[PATCH 0/2] Add tests for longjmp with user contexts

[PATCH 0/2] Add tests for longjmp with user contexts

[H.J. Lu]

Verify that longjmp works correctly from user context to main context
and within a user context.

H.J. Lu (2):
  Add a test for longjmp from user context
  Add a test for setjmp/longjmp within user context

 stdlib/Makefile           |   2 +
 stdlib/tst-setcontext10.c |  87 +++++++++++++++++++
 stdlib/tst-setcontext11.c | 178 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 267 insertions(+)
 create mode 100644 stdlib/tst-setcontext10.c
 create mode 100644 stdlib/tst-setcontext11.c

-- 
2.43.0

[PATCH 1/2] Add a test for longjmp from user context

[H.J. Lu]

Verify that longjmp works correctly after setcontext is called to switch
to a user context.
---
 stdlib/Makefile           |  1 +
 stdlib/tst-setcontext10.c | 87 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 stdlib/tst-setcontext10.c

diff --git a/stdlib/Makefile b/stdlib/Makefile
index 0b154e57c5..8c6249aab4 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -234,6 +234,7 @@ tests := \
   tst-setcontext7 \
   tst-setcontext8 \
   tst-setcontext9 \
+  tst-setcontext10 \
   tst-strfmon_l \
   tst-strfrom \
   tst-strfrom-locale \
diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
new file mode 100644
index 0000000000..2926753cb1
--- /dev/null
+++ b/stdlib/tst-setcontext10.c
@@ -0,0 +1,87 @@
+/* Check longjmp from user context to main context.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <setjmp.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+static jmp_buf jmpbuf;
+static ucontext_t ctx;
+
+static void f2 (void);
+
+static void
+__attribute__ ((noinline, noclone))
+f1 (void)
+{
+  printf ("start f1\n");
+  f2 ();
+}
+
+static void
+__attribute__ ((noinline, noclone))
+f2 (void)
+{
+  printf ("start f2\n");
+  if (setcontext (&ctx) != 0)
+    {
+      printf ("%s: setcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+}
+
+static void
+f3 (void)
+{
+  printf ("start f3\n");
+  longjmp (jmpbuf, 1);
+}
+
+static int
+__attribute__ ((noinline, noclone))
+do_test_1 (void)
+{
+  char st1[32768];
+
+  if (setjmp (jmpbuf) != 0)
+    return 0;
+
+  puts ("making contexts");
+  if (getcontext (&ctx) != 0)
+    {
+      printf ("%s: getcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+  ctx.uc_stack.ss_sp = st1;
+  ctx.uc_stack.ss_size = sizeof st1;
+  ctx.uc_link = NULL;
+  makecontext (&ctx, (void (*) (void)) f3, 0);
+  f1 ();
+  puts ("FAIL: returned from f1 ()");
+  exit (EXIT_FAILURE);
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ();
+}
+
+#include <support/test-driver.c>
-- 
2.43.0

Re: [PATCH 1/2] Add a test for longjmp from user context

[Noah Goldstein]

On Thu, Dec 14, 2023 at 1:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Verify that longjmp works correctly after setcontext is called to switch
> to a user context.
> ---
>  stdlib/Makefile           |  1 +
>  stdlib/tst-setcontext10.c | 87 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 88 insertions(+)
>  create mode 100644 stdlib/tst-setcontext10.c
>
> diff --git a/stdlib/Makefile b/stdlib/Makefile
> index 0b154e57c5..8c6249aab4 100644
> --- a/stdlib/Makefile
> +++ b/stdlib/Makefile
> @@ -234,6 +234,7 @@ tests := \
>    tst-setcontext7 \
>    tst-setcontext8 \
>    tst-setcontext9 \
> +  tst-setcontext10 \
>    tst-strfmon_l \
>    tst-strfrom \
>    tst-strfrom-locale \
> diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
> new file mode 100644
> index 0000000000..2926753cb1
> --- /dev/null
> +++ b/stdlib/tst-setcontext10.c
> @@ -0,0 +1,87 @@
> +/* Check longjmp from user context to main context.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <setjmp.h>
> +#include <ucontext.h>
> +#include <unistd.h>
> +
> +static jmp_buf jmpbuf;
> +static ucontext_t ctx;
> +
> +static void f2 (void);
> +
> +static void
> +__attribute__ ((noinline, noclone))
> +f1 (void)
> +{
> +  printf ("start f1\n");
> +  f2 ();
> +}
> +
> +static void
> +__attribute__ ((noinline, noclone))
> +f2 (void)
> +{
> +  printf ("start f2\n");
> +  if (setcontext (&ctx) != 0)
> +    {
> +      printf ("%s: setcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +}
> +
> +static void
> +f3 (void)
> +{
> +  printf ("start f3\n");
> +  longjmp (jmpbuf, 1);
> +}
> +
> +static int
> +__attribute__ ((noinline, noclone))
> +do_test_1 (void)
> +{
> +  char st1[32768];
> +
> +  if (setjmp (jmpbuf) != 0)
> +    return 0;
> +
> +  puts ("making contexts");
> +  if (getcontext (&ctx) != 0)
> +    {
> +      printf ("%s: getcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +  ctx.uc_stack.ss_sp = st1;
> +  ctx.uc_stack.ss_size = sizeof st1;
> +  ctx.uc_link = NULL;
> +  makecontext (&ctx, (void (*) (void)) f3, 0);
> +  f1 ();
> +  puts ("FAIL: returned from f1 ()");
> +  exit (EXIT_FAILURE);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  return do_test_1 ();
> +}
> +
> +#include <support/test-driver.c>
> --
> 2.43.0
>

