| Message ID | 20170622231228.1050-1-david@redhat.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/target/s390x/translate.c b/target/s390x/translate.c index 188ab8b..81419dd 100644 --- a/target/s390x/translate.c +++ b/target/s390x/translate.c @@ -3450,12 +3450,6 @@ static ExitStatus op_risbg(DisasContext *s, DisasOps *o) pos += 32; } - /* In some cases we can implement this with extract. */ - if (imask == 0 && pos == 0 && len > 0 && rot + len <= 64) { - tcg_gen_extract_i64(o->out, o->in2, rot, len); - return NO_EXIT; - } - /* In some cases we can implement this with deposit. */ if (len > 0 && (imask == 0 || ~mask == imask)) { /* Note that we rotate the bits to be inserted to the lsb, not to
If we have for example: r3 contains 0x00000000ffffffff ec 33 3f bf 61 55 risbg %r3,%r3,63,191,97 We want to rotate 33 to the left and only keep MSB bit 63 of that. So the result is then exactly 1 (we're reading the sign of the 32 bit value). Current code assumes that we can do that via an extract, which is not true (at least not that easy) and produces a 0. Let's just get rid of this special handling. Signed-off-by: David Hildenbrand <david@redhat.com> --- This effectively allows to start a linux kernel, compiled for z10 using the qemu model under tcg (with other patches currently on the list): qemu-system-s390x ... -cpu qemu,mvcos=on,stfle=on,ldisp=on,ldisphp=on, \ eimm=on,stckf=on,csst=on,csst2=on,ginste=on, \ exrl=on ... I found this by compiling the kvm-unit-tests for z10 and noticing elementary selftests failing. The kernel would trigger weird BUG_ONs very early while starting up, which basically gave not really many hints of what was actually going wrong. target/s390x/translate.c | 6 ------ 1 file changed, 6 deletions(-)