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bpf: Add bpf_dynptr_from_mem for local dynptrs

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This patch adds a new api bpf_dynptr_from_mem:

long bpf_dynptr_from_mem(void *data, u32 size, u64 flags, struct bpf_dynptr *ptr);

which initializes a dynptr to point to a bpf program's local memory. For now
only local memory that is of reg type PTR_TO_MAP_VALUE is supported.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220523210712.3641569-3-joannelkoong@gmail.com
This commit is contained in:
Joanne Koong
2022-05-23 14:07:08 -07:00
committed by Andrii Nakryiko
parent 97e03f5210
commit 263ae152e9
4 changed files with 95 additions and 0 deletions
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12
tools/include/uapi/linux/bpf.h
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@@ -5178,6 +5178,17 @@ union bpf_attr {
* Dynamically cast a *sk* pointer to a *mptcp_sock* pointer.
* Return
* *sk* if casting is valid, or **NULL** otherwise.
*
* long bpf_dynptr_from_mem(void *data, u32 size, u64 flags, struct bpf_dynptr *ptr)
* Description
* Get a dynptr to local memory *data*.
*
* *data* must be a ptr to a map value.
* The maximum *size* supported is DYNPTR_MAX_SIZE.
* *flags* is currently unused.
* Return
* 0 on success, -E2BIG if the size exceeds DYNPTR_MAX_SIZE,
* -EINVAL if flags is not 0.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5377,6 +5388,7 @@ union bpf_attr {
FN(kptr_xchg), \
FN(map_lookup_percpu_elem), \
FN(skc_to_mptcp_sock), \
FN(dynptr_from_mem), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper