kernel.git/tools/bpf/bpftool/btf.c, branch master

bpftool: Use appropriate permissions for map access

2025-06-20T18:13:03Z

Modify several functions in tools/bpf/bpftool/common.c to allow specification of requested access for file descriptors, such as read-only access. Update bpftool to request only read access for maps when write access is not required. This fixes errors when reading from maps that are protected from modification via security_bpf_map. Signed-off-by: Slava Imameev Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/r/20250620151812.13952-1-slava.imameev@crowdstrike.com Signed-off-by: Alexei Starovoitov

bpftool: Using the right format specifiers

2025-03-17T20:50:56Z

Fixed some formatting specifiers errors, such as using %d for int and %u for unsigned int, as well as other byte-length types. Perform type cast using the type derived from the data type itself, for example, if it's originally an int, it will be cast to unsigned int if forced to unsigned. Signed-off-by: Jiayuan Chen Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250311112809.81901-3-jiayuan.chen@linux.dev

bpftool: btf: Support dumping a specific types from file

2024-12-13T22:35:42Z

Some projects, for example xdp-tools [0], prefer to check in a minimized vmlinux.h rather than the complete file which can get rather large. However, when you try to add a minimized version of a complex struct (eg struct xfrm_state), things can get quite complex if you're trying to manually untangle and deduplicate the dependencies. This commit teaches bpftool to do a minimized dump of a specific types by providing a optional root_id argument(s). Example usage: $ ./bpftool btf dump file ~/dev/linux/vmlinux | rg "STRUCT 'xfrm_state'" [12643] STRUCT 'xfrm_state' size=912 vlen=58 $ ./bpftool btf dump file ~/dev/linux/vmlinux root_id 12643 format c #ifndef __VMLINUX_H__ #define __VMLINUX_H__ [..] struct xfrm_type_offload; struct xfrm_sec_ctx; struct xfrm_state { possible_net_t xs_net; union { struct hlist_node gclist; struct hlist_node bydst; }; union { struct hlist_node dev_gclist; struct hlist_node bysrc; }; struct hlist_node byspi; [..] [0]: https://github.com/xdp-project/xdp-tools/blob/master/headers/bpf/vmlinux.h Signed-off-by: Daniel Xu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/04feb860c0a56a7da66f923551484e1483a72074.1734119028.git.dxu@dxuuu.xyz

bpftool: btf: Validate root_type_ids early

2024-12-13T22:35:42Z

Handle invalid root_type_ids early, as an invalid ID will cause dumpers to half-emit valid boilerplate and then bail with an unclean exit. This is ugly and possibly confusing for users, so preemptively handle the common error case before any dumping begins. Signed-off-by: Daniel Xu Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/33e09a08a6072f8381cb976218a009709309b7e1.1734119028.git.dxu@dxuuu.xyz

bpftool: Cast variable `var` to long long

2024-11-13T20:17:12Z

When the SIGNED condition is met, the variable `var` should be cast to `long long` instead of `unsigned long long`. Signed-off-by: Luo Yifan Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20241112073701.283362-1-luoyifan@cmss.chinamobile.com

bpftool: __bpf_fastcall for kfuncs marked with special decl_tag

2024-10-04T00:47:53Z

Generate __attribute__((bpf_fastcall)) for kfuncs marked with "bpf_fastcall" decl tag. E.g. for the following BTF: $ bpftool btf dump file vmlinux ... [A] FUNC 'bpf_rdonly_cast' type_id=... ... [B] DECL_TAG 'bpf_kfunc' type_id=A component_idx=-1 [C] DECL_TAG 'bpf_fastcall' type_id=A component_idx=-1 Generate the following vmlinux.h: #ifndef __VMLINUX_H__ #define __VMLINUX_H__ ... #ifndef __bpf_fastcall #if __has_attribute(bpf_fastcall) #define __bpf_fastcall __attribute__((bpf_fastcall)) #else #define __bpf_fastcall #endif #endif ... __bpf_fastcall extern void *bpf_rdonly_cast(...) ...; The "bpf_fastcall" / "bpf_kfunc" tags pair would generated by pahole when constructing vmlinux BTF. While at it, sort printed kfuncs by name for better vmlinux.h stability. Signed-off-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240916091712.2929279-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov

bpftool: Improve btf c dump sorting stability

2024-09-06T21:06:30Z

Existing algorithm for BTF C dump sorting uses only types and names of the structs and unions for ordering. As dump contains structs with the same names but different contents, relative to each other ordering of those structs will be accidental. This patch addresses this problem by introducing a new sorting field that contains hash of the struct/union field names and types to disambiguate comparison of the non-unique named structs. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240906132453.146085-1-mykyta.yatsenko5@gmail.com

bpftool: Fix handling enum64 in btf dump sorting

2024-09-02T20:44:51Z

Wrong function is used to access the first enum64 element. Substituting btf_enum(t) with btf_enum64(t) for BTF_KIND_ENUM64. Fixes: 94133cf24bb3 ("bpftool: Introduce btf c dump sorting") Signed-off-by: Mykyta Yatsenko Signed-off-by: Daniel Borkmann Acked-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240902171721.105253-1-mykyta.yatsenko5@gmail.com

bpftool: Support dumping kfunc prototypes from BTF

2024-06-12T18:01:32Z

This patch enables dumping kfunc prototypes from bpftool. This is useful b/c with this patch, end users will no longer have to manually define kfunc prototypes. For the kernel tree, this also means we can optionally drop kfunc prototypes from: tools/testing/selftests/bpf/bpf_kfuncs.h tools/testing/selftests/bpf/bpf_experimental.h Example usage: $ make PAHOLE=/home/dxu/dev/pahole/build/pahole -j30 vmlinux $ ./tools/bpf/bpftool/bpftool btf dump file ./vmlinux format c | rg "__ksym;" | head -3 extern void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) __weak __ksym; extern void cgroup_rstat_flush(struct cgroup *cgrp) __weak __ksym; extern struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags) __weak __ksym; Signed-off-by: Daniel Xu Link: https://lore.kernel.org/r/bf6c08f9263c4bd9d10a717de95199d766a13f61.1718207789.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov

bpftool: Introduce btf c dump sorting

2024-05-18T17:46:16Z

Sort bpftool c dump output; aiming to simplify vmlinux.h diffing and forcing more natural type definitions ordering. Definitions are sorted first by their BTF kind ranks, then by their base type name and by their own name. Type ranks Assign ranks to btf kinds (defined in function btf_type_rank) to set next order: 1. Anonymous enums/enums64 2. Named enums/enums64 3. Trivial types typedefs (ints, then floats) 4. Structs/Unions 5. Function prototypes 6. Forward declarations Type rank is set to maximum for unnamed reference types, structs and unions to avoid emitting those types early. They will be emitted as part of the type chain starting with named type. Lexicographical ordering Each type is assigned a sort_name and own_name. sort_name is the resolved name of the final base type for reference types (typedef, pointer, array etc). Sorting by sort_name allows to group typedefs of the same base type. sort_name for non-reference type is the same as own_name. own_name is a direct name of particular type, is used as final sorting step. Signed-off-by: Mykyta Yatsenko Signed-off-by: Andrii Nakryiko Tested-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240514131221.20585-1-yatsenko@meta.com Signed-off-by: Alexei Starovoitov