[PATCH v2 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro

[PATCH v2 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro

[Florian Weimer]

And keep the previous definition if it exists.  This allows
disabling IA64_USE_NEW_STUB while keeping USE_DL_SYSINFO defined.
---
v2: New patch.
 sysdeps/unix/sysv/linux/ia64/brk.c    |  3 +--
 sysdeps/unix/sysv/linux/ia64/sysdep.h | 21 +++++++++++++--------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/ia64/brk.c b/sysdeps/unix/sysv/linux/ia64/brk.c
index 65142aeae9..e1fa88f9b0 100644
--- a/sysdeps/unix/sysv/linux/ia64/brk.c
+++ b/sysdeps/unix/sysv/linux/ia64/brk.c
@@ -16,7 +16,6 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <dl-sysdep.h>
 /* brk is used by statup before TCB is properly set.  */
-#undef USE_DL_SYSINFO
+#define IA64_USE_NEW_STUB 0
 #include <sysdeps/unix/sysv/linux/brk.c>
diff --git a/sysdeps/unix/sysv/linux/ia64/sysdep.h b/sysdeps/unix/sysv/linux/ia64/sysdep.h
index 193ecee023..72b72acb6f 100644
--- a/sysdeps/unix/sysv/linux/ia64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/ia64/sysdep.h
@@ -44,12 +44,17 @@
 #undef SYS_ify
 #define SYS_ify(syscall_name)	__NR_##syscall_name
 
-#if defined USE_DL_SYSINFO \
+#ifndef IA64_USE_NEW_STUB
+# if defined USE_DL_SYSINFO \
 	&& (IS_IN (libc) \
 	    || IS_IN (libpthread) || IS_IN (librt))
-# define IA64_USE_NEW_STUB
-#else
-# undef IA64_USE_NEW_STUB
+#  define IA64_USE_NEW_STUB 1
+# else
+#  define IA64_USE_NEW_STUB 0
+# endif
+#endif
+#if IA64_USE_NEW_STUB && !USE_DL_SYSINFO
+# error IA64_USE_NEW_STUB needs USE_DL_SYSINFO
 #endif
 
 #ifdef __ASSEMBLER__
@@ -101,7 +106,7 @@
 	mov r15=num;				\
 	break __IA64_BREAK_SYSCALL
 
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
 # ifdef SHARED
 #  define DO_CALL(num)				\
 	.prologue;				\
@@ -185,7 +190,7 @@
    (non-negative) errno on error or the return value on success.
  */
 
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
 
 # define INTERNAL_SYSCALL_NCS(name, nr, args...)			      \
 ({									      \
@@ -277,7 +282,7 @@
 #define ASM_OUTARGS_5	ASM_OUTARGS_4, "=r" (_out4)
 #define ASM_OUTARGS_6	ASM_OUTARGS_5, "=r" (_out5)
 
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
 #define ASM_ARGS_0
 #define ASM_ARGS_1	ASM_ARGS_0, "4" (_out0)
 #define ASM_ARGS_2	ASM_ARGS_1, "5" (_out1)
@@ -313,7 +318,7 @@
   /* Branch registers.  */						\
   "b6"
 
-#ifdef IA64_USE_NEW_STUB
+#if IA64_USE_NEW_STUB
 # define ASM_CLOBBERS_6	ASM_CLOBBERS_6_COMMON
 #else
 # define ASM_CLOBBERS_6	ASM_CLOBBERS_6_COMMON , "b7"

base-commit: c1b68685d438373efe64e5f076f4215723004dfb
-- 
2.35.1

[PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Florian Weimer]

On i386 and ia64, the TCB is not available at this point.
---
v2: Add ia64 override.  On i386, use non-TCB version for non-PIE static, too.
 sysdeps/unix/sysv/linux/i386/startup.h | 21 ++------------
 sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
 sysdeps/unix/sysv/linux/startup.h      | 38 ++++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 18 deletions(-)
 create mode 100644 sysdeps/unix/sysv/linux/ia64/startup.h
 create mode 100644 sysdeps/unix/sysv/linux/startup.h

diff --git a/sysdeps/unix/sysv/linux/i386/startup.h b/sysdeps/unix/sysv/linux/i386/startup.h
index 67c9310f3a..85534d09f1 100644
--- a/sysdeps/unix/sysv/linux/i386/startup.h
+++ b/sysdeps/unix/sysv/linux/i386/startup.h
@@ -16,22 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#if BUILD_PIE_DEFAULT
-/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */
-# define I386_USE_SYSENTER 0
+/* Can't use "call *%gs:SYSINFO_OFFSET" during statup.  */
+#define I386_USE_SYSENTER 0
 
-# include <sysdep.h>
-# include <abort-instr.h>
-
-__attribute__ ((__noreturn__))
-static inline void
-_startup_fatal (const char *message __attribute__ ((unused)))
-{
-  /* This is only called very early during startup in static PIE.
-     FIXME: How can it be improved?  */
-  ABORT_INSTRUCTION;
-  __builtin_unreachable ();
-}
-#else
-# include_next <startup.h>
-#endif
+#include_next <startup.h>
diff --git a/sysdeps/unix/sysv/linux/ia64/startup.h b/sysdeps/unix/sysv/linux/ia64/startup.h
new file mode 100644
index 0000000000..68fcd9fea0
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/ia64/startup.h
@@ -0,0 +1,22 @@
+/* Linux/ia64 definitions of functions used by static libc main startup.
+   Copyright (C) 2017-2022 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/>.  */
+
+/* This code is used before the TCB is set up.  */
+#define IA64_USE_NEW_STUB 0
+
+#include_next <startup.h>
diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
new file mode 100644
index 0000000000..a5de941759
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/startup.h
@@ -0,0 +1,38 @@
+/* Linux definitions of functions used by static libc main startup.
+   Copyright (C) 2017-2022 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/>.  */
+
+#ifdef SHARED
+# include_next <startup.h>
+#else
+# include <sysdep.h>
+
+/* Avoid a run-time invocation of strlen.  */
+#define _startup_fatal(message)                                         \
+  do                                                                    \
+    {                                                                   \
+      size_t message_length = __builtin_strlen (message);               \
+      if (! __builtin_constant_p (message_length))                      \
+        {                                                               \
+          extern void _startup_fatal_not_constant (void);               \
+          _startup_fatal_not_constant ();                               \
+        }                                                               \
+      INTERNAL_SYSCALL_CALL (write, STDERR_FILENO, message, message_length); \
+      INTERNAL_SYSCALL_CALL (exit_group, 127);                          \
+    }                                                                   \
+  while (0)
+#endif  /* !SHARED */
-- 
2.35.1

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Adhemerval Zanella]

On 04/05/2022 13:48, Florian Weimer wrote:
> diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
> new file mode 100644
> index 0000000000..a5de941759
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/startup.h
> @@ -0,0 +1,38 @@
> +/* Linux definitions of functions used by static libc main startup.
> +   Copyright (C) 2017-2022 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/>.  */
> +
> +#ifdef SHARED
> +# include_next <startup.h>
> +#else
> +# include <sysdep.h>
> +
> +/* Avoid a run-time invocation of strlen.  */
> +#define _startup_fatal(message)                                         \
> +  do                                                                    \
> +    {                                                                   \
> +      size_t message_length = __builtin_strlen (message);               \

Shoudn't we use double underscore name to avoid clash with local variables?

> +      if (! __builtin_constant_p (message_length))                      \
> +        {                                                               \
> +          extern void _startup_fatal_not_constant (void);               \
> +          _startup_fatal_not_constant ();                               \
> +        }                                                               \
> +      INTERNAL_SYSCALL_CALL (write, STDERR_FILENO, message, message_length); \
> +      INTERNAL_SYSCALL_CALL (exit_group, 127);                          \
> +    }                                                                   \
> +  while (0)
> +#endif  /* !SHARED */

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Florian Weimer]

* Adhemerval Zanella:

> On 04/05/2022 13:48, Florian Weimer wrote:
>> diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
>> new file mode 100644
>> index 0000000000..a5de941759
>> --- /dev/null
>> +++ b/sysdeps/unix/sysv/linux/startup.h
>> @@ -0,0 +1,38 @@
>> +/* Linux definitions of functions used by static libc main startup.
>> +   Copyright (C) 2017-2022 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/>.  */
>> +
>> +#ifdef SHARED
>> +# include_next <startup.h>
>> +#else
>> +# include <sysdep.h>
>> +
>> +/* Avoid a run-time invocation of strlen.  */
>> +#define _startup_fatal(message)                                         \
>> +  do                                                                    \
>> +    {                                                                   \
>> +      size_t message_length = __builtin_strlen (message);               \
>
> Shoudn't we use double underscore name to avoid clash with local
> variables?

I think it's a problem only if message expands to something that uses
message_length, which is as likely as __message_length.  message can't
be a complex expression anyway because we don't want to call strlen at
this point.

