Date: Wed, 9 Feb 2011 01:55:42 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Ali Polatel <alip@exherbo.org> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: ptrace weirdness with 9.0-CURRENT Message-ID: <20110208235542.GH78089@deviant.kiev.zoral.com.ua> In-Reply-To: <20110208234952.GG78089@deviant.kiev.zoral.com.ua> References: <87fwrydu7s.fsf@karatren.ev> <20110208234952.GG78089@deviant.kiev.zoral.com.ua>
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--CwciIYoKw+3ryeRd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 09, 2011 at 01:49:52AM +0200, Kostik Belousov wrote: > On Wed, Feb 09, 2011 at 12:42:15AM +0200, Ali Polatel wrote: > > Hello everyone, > >=20 > > I'm the developer of pinktrace - http://dev.exherbo.org/~alip/pinktrace/ > > - a simple ptrace() wrapper library for FreeBSD and Linux. I have set up > > a FreeBSD-9.0-CURRENT VM today to test various new features recently > > added to ptrace(). This is about a behaviour difference between > > 8.1-RELEASE and 9.0-CURRENT which I've noticed through a unit test of > > pinktrace. I don't want to bother you with the internals of this library > > so I'll briefly explain the problem. > >=20 > > I've inserted the testcase I've used below. The aim is to trace a > > open(NULL, 0) call which should fail with EFAULT. Running this on two > > different VMs I get: > >=20 > > % uname -a > > FreeBSD 9.0-CURRENT FreeBSD 9.0-CURRENT #0: Wed Feb 9 05:02:31 EET 20= 11 root@:/usr/obj/usr/src/sys/GENERIC amd64 > > % sudo cat /root/world.txt > > -------------------------------------------------------------- > > >>> World build completed on Wed Feb 9 00:23:30 EET 2011 > > -------------------------------------------------------------- > > % gcc -Wall ptrace-amd64-fbsd-return.c > > % ./a.out > > retval:0 error:0 > >=20 > > $ uname -a > > FreeBSD 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Jul 19 02:36:49 UTC 20= 10 root@mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64 > > $ gcc -Wall ptrace-amd64-fbsd-return.c > > $ ./a.out > > retval:14 error:1 > > $=20 > >=20 > > Important note: I couldn't notice a problem with truss tracing a > > open(NULL, 0) call so I think this is a problem with my testcase. > > I'll be happy if you can shed some light on what I'm doing wrong here: > There is no issue with ptrace(2). Your test fails because, apparently, > rtld in HEAD calls setjmp(3) when resolving symbols, and setjmp(3) > calls sigprocmask(2). The end result is that you get SCX event for > sigprocmask, and not for your open(2). >=20 > The issue with sigprocmask call from setjmp shall be fixed, but this > is not an issue with ptrace(2). The following should fix the problem. diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c index 50ab393..948cf49 100644 --- a/libexec/rtld-elf/rtld.c +++ b/libexec/rtld-elf/rtld.c @@ -560,7 +560,7 @@ _rtld_bind(Obj_Entry *obj, Elf_Size reloff) RtldLockState lockstate; =20 rlock_acquire(rtld_bind_lock, &lockstate); - if (setjmp(lockstate.env) !=3D 0) + if (sigsetjmp(lockstate.env, 0) !=3D 0) lock_upgrade(rtld_bind_lock, &lockstate); if (obj->pltrel) rel =3D (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); @@ -2142,7 +2142,7 @@ dlopen(const char *name, int mode) ld_tracing =3D (mode & RTLD_TRACE) =3D=3D 0 ? NULL : "1"; if (ld_tracing !=3D NULL) { rlock_acquire(rtld_bind_lock, &lockstate); - if (setjmp(lockstate.env) !=3D 0) + if (sigsetjmp(lockstate.env, 0) !=3D 0) lock_upgrade(rtld_bind_lock, &lockstate); environ =3D (char **)*get_program_var_addr("environ", &lockstate); lock_release(rtld_bind_lock, &lockstate); @@ -2264,7 +2264,7 @@ do_dlsym(void *handle, const char *name, void *retadd= r, const Ver_Entry *ve, req.lockstate =3D &lockstate; =20 rlock_acquire(rtld_bind_lock, &lockstate); - if (setjmp(lockstate.env) !=3D 0) + if (sigsetjmp(lockstate.env, 0) !=3D 0) lock_upgrade(rtld_bind_lock, &lockstate); if (handle =3D=3D NULL || handle =3D=3D RTLD_NEXT || handle =3D=3D RTLD_DEFAULT || handle =3D=3D RTLD_SELF) { diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h index 8941d29..bb365a7 100644 --- a/libexec/rtld-elf/rtld.h +++ b/libexec/rtld-elf/rtld.h @@ -276,7 +276,7 @@ typedef struct Struct_DoneList { =20 struct Struct_RtldLockState { int lockstate; - jmp_buf env; + sigjmp_buf env; }; =20 /* diff --git a/libexec/rtld-elf/rtld_lock.c b/libexec/rtld-elf/rtld_lock.c index e76a4da..024e1e2 100644 --- a/libexec/rtld-elf/rtld_lock.c +++ b/libexec/rtld-elf/rtld_lock.c @@ -259,7 +259,7 @@ lock_restart_for_upgrade(RtldLockState *lockstate) case RTLD_LOCK_WLOCKED: break; case RTLD_LOCK_RLOCKED: - longjmp(lockstate->env, 1); + siglongjmp(lockstate->env, 1); break; default: assert(0); --CwciIYoKw+3ryeRd Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk1R1/4ACgkQC3+MBN1Mb4hcdwCgmzmKJ/ETTwsOX7LYBuWnUG5z uyMAoJcsD4id/vK7s7voxMFOFknTaxhs =TIlA -----END PGP SIGNATURE----- --CwciIYoKw+3ryeRd--
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