What is the success path here?

Re: [PATCH 1/2] Add a test for longjmp from user context

[H.J. Lu]

On Thu, Dec 14, 2023 at 2:39 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Thu, Dec 14, 2023 at 1:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > Verify that longjmp works correctly after setcontext is called to switch
> > to a user context.
> > ---
> >  stdlib/Makefile           |  1 +
> >  stdlib/tst-setcontext10.c | 87 +++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 88 insertions(+)
> >  create mode 100644 stdlib/tst-setcontext10.c
> >
> > diff --git a/stdlib/Makefile b/stdlib/Makefile
> > index 0b154e57c5..8c6249aab4 100644
> > --- a/stdlib/Makefile
> > +++ b/stdlib/Makefile
> > @@ -234,6 +234,7 @@ tests := \
> >    tst-setcontext7 \
> >    tst-setcontext8 \
> >    tst-setcontext9 \
> > +  tst-setcontext10 \
> >    tst-strfmon_l \
> >    tst-strfrom \
> >    tst-strfrom-locale \
> > diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
> > new file mode 100644
> > index 0000000000..2926753cb1
> > --- /dev/null
> > +++ b/stdlib/tst-setcontext10.c
> > @@ -0,0 +1,87 @@
> > +/* Check longjmp from user context to main context.
> > +   Copyright (C) 2023 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <https://www.gnu.org/licenses/>.  */
> > +
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <setjmp.h>
> > +#include <ucontext.h>
> > +#include <unistd.h>
> > +
> > +static jmp_buf jmpbuf;
> > +static ucontext_t ctx;
> > +
> > +static void f2 (void);
> > +
> > +static void
> > +__attribute__ ((noinline, noclone))
> > +f1 (void)
> > +{
> > +  printf ("start f1\n");
> > +  f2 ();
> > +}
> > +
> > +static void
> > +__attribute__ ((noinline, noclone))
> > +f2 (void)
> > +{
> > +  printf ("start f2\n");
> > +  if (setcontext (&ctx) != 0)
> > +    {
> > +      printf ("%s: setcontext: %m\n", __FUNCTION__);
> > +      exit (EXIT_FAILURE);
> > +    }
> > +}
> > +
> > +static void
> > +f3 (void)
> > +{
> > +  printf ("start f3\n");
> > +  longjmp (jmpbuf, 1);
> > +}
> > +
> > +static int
> > +__attribute__ ((noinline, noclone))
> > +do_test_1 (void)
> > +{
> > +  char st1[32768];
> > +
> > +  if (setjmp (jmpbuf) != 0)
> > +    return 0;
> > +
> > +  puts ("making contexts");
> > +  if (getcontext (&ctx) != 0)
> > +    {
> > +      printf ("%s: getcontext: %m\n", __FUNCTION__);
> > +      exit (EXIT_FAILURE);
> > +    }
> > +  ctx.uc_stack.ss_sp = st1;
> > +  ctx.uc_stack.ss_size = sizeof st1;
> > +  ctx.uc_link = NULL;
> > +  makecontext (&ctx, (void (*) (void)) f3, 0);
> > +  f1 ();
> > +  puts ("FAIL: returned from f1 ()");
> > +  exit (EXIT_FAILURE);
> > +}
> > +
> > +static int
> > +do_test (void)
> > +{
> > +  return do_test_1 ();
> > +}
> > +
> > +#include <support/test-driver.c>
> > --
> > 2.43.0
> >
>
> What is the success path here?

When longjmp is called from the user context, do_test_1
returns 0:

if (setjmp (jmpbuf) != 0)
  return 0;

-- 
H.J.

