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-rw-r--r--tools/lib/bpf/bpf_core_read.h347
1 files changed, 284 insertions, 63 deletions
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index 7009dc90e012..496e6a8ee0dc 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -19,32 +19,53 @@ enum bpf_field_info_kind {
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 == __LITTLE_ENDIAN
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define __CORE_BITFIELD_PROBE_READ(dst, src, fld) \
- bpf_probe_read((void *)dst, \
- __CORE_RELO(src, fld, BYTE_SIZE), \
- (const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
+ 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((void *)dst + (8 - __CORE_RELO(src, fld, BYTE_SIZE)), \
- __CORE_RELO(src, fld, BYTE_SIZE), \
- (const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
+ 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() to read underlying integer
- * storage. Macro functions as an expression and its return type is
- * bpf_probe_read()'s return value: 0, on success, <0 on error.
+ * 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; \
@@ -68,11 +89,19 @@ enum bpf_field_info_kind {
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; \
- case 2: val = *(const unsigned short *)p; \
- case 4: val = *(const unsigned int *)p; \
- case 8: val = *(const unsigned long long *)p; \
+ 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)) \
@@ -82,25 +111,124 @@ enum bpf_field_info_kind {
val; \
})
+#define ___bpf_field_ref1(field) (field)
+#define ___bpf_field_ref2(type, field) (((typeof(type) *)0)->field)
+#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(field, BPF_FIELD_EXISTS)
+#define bpf_core_field_exists(field...) \
+ __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_EXISTS)
/*
- * Convenience macro to get byte size of a field. Works for integers,
+ * 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(*(typeof(type) *)0, 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(*(typeof(type) *)0, 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(*(typeof(type) *)0, 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(*(typeof(type) *)0, 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(*(typeof(type) *)0, 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.
+ */
+#define bpf_core_enum_value_exists(enum_type, enum_value) \
+ __builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_EXISTS)
+
+/*
+ * 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.
*/
-#define bpf_core_field_size(field) \
- __builtin_preserve_field_info(field, BPF_FIELD_BYTE_SIZE)
+#define bpf_core_enum_value(enum_type, enum_value) \
+ __builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_VALUE)
/*
- * bpf_core_read() abstracts away bpf_probe_read() call and captures offset
- * relocation for source address using __builtin_preserve_access_index()
+ * 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
@@ -115,17 +243,22 @@ enum bpf_field_info_kind {
* (local) BTF, used to record relocation.
*/
#define bpf_core_read(dst, sz, src) \
- bpf_probe_read(dst, sz, \
- (const void *)__builtin_preserve_access_index(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_str(dst, sz, \
- (const void *)__builtin_preserve_access_index(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))
#define ___concat(a, b) a ## b
#define ___apply(fn, n) ___concat(fn, n)
@@ -184,30 +317,29 @@ enum bpf_field_info_kind {
read_fn((void *)(dst), sizeof(*(dst)), &((src_type)(src))->accessor)
/* "recursively" read a sequence of inner pointers using local __t var */
-#define ___rd_first(src, a) ___read(bpf_core_read, &__t, ___type(src), src, a);
-#define ___rd_last(...) \
- ___read(bpf_core_read, &__t, \
- ___type(___nolast(__VA_ARGS__)), __t, ___last(__VA_ARGS__));
-#define ___rd_p1(...) const void *__t; ___rd_first(__VA_ARGS__)
-#define ___rd_p2(...) ___rd_p1(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p3(...) ___rd_p2(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p4(...) ___rd_p3(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p5(...) ___rd_p4(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p6(...) ___rd_p5(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p7(...) ___rd_p6(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p8(...) ___rd_p7(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___rd_p9(...) ___rd_p8(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
-#define ___read_ptrs(src, ...) \
- ___apply(___rd_p, ___narg(__VA_ARGS__))(src, __VA_ARGS__)
-
-#define ___core_read0(fn, dst, src, a) \
+#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, dst, src, ...) \
- ___read_ptrs(src, ___nolast(__VA_ARGS__)) \
+#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, dst, src, a, ...) \
- ___apply(___core_read, ___empty(__VA_ARGS__))(fn, dst, \
+#define ___core_read(fn, fn_ptr, dst, src, a, ...) \
+ ___apply(___core_read, ___empty(__VA_ARGS__))(fn, fn_ptr, dst, \
src, a, ##__VA_ARGS__)
/*
@@ -215,20 +347,73 @@ enum bpf_field_info_kind {
* 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, dst, src, a, ##__VA_ARGS__) \
- })
+#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, bpf_probe_read, \
+ 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, dst, src, a, ##__VA_ARGS__) \
- })
+#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_str, bpf_probe_read, \
+ 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
@@ -239,25 +424,61 @@ enum bpf_field_info_kind {
* 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() wrapper) calls, logically equivalent to:
+ * 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()
- * calls using __builtin_preserve_access_index() to emit CO-RE relocations.
+ * 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; \
- })
+#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