, x) x |
| #define ___last4(a, b, c, x) x |
| #define ___last5(a, b, c, d, x) x |
| #define ___last6(a, b, c, d, e, x) x |
| #define ___last7(a, b, c, d, e, f, x) x |
| #define ___last8(a, b, c, d, e, f, g, x) x |
| #define ___last9(a, b, c, d, e, f, g, h, x) x |
| #define ___last10(a, b, c, d, e, f, g, h, i, x) x |
| #define ___last(...) ___apply(___last, ___narg(__VA_ARGS__))(__VA_ARGS__) |
| |
| #define ___nolast2(a, _) a |
| #define ___nolast3(a, b, _) a, b |
| #define ___nolast4(a, b, c, _) a, b, c |
| #define ___nolast5(a, b, c, d, _) a, b, c, d |
| #define ___nolast6(a, b, c, d, e, _) a, b, c, d, e |
| #define ___nolast7(a, b, c, d, e, f, _) a, b, c, d, e, f |
| #define ___nolast8(a, b, c, d, e, f, g, _) a, b, c, d, e, f, g |
| #define ___nolast9(a, b, c, d, e, f, g, h, _) a, b, c, d, e, f, g, h |
| #define ___nolast10(a, b, c, d, e, f, g, h, i, _) a, b, c, d, e, f, g, h, i |
| #define ___nolast(...) ___apply(___nolast, ___narg(__VA_ARGS__))(__VA_ARGS__) |
| |
| #define ___arrow1(a) a |
| #define ___arrow2(a, b) a->b |
| #define ___arrow3(a, b, c) a->b->c |
| #define ___arrow4(a, b, c, d) a->b->c->d |
| #define ___arrow5(a, b, c, d, e) a->b->c->d->e |
| #define ___arrow6(a, b, c, d, e, f) a->b->c->d->e->f |
| #define ___arrow7(a, b, c, d, e, f, g) a->b->c->d->e->f->g |
| #define ___arrow8(a, b, c, d, e, f, g, h) a->b->c->d->e->f->g->h |
| #define ___arrow9(a, b, c, d, e, f, g, h, i) a->b->c->d->e->f->g->h->i |
| #define ___arrow10(a, b, c, d, e, f, g, h, i, j) a->b->c->d->e->f->g->h->i->j |
| #define ___arrow(...) ___apply(___arrow, ___narg(__VA_ARGS__))(__VA_ARGS__) |
| |
| #define ___type(...) typeof(___arrow(__VA_ARGS__)) |
| |
| #define ___read(read_fn, dst, src_type, src, accessor) \ |
| read_fn((void *)(dst), sizeof(*(dst)), &((src_type)(src))->accessor) |
| |
| /* "recursively" read a sequence of inner pointers using local __t var */ |
| #define ___rd_first(fn, src, a) ___read(fn, &__t, ___type(src), src, a); |
| #define ___rd_last(fn, ...) \ |
| ___read(fn, &__t, ___type(___nolast(__VA_ARGS__)), __t, ___last(__VA_ARGS__)); |
| #define ___rd_p1(fn, ...) const void *__t; ___rd_first(fn, __VA_ARGS__) |
| #define ___rd_p2(fn, ...) ___rd_p1(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p3(fn, ...) ___rd_p2(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p4(fn, ...) ___rd_p3(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p5(fn, ...) ___rd_p4(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p6(fn, ...) ___rd_p5(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p7(fn, ...) ___rd_p6(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p8(fn, ...) ___rd_p7(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___rd_p9(fn, ...) ___rd_p8(fn, ___nolast(__VA_ARGS__)) ___rd_last(fn, __VA_ARGS__) |
| #define ___read_ptrs(fn, src, ...) \ |
| ___apply(___rd_p, ___narg(__VA_ARGS__))(fn, src, __VA_ARGS__) |
| |
| #define ___core_read0(fn, fn_ptr, dst, src, a) \ |
| ___read(fn, dst, ___type(src), src, a); |
| #define ___core_readN(fn, fn_ptr, dst, src, ...) \ |
| ___read_ptrs(fn_ptr, src, ___nolast(__VA_ARGS__)) \ |
| ___read(fn, dst, ___type(src, ___nolast(__VA_ARGS__)), __t, \ |
| ___last(__VA_ARGS__)); |
| #define ___core_read(fn, fn_ptr, dst, src, a, ...) \ |
| ___apply(___core_read, ___empty(__VA_ARGS__))(fn, fn_ptr, dst, \ |
| src, a, ##__VA_ARGS__) |
| |
| /* |
| * BPF_CORE_READ_INTO() is a more performance-conscious variant of |
| * BPF_CORE_READ(), in which final field is read into user-provided storage. |
| * See BPF_CORE_READ() below for more details on general usage. |
| */ |
| #define BPF_CORE_READ_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_core_read, bpf_core_read, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* |
| * Variant of BPF_CORE_READ_INTO() for reading from user-space memory. |
| * |
| * NOTE: see comments for BPF_CORE_READ_USER() about the proper types use. |
| */ |
| #define BPF_CORE_READ_USER_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_core_read_user, bpf_core_read_user, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* Non-CO-RE variant of BPF_CORE_READ_INTO() */ |
| #define BPF_PROBE_READ_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_probe_read_kernel, bpf_probe_read_kernel, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* Non-CO-RE variant of BPF_CORE_READ_USER_INTO(). |
