s390/bpf,jit: fix prolog oddity

The prolog of functions generated by the bpf jit compiler uses an
instruction sequence with an "ahi" instruction to create stack space
instead of using an "aghi" instruction. Using the 32-bit "ahi" is not
wrong as the stack we are operating on is an order-4 allocation which
is always aligned to 16KB. But it is more consistent to use an "aghi"
as the stack pointer is a 64-bit value.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 49425ca801d56b9c04bebb3ff1801700616d7ebf..16871da3737164d986412ff40cc8fb95c2c7119b 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -156,8 +156,8 @@ static void bpf_jit_prologue(struct bpf_jit *jit)
                EMIT6(0xeb8ff058, 0x0024);
                /* lgr %r14,%r15 */
                EMIT4(0xb90400ef);
-               /* ahi %r15,<offset> */
-               EMIT4_IMM(0xa7fa0000, (jit->seen & SEEN_MEM) ? -112 : -80);
+               /* aghi %r15,<offset> */
+               EMIT4_IMM(0xa7fb0000, (jit->seen & SEEN_MEM) ? -112 : -80);
                /* stg %r14,152(%r15) */
                EMIT6(0xe3e0f098, 0x0024);
        } else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))