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Message-ID: <YfPCkUW4XIHGTZ6z@FVFF77S0Q05N>
Date: Fri, 28 Jan 2022 10:16:49 +0000
From: Mark Rutland <mark.rutland@....com>
To: Hou Tao <houtao1@...wei.com>
Cc: Alexei Starovoitov <ast@...nel.org>,
Martin KaFai Lau <kafai@...com>, Yonghong Song <yhs@...com>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Song Liu <songliubraving@...com>,
"David S . Miller" <davem@...emloft.net>,
John Fastabend <john.fastabend@...il.com>,
netdev@...r.kernel.org, bpf@...r.kernel.org,
Zi Shen Lim <zlim.lnx@...il.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Julien Thierry <jthierry@...hat.com>,
Ard Biesheuvel <ardb@...nel.org>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH bpf-next 2/2] arm64, bpf: support more atomic operations
On Fri, Jan 21, 2022 at 09:56:32PM +0800, Hou Tao wrote:
> Atomics for eBPF patch series adds support for atomic[64]_fetch_add,
> atomic[64]_[fetch_]{and,or,xor} and atomic[64]_{xchg|cmpxchg}, but
> it only add support for x86-64, so support these atomic operations
> for arm64 as well.
What ordering semantics are the BPF atomics supposed to have?
e.g. are those meant to be sequentially consistent, entirely relaxed, or
somewhere imbetween?
> Basically the implementation procedure is almost mechanical translation
> of code snippets in atomic_ll_sc.h & atomic_lse.h & cmpxchg.h located
> under arch/arm64/include/asm. An extra temporary register is needed
> for (BPF_ADD | BPF_FETCH) to save the value of src register, instead of
> adding TMP_REG_4 just use BPF_REG_AX instead.
>
> For cpus_have_cap(ARM64_HAS_LSE_ATOMICS) case and no-LSE-ATOMICS case,
> both ./test_verifier and "./test_progs -t atomic" are exercised and
> passed correspondingly.
>
> Signed-off-by: Hou Tao <houtao1@...wei.com>
> ---
> arch/arm64/include/asm/insn.h | 45 +++++--
> arch/arm64/lib/insn.c | 155 +++++++++++++++++++++---
Could we please split the arm64 insn bits into a preparatory patch?
That way it's easier for folk familiar with the A64 ISA to review that in
isolation from the BPF bis which they might know nothign about.
> arch/arm64/net/bpf_jit.h | 43 ++++++-
> arch/arm64/net/bpf_jit_comp.c | 216 +++++++++++++++++++++++++++-------
> 4 files changed, 394 insertions(+), 65 deletions(-)
>
> diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
> index 6b776c8667b2..1416d636f1af 100644
> --- a/arch/arm64/include/asm/insn.h
> +++ b/arch/arm64/include/asm/insn.h
> @@ -280,6 +280,23 @@ enum aarch64_insn_adr_type {
> AARCH64_INSN_ADR_TYPE_ADR,
> };
>
> +enum aarch64_insn_mem_atomic_op {
> + AARCH64_INSN_MEM_ATOMIC_ADD,
> + AARCH64_INSN_MEM_ATOMIC_BIC,
> + AARCH64_INSN_MEM_ATOMIC_EOR,
> + AARCH64_INSN_MEM_ATOMIC_ORR,
> + AARCH64_INSN_MEM_ATOMIC_SWP,
> +};
Is "BIC" the "CLR" instructions, and "ORR" the "SET" instructions?
I think it'd be best to use the "SET" and "CLR" naming here for consistency
with the actual instruction names.
> +
> +enum aarch64_insn_mem_order_type {
> + AARCH64_INSN_MEM_ORDER_NONE,
> + AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL,
> +};
I think this is an over-simplification. There are instructions with all
combinations of acquire+release, e.g.
| REL |
| N | Y |
-----+--------+---------|
A N | LDCLR | LCDLRL |
C --+--------+---------|
Q Y | LDCLRA | LDCLRAL |
------------------------'
... so I reckon we need:
enum aarch64_insn_mem_order_type {
AARCH64_INSN_MEM_ORDER_NONE,
AARCH64_INSN_MEM_ORDER_ACQ,
AARCH64_INSN_MEM_ORDER_REL,
AARCH64_INSN_MEM_ORDER_ACQREL
};
> +
> +enum aarch64_insn_mb_type {
> + AARCH64_INSN_MB_ISH,
> +};
Similarly, I think we want to be able to encode the other cases here.
