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/*
* 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
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