| * |
| * As no CO-RE relocations are emitted, source types can be arbitrary and are |
| * not restricted to kernel types only. |
| */ |
| #define BPF_PROBE_READ_USER_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_probe_read_user, bpf_probe_read_user, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* |
| * BPF_CORE_READ_STR_INTO() does same "pointer chasing" as |
| * BPF_CORE_READ() for intermediate pointers, but then executes (and returns |
| * corresponding error code) bpf_core_read_str() for final string read. |
| */ |
| #define BPF_CORE_READ_STR_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_core_read_str, bpf_core_read, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* |
| * Variant of BPF_CORE_READ_STR_INTO() for reading from user-space memory. |
| * |
| * NOTE: see comments for BPF_CORE_READ_USER() about the proper types use. |
| */ |
| #define BPF_CORE_READ_USER_STR_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_core_read_user_str, bpf_core_read_user, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* Non-CO-RE variant of BPF_CORE_READ_STR_INTO() */ |
| #define BPF_PROBE_READ_STR_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_probe_read_kernel_str, bpf_probe_read_kernel, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* |
| * Non-CO-RE variant of BPF_CORE_READ_USER_STR_INTO(). |
| * |
| * As no CO-RE relocations are emitted, source types can be arbitrary and are |
| * not restricted to kernel types only. |
| */ |
| #define BPF_PROBE_READ_USER_STR_INTO(dst, src, a, ...) ({ \ |
| ___core_read(bpf_probe_read_user_str, bpf_probe_read_user, \ |
| dst, (src), a, ##__VA_ARGS__) \ |
| }) |
| |
| /* |
| * BPF_CORE_READ() is used to simplify BPF CO-RE relocatable read, especially |
| * when there are few pointer chasing steps. |
| * E.g., what in non-BPF world (or in BPF w/ BCC) would be something like: |
| * int x = s->a.b.c->d.e->f->g; |
| * can be succinctly achieved using BPF_CORE_READ as: |
| * int x = BPF_CORE_READ(s, a.b.c, d.e, f, g); |
| * |
| * BPF_CORE_READ will decompose above statement into 4 bpf_core_read (BPF |
| * CO-RE relocatable bpf_probe_read_kernel() wrapper) calls, logically |
| * equivalent to: |
| * 1. const void *__t = s->a.b.c; |
| * 2. __t = __t->d.e; |
| * 3. __t = __t->f; |
| * 4. return __t->g; |
| * |
| * Equivalence is logical, because there is a heavy type casting/preservation |
| * involved, as well as all the reads are happening through |
| * bpf_probe_read_kernel() calls using __builtin_preserve_access_index() to |
| * emit CO-RE relocations. |
| * |
| * N.B. Only up to 9 "field accessors" are supported, which should be more |
| * than enough for any practical purpose. |
| */ |
| #define BPF_CORE_READ(src, a, ...) ({ \ |
| ___type((src), a, ##__VA_ARGS__) __r; \ |
| BPF_CORE_READ_INTO(&__r, (src), a, ##__VA_ARGS__); \ |
| __r; \ |
| }) |
| |
| /* |
| * Variant of BPF_CORE_READ() for reading from user-space memory. |
| * |
| * NOTE: all the source types involved are still *kernel types* and need to |
| * exist in kernel (or kernel module) BTF, otherwise CO-RE relocation will |
| * fail. Custom user types are not relocatable with CO-RE. |
| * The typical situation in which BPF_CORE_READ_USER() might be used is to |
| * read kernel UAPI types from the user-space memory passed in as a syscall |
| * input argument. |
| */ |
| #define BPF_CORE_READ_USER(src, a, ...) ({ \ |
| ___type((src), a, ##__VA_ARGS__) __r; \ |
| BPF_CORE_READ_USER_INTO(&__r, (src), a, ##__VA_ARGS__); \ |
| __r; \ |
| }) |
| |
| /* Non-CO-RE variant of BPF_CORE_READ() */ |
| #define BPF_PROBE_READ(src, a, ...) ({ \ |
| ___type((src), a, ##__VA_ARGS__) __r; \ |
| BPF_PROBE_READ_INTO(&__r, (src), a, ##__VA_ARGS__); \ |
| __r; \ |
| }) |
| |
| /* |
| * Non-CO-RE variant of BPF_CORE_READ_USER(). |
| * |
| * As no CO-RE relocations are emitted, source types can be arbitrary and are |
| * not restricted to kernel types only. |
| */ |
| #define BPF_PROBE_READ_USER(src, a, ...) ({ \ |
| ___type((src), a, ##__VA_ARGS__) __r; \ |
| BPF_PROBE_READ_USER_INTO(&__r, (src), a, ##__VA_ARGS__); \ |
| __r; \ |
| }) |
| |
| #endif |
| |