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nfp: bpf: add support for atomic add of unknown values

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Allow atomic add to be used even when the value is not guaranteed
to fit into a 16 bit immediate.  This requires the value to be pulled
as data, and therefore use of a transfer register and a context swap.

Track the information about possible lengths of the value, if it's
guaranteed to be larger than 16bits don't generate the code for the
optimized case at all.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jakub Kicinski 2018-03-28 17:48:36 -07:00 committed by Alexei Starovoitov
parent b556ddd9c1
commit 41aed09cf6
5 changed files with 88 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
drivers/net/ethernet/netronome/nfp/bpf/jit.c
View File

@ -2125,12 +2125,49 @@ static int mem_stx8(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
static int
mem_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta, bool is64)
{
swreg addra, addrb, off, prev_alu = imm_a(nfp_prog);
u8 dst_gpr = meta->insn.dst_reg * 2;
u8 src_gpr = meta->insn.src_reg * 2;
unsigned int full_add, out;
swreg addra, addrb, off;
off = ur_load_imm_any(nfp_prog, meta->insn.off, imm_b(nfp_prog));
/* We can fit 16 bits into command immediate, if we know the immediate
* is guaranteed to either always or never fit into 16 bit we only
* generate code to handle that particular case, otherwise generate
* code for both.
*/
out = nfp_prog_current_offset(nfp_prog);
full_add = nfp_prog_current_offset(nfp_prog);
if (meta->insn.off) {
out += 2;
full_add += 2;
}
if (meta->xadd_maybe_16bit) {
out += 3;
full_add += 3;
}
if (meta->xadd_over_16bit)
out += 2 + is64;
if (meta->xadd_maybe_16bit && meta->xadd_over_16bit) {
out += 5;
full_add += 5;
}
/* Generate the branch for choosing add_imm vs add */
if (meta->xadd_maybe_16bit && meta->xadd_over_16bit) {
swreg max_imm = imm_a(nfp_prog);
wrp_immed(nfp_prog, max_imm, 0xffff);
emit_alu(nfp_prog, reg_none(),
max_imm, ALU_OP_SUB, reg_b(src_gpr));
emit_alu(nfp_prog, reg_none(),
reg_imm(0), ALU_OP_SUB_C, reg_b(src_gpr + 1));
emit_br(nfp_prog, BR_BLO, full_add, meta->insn.off ? 2 : 0);
/* defer for add */
}
/* If insn has an offset add to the address */
if (!meta->insn.off) {
addra = reg_a(dst_gpr);
@ -2144,13 +2181,38 @@ mem_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta, bool is64)
addrb = imma_b(nfp_prog);
}
wrp_immed(nfp_prog, prev_alu,
FIELD_PREP(CMD_OVE_DATA, 2) |
CMD_OVE_LEN |
FIELD_PREP(CMD_OV_LEN, 0x8 | is64 << 2));
wrp_reg_or_subpart(nfp_prog, prev_alu, reg_b(src_gpr), 2, 2);
emit_cmd_indir(nfp_prog, CMD_TGT_ADD_IMM, CMD_MODE_40b_BA, 0,
addra, addrb, 0, CMD_CTX_NO_SWAP);
/* Generate the add_imm if 16 bits are possible */
if (meta->xadd_maybe_16bit) {
swreg prev_alu = imm_a(nfp_prog);
wrp_immed(nfp_prog, prev_alu,
FIELD_PREP(CMD_OVE_DATA, 2) |
CMD_OVE_LEN |
FIELD_PREP(CMD_OV_LEN, 0x8 | is64 << 2));
wrp_reg_or_subpart(nfp_prog, prev_alu, reg_b(src_gpr), 2, 2);
emit_cmd_indir(nfp_prog, CMD_TGT_ADD_IMM, CMD_MODE_40b_BA, 0,
addra, addrb, 0, CMD_CTX_NO_SWAP);
if (meta->xadd_over_16bit)
emit_br(nfp_prog, BR_UNC, out, 0);
}
if (!nfp_prog_confirm_current_offset(nfp_prog, full_add))
return -EINVAL;
/* Generate the add if 16 bits are not guaranteed */
if (meta->xadd_over_16bit) {
emit_cmd(nfp_prog, CMD_TGT_ADD, CMD_MODE_40b_BA, 0,
addra, addrb, is64 << 2,
is64 ? CMD_CTX_SWAP_DEFER2 : CMD_CTX_SWAP_DEFER1);
wrp_mov(nfp_prog, reg_xfer(0), reg_a(src_gpr));
if (is64)
wrp_mov(nfp_prog, reg_xfer(1), reg_a(src_gpr + 1));
}
if (!nfp_prog_confirm_current_offset(nfp_prog, out))
return -EINVAL;
return 0;
}