Re: [PATCH 1/2] Add a test for longjmp from user context

[Noah Goldstein]

On Thu, Dec 14, 2023 at 4:43 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Thu, Dec 14, 2023 at 2:39 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > On Thu, Dec 14, 2023 at 1:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > Verify that longjmp works correctly after setcontext is called to switch
> > > to a user context.
> > > ---
> > >  stdlib/Makefile           |  1 +
> > >  stdlib/tst-setcontext10.c | 87 +++++++++++++++++++++++++++++++++++++++
> > >  2 files changed, 88 insertions(+)
> > >  create mode 100644 stdlib/tst-setcontext10.c
> > >
> > > diff --git a/stdlib/Makefile b/stdlib/Makefile
> > > index 0b154e57c5..8c6249aab4 100644
> > > --- a/stdlib/Makefile
> > > +++ b/stdlib/Makefile
> > > @@ -234,6 +234,7 @@ tests := \
> > >    tst-setcontext7 \
> > >    tst-setcontext8 \
> > >    tst-setcontext9 \
> > > +  tst-setcontext10 \
> > >    tst-strfmon_l \
> > >    tst-strfrom \
> > >    tst-strfrom-locale \
> > > diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
> > > new file mode 100644
> > > index 0000000000..2926753cb1
> > > --- /dev/null
> > > +++ b/stdlib/tst-setcontext10.c
> > > @@ -0,0 +1,87 @@
> > > +/* Check longjmp from user context to main context.
> > > +   Copyright (C) 2023 Free Software Foundation, Inc.
> > > +   This file is part of the GNU C Library.
> > > +
> > > +   The GNU C Library is free software; you can redistribute it and/or
> > > +   modify it under the terms of the GNU Lesser General Public
> > > +   License as published by the Free Software Foundation; either
> > > +   version 2.1 of the License, or (at your option) any later version.
> > > +
> > > +   The GNU C Library is distributed in the hope that it will be useful,
> > > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > > +   Lesser General Public License for more details.
> > > +
> > > +   You should have received a copy of the GNU Lesser General Public
> > > +   License along with the GNU C Library; if not, see
> > > +   <https://www.gnu.org/licenses/>.  */
> > > +
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <setjmp.h>
> > > +#include <ucontext.h>
> > > +#include <unistd.h>
> > > +
> > > +static jmp_buf jmpbuf;
> > > +static ucontext_t ctx;
> > > +
> > > +static void f2 (void);
> > > +
> > > +static void
> > > +__attribute__ ((noinline, noclone))
> > > +f1 (void)
> > > +{
> > > +  printf ("start f1\n");
> > > +  f2 ();
> > > +}
> > > +
> > > +static void
> > > +__attribute__ ((noinline, noclone))
> > > +f2 (void)
> > > +{
> > > +  printf ("start f2\n");
> > > +  if (setcontext (&ctx) != 0)
> > > +    {
> > > +      printf ("%s: setcontext: %m\n", __FUNCTION__);
> > > +      exit (EXIT_FAILURE);
> > > +    }
> > > +}
> > > +
> > > +static void
> > > +f3 (void)
> > > +{
> > > +  printf ("start f3\n");
> > > +  longjmp (jmpbuf, 1);
> > > +}
> > > +
> > > +static int
> > > +__attribute__ ((noinline, noclone))
> > > +do_test_1 (void)
> > > +{
> > > +  char st1[32768];
> > > +
> > > +  if (setjmp (jmpbuf) != 0)
> > > +    return 0;
> > > +
> > > +  puts ("making contexts");
> > > +  if (getcontext (&ctx) != 0)
> > > +    {
> > > +      printf ("%s: getcontext: %m\n", __FUNCTION__);
> > > +      exit (EXIT_FAILURE);
> > > +    }
> > > +  ctx.uc_stack.ss_sp = st1;
> > > +  ctx.uc_stack.ss_size = sizeof st1;
> > > +  ctx.uc_link = NULL;
> > > +  makecontext (&ctx, (void (*) (void)) f3, 0);
> > > +  f1 ();
> > > +  puts ("FAIL: returned from f1 ()");
> > > +  exit (EXIT_FAILURE);
> > > +}
> > > +
> > > +static int
> > > +do_test (void)
> > > +{
> > > +  return do_test_1 ();
> > > +}
> > > +
> > > +#include <support/test-driver.c>
> > > --
> > > 2.43.0
> > >
> >
> > What is the success path here?
>
> When longjmp is called from the user context, do_test_1
> returns 0:
>
> if (setjmp (jmpbuf) != 0)
>   return 0;
>
> --
> H.J.

LGTM.

Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

Re: [PATCH 1/2] Add a test for longjmp from user context

[Adhemerval Zanella Netto]

On 14/12/23 21:04, Noah Goldstein wrote:
> On Thu, Dec 14, 2023 at 4:43 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>>
>> On Thu, Dec 14, 2023 at 2:39 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>>>
>>> On Thu, Dec 14, 2023 at 1:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>>>>
>>>> Verify that longjmp works correctly after setcontext is called to switch
>>>> to a user context.
>>>> ---
>>>>  stdlib/Makefile           |  1 +
>>>>  stdlib/tst-setcontext10.c | 87 +++++++++++++++++++++++++++++++++++++++
>>>>  2 files changed, 88 insertions(+)
>>>>  create mode 100644 stdlib/tst-setcontext10.c
>>>>
>>>> diff --git a/stdlib/Makefile b/stdlib/Makefile
>>>> index 0b154e57c5..8c6249aab4 100644
>>>> --- a/stdlib/Makefile
>>>> +++ b/stdlib/Makefile
>>>> @@ -234,6 +234,7 @@ tests := \
>>>>    tst-setcontext7 \
>>>>    tst-setcontext8 \
>>>>    tst-setcontext9 \
>>>> +  tst-setcontext10 \
>>>>    tst-strfmon_l \
>>>>    tst-strfrom \
>>>>    tst-strfrom-locale \
>>>> diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
>>>> new file mode 100644
>>>> index 0000000000..2926753cb1
>>>> --- /dev/null
>>>> +++ b/stdlib/tst-setcontext10.c
>>>> @@ -0,0 +1,87 @@
>>>> +/* Check longjmp from user context to main context.
>>>> +   Copyright (C) 2023 Free Software Foundation, Inc.
>>>> +   This file is part of the GNU C Library.
>>>> +
>>>> +   The GNU C Library is free software; you can redistribute it and/or
>>>> +   modify it under the terms of the GNU Lesser General Public
>>>> +   License as published by the Free Software Foundation; either
>>>> +   version 2.1 of the License, or (at your option) any later version.
>>>> +
>>>> +   The GNU C Library is distributed in the hope that it will be useful,
>>>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>>>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>>> +   Lesser General Public License for more details.
>>>> +
>>>> +   You should have received a copy of the GNU Lesser General Public
>>>> +   License along with the GNU C Library; if not, see
>>>> +   <https://www.gnu.org/licenses/>.  */
>>>> +
>>>> +#include <stdio.h>
>>>> +#include <stdlib.h>
>>>> +#include <setjmp.h>
>>>> +#include <ucontext.h>
>>>> +#include <unistd.h>
>>>> +
>>>> +static jmp_buf jmpbuf;
>>>> +static ucontext_t ctx;
>>>> +
>>>> +static void f2 (void);
>>>> +
>>>> +static void
>>>> +__attribute__ ((noinline, noclone))
>>>> +f1 (void)
>>>> +{
>>>> +  printf ("start f1\n");
>>>> +  f2 ();
>>>> +}
>>>> +
>>>> +static void
>>>> +__attribute__ ((noinline, noclone))
>>>> +f2 (void)
>>>> +{
>>>> +  printf ("start f2\n");
>>>> +  if (setcontext (&ctx) != 0)
>>>> +    {
>>>> +      printf ("%s: setcontext: %m\n", __FUNCTION__);
>>>> +      exit (EXIT_FAILURE);
>>>> +    }
>>>> +}
>>>> +
>>>> +static void
>>>> +f3 (void)
>>>> +{
>>>> +  printf ("start f3\n");
>>>> +  longjmp (jmpbuf, 1);
>>>> +}
>>>> +
>>>> +static int
>>>> +__attribute__ ((noinline, noclone))
>>>> +do_test_1 (void)
>>>> +{
>>>> +  char st1[32768];
>>>> +
>>>> +  if (setjmp (jmpbuf) != 0)
>>>> +    return 0;
>>>> +
>>>> +  puts ("making contexts");
>>>> +  if (getcontext (&ctx) != 0)
>>>> +    {
>>>> +      printf ("%s: getcontext: %m\n", __FUNCTION__);
>>>> +      exit (EXIT_FAILURE);
>>>> +    }
>>>> +  ctx.uc_stack.ss_sp = st1;
>>>> +  ctx.uc_stack.ss_size = sizeof st1;
>>>> +  ctx.uc_link = NULL;
>>>> +  makecontext (&ctx, (void (*) (void)) f3, 0);
>>>> +  f1 ();
>>>> +  puts ("FAIL: returned from f1 ()");
>>>> +  exit (EXIT_FAILURE);
>>>> +}
>>>> +
>>>> +static int
>>>> +do_test (void)
>>>> +{
>>>> +  return do_test_1 ();
>>>> +}
>>>> +
>>>> +#include <support/test-driver.c>
>>>> --
>>>> 2.43.0
>>>>
>>>
>>> What is the success path here?
>>
>> When longjmp is called from the user context, do_test_1
>> returns 0:
>>
>> if (setjmp (jmpbuf) != 0)
>>   return 0;
>>
>> --
>> H.J.
> 
> LGTM.
> 
> Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