Thanks,
Florian

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Florian Weimer]

* Florian Weimer:

> * Adhemerval Zanella:
>
>> On 04/05/2022 13:48, Florian Weimer wrote:
>>> diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
>>> new file mode 100644
>>> index 0000000000..a5de941759
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/startup.h
>>> @@ -0,0 +1,38 @@
>>> +/* Linux definitions of functions used by static libc main startup.
>>> +   Copyright (C) 2017-2022 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/>.  */
>>> +
>>> +#ifdef SHARED
>>> +# include_next <startup.h>
>>> +#else
>>> +# include <sysdep.h>
>>> +
>>> +/* Avoid a run-time invocation of strlen.  */
>>> +#define _startup_fatal(message)                                         \
>>> +  do                                                                    \
>>> +    {                                                                   \
>>> +      size_t message_length = __builtin_strlen (message);               \
>>
>> Shoudn't we use double underscore name to avoid clash with local
>> variables?
>
> I think it's a problem only if message expands to something that uses
> message_length, which is as likely as __message_length.  message can't
> be a complex expression anyway because we don't want to call strlen at
> this point.

Never mind, I'm making the change.

Thanks,
Florian

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[H.J. Lu]

On Wed, May 4, 2022 at 9:48 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> On i386 and ia64, the TCB is not available at this point.
> ---
> v2: Add ia64 override.  On i386, use non-TCB version for non-PIE static, too.
>  sysdeps/unix/sysv/linux/i386/startup.h | 21 ++------------
>  sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
>  sysdeps/unix/sysv/linux/startup.h      | 38 ++++++++++++++++++++++++++
>  3 files changed, 63 insertions(+), 18 deletions(-)
>  create mode 100644 sysdeps/unix/sysv/linux/ia64/startup.h
>  create mode 100644 sysdeps/unix/sysv/linux/startup.h
>
> diff --git a/sysdeps/unix/sysv/linux/i386/startup.h b/sysdeps/unix/sysv/linux/i386/startup.h
> index 67c9310f3a..85534d09f1 100644
> --- a/sysdeps/unix/sysv/linux/i386/startup.h
> +++ b/sysdeps/unix/sysv/linux/i386/startup.h
> @@ -16,22 +16,7 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>
> -#if BUILD_PIE_DEFAULT
> -/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */
> -# define I386_USE_SYSENTER 0
> +/* Can't use "call *%gs:SYSINFO_OFFSET" during statup.  */
> +#define I386_USE_SYSENTER 0
>
> -# include <sysdep.h>
> -# include <abort-instr.h>
> -
> -__attribute__ ((__noreturn__))
> -static inline void
> -_startup_fatal (const char *message __attribute__ ((unused)))
> -{
> -  /* This is only called very early during startup in static PIE.
> -     FIXME: How can it be improved?  */
> -  ABORT_INSTRUCTION;
> -  __builtin_unreachable ();
> -}
> -#else
> -# include_next <startup.h>
> -#endif
> +#include_next <startup.h>
> diff --git a/sysdeps/unix/sysv/linux/ia64/startup.h b/sysdeps/unix/sysv/linux/ia64/startup.h
> new file mode 100644
> index 0000000000..68fcd9fea0
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/ia64/startup.h
> @@ -0,0 +1,22 @@
> +/* Linux/ia64 definitions of functions used by static libc main startup.
> +   Copyright (C) 2017-2022 Free Software Foundation, Inc.

Just 2022.

> +   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/>.  */
> +
> +/* This code is used before the TCB is set up.  */
> +#define IA64_USE_NEW_STUB 0
> +
> +#include_next <startup.h>
> diff --git a/sysdeps/unix/sysv/linux/startup.h b/sysdeps/unix/sysv/linux/startup.h
> new file mode 100644
> index 0000000000..a5de941759
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/startup.h
> @@ -0,0 +1,38 @@
> +/* Linux definitions of functions used by static libc main startup.
> +   Copyright (C) 2017-2022 Free Software Foundation, Inc.

Just 2022.

> +   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/>.  */
> +
> +#ifdef SHARED

Will SHARED ever be defined?

> +# include_next <startup.h>
> +#else
> +# include <sysdep.h>
> +
> +/* Avoid a run-time invocation of strlen.  */
> +#define _startup_fatal(message)                                         \
> +  do                                                                    \
> +    {                                                                   \
> +      size_t message_length = __builtin_strlen (message);               \
> +      if (! __builtin_constant_p (message_length))                      \
> +        {                                                               \
> +          extern void _startup_fatal_not_constant (void);               \
> +          _startup_fatal_not_constant ();                               \
> +        }                                                               \
> +      INTERNAL_SYSCALL_CALL (write, STDERR_FILENO, message, message_length); \
> +      INTERNAL_SYSCALL_CALL (exit_group, 127);                          \
> +    }                                                                   \
> +  while (0)
> +#endif  /* !SHARED */
> --
> 2.35.1
>
>


-- 
H.J.

