diff options
Diffstat (limited to 'kernel/arch/s390/net/bpf_jit.S')
| -rw-r--r-- | kernel/arch/s390/net/bpf_jit.S | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/kernel/arch/s390/net/bpf_jit.S b/kernel/arch/s390/net/bpf_jit.S new file mode 100644 index 000000000..a1c917d88 --- /dev/null +++ b/kernel/arch/s390/net/bpf_jit.S @@ -0,0 +1,115 @@ +/* + * BPF Jit compiler for s390, help functions. + * + * Copyright IBM Corp. 2012,2015 + * + * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> + * Michael Holzheu <holzheu@linux.vnet.ibm.com> + */ + +#include <linux/linkage.h> +#include "bpf_jit.h" + +/* + * Calling convention: + * registers %r7-%r10, %r11,%r13, and %r15 are call saved + * + * Input (64 bit): + * %r3 (%b2) = offset into skb data + * %r6 (%b5) = return address + * %r7 (%b6) = skb pointer + * %r12 = skb data pointer + * + * Output: + * %r14= %b0 = return value (read skb value) + * + * Work registers: %r2,%r4,%r5,%r14 + * + * skb_copy_bits takes 4 parameters: + * %r2 = skb pointer + * %r3 = offset into skb data + * %r4 = pointer to temp buffer + * %r5 = length to copy + * Return value in %r2: 0 = ok + * + * bpf_internal_load_pointer_neg_helper takes 3 parameters: + * %r2 = skb pointer + * %r3 = offset into data + * %r4 = length to copy + * Return value in %r2: Pointer to data + */ + +#define SKF_MAX_NEG_OFF -0x200000 /* SKF_LL_OFF from filter.h */ + +/* + * Load SIZE bytes from SKB + */ +#define sk_load_common(NAME, SIZE, LOAD) \ +ENTRY(sk_load_##NAME); \ + ltgr %r3,%r3; /* Is offset negative? */ \ + jl sk_load_##NAME##_slow_neg; \ +ENTRY(sk_load_##NAME##_pos); \ + aghi %r3,SIZE; /* Offset + SIZE */ \ + clg %r3,STK_OFF_HLEN(%r15); /* Offset + SIZE > hlen? */ \ + jh sk_load_##NAME##_slow; \ + LOAD %r14,-SIZE(%r3,%r12); /* Get data from skb */ \ + b OFF_OK(%r6); /* Return */ \ + \ +sk_load_##NAME##_slow:; \ + lgr %r2,%r7; /* Arg1 = skb pointer */ \ + aghi %r3,-SIZE; /* Arg2 = offset */ \ + la %r4,STK_OFF_TMP(%r15); /* Arg3 = temp bufffer */ \ + lghi %r5,SIZE; /* Arg4 = size */ \ + brasl %r14,skb_copy_bits; /* Get data from skb */ \ + LOAD %r14,STK_OFF_TMP(%r15); /* Load from temp bufffer */ \ + ltgr %r2,%r2; /* Set cc to (%r2 != 0) */ \ + br %r6; /* Return */ + +sk_load_common(word, 4, llgf) /* r14 = *(u32 *) (skb->data+offset) */ +sk_load_common(half, 2, llgh) /* r14 = *(u16 *) (skb->data+offset) */ + +/* + * Load 1 byte from SKB (optimized version) + */ + /* r14 = *(u8 *) (skb->data+offset) */ +ENTRY(sk_load_byte) + ltgr %r3,%r3 # Is offset negative? + jl sk_load_byte_slow_neg +ENTRY(sk_load_byte_pos) + clg %r3,STK_OFF_HLEN(%r15) # Offset >= hlen? + jnl sk_load_byte_slow + llgc %r14,0(%r3,%r12) # Get byte from skb + b OFF_OK(%r6) # Return OK + +sk_load_byte_slow: + lgr %r2,%r7 # Arg1 = skb pointer + # Arg2 = offset + la %r4,STK_OFF_TMP(%r15) # Arg3 = pointer to temp buffer + lghi %r5,1 # Arg4 = size (1 byte) + brasl %r14,skb_copy_bits # Get data from skb + llgc %r14,STK_OFF_TMP(%r15) # Load result from temp buffer + ltgr %r2,%r2 # Set cc to (%r2 != 0) + br %r6 # Return cc + +#define sk_negative_common(NAME, SIZE, LOAD) \ +sk_load_##NAME##_slow_neg:; \ + cgfi %r3,SKF_MAX_NEG_OFF; \ + jl bpf_error; \ + lgr %r2,%r7; /* Arg1 = skb pointer */ \ + /* Arg2 = offset */ \ + lghi %r4,SIZE; /* Arg3 = size */ \ + brasl %r14,bpf_internal_load_pointer_neg_helper; \ + ltgr %r2,%r2; \ + jz bpf_error; \ + LOAD %r14,0(%r2); /* Get data from pointer */ \ + xr %r3,%r3; /* Set cc to zero */ \ + br %r6; /* Return cc */ + +sk_negative_common(word, 4, llgf) +sk_negative_common(half, 2, llgh) +sk_negative_common(byte, 1, llgc) + +bpf_error: +# force a return 0 from jit handler + ltgr %r15,%r15 # Set condition code + br %r6 |