Re: [PATCH] Use __builtin_trap() for abort() if inhibit_libc
On Tue, Aug 17, 2021 at 1:43 AM Sebastian Huber wrote: > > abort() is used in gcc_assert() and gcc_unreachable() which is used by target > libraries such as libgcov.a. This patch changes the abort() definition under > certain conditions. If inhibit_libc is defined and abort is not already > defined, then abort() is defined to __builtin_trap(). > > The inhibit_libc define is usually defined if GCC is built for targets running > in embedded systems which may optionally use a C standard library. If > inhibit_libc is defined, then there may be still a full featured abort() > available. abort() is a heavy weight function which depends on signals and > file streams. For statically linked applications, this means that a > dependency > on gcc_assert() pulls in the support for signals and file streams. This could > prevent using gcov to test low end targets for example. Using > __builtin_trap() > avoids these dependencies if the target implements a "trap" instruction. The > application or operating system could use a trap handler to react to failed > GCC > runtime checks which caused a trap. This also breaks sometimes compiling of emutls.c on some targets like uclibc ... See https://gcc.gnu.org/PR110775 for some more details there. Thanks, Andrew > > gcc/ > > * tsystem.h (abort): Define abort() if inhibit_libc is defined and it > is not already defined. > --- > gcc/tsystem.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/gcc/tsystem.h b/gcc/tsystem.h > index e1e6a96a4f48..5c72c69ff3ed 100644 > --- a/gcc/tsystem.h > +++ b/gcc/tsystem.h > @@ -59,7 +59,7 @@ extern int atexit (void (*)(void)); > #endif > > #ifndef abort > -extern void abort (void) __attribute__ ((__noreturn__)); > +#define abort() __builtin_trap () > #endif > > #ifndef strlen > -- > 2.26.2 >
Re: [PATCH] Use __builtin_trap() for abort() if inhibit_libc
On 30/08/2021 13:44, Richard Biener wrote: On Mon, Aug 30, 2021 at 12:55 PM Sebastian Huber wrote: Hello Christophe, it seems there are a couple of more abort() declarations: libgcc/unwind-arm-common.inc:extern void abort (void); libgcc/config/c6x/pr-support.c:extern void abort (void); libgcc/config/arm/pr-support.c:extern void abort (void); libgcc/config/arm/linux-atomic-64bit.c:extern void abort (void); libgcc/fp-bit.c: external to abort if abort is not used by the function, and the stubs libgcc/fp-bit.c:extern void abort (void); I will prepare a patch. Less likley to break might be to simply wrap 'abort' in parentheses to avoid macro expansion? I think the abort declaration in libgcc/unwind-arm-common.inc is the only problematic spot since unwind-arm-common.inc includes tsystem.h. -- embedded brains GmbH Herr Sebastian HUBER Dornierstr. 4 82178 Puchheim Germany email: sebastian.hu...@embedded-brains.de phone: +49-89-18 94 741 - 16 fax: +49-89-18 94 741 - 08 Registergericht: Amtsgericht München Registernummer: HRB 157899 Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler Unsere Datenschutzerklärung finden Sie hier: https://embedded-brains.de/datenschutzerklaerung/
Re: [PATCH] Use __builtin_trap() for abort() if inhibit_libc
On Mon, Aug 30, 2021 at 12:55 PM Sebastian Huber wrote: > > Hello Christophe, > > it seems there are a couple of more abort() declarations: > > libgcc/unwind-arm-common.inc:extern void abort (void); > libgcc/config/c6x/pr-support.c:extern void abort (void); > libgcc/config/arm/pr-support.c:extern void abort (void); > libgcc/config/arm/linux-atomic-64bit.c:extern void abort (void); > libgcc/fp-bit.c: external to abort if abort is not used by the > function, and the stubs > libgcc/fp-bit.c:extern void abort (void); > > I will prepare a patch. Less likley to break might be to simply wrap 'abort' in parentheses to avoid macro expansion? > -- > embedded brains GmbH > Herr Sebastian HUBER > Dornierstr. 4 > 82178 Puchheim > Germany > email: sebastian.hu...@embedded-brains.de > phone: +49-89-18 94 741 - 16 > fax: +49-89-18 94 741 - 08 > > Registergericht: Amtsgericht München > Registernummer: HRB 157899 > Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler > Unsere Datenschutzerklärung finden Sie hier: > https://embedded-brains.de/datenschutzerklaerung/
Re: [PATCH] Use __builtin_trap() for abort() if inhibit_libc
Hello Christophe, it seems there are a couple of more abort() declarations: libgcc/unwind-arm-common.inc:extern void abort (void); libgcc/config/c6x/pr-support.c:extern void abort (void); libgcc/config/arm/pr-support.c:extern void abort (void); libgcc/config/arm/linux-atomic-64bit.c:extern void abort (void); libgcc/fp-bit.c: external to abort if abort is not used by the function, and the stubs libgcc/fp-bit.c:extern void abort (void); I will prepare a patch. -- embedded brains GmbH Herr Sebastian HUBER Dornierstr. 4 82178 Puchheim Germany email: sebastian.hu...@embedded-brains.de phone: +49-89-18 94 741 - 16 fax: +49-89-18 94 741 - 08 Registergericht: Amtsgericht München Registernummer: HRB 157899 Vertretungsberechtigte Geschäftsführer: Peter Rasmussen, Thomas Dörfler Unsere Datenschutzerklärung finden Sie hier: https://embedded-brains.de/datenschutzerklaerung/
Re: [PATCH] Use __builtin_trap() for abort() if inhibit_libc