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Florian Weimer]

* H. J. Lu:

>> diff --git a/sysdeps/unix/sysv/linux/ia64/startup.h b/sysdeps/unix/sysv/linux/ia64/startup.h
>> new file mode 100644
>> index 0000000000..68fcd9fea0
>> --- /dev/null
>> +++ b/sysdeps/unix/sysv/linux/ia64/startup.h
>> @@ -0,0 +1,22 @@
>> +/* Linux/ia64 definitions of functions used by static libc main startup.
>> +   Copyright (C) 2017-2022 Free Software Foundation, Inc.
>
> Just 2022.

The file started out as a copy, but it's a borderline case.  I'm going
to make the change.

>> +   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/>.  */
>> +
>> +#ifdef SHARED
>
> Will SHARED ever be defined?

I believe so, see elf/dl-tunables.c.

Thanks,
Florian

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Alejandro Colomar]

Hi Florian,

On 5/4/22 20:34, H.J. Lu via Libc-alpha wrote:
> On Wed, May 4, 2022 at 9:48 AM Florian Weimer <fweimer@redhat.com> wrote:
>>
>> On i386 and ia64, the TCB is not available at this point.
>> ---
>> v2: Add ia64 override.  On i386, use non-TCB version for non-PIE static, too.
>>   sysdeps/unix/sysv/linux/i386/startup.h | 21 ++------------
>>   sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
>>   sysdeps/unix/sysv/linux/startup.h      | 38 ++++++++++++++++++++++++++
>>   3 files changed, 63 insertions(+), 18 deletions(-)
>>   create mode 100644 sysdeps/unix/sysv/linux/ia64/startup.h
>>   create mode 100644 sysdeps/unix/sysv/linux/startup.h
>>
>> diff --git a/sysdeps/unix/sysv/linux/i386/startup.h b/sysdeps/unix/sysv/linux/i386/startup.h
>> index 67c9310f3a..85534d09f1 100644
>> --- a/sysdeps/unix/sysv/linux/i386/startup.h
>> +++ b/sysdeps/unix/sysv/linux/i386/startup.h
>> @@ -16,22 +16,7 @@
>>      License along with the GNU C Library; if not, see
>>      <https://www.gnu.org/licenses/>.  */
>>
>> -#if BUILD_PIE_DEFAULT
>> -/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */
>> -# define I386_USE_SYSENTER 0
>> +/* Can't use "call *%gs:SYSINFO_OFFSET" during statup.  */

Typo?

s/statup/startup/

Cheers,

Alex
-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: [PATCH v2 2/3] Linux: Implement a useful version of _startup_fatal

[Florian Weimer]

* Alejandro Colomar:

> Hi Florian,
>
> On 5/4/22 20:34, H.J. Lu via Libc-alpha wrote:
>> On Wed, May 4, 2022 at 9:48 AM Florian Weimer <fweimer@redhat.com> wrote:
>>>
>>> On i386 and ia64, the TCB is not available at this point.
>>> ---
>>> v2: Add ia64 override.  On i386, use non-TCB version for non-PIE static, too.
>>>   sysdeps/unix/sysv/linux/i386/startup.h | 21 ++------------
>>>   sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
>>>   sysdeps/unix/sysv/linux/startup.h      | 38 ++++++++++++++++++++++++++
>>>   3 files changed, 63 insertions(+), 18 deletions(-)
>>>   create mode 100644 sysdeps/unix/sysv/linux/ia64/startup.h
>>>   create mode 100644 sysdeps/unix/sysv/linux/startup.h
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/i386/startup.h b/sysdeps/unix/sysv/linux/i386/startup.h
>>> index 67c9310f3a..85534d09f1 100644
>>> --- a/sysdeps/unix/sysv/linux/i386/startup.h
>>> +++ b/sysdeps/unix/sysv/linux/i386/startup.h
>>> @@ -16,22 +16,7 @@
>>>      License along with the GNU C Library; if not, see
>>>      <https://www.gnu.org/licenses/>.  */
>>>
>>> -#if BUILD_PIE_DEFAULT
>>> -/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */
>>> -# define I386_USE_SYSENTER 0
>>> +/* Can't use "call *%gs:SYSINFO_OFFSET" during statup.  */
>
> Typo?
>
> s/statup/startup/

I've fixed this in the two files I changed.

Thanks,
Florian

[PATCH v2 3/3] csu: Implement and use _dl_early_allocate during static startup

[Florian Weimer]

This implements mmap fallback for a brk failure during TLS
allocation.

