[v2,2/3] Linux: Implement a useful version of _startup_fatal
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Commit Message
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
Comments
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 */
* 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
* 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
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. 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
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:
> 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
@@ -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>
new file mode 100644
@@ -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>
new file mode 100644
@@ -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 */