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Re: [PATCH] i386: Add _startup_sbrk and _startup_fatal [BZ #21913]

• From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
• To: libc-alpha at sourceware dot org
• Date: Mon, 7 Aug 2017 10:34:46 -0300
• Subject: Re: [PATCH] i386: Add _startup_sbrk and _startup_fatal [BZ #21913]
• Authentication-results: sourceware.org; auth=none
• References: <20170806222606.GA13700@gmail.com>

On 06/08/2017 19:26, H.J. Lu wrote:[..]> diff --git a/sysdeps/generic/startup.h b/sysdeps/generic/startup.h> new file mode 100644> index 0000000000..aa63b31181> --- /dev/null> +++ b/sysdeps/generic/startup.h> @@ -0,0 +1,30 @@> +/* Generic definitions of functions used by static libc main startup.> +   Copyright (C) 2017 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> +   <http://www.gnu.org/licenses/>.  */> +> +static inline void *> +_startup_sbrk (intptr_t __delta)> +{> +  return __sbrk (__delta);> +}> +> +__attribute__ ((__noreturn__))> +static inline void> +_startup_fatal (const char *__message)> +{> +  __libc_fatal (__message);> +}I think there is no need of underlying prefixes for inline functions.> diff --git a/sysdeps/unix/sysv/linux/i386/Makefile b/sysdeps/unix/sysv/linux/i386/Makefile> index 4080b8c966..cefa1511f6 100644> --- a/sysdeps/unix/sysv/linux/i386/Makefile> +++ b/sysdeps/unix/sysv/linux/i386/Makefile> @@ -31,6 +31,10 @@ sysdep_routines += divdi3>  shared-only-routines += divdi3>  CPPFLAGS-divdi3.c = -Din_divdi3_c>  endif> +ifneq (,$(pic-default))> +sysdep_routines += startup_sbrk> +static-only-routines += startup_sbrk> +endif>  endif>  >  ifeq ($(subdir),nptl)> diff --git a/sysdeps/unix/sysv/linux/i386/startup.h b/sysdeps/unix/sysv/linux/i386/startup.h> new file mode 100644> index 0000000000..ccfba45153> --- /dev/null> +++ b/sysdeps/unix/sysv/linux/i386/startup.h> @@ -0,0 +1,38 @@> +/* Linux/i386 definitions of functions used by static libc main startup.> +   Copyright (C) 2017 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> +   <http://www.gnu.org/licenses/>.  */> +> +#if defined PIC && !defined SHAREDWe already check and set build-pie-default on configure/make.in, wouldn'tbe useful if we also define a BUILD_PIE as well?> +# include <abort-instr.h>> +> +/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */> +# define I386_USE_SYSENTER 0> +> +extern void * _startup_sbrk (intptr_t) attribute_hidden;> +> +__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 ();> +}Maybe also provide a __writev using 'int $0x80' so it can use _dl_debug_printf?> +#else> +# include_next <startup.h>> +#endif> diff --git a/sysdeps/unix/sysv/linux/i386/startup_sbrk.c b/sysdeps/unix/sysv/linux/i386/startup_sbrk.c> new file mode 100644> index 0000000000..8239938ddf> --- /dev/null> +++ b/sysdeps/unix/sysv/linux/i386/startup_sbrk.cI am not very found of replicating generic code, but for this case it seemsthat i386 version seems to have too many specific cases that I am not sureif it worth trying to consolidate it.> @@ -0,0 +1,67 @@> +/* Linux/i386 definitions of _startup_sbrk.> +   Copyright (C) 2017 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> +   <http://www.gnu.org/licenses/>.  */> +> +#include <unistd.h>> +#include <startup.h>> +#include <errno.h>> +#include <sysdep.h>> +> +/* Defined in brk.c.  */> +extern void *__curbrk attribute_hidden;> +> +static int> +startup_brk (void *addr)> +{> +  INTERNAL_SYSCALL_DECL (err);> +  void *newbrk = (void *) INTERNAL_SYSCALL_CALL (brk, err, addr);> +  __curbrk = newbrk;> +  if (newbrk < addr)> +    _startup_fatal (NULL);> +  return 0;> +}> +> +/* Extend the process's data space by INCREMENT.  If INCREMENT is negative,> +   shrink data space by - INCREMENT.  Return start of new space allocated,> +   or call _startup_fatal for errors.  */> +> +void *> +_startup_sbrk (intptr_t increment)> +{> +  void *oldbrk;> +> +  /* Update __curbrk from the kernel's brk value.  That way two separate> +     instances of __brk and __sbrk can share the heap, returning> +     interleaved pieces of it.  */> +  if (__curbrk == NULL)> +    if (startup_brk (0) < 0)/* Initialize the break.  */> +      _startup_fatal (NULL);> +> +  if (increment == 0)> +    return __curbrk;> +> +  oldbrk = __curbrk;> +  if (increment > 0> +      ? ((uintptr_t) oldbrk + (uintptr_t) increment < (uintptr_t) oldbrk)> +      : ((uintptr_t) oldbrk < (uintptr_t) -increment))> +    _startup_fatal (NULL);> +> +  if (startup_brk (oldbrk + increment) < 0)> +    _startup_fatal (NULL);> +> +  return oldbrk;> +}>

• Follow-Ups:
  • Re: [PATCH] i386: Add _startup_sbrk and _startup_fatal [BZ #21913]
    • From: H.J. Lu

• References:
  • [PATCH] i386: Add _startup_sbrk and _startup_fatal [BZ #21913]
    • From: H.J. Lu