Hi, On Tue, Aug 17, 2021 at 10:43 AM Sebastian Huber < sebastian.hu...@embedded-brains.de> wrote: > abort() is used in gcc_assert() and gcc_unreachable() which is used by > target > libraries such as libgcov.a. This patch changes the abort() definition > under > certain conditions. If inhibit_libc is defined and abort is not already > defined, then abort() is defined to __builtin_trap(). > > The inhibit_libc define is usually defined if GCC is built for targets > running > in embedded systems which may optionally use a C standard library. If > inhibit_libc is defined, then there may be still a full featured abort() > available. abort() is a heavy weight function which depends on signals and > file streams. For statically linked applications, this means that a > dependency > on gcc_assert() pulls in the support for signals and file streams. This > could > prevent using gcov to test low end targets for example. Using > __builtin_trap() > avoids these dependencies if the target implements a "trap" instruction. > The > application or operating system could use a trap handler to react to > failed GCC > runtime checks which caused a trap. > > gcc/ > > * tsystem.h (abort): Define abort() if inhibit_libc is defined and > it > is not already defined. > This causes a build failure on arm: In file included from /libgcc/config/arm/unwind-arm.c:144: /libgcc/unwind-arm-common.inc:55:24: error: macro "abort" passed 1 arguments, but takes just 0 55 | extern void abort (void); This small patch should fix it: diff --git a/libgcc/unwind-arm-common.inc b/libgcc/unwind-arm-common.inc index c9b70c10d4f..77ec02ec811 100644 --- a/libgcc/unwind-arm-common.inc +++ b/libgcc/unwind-arm-common.inc @@ -50,10 +50,6 @@ #define ARM_SIGCONTEXT_R0 0xc #endif -/* We add a prototype for abort here to avoid creating a dependency on - target headers. */ -extern void abort (void); - /* Definitions for C++ runtime support routines. We make these weak declarations to avoid pulling in libsupc++ unnecessarily. */ typedef unsigned char bool; Christophe > --- > gcc/tsystem.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/gcc/tsystem.h b/gcc/tsystem.h > index e1e6a96a4f48..5c72c69ff3ed 100644 > --- a/gcc/tsystem.h > +++ b/gcc/tsystem.h > @@ -59,7 +59,7 @@ extern int atexit (void (*)(void)); > #endif > > #ifndef abort > -extern void abort (void) __attribute__ ((__noreturn__)); > +#define abort() __builtin_trap () > #endif > > #ifndef strlen > -- > 2.26.2 > >
Re: [PATCH] Use __builtin_trap() for abort() if inhibit_libc
On 8/17/2021 2:41 AM, Sebastian Huber wrote: abort() is used in gcc_assert() and gcc_unreachable() which is used by target libraries such as libgcov.a. This patch changes the abort() definition under certain conditions. If inhibit_libc is defined and abort is not already defined, then abort() is defined to __builtin_trap(). The inhibit_libc define is usually defined if GCC is built for targets running in embedded systems which may optionally use a C standard library. If inhibit_libc is defined, then there may be still a full featured abort() available. abort() is a heavy weight function which depends on signals and file streams. For statically linked applications, this means that a dependency on gcc_assert() pulls in the support for signals and file streams. This could prevent using gcov to test low end targets for example. Using __builtin_trap() avoids these dependencies if the target implements a "trap" instruction. The application or operating system could use a trap handler to react to failed GCC runtime checks which caused a trap. gcc/ * tsystem.h (abort): Define abort() if inhibit_libc is defined and it is not already defined. OK. Jeff
[PATCH] Use __builtin_trap() for abort() if inhibit_libc
abort() is used in gcc_assert() and gcc_unreachable() which is used by target libraries such as libgcov.a. This patch changes the abort() definition under certain conditions. If inhibit_libc is defined and abort is not already defined, then abort() is defined to __builtin_trap(). The inhibit_libc define is usually defined if GCC is built for targets running in embedded systems which may optionally use a C standard library. If inhibit_libc is defined, then there may be still a full featured abort() available. abort() is a heavy weight function which depends on signals and file streams. For statically linked applications, this means that a dependency on gcc_assert() pulls in the support for signals and file streams. This could prevent using gcov to test low end targets for example. Using __builtin_trap() avoids these dependencies if the target implements a "trap" instruction. The application or operating system could use a trap handler to react to failed GCC runtime checks which caused a trap. gcc/ * tsystem.h (abort): Define abort() if inhibit_libc is defined and it is not already defined. --- gcc/tsystem.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/tsystem.h b/gcc/tsystem.h index e1e6a96a4f48..5c72c69ff3ed 100644 --- a/gcc/tsystem.h +++ b/gcc/tsystem.h @@ -59,7 +59,7 @@ extern int atexit (void (*)(void)); #endif #ifndef abort -extern void abort (void) __attribute__ ((__noreturn__)); +#define abort() __builtin_trap () #endif #ifndef strlen -- 2.26.2
