116 lines
3.3 KiB
ArmAsm
116 lines
3.3 KiB
ArmAsm
/*
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* BPF Jit compiler for s390, help functions.
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*
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* Copyright IBM Corp. 2012,2015
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*
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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* Michael Holzheu <holzheu@linux.vnet.ibm.com>
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*/
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#include <linux/linkage.h>
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#include "bpf_jit.h"
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/*
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* Calling convention:
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* registers %r7-%r10, %r11,%r13, and %r15 are call saved
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*
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* Input (64 bit):
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* %r3 (%b2) = offset into skb data
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* %r6 (%b5) = return address
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* %r7 (%b6) = skb pointer
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* %r12 = skb data pointer
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*
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* Output:
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* %r14= %b0 = return value (read skb value)
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*
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* Work registers: %r2,%r4,%r5,%r14
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*
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* skb_copy_bits takes 4 parameters:
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* %r2 = skb pointer
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* %r3 = offset into skb data
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* %r4 = pointer to temp buffer
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* %r5 = length to copy
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* Return value in %r2: 0 = ok
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*
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* bpf_internal_load_pointer_neg_helper takes 3 parameters:
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* %r2 = skb pointer
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* %r3 = offset into data
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* %r4 = length to copy
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* Return value in %r2: Pointer to data
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*/
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#define SKF_MAX_NEG_OFF -0x200000 /* SKF_LL_OFF from filter.h */
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/*
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* Load SIZE bytes from SKB
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*/
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#define sk_load_common(NAME, SIZE, LOAD) \
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ENTRY(sk_load_##NAME); \
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ltgr %r3,%r3; /* Is offset negative? */ \
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jl sk_load_##NAME##_slow_neg; \
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ENTRY(sk_load_##NAME##_pos); \
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aghi %r3,SIZE; /* Offset + SIZE */ \
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clg %r3,STK_OFF_HLEN(%r15); /* Offset + SIZE > hlen? */ \
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jh sk_load_##NAME##_slow; \
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LOAD %r14,-SIZE(%r3,%r12); /* Get data from skb */ \
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b OFF_OK(%r6); /* Return */ \
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\
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sk_load_##NAME##_slow:; \
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lgr %r2,%r7; /* Arg1 = skb pointer */ \
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aghi %r3,-SIZE; /* Arg2 = offset */ \
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la %r4,STK_OFF_TMP(%r15); /* Arg3 = temp bufffer */ \
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lghi %r5,SIZE; /* Arg4 = size */ \
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brasl %r14,skb_copy_bits; /* Get data from skb */ \
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LOAD %r14,STK_OFF_TMP(%r15); /* Load from temp bufffer */ \
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ltgr %r2,%r2; /* Set cc to (%r2 != 0) */ \
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br %r6; /* Return */
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sk_load_common(word, 4, llgf) /* r14 = *(u32 *) (skb->data+offset) */
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sk_load_common(half, 2, llgh) /* r14 = *(u16 *) (skb->data+offset) */
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/*
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* Load 1 byte from SKB (optimized version)
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*/
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/* r14 = *(u8 *) (skb->data+offset) */
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ENTRY(sk_load_byte)
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ltgr %r3,%r3 # Is offset negative?
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jl sk_load_byte_slow_neg
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ENTRY(sk_load_byte_pos)
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clg %r3,STK_OFF_HLEN(%r15) # Offset >= hlen?
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jnl sk_load_byte_slow
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llgc %r14,0(%r3,%r12) # Get byte from skb
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b OFF_OK(%r6) # Return OK
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sk_load_byte_slow:
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lgr %r2,%r7 # Arg1 = skb pointer
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# Arg2 = offset
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la %r4,STK_OFF_TMP(%r15) # Arg3 = pointer to temp buffer
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lghi %r5,1 # Arg4 = size (1 byte)
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brasl %r14,skb_copy_bits # Get data from skb
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llgc %r14,STK_OFF_TMP(%r15) # Load result from temp buffer
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ltgr %r2,%r2 # Set cc to (%r2 != 0)
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br %r6 # Return cc
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#define sk_negative_common(NAME, SIZE, LOAD) \
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sk_load_##NAME##_slow_neg:; \
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cgfi %r3,SKF_MAX_NEG_OFF; \
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jl bpf_error; \
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lgr %r2,%r7; /* Arg1 = skb pointer */ \
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/* Arg2 = offset */ \
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lghi %r4,SIZE; /* Arg3 = size */ \
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brasl %r14,bpf_internal_load_pointer_neg_helper; \
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ltgr %r2,%r2; \
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jz bpf_error; \
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LOAD %r14,0(%r2); /* Get data from pointer */ \
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xr %r3,%r3; /* Set cc to zero */ \
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br %r6; /* Return cc */
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sk_negative_common(word, 4, llgf)
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sk_negative_common(half, 2, llgh)
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sk_negative_common(byte, 1, llgc)
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bpf_error:
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# force a return 0 from jit handler
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ltgr %r15,%r15 # Set condition code
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br %r6
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