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bpf: Introduce 8-byte BTF set

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Introduce support for defining flags for kfuncs using a new set of
macros, BTF_SET8_START/BTF_SET8_END, which define a set which contains
8 byte elements (each of which consists of a pair of BTF ID and flags),
using a new BTF_ID_FLAGS macro.

This will be used to tag kfuncs registered for a certain program type
as acquire, release, sleepable, ret_null, etc. without having to create
more and more sets which was proving to be an unscalable solution.

Now, when looking up whether a kfunc is allowed for a certain program,
we can also obtain its kfunc flags in the same call and avoid further
lookups.

The resolve_btfids change is split into a separate patch.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220721134245.2450-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kumar Kartikeya Dwivedi 2022-07-21 15:42:33 +02:00 committed by Alexei Starovoitov
parent 5cb62b7598
commit ab21d6063c
1 changed files with 64 additions and 4 deletions
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68
include/linux/btf_ids.h
View file

@ -8,6 +8,15 @@ struct btf_id_set {
u32 ids[];
};
struct btf_id_set8 {
u32 cnt;
u32 flags;
struct {
u32 id;
u32 flags;
} pairs[];
};
#ifdef CONFIG_DEBUG_INFO_BTF
#include <linux/compiler.h> /* for __PASTE */
@ -25,7 +34,7 @@ struct btf_id_set {
#define BTF_IDS_SECTION ".BTF_ids"
#define ____BTF_ID(symbol) \
#define ____BTF_ID(symbol, word) \
asm( \
".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
".local " #symbol " ; \n" \
@ -33,10 +42,11 @@ asm( \
".size " #symbol ", 4; \n" \
#symbol ": \n" \
".zero 4 \n" \
word \
".popsection; \n");
#define __BTF_ID(symbol) \
____BTF_ID(symbol)
#define __BTF_ID(symbol, word) \
____BTF_ID(symbol, word)
#define __ID(prefix) \
__PASTE(prefix, __COUNTER__)
@ -46,7 +56,14 @@ asm( \
* to 4 zero bytes.
*/
#define BTF_ID(prefix, name) \
__BTF_ID(__ID(__BTF_ID__##prefix##__##name##__))
__BTF_ID(__ID(__BTF_ID__##prefix##__##name##__), "")
#define ____BTF_ID_FLAGS(prefix, name, flags) \
__BTF_ID(__ID(__BTF_ID__##prefix##__##name##__), ".long " #flags "\n")
#define __BTF_ID_FLAGS(prefix, name, flags, ...) \
____BTF_ID_FLAGS(prefix, name, flags)
#define BTF_ID_FLAGS(prefix, name, ...) \
__BTF_ID_FLAGS(prefix, name, ##__VA_ARGS__, 0)
/*
* The BTF_ID_LIST macro defines pure (unsorted) list
@ -145,10 +162,51 @@ asm( \
".popsection; \n"); \
extern struct btf_id_set name;
/*
* The BTF_SET8_START/END macros pair defines sorted list of
* BTF IDs and their flags plus its members count, with the
* following layout:
*
* BTF_SET8_START(list)
* BTF_ID_FLAGS(type1, name1, flags)
* BTF_ID_FLAGS(type2, name2, flags)
* BTF_SET8_END(list)
*
* __BTF_ID__set8__list:
* .zero 8
* list:
* __BTF_ID__type1__name1__3:
* .zero 4
* .word (1 << 0) | (1 << 2)
* __BTF_ID__type2__name2__5:
* .zero 4
* .word (1 << 3) | (1 << 1) | (1 << 2)
*
*/
#define __BTF_SET8_START(name, scope) \
asm( \
".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
"." #scope " __BTF_ID__set8__" #name "; \n" \
"__BTF_ID__set8__" #name ":; \n" \
".zero 8 \n" \
".popsection; \n");
#define BTF_SET8_START(name) \
__BTF_ID_LIST(name, local) \
__BTF_SET8_START(name, local)
#define BTF_SET8_END(name) \
asm( \
".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
".size __BTF_ID__set8__" #name ", .-" #name " \n" \
".popsection; \n"); \
extern struct btf_id_set8 name;
#else
#define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
#define BTF_ID(prefix, name)
#define BTF_ID_FLAGS(prefix, name, flags)
#define BTF_ID_UNUSED
#define BTF_ID_LIST_GLOBAL(name, n) u32 __maybe_unused name[n];
#define BTF_ID_LIST_SINGLE(name, prefix, typename) static u32 __maybe_unused name[1];
@ -156,6 +214,8 @@ extern struct btf_id_set name;
#define BTF_SET_START(name) static struct btf_id_set __maybe_unused name = { 0 };
#define BTF_SET_START_GLOBAL(name) static struct btf_id_set __maybe_unused name = { 0 };
#define BTF_SET_END(name)
#define BTF_SET8_START(name) static struct btf_id_set8 __maybe_unused name = { 0 };
#define BTF_SET8_END(name) static struct btf_id_set8 __maybe_unused name = { 0 };
#endif /* CONFIG_DEBUG_INFO_BTF */