diff options
Diffstat (limited to 'kernel/arch/powerpc/net')
| -rw-r--r-- | kernel/arch/powerpc/net/Makefile | 4 | ||||
| -rw-r--r-- | kernel/arch/powerpc/net/bpf_jit.h | 319 | ||||
| -rw-r--r-- | kernel/arch/powerpc/net/bpf_jit_asm.S | 229 | ||||
| -rw-r--r-- | kernel/arch/powerpc/net/bpf_jit_comp.c | 695 |
4 files changed, 1247 insertions, 0 deletions
diff --git a/kernel/arch/powerpc/net/Makefile b/kernel/arch/powerpc/net/Makefile new file mode 100644 index 000000000..1306a58ac --- /dev/null +++ b/kernel/arch/powerpc/net/Makefile @@ -0,0 +1,4 @@ +# +# Arch-specific network modules +# +obj-$(CONFIG_BPF_JIT) += bpf_jit_asm.o bpf_jit_comp.o diff --git a/kernel/arch/powerpc/net/bpf_jit.h b/kernel/arch/powerpc/net/bpf_jit.h new file mode 100644 index 000000000..889fd199a --- /dev/null +++ b/kernel/arch/powerpc/net/bpf_jit.h @@ -0,0 +1,319 @@ +/* bpf_jit.h: BPF JIT compiler for PPC64 + * + * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ +#ifndef _BPF_JIT_H +#define _BPF_JIT_H + +#ifdef CONFIG_PPC64 +#define BPF_PPC_STACK_R3_OFF 48 +#define BPF_PPC_STACK_LOCALS 32 +#define BPF_PPC_STACK_BASIC (48+64) +#define BPF_PPC_STACK_SAVE (18*8) +#define BPF_PPC_STACKFRAME (BPF_PPC_STACK_BASIC+BPF_PPC_STACK_LOCALS+ \ + BPF_PPC_STACK_SAVE) +#define BPF_PPC_SLOWPATH_FRAME (48+64) +#else +#define BPF_PPC_STACK_R3_OFF 24 +#define BPF_PPC_STACK_LOCALS 16 +#define BPF_PPC_STACK_BASIC (24+32) +#define BPF_PPC_STACK_SAVE (18*4) +#define BPF_PPC_STACKFRAME (BPF_PPC_STACK_BASIC+BPF_PPC_STACK_LOCALS+ \ + BPF_PPC_STACK_SAVE) +#define BPF_PPC_SLOWPATH_FRAME (24+32) +#endif + +#define REG_SZ (BITS_PER_LONG/8) + +/* + * Generated code register usage: + * + * As normal PPC C ABI (e.g. r1=sp, r2=TOC), with: + * + * skb r3 (Entry parameter) + * A register r4 + * X register r5 + * addr param r6 + * r7-r10 scratch + * skb->data r14 + * skb headlen r15 (skb->len - skb->data_len) + * m[0] r16 + * m[...] ... + * m[15] r31 + */ +#define r_skb 3 +#define r_ret 3 +#define r_A 4 +#define r_X 5 +#define r_addr 6 +#define r_scratch1 7 +#define r_scratch2 8 +#define r_D 14 +#define r_HL 15 +#define r_M 16 + +#ifndef __ASSEMBLY__ + +/* + * Assembly helpers from arch/powerpc/net/bpf_jit.S: + */ +#define DECLARE_LOAD_FUNC(func) \ + extern u8 func[], func##_negative_offset[], func##_positive_offset[] + +DECLARE_LOAD_FUNC(sk_load_word); +DECLARE_LOAD_FUNC(sk_load_half); +DECLARE_LOAD_FUNC(sk_load_byte); +DECLARE_LOAD_FUNC(sk_load_byte_msh); + +#ifdef CONFIG_PPC64 +#define FUNCTION_DESCR_SIZE 24 +#else +#define FUNCTION_DESCR_SIZE 0 +#endif + +/* + * 16-bit immediate helper macros: HA() is for use with sign-extending instrs + * (e.g. LD, ADDI). If the bottom 16 bits is "-ve", add another bit into the + * top half to negate the effect (i.e. 0xffff + 1 = 0x(1)0000). + */ +#define IMM_H(i) ((uintptr_t)(i)>>16) +#define IMM_HA(i) (((uintptr_t)(i)>>16) + \ + (((uintptr_t)(i) & 0x8000) >> 15)) +#define IMM_L(i) ((uintptr_t)(i) & 0xffff) + +#define PLANT_INSTR(d, idx, instr) \ + do { if (d) { (d)[idx] = instr; } idx++; } while (0) +#define EMIT(instr) PLANT_INSTR(image, ctx->idx, instr) + +#define PPC_NOP() EMIT(PPC_INST_NOP) +#define PPC_BLR() EMIT(PPC_INST_BLR) +#define PPC_BLRL() EMIT(PPC_INST_BLRL) +#define PPC_MTLR(r) EMIT(PPC_INST_MTLR | ___PPC_RT(r)) +#define PPC_ADDI(d, a, i) EMIT(PPC_INST_ADDI | ___PPC_RT(d) | \ + ___PPC_RA(a) | IMM_L(i)) +#define PPC_MR(d, a) PPC_OR(d, a, a) +#define PPC_LI(r, i) PPC_ADDI(r, 0, i) +#define PPC_ADDIS(d, a, i) EMIT(PPC_INST_ADDIS | \ + ___PPC_RS(d) | ___PPC_RA(a) | IMM_L(i)) +#define PPC_LIS(r, i) PPC_ADDIS(r, 0, i) +#define PPC_STD(r, base, i) EMIT(PPC_INST_STD | ___PPC_RS(r) | \ + ___PPC_RA(base) | ((i) & 0xfffc)) +#define PPC_STDU(r, base, i) EMIT(PPC_INST_STDU | ___PPC_RS(r) | \ + ___PPC_RA(base) | ((i) & 0xfffc)) +#define PPC_STW(r, base, i) EMIT(PPC_INST_STW | ___PPC_RS(r) | \ + ___PPC_RA(base) | ((i) & 0xfffc)) +#define PPC_STWU(r, base, i) EMIT(PPC_INST_STWU | ___PPC_RS(r) | \ + ___PPC_RA(base) | ((i) & 0xfffc)) + +#define PPC_LBZ(r, base, i) EMIT(PPC_INST_LBZ | ___PPC_RT(r) | \ + ___PPC_RA(base) | IMM_L(i)) +#define PPC_LD(r, base, i) EMIT(PPC_INST_LD | ___PPC_RT(r) | \ + ___PPC_RA(base) | IMM_L(i)) +#define PPC_LWZ(r, base, i) EMIT(PPC_INST_LWZ | ___PPC_RT(r) | \ + ___PPC_RA(base) | IMM_L(i)) +#define PPC_LHZ(r, base, i) EMIT(PPC_INST_LHZ | ___PPC_RT(r) | \ + ___PPC_RA(base) | IMM_L(i)) +#define PPC_LHBRX(r, base, b) EMIT(PPC_INST_LHBRX | ___PPC_RT(r) | \ + ___PPC_RA(base) | ___PPC_RB(b)) + +#ifdef CONFIG_PPC64 +#define PPC_BPF_LL(r, base, i) do { PPC_LD(r, base, i); } while(0) +#define PPC_BPF_STL(r, base, i) do { PPC_STD(r, base, i); } while(0) +#define PPC_BPF_STLU(r, base, i) do { PPC_STDU(r, base, i); } while(0) +#else +#define PPC_BPF_LL(r, base, i) do { PPC_LWZ(r, base, i); } while(0) +#define PPC_BPF_STL(r, base, i) do { PPC_STW(r, base, i); } while(0) +#define PPC_BPF_STLU(r, base, i) do { PPC_STWU(r, base, i); } while(0) +#endif + +/* Convenience helpers for the above with 'far' offsets: */ +#define PPC_LBZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LBZ(r, base, i); \ + else { PPC_ADDIS(r, base, IMM_HA(i)); \ + PPC_LBZ(r, r, IMM_L(i)); } } while(0) + +#define PPC_LD_OFFS(r, base, i) do { if ((i) < 32768) PPC_LD(r, base, i); \ + else { PPC_ADDIS(r, base, IMM_HA(i)); \ + PPC_LD(r, r, IMM_L(i)); } } while(0) + +#define PPC_LWZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LWZ(r, base, i); \ + else { PPC_ADDIS(r, base, IMM_HA(i)); \ + PPC_LWZ(r, r, IMM_L(i)); } } while(0) + +#define PPC_LHZ_OFFS(r, base, i) do { if ((i) < 32768) PPC_LHZ(r, base, i); \ + else { PPC_ADDIS(r, base, IMM_HA(i)); \ + PPC_LHZ(r, r, IMM_L(i)); } } while(0) + +#ifdef CONFIG_PPC64 +#define PPC_LL_OFFS(r, base, i) do { PPC_LD_OFFS(r, base, i); } while(0) +#else +#define PPC_LL_OFFS(r, base, i) do { PPC_LWZ_OFFS(r, base, i); } while(0) +#endif + +#ifdef CONFIG_SMP +#ifdef CONFIG_PPC64 +#define PPC_BPF_LOAD_CPU(r) \ + do { BUILD_BUG_ON(FIELD_SIZEOF(struct paca_struct, paca_index) != 2); \ + PPC_LHZ_OFFS(r, 13, offsetof(struct paca_struct, paca_index)); \ + } while (0) +#else +#define PPC_BPF_LOAD_CPU(r) \ + do { BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4); \ + PPC_LHZ_OFFS(r, (1 & ~(THREAD_SIZE - 1)), \ + offsetof(struct thread_info, cpu)); \ + } while(0) +#endif +#else +#define PPC_BPF_LOAD_CPU(r) do { PPC_LI(r, 0); } while(0) +#endif + +#define PPC_CMPWI(a, i) EMIT(PPC_INST_CMPWI | ___PPC_RA(a) | IMM_L(i)) +#define PPC_CMPDI(a, i) EMIT(PPC_INST_CMPDI | ___PPC_RA(a) | IMM_L(i)) +#define PPC_CMPLWI(a, i) EMIT(PPC_INST_CMPLWI | ___PPC_RA(a) | IMM_L(i)) +#define PPC_CMPLW(a, b) EMIT(PPC_INST_CMPLW | ___PPC_RA(a) | ___PPC_RB(b)) + +#define PPC_SUB(d, a, b) EMIT(PPC_INST_SUB | ___PPC_RT(d) | \ + ___PPC_RB(a) | ___PPC_RA(b)) +#define PPC_ADD(d, a, b) EMIT(PPC_INST_ADD | ___PPC_RT(d) | \ + ___PPC_RA(a) | ___PPC_RB(b)) +#define PPC_MUL(d, a, b) EMIT(PPC_INST_MULLW | ___PPC_RT(d) | \ + ___PPC_RA(a) | ___PPC_RB(b)) +#define PPC_MULHWU(d, a, b) EMIT(PPC_INST_MULHWU | ___PPC_RT(d) | \ + ___PPC_RA(a) | ___PPC_RB(b)) +#define PPC_MULI(d, a, i) EMIT(PPC_INST_MULLI | ___PPC_RT(d) | \ + ___PPC_RA(a) | IMM_L(i)) +#define PPC_DIVWU(d, a, b) EMIT(PPC_INST_DIVWU | ___PPC_RT(d) | \ + ___PPC_RA(a) | ___PPC_RB(b)) +#define PPC_AND(d, a, b) EMIT(PPC_INST_AND | ___PPC_RA(d) | \ + ___PPC_RS(a) | ___PPC_RB(b)) +#define PPC_ANDI(d, a, i) EMIT(PPC_INST_ANDI | ___PPC_RA(d) | \ + ___PPC_RS(a) | IMM_L(i)) +#define PPC_AND_DOT(d, a, b) EMIT(PPC_INST_ANDDOT | ___PPC_RA(d) | \ + ___PPC_RS(a) | ___PPC_RB(b)) +#define PPC_OR(d, a, b) EMIT(PPC_INST_OR | ___PPC_RA(d) | \ + ___PPC_RS(a) | ___PPC_RB(b)) +#define PPC_ORI(d, a, i) EMIT(PPC_INST_ORI | ___PPC_RA(d) | \ + ___PPC_RS(a) | IMM_L(i)) +#define PPC_ORIS(d, a, i) EMIT(PPC_INST_ORIS | ___PPC_RA(d) | \ + ___PPC_RS(a) | IMM_L(i)) +#define PPC_XOR(d, a, b) EMIT(PPC_INST_XOR | ___PPC_RA(d) | \ + ___PPC_RS(a) | ___PPC_RB(b)) +#define PPC_XORI(d, a, i) EMIT(PPC_INST_XORI | ___PPC_RA(d) | \ + ___PPC_RS(a) | IMM_L(i)) +#define PPC_XORIS(d, a, i) EMIT(PPC_INST_XORIS | ___PPC_RA(d) | \ + ___PPC_RS(a) | IMM_L(i)) +#define PPC_SLW(d, a, s) EMIT(PPC_INST_SLW | ___PPC_RA(d) | \ + ___PPC_RS(a) | ___PPC_RB(s)) +#define PPC_SRW(d, a, s) EMIT(PPC_INST_SRW | ___PPC_RA(d) | \ + ___PPC_RS(a) | ___PPC_RB(s)) +/* slwi = rlwinm Rx, Ry, n, 0, 31-n */ +#define PPC_SLWI(d, a, i) EMIT(PPC_INST_RLWINM | ___PPC_RA(d) | \ + ___PPC_RS(a) | __PPC_SH(i) | \ + __PPC_MB(0) | __PPC_ME(31-(i))) +/* srwi = rlwinm Rx, Ry, 32-n, n, 31 */ +#define PPC_SRWI(d, a, i) EMIT(PPC_INST_RLWINM | ___PPC_RA(d) | \ + ___PPC_RS(a) | __PPC_SH(32-(i)) | \ + __PPC_MB(i) | __PPC_ME(31)) +/* sldi = rldicr Rx, Ry, n, 63-n */ +#define PPC_SLDI(d, a, i) EMIT(PPC_INST_RLDICR | ___PPC_RA(d) | \ + ___PPC_RS(a) | __PPC_SH(i) | \ + __PPC_MB(63-(i)) | (((i) & 0x20) >> 4)) +#define PPC_NEG(d, a) EMIT(PPC_INST_NEG | ___PPC_RT(d) | ___PPC_RA(a)) + +/* Long jump; (unconditional 'branch') */ +#define PPC_JMP(dest) EMIT(PPC_INST_BRANCH | \ + (((dest) - (ctx->idx * 4)) & 0x03fffffc)) +/* "cond" here covers BO:BI fields. */ +#define PPC_BCC_SHORT(cond, dest) EMIT(PPC_INST_BRANCH_COND | \ + (((cond) & 0x3ff) << 16) | \ + (((dest) - (ctx->idx * 4)) & \ + 0xfffc)) +#define PPC_LI32(d, i) do { PPC_LI(d, IMM_L(i)); \ + if ((u32)(uintptr_t)(i) >= 32768) { \ + PPC_ADDIS(d, d, IMM_HA(i)); \ + } } while(0) +#define PPC_LI64(d, i) do { \ + if (!