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Merge "Provide a macro to define a map along with type safe accessors"

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Maciej Żenczykowski 2019-04-20 00:28:02 +00:00 committed by Gerrit Code Review
commit edac9a3cc3
1 changed files with 56 additions and 4 deletions
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60
progs/include/bpf_helpers.h
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@ -11,11 +11,63 @@
* Helper functions called from eBPF programs written in C. These are * Helper functions called from eBPF programs written in C. These are
* implemented in the kernel sources. * implemented in the kernel sources.
*/ */
/* generic functions */ /* generic functions */
static void* (*bpf_map_lookup_elem)(void* map, void* key) = (void*) BPF_FUNC_map_lookup_elem;
static int (*bpf_map_update_elem)(void* map, void* key, void* value, /*
unsigned long long flags) = (void*) BPF_FUNC_map_update_elem; * Type-unsafe bpf map functions - avoid if possible.
static int (*bpf_map_delete_elem)(void* map, void* key) = (void*) BPF_FUNC_map_delete_elem; *
* Using these it is possible to pass in keys/values of the wrong type/size,
* or, for 'unsafe_bpf_map_lookup_elem' receive into a pointer to the wrong type.
* You will not get a compile time failure, and for certain types of errors you
* might not even get a failure from the kernel's ebpf verifier during program load,
* instead stuff might just not work right at runtime.
*
* Instead please use:
* DEFINE_BPF_MAP(foo_map, TYPE, KeyType, ValueType, num_entries)
* where TYPE can be something like HASH or ARRAY, and num_entries is an integer.
*
* This defines the map (hence this should not be used in a header file included
* from multiple locations) and provides type safe accessors:
* ValueType * bpf_foo_map_lookup_elem(KeyType *)
* int bpf_foo_map_update_elem(KeyType *, ValueType *, flags)
* int bpf_foo_map_delete_elem(KeyType *)
*
* This will make sure that if you change the type of a map you'll get compile
* errors at any spots you forget to update with the new type.
*/
static void* (*unsafe_bpf_map_lookup_elem)(void* map, void* key) = (void*)BPF_FUNC_map_lookup_elem;
static int (*unsafe_bpf_map_update_elem)(void* map, void* key, void* value,
unsigned long long flags) = (void*)
BPF_FUNC_map_update_elem;
static int (*unsafe_bpf_map_delete_elem)(void* map, void* key) = (void*)BPF_FUNC_map_delete_elem;
/* type safe macro to declare a map and related accessor functions */
#define DEFINE_BPF_MAP_NO_ACCESSORS(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
struct bpf_map_def SEC("maps") the_map = { \
.type = BPF_MAP_TYPE_##TYPE, \
.key_size = sizeof(TypeOfKey), \
.value_size = sizeof(TypeOfValue), \
.max_entries = (num_entries), \
};
#define DEFINE_BPF_MAP(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
DEFINE_BPF_MAP_NO_ACCESSORS(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
\
static inline __always_inline __unused TypeOfValue* bpf_##the_map##_lookup_elem( \
TypeOfKey* k) { \
return unsafe_bpf_map_lookup_elem(&the_map, k); \
}; \
\
static inline __always_inline __unused int bpf_##the_map##_update_elem( \
TypeOfKey* k, TypeOfValue* v, unsigned long long flags) { \
return unsafe_bpf_map_update_elem(&the_map, k, v, flags); \
}; \
\
static inline __always_inline __unused int bpf_##the_map##_delete_elem(TypeOfKey* k) { \
return unsafe_bpf_map_delete_elem(&the_map, k); \
};
static int (*bpf_probe_read)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read; static int (*bpf_probe_read)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read;
static int (*bpf_probe_read_str)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read_str; static int (*bpf_probe_read_str)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read_str;
static unsigned long long (*bpf_ktime_get_ns)(void) = (void*) BPF_FUNC_ktime_get_ns; static unsigned long long (*bpf_ktime_get_ns)(void) = (void*) BPF_FUNC_ktime_get_ns;