Thanks,
Mark.
> +
> #define __AARCH64_INSN_FUNCS(abbr, mask, val) \
> static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
> { \
> @@ -303,6 +320,11 @@ __AARCH64_INSN_FUNCS(store_post, 0x3FE00C00, 0x38000400)
> __AARCH64_INSN_FUNCS(load_post, 0x3FE00C00, 0x38400400)
> __AARCH64_INSN_FUNCS(str_reg, 0x3FE0EC00, 0x38206800)
> __AARCH64_INSN_FUNCS(ldadd, 0x3F20FC00, 0x38200000)
> +__AARCH64_INSN_FUNCS(ldclr, 0x3F20FC00, 0x38201000)
> +__AARCH64_INSN_FUNCS(ldeor, 0x3F20FC00, 0x38202000)
> +__AARCH64_INSN_FUNCS(ldset, 0x3F20FC00, 0x38203000)
> +__AARCH64_INSN_FUNCS(swp, 0x3F20FC00, 0x38208000)
> +__AARCH64_INSN_FUNCS(cas, 0x3FA07C00, 0x08A07C00)
> __AARCH64_INSN_FUNCS(ldr_reg, 0x3FE0EC00, 0x38606800)
> __AARCH64_INSN_FUNCS(ldr_lit, 0xBF000000, 0x18000000)
> __AARCH64_INSN_FUNCS(ldrsw_lit, 0xFF000000, 0x98000000)
> @@ -474,13 +496,21 @@ u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
> enum aarch64_insn_register state,
> enum aarch64_insn_size_type size,
> enum aarch64_insn_ldst_type type);
> -u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
> - enum aarch64_insn_register address,
> - enum aarch64_insn_register value,
> - enum aarch64_insn_size_type size);
> -u32 aarch64_insn_gen_stadd(enum aarch64_insn_register address,
> - enum aarch64_insn_register value,
> - enum aarch64_insn_size_type size);
> +u32 aarch64_insn_gen_store_release_ex(enum aarch64_insn_register reg,
> + enum aarch64_insn_register base,
> + enum aarch64_insn_register state,
> + enum aarch64_insn_size_type size);
> +u32 aarch64_insn_gen_atomic_ld_op(enum aarch64_insn_register result,
> + enum aarch64_insn_register address,
> + enum aarch64_insn_register value,
> + enum aarch64_insn_size_type size,
> + enum aarch64_insn_mem_atomic_op op,
> + enum aarch64_insn_mem_order_type order);
> +u32 aarch64_insn_gen_cas(enum aarch64_insn_register result,
> + enum aarch64_insn_register address,
> + enum aarch64_insn_register value,
> + enum aarch64_insn_size_type size,
> + enum aarch64_insn_mem_order_type order);
> u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst,
> enum aarch64_insn_register src,
> int imm, enum aarch64_insn_variant variant,
> @@ -541,6 +571,7 @@ u32 aarch64_insn_gen_prefetch(enum aarch64_insn_register base,
> enum aarch64_insn_prfm_type type,
> enum aarch64_insn_prfm_target target,
> enum aarch64_insn_prfm_policy policy);
> +u32 aarch64_insn_gen_dmb(enum aarch64_insn_mb_type type);
> s32 aarch64_get_branch_offset(u32 insn);
> u32 aarch64_set_branch_offset(u32 insn, s32 offset);
>
> diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c
> index fccfe363e567..2a7dde58c44b 100644
> --- a/arch/arm64/lib/insn.c
> +++ b/arch/arm64/lib/insn.c
> @@ -328,6 +328,29 @@ static u32 aarch64_insn_encode_ldst_size(enum aarch64_insn_size_type type,
> return insn;
> }
>
> +static u32 aarch64_insn_encode_ldst_order(enum aarch64_insn_mem_order_type type,
