/* 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: cmpdi 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 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_slow_path_half_neg .globl sk_load_half_positive_offset sk_load_half_positive_offset: 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_slow_path_byte_neg .globl sk_load_byte_positive_offset sk_load_byte_positive_offset: 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 */ .globl sk_load_byte_msh sk_load_byte_msh: cmpdi r_addr, 0 blt bpf_slow_path_byte_msh_neg .globl sk_load_byte_msh_positive_offset sk_load_byte_msh_positive_offset: 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 /* 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; \ nop; \ /* 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 /* 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; \ 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); \ stdu 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; \ 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; \ cmpldi r3, 0; \ beq bpf_error_slow; /* cr0 = EQ */ \ mr r_addr, r3; \ ld r_skb, (BPF_PPC_STACKFRAME+48)(r1); \ /* Great success! */ bpf_slow_path_word_neg: lis r_scratch1,-32 /* SKF_LL_OFF */ cmpd 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 */ cmpd 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 */ cmpd 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 */ cmpd 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 cmpdi r_scratch1, 0 bpf_error: /* Entered with cr0 = lt */ li r3, 0 /* Generated code will 'blt epilogue', returning 0. */ blr