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bpf: Rename BPF_XADD and prepare to encode other atomics in .imm

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A subsequent patch will add additional atomic operations. These new
operations will use the same opcode field as the existing XADD, with
the immediate discriminating different operations.

In preparation, rename the instruction mode BPF_ATOMIC and start
calling the zero immediate BPF_ADD.

This is possible (doesn't break existing valid BPF progs) because the
immediate field is currently reserved MBZ and BPF_ADD is zero.

All uses are removed from the tree but the BPF_XADD definition is
kept around to avoid breaking builds for people including kernel
headers.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-5-jackmanb@google.com
This commit is contained in:
Brendan Jackman
2021-01-14 18:17:44 +00:00
committed by Alexei Starovoitov
parent e5f02caccf
commit 91c960b005
35 changed files with 291 additions and 152 deletions
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5
tools/include/uapi/linux/bpf.h
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@@ -19,7 +19,8 @@
/* ld/ldx fields */
#define BPF_DW 0x18 /* double word (64-bit) */
#define BPF_XADD 0xc0 /* exclusive add */
#define BPF_ATOMIC 0xc0 /* atomic memory ops - op type in immediate */
#define BPF_XADD 0xc0 /* exclusive add - legacy name */
/* alu/jmp fields */
#define BPF_MOV 0xb0 /* mov reg to reg */
@@ -2448,7 +2449,7 @@ union bpf_attr {
* running simultaneously.
*
* A user should care about the synchronization by himself.
* For example, by using the **BPF_STX_XADD** instruction to alter
* For example, by using the **BPF_ATOMIC** instructions to alter
* the shared data.
* Return
* A pointer to the local storage area.