From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0D0AC3A5A9 for ; Wed, 4 Sep 2019 16:43:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7D88A20449 for ; Wed, 4 Sep 2019 16:43:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="nwB/hLSn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732055AbfIDQm6 (ORCPT ); Wed, 4 Sep 2019 12:42:58 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:36683 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731913AbfIDQm5 (ORCPT ); Wed, 4 Sep 2019 12:42:57 -0400 Received: by mail-pf1-f195.google.com with SMTP id y22so7960683pfr.3 for ; Wed, 04 Sep 2019 09:42:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=k/oSgBJoI5i7CG44m8oeHuWL1TxHBP3PuiLD3GqEJMs=; b=nwB/hLSn8C9Fkj9mb1gL3IZdiu1myDs/hI9yOnbYVwPMQzq/+T5kRyXBBJu+pVilfL 7IRiEtjBA/24FhzA3AmKhmd/sXJUIn0xXj+X/OcSYB247wOsL2jjiUMzMS3Si9jSLz3p iNpkS3Y26SHcoE9ke8ZItIXfdzQIHvSvxcg1/CLwEPZwJg59YiMNG4DpVskuIl97C1kF aw6aVY6TIGl+2KqCYIg4WiMgl8e2amGB6/4D0G14vgZzjGWzEaEnsKr53cvPyVKtIcTx KqFvOn2rofspFPjswyZusr7qO1AlM4WAqNtiuH3vHf5g0nSeN3Iu8s9fKTNm6g4kQGnK gSDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=k/oSgBJoI5i7CG44m8oeHuWL1TxHBP3PuiLD3GqEJMs=; b=XIkRmuUkQ7a7uhJ1GMQ5g6o7MdLy6WOe/bjdBIQUzvMLmNSvuFhBEdLXMTjr8ghDmT pnG32IIUJCRiLyQoYiPiUeqTUTQBce9YN0WShgYYgC9VAyR4NFuQfvZ+UD6zxqVgGGNa r1SE94QrUnc4zTo9sqfVbDQypuDbCacal7BTfrFkQDnbJDDLQatRvLdc62xXpUrmp+KE ZrzN1vnM8XojaYHMBdE+FJx4QdW9l2rfqWM2uRJ+GzCrM+4Q9wevksFanVv/2cp4zYMx TY9vK2AHJkx2mJs1GzqCuAiwSrJdhPl1btk9P2DZXx8sAYf1e5CpIcu8DYGCRVxQciDF 4gWA== X-Gm-Message-State: APjAAAURQvZqCN7bRRR2BZkCIQdWRkgeciSP/tsWgo2xGXj66omkVvMS zITvFrf3AW7JvaDmZrb5YgJmCxb/JOWThRlP8dI1RA== X-Google-Smtp-Source: APXvYqw9ghhpbkJW620d4F/i5xnGBSYo4okqbHY5PpWEgkRysrp4BZlxOoeP81KxTXsXeG8r2lv3BozPz89snZ14Gcg= X-Received: by 2002:aa7:8bcc:: with SMTP id s12mr31960729pfd.93.1567615376516; Wed, 04 Sep 2019 09:42:56 -0700 (PDT) MIME-Version: 1.0 References: <0999c80cd639b78ae27c0674069d552833227564.1561386715.git.andreyknvl@google.com> <6af3f619-4356-2f67-ed76-92beceb1e0a0@arm.com> <92ca7fd1-2aa7-3bec-384d-52033b6496c1@arm.com> In-Reply-To: <92ca7fd1-2aa7-3bec-384d-52033b6496c1@arm.com> From: Andrey Konovalov Date: Wed, 4 Sep 2019 18:42:45 +0200 Message-ID: Subject: Re: [PATCH v18 15/15] selftests, arm64: add a selftest for passing tagged pointers to kernel To: Cristian Marussi Cc: Linux ARM , Linux Memory Management List , LKML , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , Catalin Marinas , Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Kees Cook , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Luc Van Oostenryck , Dave Martin , Khalid Aziz , enh , Jason Gunthorpe , Christoph Hellwig , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Kevin Brodsky , Szabolcs Nagy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Sep 4, 2019 at 6:22 PM Cristian Marussi wrote: > > Hi Andrey ! > > On 04/09/2019 15:52, Andrey Konovalov wrote: > > On Fri, Aug 23, 2019 at 7:49 PM Cristian Marussi > > wrote: > >> > >> > >> Hi > >> > >> On 23/08/2019 18:16, Andrey Konovalov wrote: > >>> On Fri, Aug 23, 2019 at 3:56 PM Cristian Marussi > >>> wrote: > >>>> > >>>> Hi Andrey > >>>> > >>>> On 24/06/2019 15:33, Andrey Konovalov wrote: > >>>>> This patch is a part of a series that extends kernel ABI to allow t= o