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authorMichael Holzheu <holzheu@linux.vnet.ibm.com>2015-06-09 07:51:06 +0300
committerDavid S. Miller <davem@davemloft.net>2015-06-09 21:47:10 +0300
commit6651ee070b3124fe9b9db383e3a895a0e4aded65 (patch)
treecd1662179dd84ff08d76eb85037900538540c3fc /crypto
parent941742f49762ba4c908510f036b09a46c1b14513 (diff)
downloadlinux-6651ee070b3124fe9b9db383e3a895a0e4aded65.tar.xz
s390/bpf: implement bpf_tail_call() helper
bpf_tail_call() arguments: - ctx......: Context pointer - jmp_table: One of BPF_MAP_TYPE_PROG_ARRAY maps used as the jump table - index....: Index in the jump table In this implementation s390x JIT does stack unwinding and jumps into the callee program prologue. Caller and callee use the same stack. With this patch a tail call generates the following code on s390x: if (index >= array->map.max_entries) goto out 000003ff8001c7e4: e31030100016 llgf %r1,16(%r3) 000003ff8001c7ea: ec41001fa065 clgrj %r4,%r1,10,3ff8001c828 if (tail_call_cnt++ > MAX_TAIL_CALL_CNT) goto out; 000003ff8001c7f0: a7080001 lhi %r0,1 000003ff8001c7f4: eb10f25000fa laal %r1,%r0,592(%r15) 000003ff8001c7fa: ec120017207f clij %r1,32,2,3ff8001c828 prog = array->prog[index]; if (prog == NULL) goto out; 000003ff8001c800: eb140003000d sllg %r1,%r4,3 000003ff8001c806: e31310800004 lg %r1,128(%r3,%r1) 000003ff8001c80c: ec18000e007d clgij %r1,0,8,3ff8001c828 Restore registers before calling function 000003ff8001c812: eb68f2980004 lmg %r6,%r8,664(%r15) 000003ff8001c818: ebbff2c00004 lmg %r11,%r15,704(%r15) goto *(prog->bpf_func + tail_call_start); 000003ff8001c81e: e31100200004 lg %r1,32(%r1,%r0) 000003ff8001c824: 47f01006 bc 15,6(%r1) Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'crypto')
0 files changed, 0 insertions, 0 deletions