[v4,2/3] 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.
---
v4: Unchanged.
v3: Use 2022 copyright year. Fix “statup” typo. Use __message_length
local variable in _startup_fatal.
sysdeps/unix/sysv/linux/i386/startup.h | 23 +++------------
sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
sysdeps/unix/sysv/linux/startup.h | 39 ++++++++++++++++++++++++++
3 files changed, 65 insertions(+), 19 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/ia64/startup.h
create mode 100644 sysdeps/unix/sysv/linux/startup.h
Comments
On Mai 05 2022, Florian Weimer via Libc-alpha wrote:
> +/* 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 (); \
> + } \
I think that could use _Static_assert.
* Andreas Schwab:
> On Mai 05 2022, Florian Weimer via Libc-alpha wrote:
>
>> +/* 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 (); \
>> + } \
>
> I think that could use _Static_assert.
It only works for simple cases, not for arguments that require constant
progagation:
libc-tls.c: In function ‘__libc_setup_tls’:
../sysdeps/unix/sysv/linux/startup.h:29:23: error: expression in static assertion is not constant
29 | _Static_assert (__builtin_constant_p (__message_length), \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thanks,
Florian
On 05/05/2022 12:07, Florian Weimer via Libc-alpha wrote:
> On i386 and ia64, the TCB is not available at this point.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> v4: Unchanged.
> v3: Use 2022 copyright year. Fix “statup” typo. Use __message_length
> local variable in _startup_fatal.
> sysdeps/unix/sysv/linux/i386/startup.h | 23 +++------------
> sysdeps/unix/sysv/linux/ia64/startup.h | 22 +++++++++++++++
> sysdeps/unix/sysv/linux/startup.h | 39 ++++++++++++++++++++++++++
> 3 files changed, 65 insertions(+), 19 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..213805d7d2 100644
> --- a/sysdeps/unix/sysv/linux/i386/startup.h
> +++ b/sysdeps/unix/sysv/linux/i386/startup.h
> @@ -1,5 +1,5 @@
> /* Linux/i386 definitions of functions used by static libc main startup.
> - Copyright (C) 2017-2022 Free Software Foundation, Inc.
> + 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
> @@ -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 startup. */
> +#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..77f29f15a2
> --- /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) 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..39859b404a
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/startup.h
> @@ -0,0 +1,39 @@
> +/* 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 */
@@ -1,5 +1,5 @@
/* Linux/i386 definitions of functions used by static libc main startup.
- Copyright (C) 2017-2022 Free Software Foundation, Inc.
+ 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
@@ -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 startup. */
+#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) 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 +1,39 @@
+/* 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 */