scripts/tls-elf-edit.py is updated to support the new patching method.
The script no longer requires that in the input object is of ET_DYN
type.
---
v2: Unchanged.
 csu/libc-tls.c                              | 12 ++-
 elf/Makefile                                | 19 +++++
 elf/dl-early_allocate.c                     | 30 ++++++++
 elf/tst-tls-allocation-failure-static.c     | 31 ++++++++
 scripts/tst-elf-edit.py                     | 34 +++++++--
 sysdeps/generic/ldsodefs.h                  |  5 ++
 sysdeps/unix/sysv/linux/dl-early_allocate.c | 81 +++++++++++++++++++++
 7 files changed, 202 insertions(+), 10 deletions(-)
 create mode 100644 elf/dl-early_allocate.c
 create mode 100644 elf/tst-tls-allocation-failure-static.c
 create mode 100644 sysdeps/unix/sysv/linux/dl-early_allocate.c

diff --git a/csu/libc-tls.c b/csu/libc-tls.c
index bef92a7568..7d311056bc 100644
--- a/csu/libc-tls.c
+++ b/csu/libc-tls.c
@@ -145,11 +145,16 @@ __libc_setup_tls (void)
      _dl_allocate_tls_storage (in elf/dl-tls.c) does using __libc_memalign
      and dl_tls_static_align.  */
   tcb_offset = roundup (memsz + GLRO(dl_tls_static_surplus), max_align);
-  tlsblock = __sbrk (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
+  tlsblock = _dl_early_allocate (tcb_offset + TLS_INIT_TCB_SIZE + max_align);
+  if (tlsblock == NULL)
+    _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n");
 #elif TLS_DTV_AT_TP
   tcb_offset = roundup (TLS_INIT_TCB_SIZE, align ?: 1);
-  tlsblock = __sbrk (tcb_offset + memsz + max_align
-		     + TLS_PRE_TCB_SIZE + GLRO(dl_tls_static_surplus));
+  tlsblock = _dl_early_allocate (tcb_offset + memsz + max_align
+				 + TLS_PRE_TCB_SIZE
+				 + GLRO(dl_tls_static_surplus));
+  if (tlsblock == NULL)
+    _startup_fatal ("Fatal glibc error: Cannot allocate TLS block\n");
   tlsblock += TLS_PRE_TCB_SIZE;
 #else
   /* In case a model with a different layout for the TCB and DTV
@@ -157,6 +162,7 @@ __libc_setup_tls (void)
 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
 #endif
 
+
   /* Align the TLS block.  */
   tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
 		       & ~(max_align - 1));
diff --git a/elf/Makefile b/elf/Makefile
index fc9860edee..ce3345ed92 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -33,6 +33,7 @@ routines = \
   $(all-dl-routines) \
   dl-addr \
   dl-addr-obj \
+  dl-early_allocate \
   dl-error \
   dl-iteratephdr \
   dl-libc \
@@ -108,6 +109,7 @@ all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
 # But they are absent from the shared libc, because that code is in ld.so.
 elide-routines.os = \
   $(all-dl-routines) \
+  dl-early_allocate \
   dl-exception \
   dl-origin \
   dl-reloc-static-pie \
@@ -276,6 +278,7 @@ tests-static-normal := \
   tst-linkall-static \
   tst-single_threaded-pthread-static \
   tst-single_threaded-static \
+  tst-tls-allocation-failure-static \
   tst-tlsalign-extern-static \
   tst-tlsalign-static \
   # tests-static-normal
@@ -1213,6 +1216,10 @@ $(objpfx)tst-glibcelf.out: tst-glibcelf.py elf.h $(..)/scripts/glibcelf.py \
           --cc="$(CC) $(patsubst -DMODULE_NAME=%,-DMODULE_NAME=testsuite,$(CPPFLAGS))" \
 	  < /dev/null > $@ 2>&1; $(evaluate-test)
 