pass > >>>>> tagged user pointers (with the top byte set to something else other= than > >>>>> 0x00) as syscall arguments. > >>>>> > >>>>> This patch adds a simple test, that calls the uname syscall with a > >>>>> tagged user pointer as an argument. Without the kernel accepting ta= gged > >>>>> user pointers the test fails with EFAULT. > >>>>> > >>>>> Signed-off-by: Andrey Konovalov > >>>>> --- > >>>>> tools/testing/selftests/arm64/.gitignore | 1 + > >>>>> tools/testing/selftests/arm64/Makefile | 11 +++++++ > >>>>> .../testing/selftests/arm64/run_tags_test.sh | 12 ++++++++ > >>>>> tools/testing/selftests/arm64/tags_test.c | 29 +++++++++++++++= ++++ > >>>>> 4 files changed, 53 insertions(+) > >>>>> create mode 100644 tools/testing/selftests/arm64/.gitignore > >>>>> create mode 100644 tools/testing/selftests/arm64/Makefile > >>>>> create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh > >>>>> create mode 100644 tools/testing/selftests/arm64/tags_test.c > >>>> > >>>> After building a fresh Kernel from arm64/for-next-core from scratch = at: > >>>> > >>>> commit 239ab658bea3b387424501e7c416640d6752dc0c > >>>> Merge: 6bfa3134bd3a 42d038c4fb00 1243cb6a676f d55c5f28afaf d06fa5a11= 8f1 34b5560db40d > >>>> Author: Will Deacon > >>>> Date: Thu Aug 22 18:23:53 2019 +0100 > >>>> > >>>> Merge branches 'for-next/error-injection', 'for-next/tbi', 'for-= next/psci-cpuidle', 'for-next/cpu-topology' and 'for-next/52-bit-kva' into = for-next/core > >>>> > >>>> > >>>> KSFT arm64 tests build is broken for me, both setting or not KBUILD_= OUTPUT=3D > >>>> > >>>> 13:30 $ make TARGETS=3Darm64 kselftest-clean > >>>> make[1]: Entering directory '/home/crimar01/ARM/dev/src/pdsw/out_lin= ux' > >>>> rm -f -r /home/crimar01/ARM/dev/src/pdsw/out_linux//kselftest/arm64/= tags_test > >>>> make[1]: Leaving directory '/home/crimar01/ARM/dev/src/pdsw/out_linu= x' > >>>> > >>>> =E2=9C=94 ~/ARM/dev/src/pdsw/linux [arm64_for_next_core|=E2=80=A68= =E2=9A=91 23] > >>>> > >>>> 13:30 $ make TARGETS=3Darm64 kselftest > >>>> make[1]: Entering directory '/home/crimar01/ARM/dev/src/pdsw/out_lin= ux' > >>>> arch/arm64/Makefile:56: CROSS_COMPILE_COMPAT not defined or empty, t= he compat vDSO will not be built > >>>> make --no-builtin-rules INSTALL_HDR_PATH=3D$BUILD/usr \ > >>>> ARCH=3Darm64 -C ../../.. headers_install > >>>> HOSTCC scripts/basic/fixdep > >>>> HOSTCC scripts/unifdef > >>>> ... > >>>> ... > >>>> HDRINST usr/include/asm/msgbuf.h > >>>> HDRINST usr/include/asm/shmbuf.h > >>>> INSTALL /home/crimar01/ARM/dev/src/pdsw/out_linux//kselftest/usr/i= nclude > >>>> /opt/toolchains/gcc-arm-8.3-2019.03-x86_64-aarch64-linux-gnu/bin/aar= ch64-linux-gnu-gcc tags_test.c -o /home/crimar01/ARM/dev/src/pdsw/out_= linux//kselftest/arm64/tags_test > >>>> tags_test.c: In function =E2=80=98main=E2=80=99: > >>>> tags_test.c:21:12: error: =E2=80=98PR_SET_TAGGED_ADDR_CTRL=E2=80=99 = undeclared (first use in this function); did you mean =E2=80=98PR_GET_TID_A= DDRESS=E2=80=99? > >>>> if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)= =3D=3D 0) > >>>> ^~~~~~~~~~~~~~~~~~~~~~~ > >>>> PR_GET_TID_ADDRESS > >>>> tags_test.c:21:12: note: each undeclared identifier is reported only= once for each function it appears in > >>>> tags_test.c:21:37: error: =E2=80=98PR_TAGGED_ADDR_ENABLE=E2=80=99 