> + u32 insn)
> +{
> + u32 order;
> +
> + switch (type) {
> + case AARCH64_INSN_MEM_ORDER_NONE:
> + order = 0;
> + break;
> + case AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL:
> + order = 3;
> + break;
> + default:
> + pr_err("%s: unknown mem order %d\n", __func__, type);
> + return AARCH64_BREAK_FAULT;
> + }
> +
> + insn &= ~GENMASK(23, 22);
> + insn |= order << 22;
> +
> + return insn;
> +}
> +
> static inline long branch_imm_common(unsigned long pc, unsigned long addr,
> long range)
> {
> @@ -603,12 +626,49 @@ u32 aarch64_insn_gen_load_store_ex(enum aarch64_insn_register reg,
> state);
> }
>
> -u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
> - enum aarch64_insn_register address,
> - enum aarch64_insn_register value,
> - enum aarch64_insn_size_type size)
> +u32 aarch64_insn_gen_store_release_ex(enum aarch64_insn_register reg,
> + enum aarch64_insn_register base,
> + enum aarch64_insn_register state,
> + enum aarch64_insn_size_type size)
> +{
> + u32 insn = aarch64_insn_gen_load_store_ex(reg, base, state, size,
> + AARCH64_INSN_LDST_STORE_EX);
> +
> + if (insn == AARCH64_BREAK_FAULT)
> + return insn;
> +
> + return insn | BIT(15);
> +}
> +
> +u32 aarch64_insn_gen_atomic_ld_op(enum aarch64_insn_register result,
> + enum aarch64_insn_register address,
> + enum aarch64_insn_register value,
> + enum aarch64_insn_size_type size,
> + enum aarch64_insn_mem_atomic_op op,
> + enum aarch64_insn_mem_order_type order)
> {
> - u32 insn = aarch64_insn_get_ldadd_value();
> + u32 insn;
> +
> + switch (op) {
> + case AARCH64_INSN_MEM_ATOMIC_ADD:
> + insn = aarch64_insn_get_ldadd_value();
> + break;
> + case AARCH64_INSN_MEM_ATOMIC_BIC:
> + insn = aarch64_insn_get_ldclr_value();
> + break;
> + case AARCH64_INSN_MEM_ATOMIC_EOR:
> + insn = aarch64_insn_get_ldeor_value();
> + break;
> + case AARCH64_INSN_MEM_ATOMIC_ORR:
> + insn = aarch64_insn_get_ldset_value();
> + break;
> + case AARCH64_INSN_MEM_ATOMIC_SWP:
> + insn = aarch64_insn_get_swp_value();
> + break;
> + default:
> + pr_err("%s: unimplemented mem atomic op %d\n", __func__, op);
> + return AARCH64_BREAK_FAULT;
> + }
>
> switch (size) {
> case AARCH64_INSN_SIZE_32:
> @@ -621,6 +681,8 @@ u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
>
> insn = aarch64_insn_encode_ldst_size(size, insn);
>
> + insn = aarch64_insn_encode_ldst_order(order, insn);
> +
> insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn,
> result);
>
> @@ -631,16 +693,60 @@ u32 aarch64_insn_gen_ldadd(enum aarch64_insn_register result,
> value);
> }
>
> -u32 aarch64_insn_gen_stadd(enum aarch64_insn_register address,
> - enum aarch64_insn_register value,
> - enum aarch64_insn_size_type size)
> +static u32 aarch64_insn_encode_cas_order(enum aarch64_insn_mem_order_type type,
> + u32 insn)
> {
> - /*
> - * STADD is simply encoded as an alias for LDADD with XZR as
> - * the destination register.