+ifeq ($(run-built-tests),yes)
+tests-special += $(objpfx)tst-tls-allocation-failure-static-patched.out
+endif
+
 # The test requires shared _and_ PIE because the executable
 # unit test driver must be able to link with the shared object
 # that is going to eventually go into an installed DSO.
@@ -2937,3 +2944,15 @@ $(eval $(call tst-trace-skeleton,4,\
 	$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4))
 $(eval $(call tst-trace-skeleton,5,\
 	$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4:$(objpfx)libtracemod5))
+
+$(objpfx)tst-tls-allocation-failure-static-patched: \
+  $(objpfx)tst-tls-allocation-failure-static $(..)scripts/tst-elf-edit.py
+	cp $< $@
+	$(PYTHON) $(..)scripts/tst-elf-edit.py --maximize-tls-size $@
+
+$(objpfx)tst-tls-allocation-failure-static-patched.out: \
+  $(objpfx)tst-tls-allocation-failure-static-patched
+	$< > $@ 2>&1; echo "status: $$?" >> $@
+	grep -q '^Fatal glibc error: Cannot allocate TLS block$$' $@ \
+	  && grep -q '^status: 127$$' $@; \
+	  $(evaluate-test)
diff --git a/elf/dl-early_allocate.c b/elf/dl-early_allocate.c
new file mode 100644
index 0000000000..d7f59d41e5
--- /dev/null
+++ b/elf/dl-early_allocate.c
@@ -0,0 +1,30 @@
+/* Early memory allocation for the dynamic loader.  Generic version.
+   Copyright (C) 2022 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 <ldsodefs.h>
+#include <stddef.h>
+#include <unistd.h>
+
+void *
+_dl_early_allocate (size_t size)
+{
+  void *result = __sbrk (size);
+  if (result == (void *) -1)
+    _dl_fatal_printf ("Fatal glibc error: Early memory allocation failed\n");
+  return result;
+}
diff --git a/elf/tst-tls-allocation-failure-static.c b/elf/tst-tls-allocation-failure-static.c
new file mode 100644
index 0000000000..8de831b246
--- /dev/null
+++ b/elf/tst-tls-allocation-failure-static.c
@@ -0,0 +1,31 @@
+/* Base for test program with impossiblyh large PT_TLS segment.
+   Copyright (C) 2022 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/>.  */
+
+/* The test actual binary is patched using scripts/tst-elf-edit.py
+   --maximize-tls-size, and this introduces the expected test
+   allocation failure due to an excessive PT_LS p_memsz value.
+
+   Patching the binary is required because on some 64-bit targets, TLS
+   relocations can only cover a 32-bit range, and glibc-internal TLS
+   variables such as errno end up outside that range.  */
+
+int
+main (void)
+{
+  return 0;
+}
diff --git a/scripts/tst-elf-edit.py b/scripts/tst-elf-edit.py
index a514179bbf..0e19ce1e73 100644
--- a/scripts/tst-elf-edit.py
+++ b/scripts/tst-elf-edit.py
@@ -43,9 +43,11 @@ EI_DATA=5
 ELFDATA2LSB=b'\x01'
 ELFDATA2MSB=b'\x02'
 
+ET_EXEC=2
 ET_DYN=3
 
 PT_LOAD=1
+PT_TLS=7
 
 def elf_types_fmts(e_ident):
     endian = '<' if e_ident[EI_DATA] == ELFDATA2LSB else '>'
@@ -146,8 +148,15 @@ def elf_edit_align(phdr, align):
     else:
         phdr.p_align = int(align)
 
+def elf_edit_maximize_tls_size(phdr, elfclass):
+    if elfclass == ELFCLASS32:
+        # It is possible that the kernel can allocate half of the
+        # address space, so use something larger.
+        phdr.p_memsz = 0xfff00000
+    else:
+        phdr.p_memsz = 1 << 63
 
-def elf_edit(f, align):
+def elf_edit(f, opts):
     ei_nident_fmt = 'c' * EI_NIDENT
     ei_nident_len = struct.calcsize(ei_nident_fmt)
 
@@ -172,24 +181,35 @@ def elf_edit(f, align):
 
     ehdr = Elf_Ehdr(e_ident)
     ehdr.read(f)
-    if ehdr.e_type != ET_DYN:
-       error('{}: not a shared library'.format(f.name))
+    if ehdr.e_type not in (ET_EXEC, ET_DYN):
+       error('{}: not an executable or shared library'.format(f.name))
 
     phdr = Elf_Phdr(e_ident)
+    maximize_tls_size_done = False
     for i in range(0, ehdr.e_phnum):
         f.seek(ehdr.e_phoff + i * phdr.len)
         phdr.read(f)
-        if phdr.p_type == PT_LOAD:
-            elf_edit_align(phdr, align)
+        if phdr.p_type == PT_LOAD and opts.align is not None:
+            elf_edit_align(phdr, opts.align)
+            f.seek(ehdr.e_phoff + i * phdr.len)
+            phdr.write(f)
+            break
+        if phdr.p_type == PT_TLS and opts.maximize_tls_size:
+            elf_edit_maximize_tls_size(phdr, e_ident[EI_CLASS])
             f.seek(ehdr.e_phoff + i * phdr.len)
             phdr.write(f)
+            maximize_tls_size_done = True
             break
 
+    if opts.maximize_tls_size and not maximize_tls_size_done:
+        error('{}: TLS maximum size was not updated'.format(f.name))
 
 def get_parser():
     parser = argparse.ArgumentParser(description=__doc__)
-    parser.add_argument('-a', dest='align', required=True,
+    parser.add_argument('-a', dest='align',
                         help='How to set the LOAD alignment')
+    parser.add_argument('--maximize-tls-size', action='store_true',
+                        help='Set maximum PT_TLS size')
     parser.add_argument('output',
                         help='ELF file to edit')
     return parser
@@ -199,7 +219,7 @@ def main(argv):
     parser = get_parser()
     opts = parser.parse_args(argv)
     with open(opts.output, 'r+b') as fout:
-       elf_edit(fout, opts.align)
+       elf_edit(fout, opts)
 
 
 if __name__ == '__main__':
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 4a5e698db2..5d0369358d 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -1211,6 +1211,11 @@ extern struct link_map * _dl_get_dl_main_map (void)
 # endif
 #endif
 