7
drivers/net/ethernet/netronome/nfp/bpf/main.h
View File

@ -229,6 +229,8 @@ struct nfp_bpf_reg_state {
* @pkt_cache.range_start: start offset for associated packet data cache
* @pkt_cache.range_end: end offset for associated packet data cache
* @pkt_cache.do_init: this read needs to initialize packet data cache
* @xadd_over_16bit: 16bit immediate is not guaranteed
* @xadd_maybe_16bit: 16bit immediate is possible
* @jmp_dst: destination info for jump instructions
* @func_id: function id for call instructions
* @arg1: arg1 for call instructions
@ -243,6 +245,7 @@ struct nfp_bpf_reg_state {
struct nfp_insn_meta {
struct bpf_insn insn;
union {
/* pointer ops (ld/st/xadd) */
struct {
struct bpf_reg_state ptr;
struct bpf_insn *paired_st;
@ -253,8 +256,12 @@ struct nfp_insn_meta {
s16 range_end;
bool do_init;
} pkt_cache;
bool xadd_over_16bit;
bool xadd_maybe_16bit;
};
/* jump */
struct nfp_insn_meta *jmp_dst;
/* function calls */
struct {
u32 func_id;
struct bpf_reg_state arg1;

14
drivers/net/ethernet/netronome/nfp/bpf/verifier.c
View File

@ -414,16 +414,16 @@ nfp_bpf_check_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
dreg->type);
return -EOPNOTSUPP;
}
if (sreg->type != SCALAR_VALUE ||
sreg->var_off.value > 0xffff || sreg->var_off.mask > 0xffff) {
char tn_buf[48];
tnum_strn(tn_buf, sizeof(tn_buf), sreg->var_off);
pr_vlog(env, "atomic add not of a small constant scalar: %s\n",
tn_buf);
if (sreg->type != SCALAR_VALUE) {
pr_vlog(env, "atomic add not of a scalar: %d\n", sreg->type);
return -EOPNOTSUPP;
}
meta->xadd_over_16bit |=
sreg->var_off.value > 0xffff || sreg->var_off.mask > 0xffff;
meta->xadd_maybe_16bit |=
(sreg->var_off.value & ~sreg->var_off.mask) <= 0xffff;
return nfp_bpf_check_ptr(nfp_prog, meta, env, meta->insn.dst_reg);
}

1
drivers/net/ethernet/netronome/nfp/nfp_asm.c
View File

@ -48,6 +48,7 @@ const struct cmd_tgt_act cmd_tgt_act[__CMD_TGT_MAP_SIZE] = {
[CMD_TGT_READ32_SWAP] = { 0x02, 0x5c },
[CMD_TGT_READ_LE] = { 0x01, 0x40 },
[CMD_TGT_READ_SWAP_LE] = { 0x03, 0x40 },
[CMD_TGT_ADD] = { 0x00, 0x47 },
[CMD_TGT_ADD_IMM] = { 0x02, 0x47 },
};

3
drivers/net/ethernet/netronome/nfp/nfp_asm.h
View File

@ -238,6 +238,7 @@ enum cmd_tgt_map {
CMD_TGT_READ32_SWAP,
CMD_TGT_READ_LE,
CMD_TGT_READ_SWAP_LE,
CMD_TGT_ADD,
CMD_TGT_ADD_IMM,
__CMD_TGT_MAP_SIZE,
};
@ -252,6 +253,8 @@ enum cmd_mode {
enum cmd_ctx_swap {
CMD_CTX_SWAP = 0,
CMD_CTX_SWAP_DEFER1 = 1,
CMD_CTX_SWAP_DEFER2 = 2,
CMD_CTX_NO_SWAP = 3,
};