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Tue, 8 Dec 2020 01:47:49 +0000 Subject: Re: [PATCH bpf-next v4 09/11] bpf: Add bitwise atomic instructions To: Brendan Jackman , CC: Alexei Starovoitov , Daniel Borkmann , KP Singh , Florent Revest , , Jann Horn References: <20201207160734.2345502-1-jackmanb@google.com> <20201207160734.2345502-10-jackmanb@google.com> From: Yonghong Song Message-ID: <3d8192e2-6167-bbd3-e23c-ef7a4e8238c1@fb.com> Date: Mon, 7 Dec 2020 17:47:48 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 In-Reply-To: <20201207160734.2345502-10-jackmanb@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [2620:10d:c090:400::5:ee04] X-ClientProxiedBy: BY5PR16CA0013.namprd16.prod.outlook.com (2603:10b6:a03:1a0::26) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2620:10d:c085:21c8::113f] (2620:10d:c090:400::5:ee04) by BY5PR16CA0013.namprd16.prod.outlook.com (2603:10b6:a03:1a0::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3632.19 via Frontend Transport; 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This requires the use of two temporary registers, > IIUC it's safe to use BPF_REG_AX and x86's AUX_REG for this purpose. > > Signed-off-by: Brendan Jackman > --- > arch/x86/net/bpf_jit_comp.c | 50 ++++++++++++++++++++++++++- > include/linux/filter.h | 66 ++++++++++++++++++++++++++++++++++++ > kernel/bpf/core.c | 3 ++ > kernel/bpf/disasm.c | 21 +++++++++--- > kernel/bpf/verifier.c | 6 ++++ > tools/include/linux/filter.h | 66 ++++++++++++++++++++++++++++++++++++ > 6 files changed, 207 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > index 308241187582..1d4d50199293 100644 > --- a/arch/x86/net/bpf_jit_comp.c > +++ b/arch/x86/net/bpf_jit_comp.c > @@ -808,6 +808,10 @@ static int emit_atomic(u8 **pprog, u8 atomic_op, > /* emit opcode */ > switch (atomic_op) { > case BPF_ADD: > + case BPF_SUB: > + case BPF_AND: > + case BPF_OR: > + case BPF_XOR: > /* lock *(u32/u64*)(dst_reg + off) = src_reg */ > EMIT1(simple_alu_opcodes[atomic_op]); > break; [...] > diff --git a/include/linux/filter.h b/include/linux/filter.h > index e1e1fc946a7c..e100c71555a4 100644 > --- a/include/linux/filter.h > +++ b/include/linux/filter.h > @@ -264,7 +264,13 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) > * Atomic operations: > * > * BPF_ADD *(uint *) (dst_reg + off16) += src_reg > + * BPF_AND *(uint *) (dst_reg + off16) &= src_reg > + * BPF_OR *(uint *) (dst_reg + off16) |= src_reg > + * BPF_XOR *(uint *) (dst_reg + off16) ^= src_reg > * BPF_ADD | BPF_FETCH src_reg = atomic_fetch_add(dst_reg + off16, src_reg); > + * BPF_AND | BPF_FETCH src_reg = atomic_fetch_and(dst_reg + off16, src_reg); > + * BPF_OR | BPF_FETCH src_reg = atomic_fetch_or(dst_reg + off16, src_reg); > + * BPF_XOR | BPF_FETCH src_reg = atomic_fetch_xor(dst_reg + off16, src_reg); > * BPF_XCHG src_reg = atomic_xchg(dst_reg + off16, src_reg) > * BPF_CMPXCHG r0 = atomic_cmpxchg(dst_reg + off16, r0, src_reg) > */ > @@ -295,6 +301,66 @@ static inline bool insn_is_zext(const struct bpf_insn *insn) > .off = OFF, \ > .imm = BPF_ADD }) > > +/* Atomic memory and, *(uint *)(dst_reg + off16) &= src_reg */ > + > +#define BPF_ATOMIC_AND(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_AND }) > + > +/* Atomic memory and with fetch, src_reg = atomic_fetch_and(dst_reg + off, src_reg); */ > + > +#define BPF_ATOMIC_FETCH_AND(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_AND | BPF_FETCH }) > + > +/* Atomic memory or, *(uint *)(dst_reg + off16) |= src_reg */ > + > +#define BPF_ATOMIC_OR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_OR }) > + > +/* Atomic memory or with fetch, src_reg = atomic_fetch_or(dst_reg + off, src_reg); */ > + > +#define BPF_ATOMIC_FETCH_OR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_OR | BPF_FETCH }) > + > +/* Atomic memory xor, *(uint *)(dst_reg + off16) ^= src_reg */ > + > +#define BPF_ATOMIC_XOR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_XOR }) > + > +/* Atomic memory xor with fetch, src_reg = atomic_fetch_xor(dst_reg + off, src_reg); */ > + > +#define BPF_ATOMIC_FETCH_XOR(SIZE, DST, SRC, OFF) \ > + ((struct bpf_insn) { \ > + .code = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC, \ > + .dst_reg = DST, \ > + .src_reg = SRC, \ > + .off = OFF, \ > + .imm = BPF_XOR | BPF_FETCH }) Use BPF_ATOMIC macro to define all the above macros? > + > /* Atomic exchange, src_reg = atomic_xchg(dst_reg + off, src_reg) */ > > #define BPF_ATOMIC_XCHG(SIZE, DST, SRC, OFF) \ > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 1d9e5dcde03a..4b78ff89ec91 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -1642,6 +1642,9 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) > STX_ATOMIC_W: > switch (IMM) { > ATOMIC_ALU_OP(BPF_ADD, add) > + ATOMIC_ALU_OP(BPF_AND, and) > + ATOMIC_ALU_OP(BPF_OR, or) > + ATOMIC_ALU_OP(BPF_XOR, xor) > #undef ATOMIC_ALU_OP > > case BPF_XCHG: [...]