> - */
> - return aarch64_insn_gen_ldadd(AARCH64_INSN_REG_ZR, address,
> - value, size);
> + u32 order;
> +
> + switch (type) {
> + case AARCH64_INSN_MEM_ORDER_NONE:
> + order = 0;
> + break;
> + case AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL:
> + order = BIT(15) | BIT(22);
> + break;
> + default:
> + pr_err("%s: unknown mem order %d\n", __func__, type);
> + return AARCH64_BREAK_FAULT;
> + }
> +
> + insn &= ~(BIT(15) | BIT(22));
> + insn |= order;
> +
> + return insn;
> +}
> +
> +u32 aarch64_insn_gen_cas(enum aarch64_insn_register result,
> + enum aarch64_insn_register address,
> + enum aarch64_insn_register value,
> + enum aarch64_insn_size_type size,
> + enum aarch64_insn_mem_order_type order)
> +{
> + u32 insn;
> +
> + switch (size) {
> + case AARCH64_INSN_SIZE_32:
> + case AARCH64_INSN_SIZE_64:
> + break;
> + default:
> + pr_err("%s: unimplemented size encoding %d\n", __func__, size);
> + return AARCH64_BREAK_FAULT;
> + }
> +
> + insn = aarch64_insn_get_cas_value();
> +
> + insn = aarch64_insn_encode_ldst_size(size, insn);
> +
> + insn = aarch64_insn_encode_cas_order(order, insn);
> +
> + insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn,
> + result);
> +
> + insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn,
> + address);
> +
> + return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RS, insn,
> + value);
> }
>
> static u32 aarch64_insn_encode_prfm_imm(enum aarch64_insn_prfm_type type,
> @@ -1456,3 +1562,24 @@ u32 aarch64_insn_gen_extr(enum aarch64_insn_variant variant,
> insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, Rn);
> return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RM, insn, Rm);
> }
> +
> +u32 aarch64_insn_gen_dmb(enum aarch64_insn_mb_type type)
> +{
> + u32 opt;
> + u32 insn;
> +
> + switch (type) {
> + case AARCH64_INSN_MB_ISH:
> + opt = 0xb;
> + break;
> + default:
> + pr_err("%s: unknown dmb type %d\n", __func__, type);
> + return AARCH64_BREAK_FAULT;
> + }
> +
> + insn = aarch64_insn_get_dmb_value();
> + insn &= ~GENMASK(11, 8);
> + insn |= (opt << 8);
> +
> + return insn;
> +}
> diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
> index cc0cf0f5c7c3..308f96587861 100644
> --- a/arch/arm64/net/bpf_jit.h
> +++ b/arch/arm64/net/bpf_jit.h
> @@ -88,10 +88,41 @@
> /* [Rn] = Rt; (atomic) Rs = [state] */
> #define A64_STXR(sf, Rt, Rn, Rs) \
> A64_LSX(sf, Rt, Rn, Rs, STORE_EX)
> +/* smp_mb(); [Rn] = Rt; (atomic) Rs = [state] */
> +#define A64_STLXR(sf, Rt, Rn, Rs) \
> + aarch64_insn_gen_store_release_ex(Rt, Rn, Rs, A64_SIZE(sf))
>
> -/* LSE atomics */
> -#define A64_STADD(sf, Rn, Rs) \
> - aarch64_insn_gen_stadd(Rn, Rs, A64_SIZE(sf))
> +/*
> + * LSE atomics
> + *
> + * ST{ADD,CLR,SET,EOR} is simply encoded as an alias for
> + * LDD{ADD,CLR,SET,EOR} with XZR as the destination register.
> + */
> +#define A64_ST_OP(sf, Rn, Rs, op) \
> + aarch64_insn_gen_atomic_ld_op(A64_ZR, Rn, Rs, \
> + A64_SIZE(sf), AARCH64_INSN_MEM_ATOMIC_##op, \
> + AARCH64_INSN_MEM_ORDER_NONE)
> +/* [Rn] <op>= Rs */
> +#define A64_STADD(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, ADD)
> +#define A64_STCLR(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, BIC)