un= declared (first use in this function); did you mean =E2=80=98PR_GET_DUMPABL= E=E2=80=99? > >>>> if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)= =3D=3D 0) > >>>> ^~~~~~~~~~~~~~~~~~~~~ > >>>> PR_GET_DUMPABLE > >>>> ../lib.mk:138: recipe for target '/home/crimar01/ARM/dev/src/pdsw/ou= t_linux//kselftest/arm64/tags_test' failed > >>>> make[3]: *** [/home/crimar01/ARM/dev/src/pdsw/out_linux//kselftest/a= rm64/tags_test] Error 1 > >>>> Makefile:136: recipe for target 'all' failed > >>>> make[2]: *** [all] Error 2 > >>>> /home/crimar01/ARM/dev/src/pdsw/linux/Makefile:1237: recipe for targ= et 'kselftest' failed > >>>> make[1]: *** [kselftest] Error 2 > >>>> make[1]: Leaving directory '/home/crimar01/ARM/dev/src/pdsw/out_linu= x' > >>>> Makefile:179: recipe for target 'sub-make' failed > >>>> make: *** [sub-make] Error 2 > >>>> > >>>> Despite seeing KSFT installing Kernel Headers, they cannot be found. > >>>> > >>>> Fixing this patch like this make it work for me: > >>>> > >>>> diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/= selftests/arm64/Makefile > >>>> index a61b2e743e99..f9f79fb272f0 100644 > >>>> --- a/tools/testing/selftests/arm64/Makefile > >>>> +++ b/tools/testing/selftests/arm64/Makefile > >>>> @@ -4,6 +4,7 @@ > >>>> ARCH ?=3D $(shell uname -m 2>/dev/null || echo not) > >>>> > >>>> ifneq (,$(filter $(ARCH),aarch64 arm64)) > >>>> +CFLAGS +=3D -I../../../../usr/include/ > >>>> TEST_GEN_PROGS :=3D tags_test > >>>> TEST_PROGS :=3D run_tags_test.sh > >>>> endif > >>>> > >>>> but is not really a proper fix since it does NOT account for case in= which you have > >>>> installed the Kernel Headers in a non standard location like when yo= u use KBUILD_OUTPUT. > >>>> > >>>> Am I missing something ? > >>> > >>> Hm, PR_SET_TAGGED_ADDR_CTRL is defined in include/uapi/linux/prctl.h, > >>> and the test has #include so as long as you've updated > >>> your kernel headers this should work. > >>> > >>> (I'm OOO next week, I'll see if I can reproduce this once I'm back). > >> > >> Ok. Thanks for the reply. > >> > >> I think I've got it in my local tree having cloned arm64/for-next-core= : > >> > >> 18:32 $ egrep -A 10 PR_SET_TAG ./include/uapi/linux/prctl.h > >> #define PR_SET_TAGGED_ADDR_CTRL 55 > >> #define PR_GET_TAGGED_ADDR_CTRL 56 > >> # define PR_TAGGED_ADDR_ENABLE (1UL << 0) > >> > >> #endif /* _LINUX_PRCTL_H */ > >> > >> and Kernel header are locally installed in my kernel src dir (by KSFT = indeed) > >> > >> 18:34 $ egrep -RA 10 PR_SET_TAG usr/include/ > >> usr/include/linux/prctl.h:#define PR_SET_TAGGED_ADDR_CTRL = 55 > >> usr/include/linux/prctl.h-#define PR_GET_TAGGED_ADDR_CTRL = 56 > >> usr/include/linux/prctl.h-# define PR_TAGGED_ADDR_ENABLE = (1UL << 0) > >> usr/include/linux/prctl.h- > >> usr/include/linux/prctl.h-#endif /* _LINUX_PRCTL_H */ > >> > >> but how are they supposed to be found if nor the test Makefile > >> neither the KSFT Makefile who installs them pass any -I options to the > >> compiler ? > >> I suppose tries to include arch specific headers from th= e regular system path, > >> but when you are cross-compiling ? > >> > >> 18:34 $ make TARGETS=3Darm64 kselftest > >> make[1]: Entering directory '/home/crimar01/ARM/dev/src/pdsw/out_linux= ' > >> arch/arm64/Makefile:56: CROSS_COMPILE_COMPAT not defined or empty, the= compat vDSO will not be built > >> make --no-builtin-rules INSTALL_HDR_PATH=3D$BUILD/usr \ > >> ARCH=3Darm64 -C ../../.. headers_install > >> INSTALL /home/crimar01/ARM/dev/src/pdsw/out_linux/kselftest/usr/incl= ude > >> /opt/toolchains/gcc-arm-8.3-2019.03-x86_64-aarch64-linux-gnu/bin/aarch= 64-linux-gnu-gcc -Wall -O2 -g tags_test.c -o /home/crimar01/ARM/dev/src= /pdsw/out_linux/kselftest/arm64/tags/tags_test > >> tags_test.c: In function =E2=80=98main=E2=80=99: > >> tags_test.c:20:12: error: =E2=80=98PR_SET_TAGGED_ADDR_CTRL=E2=80=99 un= declared (first use in this function); did you mean =E2=80=98PR_GET_TID_ADD= RESS=E2=80=99? > >> if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0) = =3D=3D 0) > >> ^~~~~~~~~~~~~~~~~~~~~~~ > >> PR_GET_TID_ADDRESS > >> tags_test.c:20:12: note: each undeclared identifier is reported only o= nce for each function it appears in > >> tags_test.c:20:37: error: =E2=80=98PR_TAGGED_ADDR_ENABLE=E2=80=99 unde= clared (first use in this function); did you mean =E2=80=98PR_GET_DUMPABLE= =E2=80=99? > >> if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0) = =3D=3D 0) > >> ^~~~~~~~~~~~~~~~~~~~~ > >> PR_GET_DUMPABLE > >> ../../lib.mk:138: recipe for target '/home/crimar01/ARM/dev/src/pdsw/o= ut_linux/kselftest/arm64/tags/tags_test' failed > >> make[4]: *** [/home/crimar01/ARM/dev/src/pdsw/out_linux/kselftest/arm6= 4/tags/tags_test] Error 1 > >> Makefile:19: recipe for target 'all' failed > >> make[3]: *** [all] Error 2 > >> Makefile:137: recipe for target 'all' failed > >> make[2]: *** [all] Error 2 > >> /home/crimar01/ARM/dev/src/pdsw/linux/Makefile:1236: recipe for target= 'kselftest' failed > >> make[1]: *** [kselftest] Error 2 > >> make[1]: Leaving directory '/home/crimar01/ARM/dev/src/pdsw/out_linux' > >> Makefile:179: recipe for target 'sub-make' failed > >> make: *** [sub-make] Error 2 > >> > >> > >> In fact many KSFT testcases seems to brutally add default headers path= : > >> > >> tools/testing/selftests/memfd/Makefile:CFLAGS +=3D -I../../../../inclu= de/uapi/ > >> tools/testing/selftests/memfd/Makefile:CFLAGS +=3D -I../../../../inclu= de/ > >> tools/testing/selftests/memfd/Makefile:CFLAGS +=3D -I../../../../usr/i= nclude/ > >> tools/testing/selftests/net/Makefile:CFLAGS +=3D -I../../../../usr/inc= lude/ > >> tools/testing/selftests/membarrier/Makefile:CFLAGS +=3D -g -I../../../= ../usr/include/ > >> ... > > > > Hi Cristian! > > > > Indeed, I can reproduce the issue. I don't know what's the proper way > > to resolve this. Adding "CFLAGS +=3D -I../../../../usr/include/" looks > > good to me. AFAICS your series resolves this issue in a similar way, > > but I think we should fix this before the current rc is released. Do > > you want to submit a patch that adds this simple fix or should I do > > that? > > > > Please feel free to post the single line patch above to quickly fix this = before > release, so we don't have a broken build straight away. (our CI is alread= y beating me...:D) Done. > > On my side (01/11) in the meantime I'll fix the top level KSFT arm64 make= file so as to calculate > and propagate once for all the headers search path down to all KSFT arm64= / in one go, > trying to guess where they are; this is needed because the