I am seeing failures with gcc version 13.2.1 / binutils 2.41.0.20231122 with
glibc configured with --enable-stack-protector=all --enable-tunables=yes 
--enable-bind-now=yes --enable-profile=yes --enable-fortify-source=2 
--enable-hardcoded-path-in-tests --enable-cet (the hardware does not support
CET):

$ make test t=stdlib/tst-setcontext10
[...]
*** longjmp causes uninitialized stack frame ***: terminated
make[2]: Leaving directory '/home/azanella/Projects/glibc/glibc-git-master/stdlib'
FAIL: stdlib/tst-setcontext10
original exit status 1
making contexts
start f1
start f2
start f3
Didn't expect signal from child: got `Aborted'

Re: [PATCH 1/2] Add a test for longjmp from user context

[H.J. Lu]

On Tue, Dec 19, 2023 at 6:06 AM Adhemerval Zanella Netto
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 14/12/23 21:04, Noah Goldstein wrote:
> > On Thu, Dec 14, 2023 at 4:43 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> On Thu, Dec 14, 2023 at 2:39 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >>>
> >>> On Thu, Dec 14, 2023 at 1:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>>>
> >>>> Verify that longjmp works correctly after setcontext is called to switch
> >>>> to a user context.
> >>>> ---
> >>>>  stdlib/Makefile           |  1 +
> >>>>  stdlib/tst-setcontext10.c | 87 +++++++++++++++++++++++++++++++++++++++
> >>>>  2 files changed, 88 insertions(+)
> >>>>  create mode 100644 stdlib/tst-setcontext10.c
> >>>>
> >>>> diff --git a/stdlib/Makefile b/stdlib/Makefile
> >>>> index 0b154e57c5..8c6249aab4 100644
> >>>> --- a/stdlib/Makefile
> >>>> +++ b/stdlib/Makefile
> >>>> @@ -234,6 +234,7 @@ tests := \
> >>>>    tst-setcontext7 \
> >>>>    tst-setcontext8 \
> >>>>    tst-setcontext9 \
> >>>> +  tst-setcontext10 \
> >>>>    tst-strfmon_l \
> >>>>    tst-strfrom \
> >>>>    tst-strfrom-locale \
> >>>> diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
> >>>> new file mode 100644
> >>>> index 0000000000..2926753cb1
> >>>> --- /dev/null
> >>>> +++ b/stdlib/tst-setcontext10.c
> >>>> @@ -0,0 +1,87 @@
> >>>> +/* Check longjmp from user context to main context.
> >>>> +   Copyright (C) 2023 Free Software Foundation, Inc.
> >>>> +   This file is part of the GNU C Library.
> >>>> +
> >>>> +   The GNU C Library is free software; you can redistribute it and/or
> >>>> +   modify it under the terms of the GNU Lesser General Public
> >>>> +   License as published by the Free Software Foundation; either
> >>>> +   version 2.1 of the License, or (at your option) any later version.
> >>>> +
> >>>> +   The GNU C Library is distributed in the hope that it will be useful,
> >>>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> >>>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> >>>> +   Lesser General Public License for more details.
> >>>> +
> >>>> +   You should have received a copy of the GNU Lesser General Public
> >>>> +   License along with the GNU C Library; if not, see
> >>>> +   <https://www.gnu.org/licenses/>.  */
> >>>> +
> >>>> +#include <stdio.h>
> >>>> +#include <stdlib.h>