> +#define A64_STEOR(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, EOR)
> +#define A64_STSET(sf, Rn, Rs) A64_ST_OP(sf, Rn, Rs, ORR)
> +
> +#define A64_LD_OP_AL(sf, Rt, Rn, Rs, op) \
> + aarch64_insn_gen_atomic_ld_op(Rt, Rn, Rs, \
> + A64_SIZE(sf), AARCH64_INSN_MEM_ATOMIC_##op, \
> + AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL)
> +/* Rt = [Rn]; [Rn] <op>= Rs */
> +#define A64_LDADDAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, ADD)
> +#define A64_LDCLRAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, BIC)
> +#define A64_LDEORAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, EOR)
> +#define A64_LDSETAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, ORR)
> +/* Rt = [Rn]; [Rn] = Rs */
> +#define A64_SWPAL(sf, Rt, Rn, Rs) A64_LD_OP_AL(sf, Rt, Rn, Rs, SWP)
> +/* Rs = CAS(Rn, Rs, Rt) */
> +#define A64_CASAL(sf, Rt, Rn, Rs) \
> + aarch64_insn_gen_cas(Rt, Rn, Rs, A64_SIZE(sf), \
> + AARCH64_INSN_MEM_ORDER_LOAD_ACQ_STORE_REL)
>
> /* Add/subtract (immediate) */
> #define A64_ADDSUB_IMM(sf, Rd, Rn, imm12, type) \
> @@ -196,6 +227,9 @@
> #define A64_ANDS(sf, Rd, Rn, Rm) A64_LOGIC_SREG(sf, Rd, Rn, Rm, AND_SETFLAGS)
> /* Rn & Rm; set condition flags */
> #define A64_TST(sf, Rn, Rm) A64_ANDS(sf, A64_ZR, Rn, Rm)
> +/* Rd = ~Rm (alias of ORN with A64_ZR as Rn) */
> +#define A64_MVN(sf, Rd, Rm) \
> + A64_LOGIC_SREG(sf, Rd, A64_ZR, Rm, ORN)
>
> /* Logical (immediate) */
> #define A64_LOGIC_IMM(sf, Rd, Rn, imm, type) ({ \
> @@ -219,4 +253,7 @@
> #define A64_BTI_J A64_HINT(AARCH64_INSN_HINT_BTIJ)
> #define A64_BTI_JC A64_HINT(AARCH64_INSN_HINT_BTIJC)
>
> +/* DMB */
> +#define A64_DMB_ISH aarch64_insn_gen_dmb(AARCH64_INSN_MB_ISH)
> +
> #endif /* _BPF_JIT_H */
> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
> index 74f9a9b6a053..79e2c2c4c733 100644
> --- a/arch/arm64/net/bpf_jit_comp.c
> +++ b/arch/arm64/net/bpf_jit_comp.c
> @@ -27,6 +27,17 @@
> #define TCALL_CNT (MAX_BPF_JIT_REG + 2)
> #define TMP_REG_3 (MAX_BPF_JIT_REG + 3)
>
> +#define check_imm(bits, imm) do { \
> + if ((((imm) > 0) && ((imm) >> (bits))) || \
> + (((imm) < 0) && (~(imm) >> (bits)))) { \
> + pr_info("[%2d] imm=%d(0x%x) out of range\n", \
> + i, imm, imm); \
> + return -EINVAL; \
> + } \
> +} while (0)
> +#define check_imm19(imm) check_imm(19, imm)
> +#define check_imm26(imm) check_imm(26, imm)
> +
> /* Map BPF registers to A64 registers */
> static const int bpf2a64[] = {
> /* return value from in-kernel function, and exit value from eBPF */
> @@ -329,6 +340,163 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx)
> #undef jmp_offset
> }
>
> +static int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
> +{
> + const u8 code = insn->code;
> + const u8 dst = bpf2a64[insn->dst_reg];
> + const u8 src = bpf2a64[insn->src_reg];
> + const u8 tmp = bpf2a64[TMP_REG_1];
> + const u8 tmp2 = bpf2a64[TMP_REG_2];
> + const bool isdw = BPF_SIZE(code) == BPF_DW;
> + const s16 off = insn->off;
> + u8 reg;
> +
> + if (!off) {
> + reg = dst;
> + } else {
> + emit_a64_mov_i(1, tmp, off, ctx);
> + emit(A64_ADD(1, tmp, tmp, dst), ctx);
> + reg = tmp;
> + }
> +
> + switch (insn->imm) {
> + /* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
> + case BPF_ADD:
> + emit(A64_STADD(isdw, reg, src), ctx);
