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Registrating struct_ops types from modules #598

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Registrating struct_ops types from modules #598

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danielocfb
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Pull request for series with
subject: Registrating struct_ops types from modules
version: 4
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164

@danielocfb
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Upstream branch: ba8ea72
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164
version: 4

@danielocfb
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Upstream branch: 0e10fd4
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164
version: 4

@danielocfb
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Upstream branch: 99c9991
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164
version: 4

@danielocfb
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Upstream branch: 99c9991
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164
version: 4

@danielocfb
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Upstream branch: 99c9991
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164
version: 4

@danielocfb danielocfb force-pushed the bpf-next_base branch 2 times, most recently from 9caa9c3 to 5d0a354 Compare October 16, 2023 21:46
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Upstream branch: 99c9991
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793164
version: 4

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Upstream branch: 44cb03f
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=793996
version: 5

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Upstream branch: e80742d
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=799210
version: 11

@ThinkerYzu1 @d-e-s-o
bpf: refactory struct_ops type initialization to a function.
f9c5be0 
Move the majority of the code to bpf_struct_ops_init_one(), which can then
be utilized for the initialization of newly registered dynamically
allocated struct_ops types in the following patches.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: get type information with BPF_ID_LIST
47b3bbd 
Get ready to remove bpf_struct_ops_init() in the future. By using
BPF_ID_LIST, it is possible to gather type information while building
instead of runtime.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf, net: introduce bpf_struct_ops_desc.
ef2df6d 
Move some of members of bpf_struct_ops to bpf_struct_ops_desc.  When we
introduce the new API to register new bpf_struct_ops types from modules,
bpf_struct_ops may destroyed when the module is unloaded.  Moving these
members to bpf_struct_ops_desc make these data available even when the
module is unloaded.

type_id is unavailabe in bpf_struct_ops anymore. Modules should get it from
the btf received by kmod's init function.

Cc: [email protected]
Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: add struct_ops_tab to btf.
03b144b 
Maintain a registry of registered struct_ops types in the per-btf (module)
struct_ops_tab. This registry allows for easy lookup of struct_ops types
that are registered by a specific module.

It is a preparation work for supporting kernel module struct_ops in a
latter patch. Each struct_ops will be registered under its own kernel
module btf and will be stored in the newly added btf->struct_ops_tab. The
bpf verifier and bpf syscall (e.g. prog and map cmd) can find the
struct_ops and its btf type/size/id... information from
btf->struct_ops_tab.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: make struct_ops_map support btfs other than btf_vmlinux.
2f8e562 
Once new struct_ops can be registered from modules, btf_vmlinux is not
longer the only btf tht struct_ops_map would face.  st_map should remember
what btf it should use to get type information.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: lookup struct_ops types from a given module BTF.
f041ada 
This is a preparation for searching for struct_ops types from a specified
module. BTF is always btf_vmlinux now. This patch passes a pointer of BTF
to bpf_struct_ops_find_value() and bpf_struct_ops_find(). Once the new
registration API of struct_ops types is used, other BTFs besides
btf_vmlinux can also be passed to them.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: pass attached BTF to the bpf_struct_ops subsystem
9ebb865 
Every kernel module has its BTF, comprising information on types defined in
the module. The BTF fd (attr->value_type_btf_obj_fd) passed from userspace
helps the bpf_struct_ops to lookup type information and description of the
struct_ops type, which is necessary for parsing the layout of map element
values and registering maps. The descriptions are looked up by matching a
type id (attr->btf_vmlinux_value_type_id) against bpf_struct_ops_desc(s)
defined in a BTF. If the struct_ops type is defined in a module, the
bpf_struct_ops needs to know the module BTF to lookup the
bpf_struct_ops_desc.

The bpf_prog includes attach_btf in aux which is passed along with the
bpf_attr when loading the program. The purpose of attach_btf is to
determine the btf type of attach_btf_id. The attach_btf_id is then used to
identify the traced function for a trace program. In the case of struct_ops
programs, it is used to identify the struct_ops type of the struct_ops
object that a program is attached to.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: hold module for bpf_struct_ops_map.
7551a87 
To ensure that a module remains accessible whenever a struct_ops object of
a struct_ops type provided by the module is still in use.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: validate value_type
cdc4d38 
A value_type should consist of three components: refcnt, state, and data.
refcnt and state has been move to struct bpf_struct_ops_common_value to
make it easier to check the value type.

Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf, net: switch to dynamic registration
78d2b82 
Replace the static list of struct_ops types with per-btf struct_ops_tab to
enable dynamic registration.

Both bpf_dummy_ops and bpf_tcp_ca now utilize the registration function
instead of being listed in bpf_struct_ops_types.h.

Cc: [email protected]
Signed-off-by: Kui-Feng Lee <[email protected]>
@ThinkerYzu1 @d-e-s-o
libbpf: Find correct module BTFs for struct_ops maps and progs.
7ef6acb 
Locate the module BTFs for struct_ops maps and progs and pass them to the
kernel. This ensures that the kernel correctly resolves type IDs from the
appropriate module BTFs.

For the map of a struct_ops object, the FD of the module BTF is set to
bpf_map to keep a reference to the module BTF. The FD is passed to the
kernel as value_type_btf_obj_fd when the struct_ops object is loaded.

For a bpf_struct_ops prog, attach_btf_obj_fd of bpf_prog is the FD of a
module BTF in the kernel.

Signed-off-by: Kui-Feng Lee <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
@ThinkerYzu1 @d-e-s-o
bpf: export btf_ctx_access to modules.
76a9d58 
The module requires the use of btf_ctx_access() to invoke
bpf_tracing_btf_ctx_access() from a module. This function is valuable for
implementing validation functions that ensure proper access to ctx.

Signed-off-by: Kui-Feng Lee <[email protected]>
@danielocfb
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Upstream branch: e80742d
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=799210
version: 11

@ThinkerYzu1 @d-e-s-o
selftests/bpf: test case for register_bpf_struct_ops().
3bdc24c 
Create a new struct_ops type called bpf_testmod_ops within the bpf_testmod
module. When a struct_ops object is registered, the bpf_testmod module will
invoke test_2 from the module.

Signed-off-by: Kui-Feng Lee <[email protected]>
@danielocfb
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=799210 expired. Closing PR.

@danielocfb danielocfb closed this Nov 10, 2023
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