> >>>> +#include <setjmp.h>
> >>>> +#include <ucontext.h>
> >>>> +#include <unistd.h>
> >>>> +
> >>>> +static jmp_buf jmpbuf;
> >>>> +static ucontext_t ctx;
> >>>> +
> >>>> +static void f2 (void);
> >>>> +
> >>>> +static void
> >>>> +__attribute__ ((noinline, noclone))
> >>>> +f1 (void)
> >>>> +{
> >>>> +  printf ("start f1\n");
> >>>> +  f2 ();
> >>>> +}
> >>>> +
> >>>> +static void
> >>>> +__attribute__ ((noinline, noclone))
> >>>> +f2 (void)
> >>>> +{
> >>>> +  printf ("start f2\n");
> >>>> +  if (setcontext (&ctx) != 0)
> >>>> +    {
> >>>> +      printf ("%s: setcontext: %m\n", __FUNCTION__);
> >>>> +      exit (EXIT_FAILURE);
> >>>> +    }
> >>>> +}
> >>>> +
> >>>> +static void
> >>>> +f3 (void)
> >>>> +{
> >>>> +  printf ("start f3\n");
> >>>> +  longjmp (jmpbuf, 1);
> >>>> +}
> >>>> +
> >>>> +static int
> >>>> +__attribute__ ((noinline, noclone))
> >>>> +do_test_1 (void)
> >>>> +{
> >>>> +  char st1[32768];
> >>>> +
> >>>> +  if (setjmp (jmpbuf) != 0)
> >>>> +    return 0;
> >>>> +
> >>>> +  puts ("making contexts");
> >>>> +  if (getcontext (&ctx) != 0)
> >>>> +    {
> >>>> +      printf ("%s: getcontext: %m\n", __FUNCTION__);
> >>>> +      exit (EXIT_FAILURE);
> >>>> +    }
> >>>> +  ctx.uc_stack.ss_sp = st1;
> >>>> +  ctx.uc_stack.ss_size = sizeof st1;
> >>>> +  ctx.uc_link = NULL;
> >>>> +  makecontext (&ctx, (void (*) (void)) f3, 0);
> >>>> +  f1 ();
> >>>> +  puts ("FAIL: returned from f1 ()");
> >>>> +  exit (EXIT_FAILURE);
> >>>> +}
> >>>> +
> >>>> +static int
> >>>> +do_test (void)
> >>>> +{
> >>>> +  return do_test_1 ();
> >>>> +}
> >>>> +
> >>>> +#include <support/test-driver.c>
> >>>> --
> >>>> 2.43.0
> >>>>
> >>>
> >>> What is the success path here?
> >>
> >> When longjmp is called from the user context, do_test_1
> >> returns 0:
> >>
> >> if (setjmp (jmpbuf) != 0)
> >>   return 0;
> >>
> >> --
> >> H.J.
> >
> > LGTM.
> >
> > Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
>
> I am seeing failures with gcc version 13.2.1 / binutils 2.41.0.20231122 with
> glibc configured with --enable-stack-protector=all --enable-tunables=yes
> --enable-bind-now=yes --enable-profile=yes --enable-fortify-source=2
> --enable-hardcoded-path-in-tests --enable-cet (the hardware does not support
> CET):
>
> $ make test t=stdlib/tst-setcontext10
> [...]
> *** longjmp causes uninitialized stack frame ***: terminated
> make[2]: Leaving directory '/home/azanella/Projects/glibc/glibc-git-master/stdlib'
> FAIL: stdlib/tst-setcontext10
> original exit status 1
> making contexts
> start f1
> start f2
> start f3
> Didn't expect signal from child: got `Aborted'

-Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=2 doesn't
work with user context.  I submitted a patch to undefine _FORTIFY_SOURCE

-- 
H.J.

[PATCH 2/2] Add a test for setjmp/longjmp within user context

[H.J. Lu]

Verify that setjmp/longjmp works correctly within a user context.
---
 stdlib/Makefile           |   1 +
 stdlib/tst-setcontext11.c | 178 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 179 insertions(+)
 create mode 100644 stdlib/tst-setcontext11.c

