From owner-freebsd-bugs@freebsd.org Mon Oct 19 09:45:48 2020 Return-Path: Delivered-To: freebsd-bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 3A2BF44AAAF for ; Mon, 19 Oct 2020 09:45:48 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.nyi.freebsd.org (mailman.nyi.freebsd.org [IPv6:2610:1c1:1:606c::50:13]) by mx1.freebsd.org (Postfix) with ESMTP id 4CFBhX0t5Tz4MmY for ; Mon, 19 Oct 2020 09:45:48 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.nyi.freebsd.org (Postfix) id 1E07D44AAAE; Mon, 19 Oct 2020 09:45:48 +0000 (UTC) Delivered-To: bugs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 1DD3844AAAD for ; Mon, 19 Oct 2020 09:45:48 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4CFBhX01S2z4My5 for ; Mon, 19 Oct 2020 09:45:48 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id D43C5218B8 for ; Mon, 19 Oct 2020 09:45:47 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 09J9jlWu074466 for ; Mon, 19 Oct 2020 09:45:47 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 09J9jlXk074465 for bugs@FreeBSD.org; Mon, 19 Oct 2020 09:45:47 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 250454] PT_GETFPREGS on i386 oversimplifies translating FPU Tag Word Date: Mon, 19 Oct 2020 09:45:47 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: Unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: mgorny@gentoo.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter cc Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Oct 2020 09:45:48 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D250454 Bug ID: 250454 Summary: PT_GETFPREGS on i386 oversimplifies translating FPU Tag Word Product: Base System Version: Unspecified Hardware: i386 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: mgorny@gentoo.org CC: kib@FreeBSD.org The current code for translating FXSAVE area into FSAVE-alike struct for PT_GETFPREGS on i386 is oversimplifying the translation of FPU Tag Word (.en_tw). The code maps all non-empty registers into 00 (i.e. normalized value) without distinguishing between normalized values, zeroes and specials like FSAVE does. Simple reproducer (works with -m32 on amd64): #include #include #include #include #include #include #include #include int main() { int ret; int pid =3D fork(); assert(pid !=3D -1); if (pid =3D=3D 0) { int i; pthread_t t2, t3; ret =3D ptrace(PT_TRACE_ME, 0, NULL, 0); assert(ret !=3D -1); __asm__ __volatile__ ( "finit\n\t" "fldz\n\t" "fld1\n\t" "fdiv %st(1),%st(0) \n\t" "fld1\n\t" "int3\n\t" ); return 0; } pid_t waited =3D waitpid(pid, &ret, 0); assert(waited =3D=3D pid); printf("wait: %d\n", ret); struct fpreg fpr; ret =3D ptrace(PT_GETFPREGS, pid, &fpr, 0); assert (ret =3D=3D 0); printf("ftw =3D 0x%04x\n", fpr.fpr_env[2]); ret =3D ptrace(PT_CONTINUE, pid, (void*)1, 0); assert(ret =3D=3D 0); waited =3D waitpid(pid, &ret, 0); assert(waited =3D=3D pid); printf("wait: %d\n", ret); return 0; } --=20 You are receiving this mail because: You are the assignee for the bug.=