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bpf: Pull out a macro for interpreting atomic ALU operations

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Since the atomic operations that are added in subsequent commits are
all isomorphic with BPF_ADD, pull out a macro to avoid the
interpreter becoming dominated by lines of atomic-related code.

Note that this sacrificies interpreter performance (combining
STX_ATOMIC_W and STX_ATOMIC_DW into single switch case means that we
need an extra conditional branch to differentiate them) in favour of
compact and (relatively!) simple C code.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-9-jackmanb@google.com
This commit is contained in:
Brendan Jackman 2021-01-14 18:17:48 +00:00 committed by Alexei Starovoitov
parent 5ffa25502b
commit 462910670e
1 changed files with 39 additions and 41 deletions
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80
kernel/bpf/core.c
View file

@ -1618,55 +1618,53 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack)
LDX_PROBE(DW, 8)
#undef LDX_PROBE
STX_ATOMIC_W:
switch (IMM) {
case BPF_ADD:
/* lock xadd *(u32 *)(dst_reg + off16) += src_reg */
atomic_add((u32) SRC, (atomic_t *)(unsigned long)
(DST + insn->off));
#define ATOMIC_ALU_OP(BOP, KOP) \
case BOP: \
if (BPF_SIZE(insn->code) == BPF_W) \
atomic_##KOP((u32) SRC, (atomic_t *)(unsigned long) \
(DST + insn->off)); \
else \
atomic64_##KOP((u64) SRC, (atomic64_t *)(unsigned long) \
(DST + insn->off)); \
break; \
case BOP | BPF_FETCH: \
if (BPF_SIZE(insn->code) == BPF_W) \
SRC = (u32) atomic_fetch_##KOP( \
(u32) SRC, \
(atomic_t *)(unsigned long) (DST + insn->off)); \
else \
SRC = (u64) atomic64_fetch_##KOP( \
(u64) SRC, \
(atomic64_t *)(unsigned long) (DST + insn->off)); \
break;
case BPF_ADD | BPF_FETCH:
SRC = (u32) atomic_fetch_add(
(u32) SRC,
(atomic_t *)(unsigned long) (DST + insn->off));
break;
case BPF_XCHG:
SRC = (u32) atomic_xchg(
(atomic_t *)(unsigned long) (DST + insn->off),
(u32) SRC);
break;
case BPF_CMPXCHG:
BPF_R0 = (u32) atomic_cmpxchg(
(atomic_t *)(unsigned long) (DST + insn->off),
(u32) BPF_R0, (u32) SRC);
break;
default:
goto default_label;
}
CONT;
STX_ATOMIC_DW:
STX_ATOMIC_W:
switch (IMM) {
case BPF_ADD:
/* lock xadd *(u64 *)(dst_reg + off16) += src_reg */
atomic64_add((u64) SRC, (atomic64_t *)(unsigned long)
(DST + insn->off));
break;
case BPF_ADD | BPF_FETCH:
SRC = (u64) atomic64_fetch_add(
(u64) SRC,
(atomic64_t *)(unsigned long) (DST + insn->off));
break;
ATOMIC_ALU_OP(BPF_ADD, add)
#undef ATOMIC_ALU_OP
case BPF_XCHG:
SRC = (u64) atomic64_xchg(
(atomic64_t *)(unsigned long) (DST + insn->off),
(u64) SRC);
if (BPF_SIZE(insn->code) == BPF_W)
SRC = (u32) atomic_xchg(
(atomic_t *)(unsigned long) (DST + insn->off),
(u32) SRC);
else
SRC = (u64) atomic64_xchg(
(atomic64_t *)(unsigned long) (DST + insn->off),
(u64) SRC);
break;
case BPF_CMPXCHG:
BPF_R0 = (u64) atomic64_cmpxchg(
(atomic64_t *)(unsigned long) (DST + insn->off),
(u64) BPF_R0, (u64) SRC);
if (BPF_SIZE(insn->code) == BPF_W)
BPF_R0 = (u32) atomic_cmpxchg(
(atomic_t *)(unsigned long) (DST + insn->off),
(u32) BPF_R0, (u32) SRC);
else
BPF_R0 = (u64) atomic64_cmpxchg(
(atomic64_t *)(unsigned long) (DST + insn->off),
(u64) BPF_R0, (u64) SRC);
break;
default:
goto default_label;
}