diff --git a/stdlib/Makefile b/stdlib/Makefile
index 8c6249aab4..0b5ef699a2 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -235,6 +235,7 @@ tests := \
   tst-setcontext8 \
   tst-setcontext9 \
   tst-setcontext10 \
+  tst-setcontext11 \
   tst-strfmon_l \
   tst-strfrom \
   tst-strfrom-locale \
diff --git a/stdlib/tst-setcontext11.c b/stdlib/tst-setcontext11.c
new file mode 100644
index 0000000000..5f5df5b81b
--- /dev/null
+++ b/stdlib/tst-setcontext11.c
@@ -0,0 +1,178 @@
+/* Check setjmp/longjmp within user context.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <setjmp.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+static ucontext_t ctx[3];
+static jmp_buf jmpbuf;
+
+static int was_in_f1;
+static int was_in_f2;
+static int longjmp_called;
+
+static char st2[32768];
+
+static void
+f1 (int a0, int a1, int a2, int a3)
+{
+  printf ("start f1(a0=%x,a1=%x,a2=%x,a3=%x)\n", a0, a1, a2, a3);
+
+  if (a0 != 1 || a1 != 2 || a2 != 3 || a3 != -4)
+    {
+      puts ("arg mismatch");
+      exit (EXIT_FAILURE);
+    }
+
+  if (swapcontext (&ctx[1], &ctx[2]) != 0)
+    {
+      printf ("%s: swapcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+  puts ("finish f1");
+  was_in_f1 = 1;
+}
+
+static void
+__attribute__ ((noinline, noclone))
+call_longjmp (void)
+{
+  longjmp_called = 1;
+  longjmp (jmpbuf, 1);
+}
+
+static void
+f2 (void)
+{
+  if (!longjmp_called)
+    {
+      if (setjmp (jmpbuf) == 0)
+	call_longjmp ();
+    }
+
+  puts ("start f2");
+  if (swapcontext (&ctx[2], &ctx[1]) != 0)
+    {
+      printf ("%s: swapcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+  puts ("finish f2");
+  was_in_f2 = 1;
+}
+
+volatile int global;
+static int back_in_main;
+
+static void
+check_called (void)
+{
+  if (back_in_main == 0)
+    {
+      puts ("program did not reach main again");
+      _exit (EXIT_FAILURE);
+    }
+}
+
+static int
+do_test (void)
+{
+  atexit (check_called);
+
+  char st1[32768];
+
+  puts ("making contexts");
+  if (getcontext (&ctx[1]) != 0)
+    {
+      if (errno == ENOSYS)
+	{
+	  back_in_main = 1;
+	  exit (EXIT_SUCCESS);
+	}
+
+      printf ("%s: getcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+
+  /* Play some tricks with this context.  */
+  if (++global == 1)
+    if (setcontext (&ctx[1]) != 0)
+      {
+	printf ("%s: setcontext: %m\n", __FUNCTION__);
+	exit (EXIT_FAILURE);
+      }
+  if (global != 2)
+    {
+      printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+
+  ctx[1].uc_stack.ss_sp = st1;
+  ctx[1].uc_stack.ss_size = sizeof st1;
+  ctx[1].uc_link = &ctx[0];
+  {
+    ucontext_t tempctx = ctx[1];
+    makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);
+
+    /* Without this check, a stub makecontext can make us spin forever.  */
+    if (memcmp (&tempctx, &ctx[1], sizeof ctx[1]) == 0)
+      {
+	puts ("makecontext was a no-op, presuming not implemented");
+	return 0;
+      }
+  }
+
+  if (getcontext (&ctx[2]) != 0)
+    {
+      printf ("%s: second getcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+  ctx[2].uc_stack.ss_sp = st2;
+  ctx[2].uc_stack.ss_size = sizeof st2;
+  ctx[2].uc_link = &ctx[1];
+  makecontext (&ctx[2], f2, 0);
+
+  puts ("swapping contexts");
+  if (swapcontext (&ctx[0], &ctx[2]) != 0)
+    {
+      printf ("%s: swapcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+  puts ("back at main program");
+  back_in_main = 1;
+
+  if (was_in_f1 == 0)
+    {
+      puts ("didn't reach f1");
+      exit (EXIT_FAILURE);
+    }
+  if (was_in_f2 == 0)
+    {
+      puts ("didn't reach f2");
+      exit (EXIT_FAILURE);
+    }
+
+  puts ("test succeeded");
+  return 0;
+}
+
+#include <support/test-driver.c>
-- 
2.43.0

Re: [PATCH 2/2] Add a test for setjmp/longjmp within user context

[Noah Goldstein]