> + break;
> + case BPF_AND:
> + emit(A64_MVN(isdw, tmp2, src), ctx);
> + emit(A64_STCLR(isdw, reg, tmp2), ctx);
> + break;
> + case BPF_OR:
> + emit(A64_STSET(isdw, reg, src), ctx);
> + break;
> + case BPF_XOR:
> + emit(A64_STEOR(isdw, reg, src), ctx);
> + break;
> + /* src_reg = atomic_fetch_add(dst_reg + off, src_reg) */
> + case BPF_ADD | BPF_FETCH:
> + emit(A64_LDADDAL(isdw, src, reg, src), ctx);
> + break;
> + case BPF_AND | BPF_FETCH:
> + emit(A64_MVN(isdw, tmp2, src), ctx);
> + emit(A64_LDCLRAL(isdw, src, reg, tmp2), ctx);
> + break;
> + case BPF_OR | BPF_FETCH:
> + emit(A64_LDSETAL(isdw, src, reg, src), ctx);
> + break;
> + case BPF_XOR | BPF_FETCH:
> + emit(A64_LDEORAL(isdw, src, reg, src), ctx);
> + break;
> + /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
> + case BPF_XCHG:
> + emit(A64_SWPAL(isdw, src, reg, src), ctx);
> + break;
> + /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
> + case BPF_CMPXCHG:
> + emit(A64_CASAL(isdw, src, reg, bpf2a64[BPF_REG_0]), ctx);
> + break;
> + default:
> + pr_err_once("unknown atomic op code %02x\n", insn->imm);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
> +{
> + const u8 code = insn->code;
> + const u8 dst = bpf2a64[insn->dst_reg];
> + const u8 src = bpf2a64[insn->src_reg];
> + const u8 tmp = bpf2a64[TMP_REG_1];
> + const u8 tmp2 = bpf2a64[TMP_REG_2];
> + const u8 tmp3 = bpf2a64[TMP_REG_3];
> + const int i = insn - ctx->prog->insnsi;
> + const s32 imm = insn->imm;
> + const s16 off = insn->off;
> + const bool isdw = BPF_SIZE(code) == BPF_DW;
> + u8 reg;
> + s32 jmp_offset;
> +
> + if (!off) {
> + reg = dst;
> + } else {
> + emit_a64_mov_i(1, tmp, off, ctx);
> + emit(A64_ADD(1, tmp, tmp, dst), ctx);
> + reg = tmp;
> + }
> +
> + if (imm == BPF_ADD || imm == BPF_AND ||
> + imm == BPF_OR || imm == BPF_XOR) {
> + /* lock *(u32/u64 *)(dst_reg + off) <op>= src_reg */
> + emit(A64_LDXR(isdw, tmp2, reg), ctx);
> + if (imm == BPF_ADD)
> + emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
> + else if (imm == BPF_AND)
> + emit(A64_AND(isdw, tmp2, tmp2, src), ctx);
> + else if (imm == BPF_OR)
> + emit(A64_ORR(isdw, tmp2, tmp2, src), ctx);
> + else
> + emit(A64_EOR(isdw, tmp2, tmp2, src), ctx);
> + emit(A64_STXR(isdw, tmp2, reg, tmp3), ctx);
> + jmp_offset = -3;
> + check_imm19(jmp_offset);
> + emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
> + } else if (imm == (BPF_ADD | BPF_FETCH) ||
> + imm == (BPF_AND | BPF_FETCH) ||
> + imm == (BPF_OR | BPF_FETCH) ||
> + imm == (BPF_XOR | BPF_FETCH)) {
> + /* src_reg = atomic_fetch_add(dst_reg + off, src_reg) */
> + const u8 ax = bpf2a64[BPF_REG_AX];
> +
> + emit(A64_MOV(isdw, ax, src), ctx);
> + emit(A64_LDXR(isdw, src, reg), ctx);
> + if (imm == (BPF_ADD | BPF_FETCH))
> + emit(A64_ADD(isdw, tmp2, src, ax), ctx);
> + else if (imm == (BPF_AND | BPF_FETCH))
> + emit(A64_AND(isdw, tmp2, src, ax), ctx);
> + else if (imm == (BPF_OR | BPF_FETCH))
> + emit(A64_ORR(isdw, tmp2, src, ax), ctx);
> + else
> + emit(A64_EOR(isdw, tmp2, src, ax), ctx);
> + emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
> + jmp_offset = -3;
> + check_imm19(jmp_offset);
> + emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
> + emit(A64_DMB_ISH, ctx);
