diff options
Diffstat (limited to 'arch/powerpc/net/bpf_jit_64.S')
| -rw-r--r-- | arch/powerpc/net/bpf_jit_64.S | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/arch/powerpc/net/bpf_jit_64.S b/arch/powerpc/net/bpf_jit_64.S new file mode 100644 index 000000000000..ff4506e85cce --- /dev/null +++ b/arch/powerpc/net/bpf_jit_64.S @@ -0,0 +1,138 @@ +/* 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.) + * + * Technically, the "is addr < 0" check is unnecessary & slowing down + * the ABS path, as it's statically checked on generation. + */ + .globl sk_load_word +sk_load_word: + cmpdi r_addr, 0 + blt bpf_error + /* Are we accessing past headlen? */ + subi r_scratch1, r_HL, 4 + cmpd r_scratch1, r_addr + blt bpf_slow_path_word + /* Nope, just hitting the header. cr0 here is eq or gt! */ + lwzx r_A, r_D, r_addr + /* When big endian we don't need to byteswap. */ + blr /* Return success, cr0 != LT */ + + .globl sk_load_half +sk_load_half: + cmpdi r_addr, 0 + blt bpf_error + subi r_scratch1, r_HL, 2 + cmpd r_scratch1, r_addr + blt bpf_slow_path_half + lhzx r_A, r_D, r_addr + blr + + .globl sk_load_byte +sk_load_byte: + cmpdi r_addr, 0 + blt bpf_error + cmpd r_HL, r_addr + ble bpf_slow_path_byte + lbzx r_A, r_D, r_addr + blr + +/* + * BPF_S_LDX_B_MSH: ldxb 4*([offset]&0xf) + * r_addr is the offset value, already known positive + */ + .globl sk_load_byte_msh +sk_load_byte_msh: + cmpd 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 + +bpf_error: + /* Entered with cr0 = lt */ + li r3, 0 + /* Generated code will 'blt epilogue', returning 0. */ + 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; \ + std r0, 16(r1); \ + /* R3 goes in parameter space of caller's frame */ \ + std r_skb, (BPF_PPC_STACKFRAME+48)(r1); \ + std r_A, (BPF_PPC_STACK_BASIC+(0*8))(r1); \ + std r_X, (BPF_PPC_STACK_BASIC+(1*8))(r1); \ + addi r5, r1, BPF_PPC_STACK_BASIC+(2*8); \ + stdu r1, -BPF_PPC_SLOWPATH_FRAME(r1); \ + /* R3 = r_skb, as passed */ \ + mr r4, r_addr; \ + li r6, SIZE; \ + bl skb_copy_bits; \ + /* R3 = 0 on success */ \ + addi r1, r1, BPF_PPC_SLOWPATH_FRAME; \ + ld r0, 16(r1); \ + ld r_A, (BPF_PPC_STACK_BASIC+(0*8))(r1); \ + ld r_X, (BPF_PPC_STACK_BASIC+(1*8))(r1); \ + mtlr r0; \ + cmpdi r3, 0; \ + blt bpf_error; /* cr0 = LT */ \ + ld r_skb, (BPF_PPC_STACKFRAME+48)(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*8)(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 |