From e1cf4befa297b149149f633eff746593e400c030 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 4 May 2018 01:08:22 +0200 Subject: [PATCH] bpf, s390x: remove ld_abs/ld_ind Since LD_ABS/LD_IND instructions are now removed from the core and reimplemented through a combination of inlined BPF instructions and a slow-path helper, we can get rid of the complexity from s390x JIT. Tested on s390x instance on LinuxONE. Signed-off-by: Daniel Borkmann Cc: Michael Holzheu Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov --- arch/s390/net/Makefile | 2 +- arch/s390/net/bpf_jit.S | 116 -------------------------------- arch/s390/net/bpf_jit.h | 20 +----- arch/s390/net/bpf_jit_comp.c | 127 +++-------------------------------- 4 files changed, 13 insertions(+), 252 deletions(-) delete mode 100644 arch/s390/net/bpf_jit.S diff --git a/arch/s390/net/Makefile b/arch/s390/net/Makefile index e0d5f245e42b..d4663b4bf509 100644 --- a/arch/s390/net/Makefile +++ b/arch/s390/net/Makefile @@ -2,4 +2,4 @@ # # Arch-specific network modules # -obj-$(CONFIG_BPF_JIT) += bpf_jit.o bpf_jit_comp.o +obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o diff --git a/arch/s390/net/bpf_jit.S b/arch/s390/net/bpf_jit.S deleted file mode 100644 index 25bb4643c4f4..000000000000 --- a/arch/s390/net/bpf_jit.S +++ /dev/null @@ -1,116 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* - * BPF Jit compiler for s390, help functions. - * - * Copyright IBM Corp. 2012,2015 - * - * Author(s): Martin Schwidefsky - * Michael Holzheu - */ - -#include -#include "bpf_jit.h" - -/* - * Calling convention: - * registers %r7-%r10, %r11,%r13, and %r15 are call saved - * - * Input (64 bit): - * %r3 (%b2) = offset into skb data - * %r6 (%b5) = return address - * %r7 (%b6) = skb pointer - * %r12 = skb data pointer - * - * Output: - * %r14= %b0 = return value (read skb value) - * - * Work registers: %r2,%r4,%r5,%r14 - * - * skb_copy_bits takes 4 parameters: - * %r2 = skb pointer - * %r3 = offset into skb data - * %r4 = pointer to temp buffer - * %r5 = length to copy - * Return value in %r2: 0 = ok - * - * bpf_internal_load_pointer_neg_helper takes 3 parameters: - * %r2 = skb pointer - * %r3 = offset into data - * %r4 = length to copy - * Return value in %r2: Pointer to data - */ - -#define SKF_MAX_NEG_OFF -0x200000 /* SKF_LL_OFF from filter.h */ - -/* - * Load SIZE bytes from SKB - */ -#define sk_load_common(NAME, SIZE, LOAD) \ -ENTRY(sk_load_##NAME); \ - ltgr %r3,%r3; /* Is offset negative? */ \ - jl sk_load_##NAME##_slow_neg; \ -ENTRY(sk_load_##NAME##_pos); \ - aghi %r3,SIZE; /* Offset + SIZE */ \ - clg %r3,STK_OFF_HLEN(%r15); /* Offset + SIZE > hlen? */ \ - jh sk_load_##NAME##_slow; \ - LOAD %r14,-SIZE(%r3,%r12); /* Get data from skb */ \ - b OFF_OK(%r6); /* Return */ \ - \ -sk_load_##NAME##_slow:; \ - lgr %r2,%r7; /* Arg1 = skb pointer */ \ - aghi %r3,-SIZE; /* Arg2 = offset */ \ - la %r4,STK_OFF_TMP(%r15); /* Arg3 = temp bufffer */ \ - lghi %r5,SIZE; /* Arg4 = size */ \ - brasl %r14,skb_copy_bits; /* Get data from skb */ \ - LOAD %r14,STK_OFF_TMP(%r15); /* Load from temp bufffer */ \ - ltgr %r2,%r2; /* Set cc to (%r2 != 0) */ \ - br %r6; /* Return */ - -sk_load_common(word, 