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