((uintptr_t)(i) & 0xffffffff00000000ULL)) \ + PPC_LI32(d, i); \ + else { \ + PPC_LIS(d, ((uintptr_t)(i) >> 48)); \ + if ((uintptr_t)(i) & 0x0000ffff00000000ULL) \ + PPC_ORI(d, d, \ + ((uintptr_t)(i) >> 32) & 0xffff); \ + PPC_SLDI(d, d, 32); \ + if ((uintptr_t)(i) & 0x00000000ffff0000ULL) \ + PPC_ORIS(d, d, \ + ((uintptr_t)(i) >> 16) & 0xffff); \ + if ((uintptr_t)(i) & 0x000000000000ffffULL) \ + PPC_ORI(d, d, (uintptr_t)(i) & 0xffff); \ + } } while (0); + +#ifdef CONFIG_PPC64 +#define PPC_FUNC_ADDR(d,i) do { PPC_LI64(d, i); } while(0) +#else +#define PPC_FUNC_ADDR(d,i) do { PPC_LI32(d, i); } while(0) +#endif + +#define PPC_LHBRX_OFFS(r, base, i) \ + do { PPC_LI32(r, i); PPC_LHBRX(r, r, base); } while(0) +#ifdef __LITTLE_ENDIAN__ +#define PPC_NTOHS_OFFS(r, base, i) PPC_LHBRX_OFFS(r, base, i) +#else +#define PPC_NTOHS_OFFS(r, base, i) PPC_LHZ_OFFS(r, base, i) +#endif + +static inline bool is_nearbranch(int offset) +{ + return (offset < 32768) && (offset >= -32768); +} + +/* + * The fly in the ointment of code size changing from pass to pass is + * avoided by padding the short branch case with a NOP. If code size differs + * with different branch reaches we will have the issue of code moving from + * one pass to the next and will need a few passes to converge on a stable + * state. + */ +#define PPC_BCC(cond, dest) do { \ + if (is_nearbranch((dest) - (ctx->idx * 4))) { \ + PPC_BCC_SHORT(cond, dest); \ + PPC_NOP(); \ + } else { \ + /* Flip the 'T or F' bit to invert comparison */ \ + PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, (ctx->idx+2)*4); \ + PPC_JMP(dest); \ + } } while(0) + +/* To create a branch condition, select a bit of cr0... */ +#define CR0_LT 0 +#define CR0_GT 1 +#define CR0_EQ 2 +/* ...and modify BO[3] */ +#define COND_CMP_TRUE 0x100 +#define COND_CMP_FALSE 0x000 +/* Together, they make all required comparisons: */ +#define COND_GT (CR0_GT | COND_CMP_TRUE) +#define COND_GE (CR0_LT | COND_CMP_FALSE) +#define COND_EQ (CR0_EQ | COND_CMP_TRUE) +#define COND_NE (CR0_EQ | COND_CMP_FALSE) +#define COND_LT (CR0_LT | COND_CMP_TRUE) + +#define SEEN_DATAREF 0x10000 /* might call external helpers */ +#define SEEN_XREG 0x20000 /* X reg is used */ +#define SEEN_MEM 0x40000 /* SEEN_MEM+(1<<n) = use mem[n] for temporary + * storage */ +#define SEEN_MEM_MSK 0x0ffff + +struct codegen_context { + unsigned int seen; + unsigned int idx; + int pc_ret0; /* bpf index of first RET #0 instruction (if any) */ +}; + +#endif + +#endif diff --git a/kernel/arch/powerpc/net/bpf_jit_asm.S b/kernel/arch/powerpc/net/bpf_jit_asm.S new file mode 100644 index 000000000..8ff5a3b5d --- /dev/null +++ b/kernel/arch/powerpc/net/bpf_jit_asm.S @@ -0,0 +1,229 @@ +/* bpf_jit.S: Packet/header access helper functions + * for PPC64 BPF compiler. + * + * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ + +#include <asm/ppc_asm.h> +#include "bpf_jit.h" + +/* + * All of these routines are called directly from generated code, + * whose register usage is: + * + * r3 skb + * r4,r5 A,X + * r6 *** address parameter to helper *** + * r7-r10 scratch + * r14 skb->data + * r15 skb headlen + * r16-31 M[] + */ + +/* + * To consider: These helpers are so small it could be better to just + * generate them inline. Inline code can do the simple headlen check + * then branch directly to slow_path_XXX if required. (In fact, could + * load a spare GPR with the address of slow_path_generic and pass size + * as an argument, making the call site a mtlr, li and bllr.) + */ + .globl sk_load_word +sk_load_word: + PPC_LCMPI r_addr, 0 + blt bpf_slow_path_word_neg + .globl sk_load_word_positive_offset +sk_load_word_positive_offset: + /* Are we accessing past headlen? */ + subi r_scratch1, r_HL, 4 + PPC_LCMP r_scratch1, r_addr + blt bpf_slow_path_word + /* Nope, just hitting the header. cr0 here is eq or gt! */ +#ifdef __LITTLE_ENDIAN__ + lwbrx r_A, r_D, r_addr +#else + lwzx r_A, r_D, r_addr +#endif + blr /* Return success, cr0 != LT */ + + .globl sk_load_half +sk_load_half: + PPC_LCMPI r_addr, 0 + blt bpf_slow_path_half_neg + .globl sk_load_half_positive_offset +sk_load_half_positive_offset: + subi r_scratch1, r_HL, 2 + PPC_LCMP r_scratch1, r_addr + blt bpf_slow_path_half +#ifdef __LITTLE_ENDIAN__ + lhbrx r_A, r_D, r_addr +#else + lhzx r_A, r_D, r_addr +#endif + blr + + .globl sk_load_byte +sk_load_byte: + PPC_LCMPI r_addr, 0 + blt bpf_slow_path_byte_neg + .globl sk_load_byte_positive_offset +sk_load_byte_positive_offset: + PPC_LCMP r_HL, r_addr + ble bpf_slow_path_byte + lbzx r_A, r_D, r_addr + blr + +/* + * BPF_LDX | BPF_B | BPF_MSH: ldxb 4*([offset]&0xf) + * r_addr is the offset value + */ + .globl sk_load_byte_msh +sk_load_byte_msh: + PPC_LCMPI r_addr, 0 + blt bpf_slow_path_byte_msh_neg + .globl sk_load_byte_msh_positive_offset +sk_load_byte_msh_positive_offset: + PPC_LCMP r_HL, r_addr + ble bpf_slow_path_byte_msh + lbzx r_X, r_D, r_addr + rlwinm r_X, r_X, 2, 32-4-2, 31-2 + blr + +/* Call out to skb_copy_bits: + * We'll need to back up our volatile regs first; we have + * local variable space at r1+(BPF_PPC_STACK_BASIC). + * Allocate a new stack frame here to remain ABI-compliant in + * stashing LR. + */ +#define bpf_slow_path_common(SIZE) \ + mflr r0; \ + PPC_STL r0, PPC_LR_STKOFF(r1); \ + /* R3 goes in parameter space of caller's frame */ \ + PPC_STL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \ + PPC_STL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \ + PPC_STL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \ + addi r5, r1, BPF_PPC_STACK_BASIC+(2*REG_SZ); \ + PPC_STLU r1, -BPF_PPC_SLOWPATH_FRAME(r1); \ + /* R3 = r_skb, as passed */ \ + mr r4, r_addr; \ + li r6, SIZE; \ + bl skb_copy_bits; \ + nop; \ + /* R3 = 0 on success */ \ + addi r1, r1, BPF_PPC_SLOWPATH_FRAME; \ + PPC_LL r0, PPC_LR_STKOFF(r1); \ + PPC_LL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \ + PPC_LL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \ + mtlr r0; \ + PPC_LCMPI r3, 0; \ + blt bpf_error; /* cr0 = LT */ \ + PPC_LL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \ + /* Great success! */ + +bpf_slow_path_word: + bpf_slow_path_common(4) + /* Data value is on stack, and cr0 != LT */ + lwz r_A, BPF_PPC_STACK_BASIC+(2*REG_SZ)(r1) + blr + +bpf_slow_path_half: + bpf_slow_path_common(2) + lhz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1) + blr + +bpf_slow_path_byte: + bpf_slow_path_common(1) + lbz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1) + blr + +bpf_slow_path_byte_msh: + bpf_slow_path_common(1) + lbz r_X, BPF_PPC_STACK_BASIC+(2*8)(r1) + rlwinm r_X, r_X, 2, 32-4-2, 31-2 + blr + +/* Call out to bpf_internal_load_pointer_neg_helper: + * We'll need to back up our volatile regs first; we have + * local variable space at r1+(BPF_PPC_STACK_BASIC). + * Allocate a new stack frame here to remain ABI-compliant in + * stashing LR. + */ +#define sk_negative_common(SIZE) \ + mflr r0; \ + PPC_STL r0, PPC_LR_STKOFF(r1); \ + /* R3 goes in parameter space of caller's frame */ \ + PPC_STL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \ + PPC_STL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \ + PPC_STL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \ + PPC_STLU r1, -BPF_PPC_SLOWPATH_FRAME(r1); \ + /* R3 = r_skb, as passed */ \ + mr r4, r_addr; \ + li r5, SIZE; \ + bl bpf_internal_load_pointer_neg_helper; \ + nop; \ + /* R3 != 0 on success */ \ + addi r1, r1, BPF_PPC_SLOWPATH_FRAME; \ + PPC_LL r0, PPC_LR_STKOFF(r1); \ + PPC_LL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \ + PPC_LL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \ + mtlr r0; \ + PPC_LCMPLI r3, 0; \ + beq bpf_error_slow; /* cr0 = EQ */ \ + mr r_addr, r3; \ + PPC_LL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \ + /* Great success! */ + +bpf_slow_path_word_neg: + lis r_scratch1,-32 /* SKF_LL_OFF */ + PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + .globl sk_load_word_negative_offset +sk_load_word_negative_offset: + sk_negative_common(4) + lwz r_A, 0(r_addr) + blr + +bpf_slow_path_half_neg: + lis r_scratch1,-32 /* SKF_LL_OFF */ + PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + .globl sk_load_half_negative_offset +sk_load_half_negative_offset: + sk_negative_common(2) + lhz r_A, 0(r_addr) + blr + +bpf_slow_path_byte_neg: + lis r_scratch1,-32 /* SKF_LL_OFF */ + PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + .globl sk_load_byte_negative_offset +sk_load_byte_negative_offset: + sk_negative_common(1) + lbz r_A, 0(r_addr) + blr + +bpf_slow_path_byte_msh_neg: + lis r_scratch1,-32 /* SKF_LL_OFF */ + PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + .globl sk_load_byte_msh_negative_offset +sk_load_byte_msh_negative_offset: + sk_negative_common(1) + lbz r_X, 0(r_addr) + rlwinm r_X, r_X, 2, 32-4-2, 31-2 + blr + +bpf_error_slow: + /* fabricate a cr0 = lt */ + li r_scratch1, -1 + PPC_LCMPI r_scratch1, 0 +bpf_error: + /* Entered with cr0 = lt */ + li r3, 0 + /* Generated code will 'blt epilogue', returning 0. */ + blr diff --git a/kernel/arch/powerpc/net/bpf_jit_comp.c b/kernel/arch/powerpc/net/bpf_jit_comp.c new file mode 100644 index 000000000..17cea18a0 --- /dev/null +++ b/kernel/arch/powerpc/net/bpf_jit_comp.c @@ -0,0 +1,695 @@ +/* bpf_jit_comp.c: BPF JIT compiler + * + * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation + * + * Based on the x86 BPF compiler, by Eric Dumazet (eric.dumazet@gmail.com) + * Ported to ppc32 by Denis Kirjanov <kda@linux-powerpc.org> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ +#include <linux/moduleloader.h> +#include <asm/cacheflush.h> +#include <linux/netdevice.h> +#include <linux/filter.h> +#include <linux/if_vlan.h> + +#include "bpf_jit.h" + +int bpf_jit_enable __read_mostly; + +static inline void bpf_flush_icache(void *start, void *end) +{ + smp_wmb(); + flush_icache_range((unsigned long)start, (unsigned long)end); +} + +static void bpf_jit_build_prologue(struct bpf_prog *fp, u32 *image, + struct codegen_context *ctx) +{ + int i; + const struct sock_filter *filter = fp->insns; + + if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) { + /* Make stackframe */ + if (ctx->seen & SEEN_DATAREF) { + /* If we call any helpers (for loads), save LR */ + EMIT(PPC_INST_MFLR | __PPC_RT(R0)); + PPC_BPF_STL(0, 1, PPC_LR_STKOFF); + + /* Back up non-volatile regs. */ + PPC_BPF_STL(r_D, 1, -(REG_SZ*(32-r_D))); + PPC_BPF_STL(r_HL, 1, -(REG_SZ*(32-r_HL))); + } + if (ctx->seen & SEEN_MEM) { + /* + * Conditionally save regs r15-r31 as some will be used + * for M[] data. + */ + for (i = r_M; i < (r_M+16); i++) { + if (ctx->seen & (1 << (i-r_M))) + PPC_BPF_STL(i, 1, -(REG_SZ*(32-i))); + } + } + PPC_BPF_STLU(1, 1, -BPF_PPC_STACKFRAME); + } + + if (ctx->seen & SEEN_DATAREF) { + /* + * If this filter needs to access skb data, + * prepare r_D and r_HL: + * r_HL = skb->len - skb->data_len + * r_D = skb->data + */ + PPC_LWZ_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff, + data_len)); + PPC_LWZ_OFFS(r_HL, r_skb, offsetof(struct sk_buff, len)); + PPC_SUB(r_HL, r_HL, r_scratch1); + PPC_LL_OFFS(r_D, r_skb, offsetof(struct sk_buff, data)); + } + + if (ctx->seen & SEEN_XREG) { + /* + * TODO: Could also detect whether first instr. sets X and + * avoid this (as below, with A). + */ + PPC_LI(r_X, 0); + } + + switch (filter[0].code) { + case BPF_RET | BPF_K: + case BPF_LD | BPF_W | BPF_LEN: + case BPF_LD | BPF_W | BPF_ABS: + case BPF_LD | BPF_H | BPF_ABS: + case BPF_LD | BPF_B | BPF_ABS: + /* first instruction sets A register (or is RET 'constant') */ + break; + default: + /* make sure we dont leak kernel information to user */ + PPC_LI(r_A, 0); + } +} + +static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) +{ + int i; + + if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) { + PPC_ADDI(1, 1, BPF_PPC_STACKFRAME); + if (ctx->seen & SEEN_DATAREF) { + PPC_BPF_LL(0, 1, PPC_LR_STKOFF); + PPC_MTLR(0); + PPC_BPF_LL(r_D, 1, -(REG_SZ*(32-r_D))); + PPC_BPF_LL(r_HL, 1, -(REG_SZ*(32-r_HL))); + } + if (ctx->seen & SEEN_MEM) { + /* Restore any saved non-vol registers */ + for (i = r_M; i < (r_M+16); i++) { + if (ctx->seen & (1 << (i-r_M))) + PPC_BPF_LL(i, 1, -(REG_SZ*(32-i))); + } + } + } + /* The RETs have left a return value in R3. */ + + PPC_BLR(); +} + +#define CHOOSE_LOAD_FUNC(K, func) \ + ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) + +/* Assemble the body code between the prologue & epilogue. */ +static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, + struct codegen_context *ctx, + unsigned int *addrs) +{ + const struct sock_filter *filter = fp->insns; + int flen = fp->len; + u8 *func; + unsigned int true_cond; + int i; + + /* Start of epilogue code */ + unsigned int exit_addr = addrs[flen]; + + for (i = 0; i < flen; i++) { + unsigned int K = filter[i].k; + u16 code = bpf_anc_helper(&filter[i]); + + /* + * addrs[] maps a BPF bytecode address into a real offset from + * the start of the body code. + */ + addrs[i] = ctx->idx * 4; + + switch (code) { + /*** ALU ops ***/ + case BPF_ALU | BPF_ADD | BPF_X: /* A += X; */ + ctx->seen |= SEEN_XREG; + PPC_ADD(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_ADD | BPF_K: /* A += K; */ + if (!K) + break; + PPC_ADDI(r_A, r_A, IMM_L(K)); + if (K >= 32768) + PPC_ADDIS(r_A, r_A, IMM_HA(K)); + break; + case BPF_ALU | BPF_SUB | BPF_X: /* A -= X; */ + ctx->seen |= SEEN_XREG; + PPC_SUB(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_SUB | BPF_K: /* A -= K */ + if (!K) + break; + PPC_ADDI(r_A, r_A, IMM_L(-K)); + if (K >= 32768) + PPC_ADDIS(r_A, r_A, IMM_HA(-K)); + break; + case BPF_ALU | BPF_MUL | BPF_X: /* A *= X; */ + ctx->seen |= SEEN_XREG; + PPC_MUL(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_MUL | BPF_K: /* A *= K */ + if (K < 32768) + PPC_MULI(r_A, r_A, K); + else { + PPC_LI32(r_scratch1, K); + PPC_MUL(r_A, r_A, r_scratch1); + } + break; + case BPF_ALU | BPF_MOD | BPF_X: /* A %= X; */ + case BPF_ALU | BPF_DIV | BPF_X: /* A /= X; */ + ctx->seen |= SEEN_XREG; + PPC_CMPWI(r_X, 0); + if (ctx->pc_ret0 != -1) { + PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]); + } else { + PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12); + PPC_LI(r_ret, 0); + PPC_JMP(exit_addr); + } + if (code == (BPF_ALU | BPF_MOD | BPF_X)) { + PPC_DIVWU(r_scratch1, r_A, r_X); + PPC_MUL(r_scratch1, r_X, r_scratch1); + PPC_SUB(r_A, r_A, r_scratch1); + } else { + PPC_DIVWU(r_A, r_A, r_X); + } + break; + case BPF_ALU | BPF_MOD | BPF_K: /* A %= K; */ + PPC_LI32(r_scratch2, K); + PPC_DIVWU(r_scratch1, r_A, r_scratch2); + PPC_MUL(r_scratch1, r_scratch2, r_scratch1); + PPC_SUB(r_A, r_A, r_scratch1); + break; + case BPF_ALU | BPF_DIV | BPF_K: /* A /= K */ + if (K == 1) + break; + PPC_LI32(r_scratch1, K); + PPC_DIVWU(r_A, r_A, r_scratch1); + break; + case BPF_ALU | BPF_AND | BPF_X: + ctx->seen |= SEEN_XREG; + PPC_AND(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_AND | BPF_K: + if (!IMM_H(K)) + PPC_ANDI(r_A, r_A, K); + else { + PPC_LI32(r_scratch1, K); + PPC_AND(r_A, r_A, r_scratch1); + } + break; + case BPF_ALU | BPF_OR | BPF_X: + ctx->seen |= SEEN_XREG; + PPC_OR(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_OR | BPF_K: + if (IMM_L(K)) + PPC_ORI(r_A, r_A, IMM_L(K)); + if (K >= 65536) + PPC_ORIS(r_A, r_A, IMM_H(K)); + break; + case BPF_ANC | SKF_AD_ALU_XOR_X: + case BPF_ALU | BPF_XOR | BPF_X: /* A ^= X */ + ctx->seen |= SEEN_XREG; + PPC_XOR(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_XOR | BPF_K: /* A ^= K */ + if (IMM_L(K)) + PPC_XORI(r_A, r_A, IMM_L(K)); + if (K >= 65536) + PPC_XORIS(r_A, r_A, IMM_H(K)); + break; + case BPF_ALU | BPF_LSH | BPF_X: /* A <<= X; */ + ctx->seen |= SEEN_XREG; + PPC_SLW(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_LSH | BPF_K: + if (K == 0) + break; + else + PPC_SLWI(r_A, r_A, K); + break; + case BPF_ALU | BPF_RSH | BPF_X: /* A >>= X; */ + ctx->seen |= SEEN_XREG; + PPC_SRW(r_A, r_A, r_X); + break; + case BPF_ALU | BPF_RSH | BPF_K: /* A >>= K; */ + if (K == 0) + break; + else + PPC_SRWI(r_A, r_A, K); + break; + case BPF_ALU | BPF_NEG: + PPC_NEG(r_A, r_A); + break; + case BPF_RET | BPF_K: + PPC_LI32(r_ret, K); + if (!K) { + if (ctx->pc_ret0 == -1) + ctx->pc_ret0 = i; + } + /* + * If this isn't the very last instruction, branch to + * the epilogue if we've stuff to clean up. Otherwise, + * if there's nothing to tidy, just return. If we /are/ + * the last instruction, we're about to fall through to + * the epilogue to return. + */ + if (i != flen - 1) { + /* + * Note: 'seen' is properly valid only on pass + * #2. Both parts of this conditional are the + * same instruction size though, meaning the + * first pass will still correctly determine the + * code size/addresses. + */ + if (ctx->seen) + PPC_JMP(exit_addr); + else + PPC_BLR(); + } + break; + case BPF_RET | BPF_A: + PPC_MR(r_ret, r_A); + if (i != flen - 1) { + if (ctx->seen) + PPC_JMP(exit_addr); + else + PPC_BLR(); + } + break; + case BPF_MISC | BPF_TAX: /* X = A */ + PPC_MR(r_X, r_A); + break; + case BPF_MISC | BPF_TXA: /* A = X */ + ctx->seen |= SEEN_XREG; + PPC_MR(r_A, r_X); + break; + + /*** Constant loads/M[] access ***/ + case BPF_LD | BPF_IMM: /* A = K */ + PPC_LI32(r_A, K); + break; + case BPF_LDX | BPF_IMM: /* X = K */ + PPC_LI32(r_X, K); + break; + case BPF_LD | BPF_MEM: /* A = mem[K] */ + PPC_MR(r_A, r_M + (K & 0xf)); + ctx->seen |= SEEN_MEM | (1<<(K & 0xf)); + break; + case BPF_LDX | BPF_MEM: /* X = mem[K] */ + PPC_MR(r_X, r_M + (K & 0xf)); + ctx->seen |= SEEN_MEM | (1<<(K & 0xf)); + break; + case BPF_ST: /* mem[K] = A */ + PPC_MR(r_M + (K & 0xf), r_A); + ctx->seen |= SEEN_MEM | (1<<(K & 0xf)); + break; + case BPF_STX: /* mem[K] = X */ + PPC_MR(r_M + (K & 0xf), r_X); + ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf)); + break; + case BPF_LD | BPF_W | BPF_LEN: /* A = skb->len; */ + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); + PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len)); + break; + case BPF_LDX | BPF_W | BPF_LEN: /* X = skb->len; */ + PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len)); + break; + + /*** Ancillary info loads ***/ + case BPF_ANC | SKF_AD_PROTOCOL: /* A = ntohs(skb->protocol); */ + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, + protocol) != 2); + PPC_NTOHS_OFFS(r_A, r_skb, offsetof(struct sk_buff, + protocol)); + break; + case BPF_ANC | SKF_AD_IFINDEX: + case BPF_ANC | SKF_AD_HATYPE: + BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, + ifindex) != 4); + BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, + type) != 2); + PPC_LL_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff, + dev)); + PPC_CMPDI(r_scratch1, 0); + if (ctx->pc_ret0 != -1) { + PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]); + } else { + /* Exit, returning 0; first pass hits here. */ + PPC_BCC_SHORT(COND_NE, ctx->idx * 4 + 12); + PPC_LI(r_ret, 0); + PPC_JMP(exit_addr); + } + if (code == (BPF_ANC | SKF_AD_IFINDEX)) { + PPC_LWZ_OFFS(r_A, r_scratch1, + offsetof(struct net_device, ifindex)); + } else { + PPC_LHZ_OFFS(r_A, r_scratch1, + offsetof(struct net_device, type)); + } + + break; + case BPF_ANC | SKF_AD_MARK: + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); + PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, + mark)); + break; + case BPF_ANC | SKF_AD_RXHASH: + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4); + PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, + hash)); + break; + case BPF_ANC | SKF_AD_VLAN_TAG: + case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT: + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); + BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000); + + PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, + vlan_tci)); + if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) { + PPC_ANDI(r_A, r_A, ~VLAN_TAG_PRESENT); + } else { + PPC_ANDI(r_A, r_A, VLAN_TAG_PRESENT); + PPC_SRWI(r_A, r_A, 12); + } + break; + case BPF_ANC | SKF_AD_QUEUE: + BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, + queue_mapping) != 2); + PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, + queue_mapping)); + break; + case BPF_ANC | SKF_AD_PKTTYPE: + PPC_LBZ_OFFS(r_A, r_skb, PKT_TYPE_OFFSET()); + PPC_ANDI(r_A, r_A, PKT_TYPE_MAX); + PPC_SRWI(r_A, r_A, 5); + break; + case BPF_ANC | SKF_AD_CPU: + PPC_BPF_LOAD_CPU(r_A); + break; + /*** Absolute loads from packet header/data ***/ + case BPF_LD | BPF_W | BPF_ABS: + func = CHOOSE_LOAD_FUNC(K, sk_load_word); + goto common_load; + case BPF_LD | BPF_H | BPF_ABS: + func = CHOOSE_LOAD_FUNC(K, sk_load_half); + goto common_load; + case BPF_LD | BPF_B | BPF_ABS: + func = CHOOSE_LOAD_FUNC(K, sk_load_byte); + common_load: + /* Load from [K]. */ + ctx->seen |= SEEN_DATAREF; + PPC_FUNC_ADDR(r_scratch1, func); + PPC_MTLR(r_scratch1); + PPC_LI32(r_addr, K); + PPC_BLRL(); + /* + * Helper returns 'lt' condition on error, and an + * appropriate return value in r3 + */ + PPC_BCC(COND_LT, exit_addr); + break; + + /*** Indirect loads from packet header/data ***/ + case BPF_LD | BPF_W | BPF_IND: + func = sk_load_word; + goto common_load_ind; + case BPF_LD | BPF_H | BPF_IND: + func = sk_load_half; + goto common_load_ind; + case BPF_LD | BPF_B | BPF_IND: + func = sk_load_byte; + common_load_ind: + /* + * Load from [X + K]. Negative offsets are tested for + * in the helper functions. + */ + ctx->seen |= SEEN_DATAREF | SEEN_XREG; + PPC_FUNC_ADDR(r_scratch1, func); + PPC_MTLR(r_scratch1); + PPC_ADDI(r_addr, r_X, IMM_L(K)); + if (K >= 32768) + PPC_ADDIS(r_addr, r_addr, IMM_HA(K)); + PPC_BLRL(); + /* If error, cr0.LT set */ + PPC_BCC(COND_LT, exit_addr); + break; + + case BPF_LDX | BPF_B | BPF_MSH: + func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh); + goto common_load; + break; + + /*** Jump and branches ***/ + case BPF_JMP | BPF_JA: + if (K != 0) + PPC_JMP(addrs[i + 1 + K]); + break; + + case BPF_JMP | BPF_JGT | BPF_K: + case BPF_JMP | BPF_JGT | BPF_X: + true_cond = COND_GT; + goto cond_branch; + case BPF_JMP | BPF_JGE | BPF_K: + case BPF_JMP | BPF_JGE | BPF_X: + true_cond = COND_GE; + goto cond_branch; + case BPF_JMP | BPF_JEQ | BPF_K: + case BPF_JMP | BPF_JEQ | BPF_X: + true_cond = COND_EQ; + goto cond_branch; + case BPF_JMP | BPF_JSET | BPF_K: + case BPF_JMP | BPF_JSET | BPF_X: + true_cond = COND_NE; + /* Fall through */ + cond_branch: + /* same targets, can avoid doing the test :) */ + if (filter[i].jt == filter[i].jf) { + if (filter[i].jt > 0) + PPC_JMP(addrs[i + 1 + filter[i].jt]); + break; + } + + switch (code) { + case BPF_JMP | BPF_JGT | BPF_X: + case BPF_JMP | BPF_JGE | BPF_X: + case BPF_JMP | BPF_JEQ | BPF_X: + ctx->seen |= SEEN_XREG; + PPC_CMPLW(r_A, r_X); + break; + case BPF_JMP | BPF_JSET | BPF_X: + ctx->seen |= SEEN_XREG; + PPC_AND_DOT(r_scratch1, r_A, r_X); + break; + case BPF_JMP | BPF_JEQ | BPF_K: + case BPF_JMP | BPF_JGT | BPF_K: + case BPF_JMP | BPF_JGE | BPF_K: + if (K < 32768) + PPC_CMPLWI(r_A, K); + else { + PPC_LI32(r_scratch1, K); + PPC_CMPLW(r_A, r_scratch1); + } + break; + case BPF_JMP | BPF_JSET | BPF_K: + if (K < 32768) + /* PPC_ANDI is /only/ dot-form */ + PPC_ANDI(r_scratch1, r_A, K); + else { + PPC_LI32(r_scratch1, K); + PPC_AND_DOT(r_scratch1, r_A, + r_scratch1); + } + break; + } + /* Sometimes branches are constructed "backward", with + * the false path being the branch and true path being + * a fallthrough to the next instruction. + */ + if (filter[i].jt == 0) + /* Swap the sense of the branch */ + PPC_BCC(true_cond ^ COND_CMP_TRUE, + addrs[i + 1 + filter[i].jf]); + else { + PPC_BCC(true_cond, addrs[i + 1 + filter[i].jt]); + if (filter[i].jf != 0) + PPC_JMP(addrs[i + 1 + filter[i].jf]); + } + break; + default: + /* The filter contains something cruel & unusual. + * We don't handle it, but also there shouldn't