4, llgf) /* r14 = *(u32 *) (skb->data+offset) */ -sk_load_common(half, 2, llgh) /* r14 = *(u16 *) (skb->data+offset) */ - -/* - * Load 1 byte from SKB (optimized version) - */ - /* r14 = *(u8 *) (skb->data+offset) */ -ENTRY(sk_load_byte) - ltgr %r3,%r3 # Is offset negative? - jl sk_load_byte_slow_neg -ENTRY(sk_load_byte_pos) - clg %r3,STK_OFF_HLEN(%r15) # Offset >= hlen? - jnl sk_load_byte_slow - llgc %r14,0(%r3,%r12) # Get byte from skb - b OFF_OK(%r6) # Return OK - -sk_load_byte_slow: - lgr %r2,%r7 # Arg1 = skb pointer - # Arg2 = offset - la %r4,STK_OFF_TMP(%r15) # Arg3 = pointer to temp buffer - lghi %r5,1 # Arg4 = size (1 byte) - brasl %r14,skb_copy_bits # Get data from skb - llgc %r14,STK_OFF_TMP(%r15) # Load result from temp buffer - ltgr %r2,%r2 # Set cc to (%r2 != 0) - br %r6 # Return cc - -#define sk_negative_common(NAME, SIZE, LOAD) \ -sk_load_##NAME##_slow_neg:; \ - cgfi %r3,SKF_MAX_NEG_OFF; \ - jl bpf_error; \ - lgr %r2,%r7; /* Arg1 = skb pointer */ \ - /* Arg2 = offset */ \ - lghi %r4,SIZE; /* Arg3 = size */ \ - brasl %r14,bpf_internal_load_pointer_neg_helper; \ - ltgr %r2,%r2; \ - jz bpf_error; \ - LOAD %r14,0(%r2); /* Get data from pointer */ \ - xr %r3,%r3; /* Set cc to zero */ \ - br %r6; /* Return cc */ - -sk_negative_common(word, 4, llgf) -sk_negative_common(half, 2, llgh) -sk_negative_common(byte, 1, llgc) - -bpf_error: -# force a return 0 from jit handler - ltgr %r15,%r15 # Set condition code - br %r6 diff --git a/arch/s390/net/bpf_jit.h b/arch/s390/net/bpf_jit.h index 5e1e5133132d..7822ea92e54a 100644 --- a/arch/s390/net/bpf_jit.h +++ b/arch/s390/net/bpf_jit.h @@ -16,9 +16,6 @@ #include #include -extern u8 sk_load_word_pos[], sk_load_half_pos[], sk_load_byte_pos[]; -extern u8 sk_load_word[], sk_load_half[], sk_load_byte[]; - #endif /* __ASSEMBLY__ */ /* @@ -36,15 +33,6 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[]; * | | | * | BPF stack | | * | | | - * +---------------+ | - * | 8 byte skbp | | - * R15+176 -> +---------------+ | - * | 8 byte hlen | | - * R15+168 -> +---------------+ | - * | 4 byte align | | - * +---------------+ | - * | 4 byte temp | | - * | for bpf_jit.S | | * R15+160 -> +---------------+ | * | new backchain | | * R15+152 -> +---------------+ | @@ -57,17 +45,11 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[]; * The stack size used by the BPF program ("BPF stack" above) is passed * via "aux->stack_depth". */ -#define STK_SPACE_ADD (8 + 8 + 4 + 4 + 160) +#define STK_SPACE_ADD (160) #define STK_160_UNUSED (160 - 12 * 8) #define STK_OFF (STK_SPACE_ADD - STK_160_UNUSED) -#define STK_OFF_TMP 160 /* Offset of tmp buffer on stack */ -#define STK_OFF_HLEN 168 /* Offset of SKB header length on stack */ -#define STK_OFF_SKBP 176 /* Offset of SKB pointer on stack */ #define STK_OFF_R6 (160 - 11 * 8) /* Offset of r6 on stack */ #define STK_OFF_TCCNT (160 - 12 * 8) /* Offset of tail_call_cnt on stack */ -/* Offset to skip condition code check */ -#define OFF_OK 4 - #endif /* __ARCH_S390_NET_BPF_JIT_H */ diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 78a19c93b380..b020bea040b7 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -47,23 +47,21 @@ struct bpf_jit { #define