diff options
Diffstat (limited to 'arch/powerpc/net/bpf_jit_asm64.S')
| -rw-r--r-- | arch/powerpc/net/bpf_jit_asm64.S | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/arch/powerpc/net/bpf_jit_asm64.S b/arch/powerpc/net/bpf_jit_asm64.S new file mode 100644 index 000000000000..7e4c51430b84 --- /dev/null +++ b/arch/powerpc/net/bpf_jit_asm64.S @@ -0,0 +1,180 @@ +/* + * bpf_jit_asm64.S: Packet/header access helper functions + * for PPC64 BPF compiler. + * + * Copyright 2016, Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> + * IBM Corporation + * + * Based on bpf_jit_asm.S by Matt Evans + * + * 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 <asm/ptrace.h> +#include "bpf_jit64.h" + +/* + * All of these routines are called directly from generated code, + * with the below register usage: + * r27 skb pointer (ctx) + * r25 skb header length + * r26 skb->data pointer + * r4 offset + * + * Result is passed back in: + * r8 data read in host endian format (accumulator) + * + * r9 is used as a temporary register + */ + +#define r_skb r27 +#define r_hlen r25 +#define r_data r26 +#define r_off r4 +#define r_val r8 +#define r_tmp r9 + +_GLOBAL_TOC(sk_load_word) + cmpdi r_off, 0 + blt bpf_slow_path_word_neg + b sk_load_word_positive_offset + +_GLOBAL_TOC(sk_load_word_positive_offset) + /* Are we accessing past headlen? */ + subi r_tmp, r_hlen, 4 + cmpd r_tmp, r_off + blt bpf_slow_path_word + /* Nope, just hitting the header. cr0 here is eq or gt! */ + LWZX_BE r_val, r_data, r_off + blr /* Return success, cr0 != LT */ + +_GLOBAL_TOC(sk_load_half) + cmpdi r_off, 0 + blt bpf_slow_path_half_neg + b sk_load_half_positive_offset + +_GLOBAL_TOC(sk_load_half_positive_offset) + subi r_tmp, r_hlen, 2 + cmpd r_tmp, r_off + blt bpf_slow_path_half + LHZX_BE r_val, r_data, r_off + blr + +_GLOBAL_TOC(sk_load_byte) + cmpdi r_off, 0 + blt bpf_slow_path_byte_neg + b sk_load_byte_positive_offset + +_GLOBAL_TOC(sk_load_byte_positive_offset) + cmpd r_hlen, r_off + ble bpf_slow_path_byte + lbzx r_val, r_data, r_off + blr + +/* + * Call out to skb_copy_bits: + * Allocate a new stack frame here to remain ABI-compliant in + * stashing LR. + */ +#define bpf_slow_path_common(SIZE) \ + mflr r0; \ + std r0, PPC_LR_STKOFF(r1); \ + stdu r1, -(STACK_FRAME_MIN_SIZE + BPF_PPC_STACK_LOCALS)(r1); \ + mr r3, r_skb; \ + /* r4 = r_off as passed */ \ + addi r5, r1, STACK_FRAME_MIN_SIZE; \ + li r6, SIZE; \ + bl skb_copy_bits; \ + nop; \ + /* save r5 */ \ + addi r5, r1, STACK_FRAME_MIN_SIZE; \ + /* r3 = 0 on success */ \ + addi r1, r1, STACK_FRAME_MIN_SIZE + BPF_PPC_STACK_LOCALS; \ + ld r0, PPC_LR_STKOFF(r1); \ + mtlr r0; \ + cmpdi r3, 0; \ + blt bpf_error; /* cr0 = LT */ + +bpf_slow_path_word: + bpf_slow_path_common(4) + /* Data value is on stack, and cr0 != LT */ + LWZX_BE r_val, 0, r5 + blr + +bpf_slow_path_half: + bpf_slow_path_common(2) + LHZX_BE r_val, 0, r5 + blr + +bpf_slow_path_byte: + bpf_slow_path_common(1) + lbzx r_val, 0, r5 + blr + +/* + * Call out to bpf_internal_load_pointer_neg_helper + */ +#define sk_negative_common(SIZE) \ + mflr r0; \ + std r0, PPC_LR_STKOFF(r1); \ + stdu r1, -STACK_FRAME_MIN_SIZE(r1); \ + mr r3, r_skb; \ + /* r4 = r_off, as passed */ \ + li r5, SIZE; \ + bl bpf_internal_load_pointer_neg_helper; \ + nop; \ + addi r1, r1, STACK_FRAME_MIN_SIZE; \ + ld r0, PPC_LR_STKOFF(r1); \ + mtlr r0; \ + /* R3 != 0 on success */ \ + cmpldi r3, 0; \ + beq bpf_error_slow; /* cr0 = EQ */ + +bpf_slow_path_word_neg: + lis r_tmp, -32 /* SKF_LL_OFF */ + cmpd r_off, r_tmp /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + b sk_load_word_negative_offset + +_GLOBAL_TOC(sk_load_word_negative_offset) + sk_negative_common(4) + LWZX_BE r_val, 0, r3 + blr + +bpf_slow_path_half_neg: + lis r_tmp, -32 /* SKF_LL_OFF */ + cmpd r_off, r_tmp /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + b sk_load_half_negative_offset + +_GLOBAL_TOC(sk_load_half_negative_offset) + sk_negative_common(2) + LHZX_BE r_val, 0, r3 + blr + +bpf_slow_path_byte_neg: + lis r_tmp, -32 /* SKF_LL_OFF */ + cmpd r_off, r_tmp /* addr < SKF_* */ + blt bpf_error /* cr0 = LT */ + b sk_load_byte_negative_offset + +_GLOBAL_TOC(sk_load_byte_negative_offset) + sk_negative_common(1) + lbzx r_val, 0, r3 + blr + +bpf_error_slow: + /* fabricate a cr0 = lt */ + li r_tmp, -1 + cmpdi r_tmp, 0 +bpf_error: + /* + * Entered with cr0 = lt + * Generated code will 'blt epilogue', returning 0. + */ + li r_val, 0 + blr |