+/* Perform early memory allocation, avoding a TCB dependency.
+   Terminate the process if allocation fails.  May attempt to use
+   brk.  */
+void *_dl_early_allocate (size_t size) attribute_hidden;
+
 /* Initialize the DSO sort algorithm to use.  */
 #if !HAVE_TUNABLES
 static inline void
diff --git a/sysdeps/unix/sysv/linux/dl-early_allocate.c b/sysdeps/unix/sysv/linux/dl-early_allocate.c
new file mode 100644
index 0000000000..2c77b6e3ff
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/dl-early_allocate.c
@@ -0,0 +1,81 @@
+/* Early memory allocation for the dynamic loader.  Generic version.
+   Copyright (C) 2022 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/>.  */
+
+/* Mark symbols hidden in static PIE for early self relocation to work.  */
+#if BUILD_PIE_DEFAULT
+# pragma GCC visibility push(hidden)
+#endif
+#include <startup.h>
+
+#include <ldsodefs.h>
+#include <stddef.h>
+#include <string.h>
+#include <sysdep.h>
+#include <unistd.h>
+
+#include <mmap_call.h>
+
+/* Defined in brk.c.  */
+extern void *__curbrk;
+
+void *
+_dl_early_allocate (size_t size)
+{
+  void *result;
+
+  if (__curbrk != NULL)
+    /* If the break has been initialized, brk must have run before,
+       so just call it once more.  */
+    {
+      result = __sbrk (size);
+      if (result == (void *) -1)
+        result = NULL;
+    }
+  else
+    {
+      /* If brk has not been invoked, there is no need to update
+         __curbrk.  The first call to brk will take care of that.  */
+      void *previous = (void *) INTERNAL_SYSCALL_CALL (brk, 0);
+      result = (void *) INTERNAL_SYSCALL_CALL (brk, previous + size);
+      if (result == previous)
+        result = NULL;
+      else
+        result = previous;
+    }
+
+  /* If brk fails, fall back to mmap.  This can happen due to
+     unfortunate ASLR layout decisions and kernel bugs, particularly
+     for static PIE.  */
+  if (result == NULL)
+    {
+      long int ret;
+      int prot = PROT_READ | PROT_WRITE;
+      int flags = MAP_PRIVATE | MAP_ANONYMOUS;
+#ifdef __NR_mmap2
+      ret = MMAP_CALL_INTERNAL (mmap2, 0, size, prot, flags, -1, 0);
+#else
+      ret = MMAP_CALL_INTERNAL (mmap, 0, size, prot, flags, -1, 0);
+#endif
+      if (INTERNAL_SYSCALL_ERROR_P (ret))
+        result = NULL;
+      else
+        result = (void *) ret;
+    }
+
+  return result;
+}
-- 
2.35.1

Re: [PATCH v2 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro

[Adhemerval Zanella]

On 04/05/2022 13:47, Florian Weimer wrote:
> And keep the previous definition if it exists.  This allows
> disabling IA64_USE_NEW_STUB while keeping USE_DL_SYSINFO defined.
> ---
> v2: New patch.
>  sysdeps/unix/sysv/linux/ia64/brk.c    |  3 +--
>  sysdeps/unix/sysv/linux/ia64/sysdep.h | 21 +++++++++++++--------
>  2 files changed, 14 insertions(+), 10 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/ia64/brk.c b/sysdeps/unix/sysv/linux/ia64/brk.c
> index 65142aeae9..e1fa88f9b0 100644
> --- a/sysdeps/unix/sysv/linux/ia64/brk.c
> +++ b/sysdeps/unix/sysv/linux/ia64/brk.c
> @@ -16,7 +16,6 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> -#include <dl-sysdep.h>
>  /* brk is used by statup before TCB is properly set.  */
> -#undef USE_DL_SYSINFO
> +#define IA64_USE_NEW_STUB 0
>  #include <sysdeps/unix/sysv/linux/brk.c>
> diff --git a/sysdeps/unix/sysv/linux/ia64/sysdep.h b/sysdeps/unix/sysv/linux/ia64/sysdep.h
> index 193ecee023..72b72acb6f 100644
> --- a/sysdeps/unix/sysv/linux/ia64/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/ia64/sysdep.h
> @@ -44,12 +44,17 @@
>  #undef SYS_ify
>  #define SYS_ify(syscall_name)	__NR_##syscall_name
>  
> -#if defined USE_DL_SYSINFO \
> +#ifndef IA64_USE_NEW_STUB
> +# if defined USE_DL_SYSINFO \
>  	&& (IS_IN (libc) \
>  	    || IS_IN (libpthread) || IS_IN (librt))

I think you can drop libpthread and librt here.