On Thu, Dec 14, 2023 at 1:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Verify that setjmp/longjmp works correctly within a user context.
> ---
>  stdlib/Makefile           |   1 +
>  stdlib/tst-setcontext11.c | 178 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 179 insertions(+)
>  create mode 100644 stdlib/tst-setcontext11.c
>
> diff --git a/stdlib/Makefile b/stdlib/Makefile
> index 8c6249aab4..0b5ef699a2 100644
> --- a/stdlib/Makefile
> +++ b/stdlib/Makefile
> @@ -235,6 +235,7 @@ tests := \
>    tst-setcontext8 \
>    tst-setcontext9 \
>    tst-setcontext10 \
> +  tst-setcontext11 \
>    tst-strfmon_l \
>    tst-strfrom \
>    tst-strfrom-locale \
> diff --git a/stdlib/tst-setcontext11.c b/stdlib/tst-setcontext11.c
> new file mode 100644
> index 0000000000..5f5df5b81b
> --- /dev/null
> +++ b/stdlib/tst-setcontext11.c
> @@ -0,0 +1,178 @@
> +/* Check setjmp/longjmp within user context.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <setjmp.h>
> +#include <ucontext.h>
> +#include <unistd.h>
> +
> +static ucontext_t ctx[3];
> +static jmp_buf jmpbuf;
> +
> +static int was_in_f1;
> +static int was_in_f2;
> +static int longjmp_called;
> +
> +static char st2[32768];
> +
> +static void
> +f1 (int a0, int a1, int a2, int a3)
> +{
> +  printf ("start f1(a0=%x,a1=%x,a2=%x,a3=%x)\n", a0, a1, a2, a3);
> +
> +  if (a0 != 1 || a1 != 2 || a2 != 3 || a3 != -4)
> +    {
> +      puts ("arg mismatch");
> +      exit (EXIT_FAILURE);
> +    }
> +
> +  if (swapcontext (&ctx[1], &ctx[2]) != 0)
> +    {
> +      printf ("%s: swapcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +  puts ("finish f1");
> +  was_in_f1 = 1;
> +}
> +
> +static void
> +__attribute__ ((noinline, noclone))
> +call_longjmp (void)
> +{
> +  longjmp_called = 1;
> +  longjmp (jmpbuf, 1);
> +}
> +
> +static void
> +f2 (void)
> +{
> +  if (!longjmp_called)
> +    {
> +      if (setjmp (jmpbuf) == 0)
> +       call_longjmp ();
> +    }
> +
> +  puts ("start f2");
> +  if (swapcontext (&ctx[2], &ctx[1]) != 0)
> +    {
> +      printf ("%s: swapcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +  puts ("finish f2");
> +  was_in_f2 = 1;
> +}
> +
> +volatile int global;
> +static int back_in_main;
> +
> +static void
> +check_called (void)
> +{
> +  if (back_in_main == 0)
> +    {
> +      puts ("program did not reach main again");
> +      _exit (EXIT_FAILURE);
> +    }
> +}
> +
> +static int
> +do_test (void)
> +{
> +  atexit (check_called);
> +
> +  char st1[32768];
> +
> +  puts ("making contexts");
> +  if (getcontext (&ctx[1]) != 0)
> +    {
> +      if (errno == ENOSYS)
> +       {
> +         back_in_main = 1;
> +         exit (EXIT_SUCCESS);
> +       }
> +
> +      printf ("%s: getcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +
> +  /* Play some tricks with this context.  */
> +  if (++global == 1)
> +    if (setcontext (&ctx[1]) != 0)
> +      {
> +       printf ("%s: setcontext: %m\n", __FUNCTION__);
> +       exit (EXIT_FAILURE);
> +      }
> +  if (global != 2)
> +    {
> +      printf ("%s: 'global' not incremented twice\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +
> +  ctx[1].uc_stack.ss_sp = st1;
> +  ctx[1].uc_stack.ss_size = sizeof st1;
> +  ctx[1].uc_link = &ctx[0];
> +  {
> +    ucontext_t tempctx = ctx[1];
> +    makecontext (&ctx[1], (void (*) (void)) f1, 4, 1, 2, 3, -4);
> +
> +    /* Without this check, a stub makecontext can make us spin forever.  */
> +    if (memcmp (&tempctx, &ctx[1], sizeof ctx[1]) == 0)
> +      {
> +       puts ("makecontext was a no-op, presuming not implemented");
> +       return 0;
> +      }
> +  }
> +
> +  if (getcontext (&ctx[2]) != 0)
> +    {
> +      printf ("%s: second getcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +  ctx[2].uc_stack.ss_sp = st2;
> +  ctx[2].uc_stack.ss_size = sizeof st2;
> +  ctx[2].uc_link = &ctx[1];
> +  makecontext (&ctx[2], f2, 0);
> +
> +  puts ("swapping contexts");
> +  if (swapcontext (&ctx[0], &ctx[2]) != 0)
> +    {
> +      printf ("%s: swapcontext: %m\n", __FUNCTION__);
> +      exit (EXIT_FAILURE);
> +    }
> +  puts ("back at main program");
> +  back_in_main = 1;
> +
> +  if (was_in_f1 == 0)
> +    {
> +      puts ("didn't reach f1");
> +      exit (EXIT_FAILURE);
> +    }
> +  if (was_in_f2 == 0)
> +    {
> +      puts ("didn't reach f2");
> +      exit (EXIT_FAILURE);
> +    }
> +
> +  puts ("test succeeded");
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> --
> 2.43.0
>

LGTM.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>