From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44811) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dOBHE-00034E-8Q for qemu-devel@nongnu.org; Thu, 22 Jun 2017 19:12:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dOBHA-0001Cl-1n for qemu-devel@nongnu.org; Thu, 22 Jun 2017 19:12:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54692) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dOBH9-0001CW-Rh for qemu-devel@nongnu.org; Thu, 22 Jun 2017 19:12:35 -0400 From: David Hildenbrand Date: Fri, 23 Jun 2017 01:12:28 +0200 Message-Id: <20170622231228.1050-1-david@redhat.com> Subject: [Qemu-devel] [PATCH v1] target-s390x: fix risbg handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: rth@twiddle.net, agraf@suse.de, Aurelien Jarno , thuth@redhat.com, david@redhat.com 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 --- 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(-) 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 -- 2.9.4