> + } else if (imm == BPF_XCHG) {
> + /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
> + emit(A64_MOV(isdw, tmp2, src), ctx);
> + emit(A64_LDXR(isdw, src, reg), ctx);
> + emit(A64_STLXR(isdw, tmp2, reg, tmp3), ctx);
> + jmp_offset = -2;
> + check_imm19(jmp_offset);
> + emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
> + emit(A64_DMB_ISH, ctx);
> + } else if (imm == BPF_CMPXCHG) {
> + /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
> + const u8 r0 = bpf2a64[BPF_REG_0];
> +
> + emit(A64_MOV(isdw, tmp2, r0), ctx);
> + emit(A64_LDXR(isdw, r0, reg), ctx);
> + emit(A64_EOR(isdw, tmp3, r0, tmp2), ctx);
> + jmp_offset = 4;
> + check_imm19(jmp_offset);
> + emit(A64_CBNZ(isdw, tmp3, jmp_offset), ctx);
> + emit(A64_STLXR(isdw, src, reg, tmp3), ctx);
> + jmp_offset = -4;
> + check_imm19(jmp_offset);
> + emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
> + emit(A64_DMB_ISH, ctx);
> + } else {
> + pr_err_once("unknown atomic op code %02x\n", imm);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> static void build_epilogue(struct jit_ctx *ctx)
> {
> const u8 r0 = bpf2a64[BPF_REG_0];
> @@ -434,29 +602,16 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
> const u8 src = bpf2a64[insn->src_reg];
> const u8 tmp = bpf2a64[TMP_REG_1];
> const u8 tmp2 = bpf2a64[TMP_REG_2];
> - const u8 tmp3 = bpf2a64[TMP_REG_3];
> const s16 off = insn->off;
> const s32 imm = insn->imm;
> const int i = insn - ctx->prog->insnsi;
> const bool is64 = BPF_CLASS(code) == BPF_ALU64 ||
> BPF_CLASS(code) == BPF_JMP;
> - const bool isdw = BPF_SIZE(code) == BPF_DW;
> - u8 jmp_cond, reg;
> + u8 jmp_cond;
> s32 jmp_offset;
> u32 a64_insn;
> int ret;
>
> -#define check_imm(bits, imm) do { \
> - if ((((imm) > 0) && ((imm) >> (bits))) || \
> - (((imm) < 0) && (~(imm) >> (bits)))) { \
> - pr_info("[%2d] imm=%d(0x%x) out of range\n", \
> - i, imm, imm); \
> - return -EINVAL; \
> - } \
> -} while (0)
> -#define check_imm19(imm) check_imm(19, imm)
> -#define check_imm26(imm) check_imm(26, imm)
> -
> switch (code) {
> /* dst = src */
> case BPF_ALU | BPF_MOV | BPF_X:
> @@ -891,33 +1046,12 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
>
> case BPF_STX | BPF_ATOMIC | BPF_W:
> case BPF_STX | BPF_ATOMIC | BPF_DW:
> - if (insn->imm != BPF_ADD) {
> - pr_err_once("unknown atomic op code %02x\n", insn->imm);
> - return -EINVAL;
> - }
> -
> - /* STX XADD: lock *(u32 *)(dst + off) += src
> - * and
> - * STX XADD: lock *(u64 *)(dst + off) += src
> - */
> -
> - if (!off) {
> - reg = dst;
> - } else {
> - emit_a64_mov_i(1, tmp, off, ctx);
> - emit(A64_ADD(1, tmp, tmp, dst), ctx);
> - reg = tmp;
> - }
> - if (cpus_have_cap(ARM64_HAS_LSE_ATOMICS)) {
> - emit(A64_STADD(isdw, reg, src), ctx);
> - } else {
> - emit(A64_LDXR(isdw, tmp2, reg), ctx);
> - emit(A64_ADD(isdw, tmp2, tmp2, src), ctx);
> - emit(A64_STXR(isdw, tmp2, reg, tmp3), ctx);
> - jmp_offset = -3;
> - check_imm19(jmp_offset);
> - emit(A64_CBNZ(0, tmp3, jmp_offset), ctx);
> - }
> + if (cpus_have_cap(ARM64_HAS_LSE_ATOMICS))
> + ret = emit_lse_atomic(insn, ctx);
> + else
> + ret = emit_ll_sc_atomic(insn, ctx);
> + if (ret)
> + return ret;
> break;
>
> default:
> --
> 2.27.0
>
>
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