BPF_SIZE_MAX 0xffff /* Max size for program (16 bit branches) */ -#define SEEN_SKB 1 /* skb access */ -#define SEEN_MEM 2 /* use mem[] for temporary storage */ -#define SEEN_RET0 4 /* ret0_ip points to a valid return 0 */ -#define SEEN_LITERAL 8 /* code uses literals */ -#define SEEN_FUNC 16 /* calls C functions */ -#define SEEN_TAIL_CALL 32 /* code uses tail calls */ -#define SEEN_REG_AX 64 /* code uses constant blinding */ -#define SEEN_STACK (SEEN_FUNC | SEEN_MEM | SEEN_SKB) +#define SEEN_MEM (1 << 0) /* use mem[] for temporary storage */ +#define SEEN_RET0 (1 << 1) /* ret0_ip points to a valid return 0 */ +#define SEEN_LITERAL (1 << 2) /* code uses literals */ +#define SEEN_FUNC (1 << 3) /* calls C functions */ +#define SEEN_TAIL_CALL (1 << 4) /* code uses tail calls */ +#define SEEN_REG_AX (1 << 5) /* code uses constant blinding */ +#define SEEN_STACK (SEEN_FUNC | SEEN_MEM) /* * s390 registers */ #define REG_W0 (MAX_BPF_JIT_REG + 0) /* Work register 1 (even) */ #define REG_W1 (MAX_BPF_JIT_REG + 1) /* Work register 2 (odd) */ -#define REG_SKB_DATA (MAX_BPF_JIT_REG + 2) /* SKB data register */ -#define REG_L (MAX_BPF_JIT_REG + 3) /* Literal pool register */ -#define REG_15 (MAX_BPF_JIT_REG + 4) /* Register 15 */ +#define REG_L (MAX_BPF_JIT_REG + 2) /* Literal pool register */ +#define REG_15 (MAX_BPF_JIT_REG + 3) /* Register 15 */ #define REG_0 REG_W0 /* Register 0 */ #define REG_1 REG_W1 /* Register 1 */ #define REG_2 BPF_REG_1 /* Register 2 */ @@ -88,10 +86,8 @@ static const int reg2hex[] = { [BPF_REG_9] = 10, /* BPF stack pointer */ [BPF_REG_FP] = 13, - /* Register for blinding (shared with REG_SKB_DATA) */ + /* Register for blinding */ [BPF_REG_AX] = 12, - /* SKB data pointer */ - [REG_SKB_DATA] = 12, /* Work registers for s390x backend */ [REG_W0] = 0, [REG_W1] = 1, @@ -384,27 +380,6 @@ static void save_restore_regs(struct bpf_jit *jit, int op, u32 stack_depth) } while (re <= 15); } -/* - * For SKB access %b1 contains the SKB pointer. For "bpf_jit.S" - * we store the SKB header length on the stack and the SKB data - * pointer in REG_SKB_DATA if BPF_REG_AX is not used. - */ -static void emit_load_skb_data_hlen(struct bpf_jit *jit) -{ - /* Header length: llgf %w1,(%b1) */ - EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_1, - offsetof(struct sk_buff, len)); - /* s %w1,(%b1) */ - EMIT4_DISP(0x5b000000, REG_W1, BPF_REG_1, - offsetof(struct sk_buff, data_len)); - /* stg %w1,ST_OFF_HLEN(%r0,%r15) */ - EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15, STK_OFF_HLEN); - if (!(jit->seen & SEEN_REG_AX)) - /* lg %skb_data,data_off(%b1) */ - EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0, - BPF_REG_1, offsetof(struct sk_buff, data)); -} - /* * Emit function prologue * @@ -445,12 +420,6 @@ static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth) EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15, 152); } - if (jit->seen & SEEN_SKB) { - emit_load_skb_data_hlen(jit); - /* stg %b1,ST_OFF_SKBP(%r0,%r15) */ - EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_1, REG_0, REG_15, - STK_OFF_SKBP); - } } /* @@ -483,12 +452,12 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i { struct bpf_insn *insn = &fp->insnsi[i]; int jmp_off, last, insn_count = 1; - unsigned int func_addr, mask; u32 dst_reg = insn->dst_reg; u32 src_reg = insn->src_reg; u32 *addrs = jit->addrs; s32 imm = insn->imm; s16 off = insn->off; + unsigned int mask; if (dst_reg == BPF_REG_AX || src_reg == BPF_REG_AX) jit->seen |= SEEN_REG_AX; @@ -970,13 +939,6 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i EMIT2(0x0d00, REG_14, REG_W1); /* lgr %b0,%r2: load return value into %b0 */ EMIT4(0xb9040000, BPF_REG_0, REG_2); - if ((jit->seen & SEEN_SKB) && - bpf_helper_changes_pkt_data((void *)func)) { - /* lg %b1,ST_OFF_SKBP(%r15) */ - EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0, - REG_15, STK_OFF_SKBP); - emit_load_skb_data_hlen(jit); - } break; } case BPF_JMP | BPF_TAIL_CALL: @@ -1176,73 +1138,6 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i jmp_off = addrs[i + off + 1] - (addrs[i + 1] - 4); EMIT4_PCREL(0xa7040000 | mask << 8, jmp_off); break; - /* - * BPF_LD - */ - case BPF_LD | BPF_ABS | BPF_B: /* b0 = *(u8 *) (skb->data+imm) */ - case BPF_LD | BPF_IND | BPF_B: /* b0 = *(u8 *) (skb->data+imm+src) */ - if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0)) - func_addr = __pa(sk_load_byte_pos); - else - func_addr = __pa(sk_load_byte); - goto call_fn; - case BPF_LD | BPF_ABS | BPF_H: /* b0 = *(u16 *) (skb->data+imm) */ - case BPF_LD | BPF_IND | BPF_H: /* b0 = *(u16 *) (skb->data+imm+src) */ - if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0)) - func_addr = __pa(sk_load_half_pos); - else - func_addr = __pa(sk_load_half); - goto call_fn; - case BPF_LD | BPF_ABS | BPF_W: /* b0 = *(u32 *) (skb->data+imm) */ - case BPF_LD | BPF_IND | BPF_W: /* b0 = *(u32 *) (skb->data+imm+src) */ - if ((BPF_MODE(insn->code) == BPF_ABS) && (imm >= 0)) - func_addr = __pa(sk_load_word_pos); - else - func_addr = __pa(sk_load_word); - goto call_fn; -call_fn: - jit->seen |= SEEN_SKB | SEEN_RET0 | SEEN_FUNC; - REG_SET_SEEN(REG_14); /* Return address of possible func call */ - - /* - * Implicit input: - * BPF_REG_6 (R7) : skb pointer - * REG_SKB_DATA (R12): skb data pointer (if no BPF_REG_AX) - * - * Calculated input: - * BPF_REG_2 (R3) : offset of byte(s) to fetch in skb - * BPF_REG_5 (R6) : return address - * - * Output: - * BPF_REG_0 (R14): data read from skb - * - * Scratch registers (BPF_REG_1-5) - */ - - /* Call function: llilf %w1,func_addr */ - EMIT6_IMM(0xc00f0000, REG_W1, func_addr); - - /* Offset: lgfi %b2,imm */ - EMIT6_IMM(0xc0010000, BPF_REG_2, imm); - if (BPF_MODE(insn->code) == BPF_IND) - /* agfr %b2,%src (%src is s32 here) */ - EMIT4(0xb9180000, BPF_REG_2, src_reg); - - /* Reload REG_SKB_DATA if BPF_REG_AX is used */ - if (jit->seen & SEEN_REG_AX) - /* lg %skb_data,data_off(%b6) */ - EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0, - BPF_REG_6, offsetof(struct sk_buff, data)); - /* basr %b5,%w1 (%b5 is call saved) */ - EMIT2(0x0d00, BPF_REG_5, REG_W1); - - /* - * Note: For fast access we jump directly after the - * jnz instruction from bpf_jit.S - */ - /* jnz */ - EMIT4_PCREL(0xa7740000, jit->ret0_ip - jit->prg); - break; default: /* too complex, give up */ pr_err("Unknown opcode %02x\n", insn->code); return -1; -- GitLab