be + * anything missing from our list. + */ + if (printk_ratelimit()) + pr_err("BPF filter opcode %04x (@%d) unsupported\n", + filter[i].code, i); + return -ENOTSUPP; + } + + } + /* Set end-of-body-code address for exit. */ + addrs[i] = ctx->idx * 4; + + return 0; +} + +void bpf_jit_compile(struct bpf_prog *fp) +{ + unsigned int proglen; + unsigned int alloclen; + u32 *image = NULL; + u32 *code_base; + unsigned int *addrs; + struct codegen_context cgctx; + int pass; + int flen = fp->len; + + if (!bpf_jit_enable) + return; + + addrs = kzalloc((flen+1) * sizeof(*addrs), GFP_KERNEL); + if (addrs == NULL) + return; + + /* + * There are multiple assembly passes as the generated code will change + * size as it settles down, figuring out the max branch offsets/exit + * paths required. + * + * The range of standard conditional branches is +/- 32Kbytes. Since + * BPF_MAXINSNS = 4096, we can only jump from (worst case) start to + * finish with 8 bytes/instruction. Not feasible, so long jumps are + * used, distinct from short branches. + * + * Current: + * + * For now, both branch types assemble to 2 words (short branches padded + * with a NOP); this is less efficient, but assembly will always complete + * after exactly 3 passes: + * + * First pass: No code buffer; Program is "faux-generated" -- no code + * emitted but maximum size of output determined (and addrs[] filled + * in). Also, we note whether we use M[], whether we use skb data, etc. + * All generation choices assumed to be 'worst-case', e.g. branches all + * far (2 instructions), return path code reduction not available, etc. + * + * Second pass: Code buffer allocated with size determined previously. + * Prologue generated to support features we have seen used. Exit paths + * determined and addrs[] is filled in again, as code may be slightly + * smaller as a result. + * + * Third pass: Code generated 'for real', and branch destinations + * determined from now-accurate addrs[] map. + * + * Ideal: + * + * If we optimise this, near branches will be shorter. On the + * first assembly pass, we should err on the side of caution and + * generate the biggest code. On subsequent passes, branches will be + * generated short or long and code size will reduce. With smaller + * code, more branches may fall into the short category, and code will + * reduce more. + * + * Finally, if we see one pass generate code the same size as the + * previous pass we have converged and should now generate code for + * real. Allocating at the end will also save the memory that would + * otherwise be wasted by the (small) current code shrinkage. + * Preferably, we should do a small number of passes (e.g. 5) and if we + * haven't converged by then, get impatient and force code to generate + * as-is, even if the odd branch would be left long. The chances of a + * long jump are tiny with all but the most enormous of BPF filter + * inputs, so we should usually converge on the third pass. + */ + + cgctx.idx = 0; + cgctx.seen = 0; + cgctx.pc_ret0 = -1; + /* Scouting faux-generate pass 0 */ + if (bpf_jit_build_body(fp, 0, &cgctx, addrs)) + /* We hit something illegal or unsupported. */ + goto out; + + /* + * Pretend to build prologue, given the features we've seen. This will + * update ctgtx.idx as it pretends to output instructions, then we can + * calculate total size from idx. + */ + bpf_jit_build_prologue(fp, 0, &cgctx); + bpf_jit_build_epilogue(0, &cgctx); + + proglen = cgctx.idx * 4; + alloclen = proglen + FUNCTION_DESCR_SIZE; + image = module_alloc(alloclen); + if (!image) + goto out; + + code_base = image + (FUNCTION_DESCR_SIZE/4); + + /* Code generation passes 1-2 */ + for (pass = 1; pass < 3; pass++) { + /* Now build the prologue, body code & epilogue for real. */ + cgctx.idx = 0; + bpf_jit_build_prologue(fp, code_base, &cgctx); + bpf_jit_build_body(fp, code_base, &cgctx, addrs); + bpf_jit_build_epilogue(code_base, &cgctx); + + if (bpf_jit_enable > 1) + pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass, + proglen - (cgctx.idx * 4), cgctx.seen); + } + + if (bpf_jit_enable > 1) + /* Note that we output the base address of the code_base + * rather than image, since opcodes are in code_base. + */ + bpf_jit_dump(flen, proglen, pass, code_base); + + if (image) { + bpf_flush_icache(code_base, code_base + (proglen/4)); +#ifdef CONFIG_PPC64 + /* Function descriptor nastiness: Address + TOC */ + ((u64 *)image)[0] = (u64)code_base; + ((u64 *)image)[1] = local_paca->kernel_toc; +#endif + fp->bpf_func = (void *)image; + fp->jited = true; + } +out: + kfree(addrs); + return; +} + +void bpf_jit_free(struct bpf_prog *fp) +{ + if (fp->jited) + module_memfree(fp->bpf_func); + + bpf_prog_unlock_free(fp); +} |