> -# define IA64_USE_NEW_STUB
> -#else
> -# undef IA64_USE_NEW_STUB
> +#  define IA64_USE_NEW_STUB 1
> +# else
> +#  define IA64_USE_NEW_STUB 0
> +# endif
> +#endif
> +#if IA64_USE_NEW_STUB && !USE_DL_SYSINFO
> +# error IA64_USE_NEW_STUB needs USE_DL_SYSINFO
>  #endif
>  
>  #ifdef __ASSEMBLER__
> @@ -101,7 +106,7 @@
>  	mov r15=num;				\
>  	break __IA64_BREAK_SYSCALL
>  
> -#ifdef IA64_USE_NEW_STUB
> +#if IA64_USE_NEW_STUB
>  # ifdef SHARED
>  #  define DO_CALL(num)				\
>  	.prologue;				\
> @@ -185,7 +190,7 @@
>     (non-negative) errno on error or the return value on success.
>   */
>  
> -#ifdef IA64_USE_NEW_STUB
> +#if IA64_USE_NEW_STUB
>  
>  # define INTERNAL_SYSCALL_NCS(name, nr, args...)			      \
>  ({									      \
> @@ -277,7 +282,7 @@
>  #define ASM_OUTARGS_5	ASM_OUTARGS_4, "=r" (_out4)
>  #define ASM_OUTARGS_6	ASM_OUTARGS_5, "=r" (_out5)
>  
> -#ifdef IA64_USE_NEW_STUB
> +#if IA64_USE_NEW_STUB
>  #define ASM_ARGS_0
>  #define ASM_ARGS_1	ASM_ARGS_0, "4" (_out0)
>  #define ASM_ARGS_2	ASM_ARGS_1, "5" (_out1)
> @@ -313,7 +318,7 @@
>    /* Branch registers.  */						\
>    "b6"
>  
> -#ifdef IA64_USE_NEW_STUB
> +#if IA64_USE_NEW_STUB
>  # define ASM_CLOBBERS_6	ASM_CLOBBERS_6_COMMON
>  #else
>  # define ASM_CLOBBERS_6	ASM_CLOBBERS_6_COMMON , "b7"
> 
> base-commit: c1b68685d438373efe64e5f076f4215723004dfb

Rest look ok.

Re: [PATCH v2 1/3] ia64: Always define IA64_USE_NEW_STUB as a flag macro

[Florian Weimer]

* Adhemerval Zanella:

> On 04/05/2022 13:47, Florian Weimer wrote:
>> And keep the previous definition if it exists.  This allows
>> disabling IA64_USE_NEW_STUB while keeping USE_DL_SYSINFO defined.
>> ---
>> v2: New patch.
>>  sysdeps/unix/sysv/linux/ia64/brk.c    |  3 +--
>>  sysdeps/unix/sysv/linux/ia64/sysdep.h | 21 +++++++++++++--------
>>  2 files changed, 14 insertions(+), 10 deletions(-)
>> 
>> diff --git a/sysdeps/unix/sysv/linux/ia64/brk.c b/sysdeps/unix/sysv/linux/ia64/brk.c
>> index 65142aeae9..e1fa88f9b0 100644
>> --- a/sysdeps/unix/sysv/linux/ia64/brk.c
>> +++ b/sysdeps/unix/sysv/linux/ia64/brk.c
>> @@ -16,7 +16,6 @@
>>     License along with the GNU C Library; if not, see
>>     <https://www.gnu.org/licenses/>.  */
>>  
>> -#include <dl-sysdep.h>
>>  /* brk is used by statup before TCB is properly set.  */
>> -#undef USE_DL_SYSINFO
>> +#define IA64_USE_NEW_STUB 0
>>  #include <sysdeps/unix/sysv/linux/brk.c>
>> diff --git a/sysdeps/unix/sysv/linux/ia64/sysdep.h b/sysdeps/unix/sysv/linux/ia64/sysdep.h
>> index 193ecee023..72b72acb6f 100644
>> --- a/sysdeps/unix/sysv/linux/ia64/sysdep.h
>> +++ b/sysdeps/unix/sysv/linux/ia64/sysdep.h
>> @@ -44,12 +44,17 @@
>>  #undef SYS_ify
>>  #define SYS_ify(syscall_name)	__NR_##syscall_name
>>  
>> -#if defined USE_DL_SYSINFO \
>> +#ifndef IA64_USE_NEW_STUB
>> +# if defined USE_DL_SYSINFO \
>>  	&& (IS_IN (libc) \
>>  	    || IS_IN (libpthread) || IS_IN (librt))
>
> I think you can drop libpthread and librt here.

Will do so in v3.

Thanks,
Florian