Commit ab21d606 authored by Kumar Kartikeya Dwivedi's avatar Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov
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bpf: Introduce 8-byte BTF set 



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: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220721134245.2450-2-memxor@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 5cb62b75

include/linux/btf_ids.h

+64 −4
Original line number Diff line number Diff line
@@ -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 */