New CreateMap API implementing bpf_map_create, Type/name accessors #138
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Signed-off-by: grantseltzer <grantseltzer@gmail.com>
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| #include <bpf/bpf_helpers.h> | ||
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| SEC("kprobe/sys_execve") | ||
| int kprobe__sys_execve(struct pt_regs *ctx) |
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// CreateMap creates a BPF map from userspace. This can be used for populating
// BPF array of maps or hash of maps. However, this function uses a low-level
// libbpf API; maps created in this way do not conform to libbpf map formats,
// and therefore do not have access to libbpf high level bpf_map__* APIS
// which causes different behavior from maps created in the kernel side code
Considering the comment above, is it possible to add links or example APIs here to demonstrate accessing the maps that are created in the user space?
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Just pushed a comment into the selftest with further explanation. If you want to try using this in Parca and are up for working on it together please tag me in the issue/PR and i'd gladly help figure it out.
Signed-off-by: grantseltzer <grantseltzer@gmail.com>
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@yanivagman can you take a look at this when you have spare time |
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Nice addition @grantseltzer
LGTM, just a small comment/question
| @@ -341,6 +470,30 @@ func (m *Module) GetMap(mapName string) (*BPFMap, error) { | |||
| }, nil | |||
| } | |||
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| func (b *BPFMap) Name() string { | |||
| cs := C.bpf_map__name(b.bpfMap) | |||
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Quoting from CreateMap above:
// and therefore do not have access to libbpf high level bpf_map__* APIS
So, this won't work for maps created with CreateMap, right?
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That's correct, the struct bpf_map is NULL which bpf_map__name() uses as it's parameter. CreateMap only provides a file descriptor for the map.
| // with a file descriptor already. If the map is already associated | ||
| // with a file descriptor the libbpf API will return error code EBUSY | ||
| func (b *BPFMap) SetType(mapType MapType) error { | ||
| errC := C.bpf_map__set_type(b.bpfMap, C.enum_bpf_map_type(int(mapType))) |
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