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0f12e584b2
Existing BTF_ID_LIST used a local static variable to store btf_ids. This patch provided a new macro BTF_ID_LIST_GLOBAL to store btf_ids in a global variable which can be shared among multiple files. The existing BTF_ID_LIST is still retained. Two reasons. First, BTF_ID_LIST is also used to build btf_ids for helper arguments which typically is an array of 5. Since typically different helpers have different signature, it makes little sense to share them. Second, some current computed btf_ids are indeed local. If later those btf_ids are shared between different files, they can use BTF_ID_LIST_GLOBAL then. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Jiri Olsa <jolsa@redhat.com> Link: https://lore.kernel.org/bpf/20200720163401.1393159-1-yhs@fb.com
100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_BTF_IDS_H
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#define _LINUX_BTF_IDS_H
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#ifdef CONFIG_DEBUG_INFO_BTF
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#include <linux/compiler.h> /* for __PASTE */
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/*
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* Following macros help to define lists of BTF IDs placed
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* in .BTF_ids section. They are initially filled with zeros
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* (during compilation) and resolved later during the
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* linking phase by resolve_btfids tool.
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*
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* Any change in list layout must be reflected in resolve_btfids
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* tool logic.
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*/
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#define BTF_IDS_SECTION ".BTF_ids"
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#define ____BTF_ID(symbol) \
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asm( \
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".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
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".local " #symbol " ; \n" \
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".type " #symbol ", STT_OBJECT; \n" \
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".size " #symbol ", 4; \n" \
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#symbol ": \n" \
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".zero 4 \n" \
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".popsection; \n");
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#define __BTF_ID(symbol) \
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____BTF_ID(symbol)
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#define __ID(prefix) \
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__PASTE(prefix, __COUNTER__)
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/*
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* The BTF_ID defines unique symbol for each ID pointing
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* to 4 zero bytes.
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*/
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#define BTF_ID(prefix, name) \
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__BTF_ID(__ID(__BTF_ID__##prefix##__##name##__))
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/*
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* The BTF_ID_LIST macro defines pure (unsorted) list
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* of BTF IDs, with following layout:
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*
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* BTF_ID_LIST(list1)
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* BTF_ID(type1, name1)
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* BTF_ID(type2, name2)
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*
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* list1:
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* __BTF_ID__type1__name1__1:
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* .zero 4
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* __BTF_ID__type2__name2__2:
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* .zero 4
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*
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*/
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#define __BTF_ID_LIST(name, scope) \
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asm( \
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".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
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"." #scope " " #name "; \n" \
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#name ":; \n" \
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".popsection; \n"); \
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#define BTF_ID_LIST(name) \
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__BTF_ID_LIST(name, local) \
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extern u32 name[];
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#define BTF_ID_LIST_GLOBAL(name) \
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__BTF_ID_LIST(name, globl)
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/*
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* The BTF_ID_UNUSED macro defines 4 zero bytes.
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* It's used when we want to define 'unused' entry
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* in BTF_ID_LIST, like:
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*
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* BTF_ID_LIST(bpf_skb_output_btf_ids)
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* BTF_ID(struct, sk_buff)
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* BTF_ID_UNUSED
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* BTF_ID(struct, task_struct)
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*/
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#define BTF_ID_UNUSED \
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asm( \
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".pushsection " BTF_IDS_SECTION ",\"a\"; \n" \
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".zero 4 \n" \
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".popsection; \n");
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#else
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#define BTF_ID_LIST(name) static u32 name[5];
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#define BTF_ID(prefix, name)
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#define BTF_ID_UNUSED
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#define BTF_ID_LIST_GLOBAL(name) u32 name[1];
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#endif /* CONFIG_DEBUG_INFO_BTF */
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#endif
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