above fix work= s fine as long > as you don't have KBUILD_OUTPUT set, once you set it, KSFT installs khead= ers in a different > place and the above -I fix is fooled again....but this is a general prob= lem also in other > KSFT tests as I can see now so I think this fix is good enough for now > (and the fix on my side, even if trivial, is not going to go into this re= lease for sure) Ah, I see. Thanks for the report! > > Thanks ! > > Cheers > > Cristian > > > Thanks! > > > >> > >> Cheers > >> > >> Cristian > >>> > >>> > >>> > >>>> > >>>> Thanks > >>>> > >>>> Cristian > >>>> > >>>>> > >>>>> diff --git a/tools/testing/selftests/arm64/.gitignore b/tools/testi= ng/selftests/arm64/.gitignore > >>>>> new file mode 100644 > >>>>> index 000000000000..e8fae8d61ed6 > >>>>> --- /dev/null > >>>>> +++ b/tools/testing/selftests/arm64/.gitignore > >>>>> @@ -0,0 +1 @@ > >>>>> +tags_test > >>>>> diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing= /selftests/arm64/Makefile > >>>>> new file mode 100644 > >>>>> index 000000000000..a61b2e743e99 > >>>>> --- /dev/null > >>>>> +++ b/tools/testing/selftests/arm64/Makefile > >>>>> @@ -0,0 +1,11 @@ > >>>>> +# SPDX-License-Identifier: GPL-2.0 > >>>>> + > >>>>> +# ARCH can be overridden by the user for cross compiling > >>>>> +ARCH ?=3D $(shell uname -m 2>/dev/null || echo not) > >>>>> + > >>>>> +ifneq (,$(filter $(ARCH),aarch64 arm64)) > >>>>> +TEST_GEN_PROGS :=3D tags_test > >>>>> +TEST_PROGS :=3D run_tags_test.sh > >>>>> +endif > >>>>> + > >>>>> +include ../lib.mk > >>>>> diff --git a/tools/testing/selftests/arm64/run_tags_test.sh b/tools= /testing/selftests/arm64/run_tags_test.sh > >>>>> new file mode 100755 > >>>>> index 000000000000..745f11379930 > >>>>> --- /dev/null > >>>>> +++ b/tools/testing/selftests/arm64/run_tags_test.sh > >>>>> @@ -0,0 +1,12 @@ > >>>>> +#!/bin/sh > >>>>> +# SPDX-License-Identifier: GPL-2.0 > >>>>> + > >>>>> +echo "--------------------" > >>>>> +echo "running tags test" > >>>>> +echo "--------------------" > >>>>> +./tags_test > >>>>> +if [ $? -ne 0 ]; then > >>>>> + echo "[FAIL]" > >>>>> +else > >>>>> + echo "[PASS]" > >>>>> +fi > >>>>> diff --git a/tools/testing/selftests/arm64/tags_test.c b/tools/test= ing/selftests/arm64/tags_test.c > >>>>> new file mode 100644 > >>>>> index 000000000000..22a1b266e373 > >>>>> --- /dev/null > >>>>> +++ b/tools/testing/selftests/arm64/tags_test.c > >>>>> @@ -0,0 +1,29 @@ > >>>>> +// SPDX-License-Identifier: GPL-2.0 > >>>>> + > >>>>> +#include > >>>>> +#include > >>>>> +#include > >>>>> +#include > >>>>> +#include > >>>>> +#include > >>>>> + > >>>>> +#define SHIFT_TAG(tag) ((uint64_t)(tag) << 56) > >>>>> +#define SET_TAG(ptr, tag) (((uint64_t)(ptr) & ~SHIFT_TAG(0xff))= | \ > >>>>> + SHIFT_TAG(tag)) > >>>>> + > >>>>> +int main(void) > >>>>> +{ > >>>>> + static int tbi_enabled =3D 0; > >>>>> + struct utsname *ptr, *tagged_ptr; > >>>>> + int err; > >>>>> + > >>>>> + if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, = 0, 0) =3D=3D 0) > >>>>> + tbi_enabled =3D 1; > >>>>> + ptr =3D (struct utsname *)malloc(sizeof(*ptr)); > >>>>> + if (tbi_enabled) > >>>>> + tagged_ptr =3D (struct utsname *)SET_TAG(ptr, 0x42); > >>>>> + err =3D uname(tagged_ptr); > >>>>> + free(ptr); > >>>>> + > >>>>> + return err; > >>>>> +} > >>>>> > >>>> > >> >