source: libcfa/src/interpose.cfa

//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// interpose.c --
//
// Author           : Thierry Delisle
// Created On       : Wed Mar 29 16:10:31 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Sun Jul 28 08:54:31 2024
// Update Count     : 220
//

#include <stdio.h>
#include <unistd.h>                                                                             // _exit, getpid
extern "C" {
#include <dlfcn.h>                                                                              // dlopen, dlsym
#include <link.h>                                                                               // dl_iterate_phdr
#include <execinfo.h>                                                                   // backtrace, messages
}

#include "bits/defs.hfa"
#include "bits/signal.hfa"                                                              // sigHandler_?
#include "concurrency/kernel/fwd.hfa"                                   // disable_interrupts, enable_interrupts
#include "startup.hfa"                                                                  // STARTUP_PRIORITY_CORE
#include <assert.h>

//=============================================================================================
// Interposing helpers
//=============================================================================================

static void preload_libgcc(void) {
        dlopen( "libgcc_s.so.1", RTLD_NOW );
        if ( const char * error = dlerror() ) abort( "interpose_symbol : internal error pre-loading libgcc, %s\n", error );
}

typedef void (* generic_fptr_t)(void);

static generic_fptr_t do_interpose_symbol( void * library, const char symbol[], const char version[] ) {
        union { generic_fptr_t fptr; void * ptr; } originalFunc;

        #if defined( _GNU_SOURCE )
        if ( version ) {
                originalFunc.ptr = dlvsym( library, symbol, version );
        } else {
                originalFunc.ptr = dlsym( library, symbol );
        } // if
        #else
        originalFunc.ptr = dlsym( library, symbol );
        #endif // _GNU_SOURCE

        if ( ! originalFunc.ptr ) {                                                     // == nullptr
                abort( "interpose_symbol : internal error, %s\n", dlerror() );
        } // if
        return originalFunc.fptr;
}

static generic_fptr_t interpose_symbol( const char symbol[], const char version[] ) {
        void * library;

        #if defined( RTLD_NEXT )
        library = RTLD_NEXT;
        #else
        // missing RTLD_NEXT => must hard-code library name, assuming libstdc++
        library = dlopen( "libc.so.6", RTLD_LAZY );
        if ( ! library ) {                                                                      // == nullptr
                abort( "interpose_symbol : failed to open libc, %s\n", dlerror() );
        } // if
        #endif // RTLD_NEXT

        return do_interpose_symbol( library, symbol, version );
}

#define INTERPOSE_LIBC( x, ver ) __cabi_libc.x = (typeof(__cabi_libc.x))interpose_symbol( #x, ver )

//=============================================================================================
// Interposition Startup logic
//=============================================================================================

static void sigHandler_segv( __CFA_SIGPARMS__ );
static void sigHandler_ill ( __CFA_SIGPARMS__ );
static void sigHandler_fpe ( __CFA_SIGPARMS__ );
static void sigHandler_abrt( __CFA_SIGPARMS__ );
static void sigHandler_term( __CFA_SIGPARMS__ );

static struct {
        void (* exit)( int ) __attribute__(( __noreturn__ ));
        void (* abort)( void ) __attribute__(( __noreturn__ ));
        int (* dl_iterate_phdr)( int (*)( struct dl_phdr_info *, size_t, void * ), void * );
} __cabi_libc;

libcfa_public int cfa_main_returned;

extern "C" {
        void __cfathreadabi_interpose_startup( generic_fptr_t (*do_interpose_symbol)( void * library, const char symbol[], const char version[] ) ) __attribute__((weak));
        void __cfaabi_interpose_startup( void ) {
                const char *version = 0p;
                cfa_main_returned = 0;

                preload_libgcc();

                #pragma GCC diagnostic push
                #pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
                INTERPOSE_LIBC( abort, version );
                INTERPOSE_LIBC( exit, version );
                INTERPOSE_LIBC( dl_iterate_phdr, version );
                #pragma GCC diagnostic pop

                if(__cfathreadabi_interpose_startup) __cfathreadabi_interpose_startup( do_interpose_symbol );

                // SKULLDUGGERY: In Ubuntu 22.04, someone augmented signal.h to allow SIGSTKSZ to be "sysconf(_SC_SIGSTKSZ)" in
                // sigstksz.h, as well as 8192 in sigstack.h. HOWEVER, they forgot to provide a mechanism to tell signal.h to
                // use sigstack.h rather than sigstksz.h. (I'm not happy.) By undefining _GNU_SOURCE before signal.h and
                // redefining it afterwards, you can get 8192, but then nothing works correctly inside of signal.h without
                // _GNU_SOURCE defined.  So what is needed is a way to get signal.h to use sigstack.h WITH _GNU_SOURCE defined.
                // Basically something is wrong with features.h and its use in signal.h.

                #undef SIGSTKSZ
                #define SIGSTKSZ 8192

                // As a precaution (and necessity), errors that result in termination are delivered on a separate stack because
                // task stacks might be very small (4K) and the signal delivery corrupts memory to the point that a clean
                // shutdown is impossible. Also, when a stack overflow encounters the non-accessible sentinel page (debug only)
                // and generates a segment fault, the signal cannot be delivered on the sentinel page. Finally, calls to abort
                // print a stack trace that uses substantial stack space.

                #define MINSTKSZ SIGSTKSZ * 8
                static char stack[MINSTKSZ] __attribute__(( aligned (16) ));
                static stack_t ss;

                ss.ss_sp = stack;
                ss.ss_size = MINSTKSZ;
                ss.ss_flags = 0;
                if ( sigaltstack( &ss, 0p ) == -1 ) {
                        abort( "__cfaabi_interpose_startup : internal error, sigaltstack error(%d) %s.", errno, strerror( errno ) );
                } // if

                // Failure handler
                 // internal errors
                __cfaabi_sigaction( SIGSEGV, sigHandler_segv, SA_SIGINFO | SA_ONSTACK ); // Invalid memory reference (default: Core)
                __cfaabi_sigaction( SIGBUS , sigHandler_segv, SA_SIGINFO | SA_ONSTACK ); // Bus error, bad memory access (default: Core)
                __cfaabi_sigaction( SIGILL , sigHandler_ill , SA_SIGINFO | SA_ONSTACK ); // Illegal Instruction (default: Core)
                __cfaabi_sigaction( SIGFPE , sigHandler_fpe , SA_SIGINFO | SA_ONSTACK ); // Floating-point exception (default: Core)

                // handlers to outside errors
                // reset in-case they insist and send it over and over
                __cfaabi_sigaction( SIGTERM, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Termination signal (default: Term)
                __cfaabi_sigaction( SIGINT , sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Interrupt from keyboard (default: Term)
                __cfaabi_sigaction( SIGHUP , sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Hangup detected on controlling terminal or death of controlling process (default: Term)
                __cfaabi_sigaction( SIGQUIT, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Quit from keyboard (default: Core)
                __cfaabi_sigaction( SIGABRT, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Abort signal from abort(3) (default: Core)
        }
}

extern "C" int dl_iterate_phdr( int (* callback)( struct dl_phdr_info *, size_t, void * ), void * data ) {
        disable_interrupts();
        int ret = __cabi_libc.dl_iterate_phdr( callback, data ); // call real routine
        enable_interrupts( false );
        return ret;
} // dl_iterate_phdr

//=============================================================================================
// Terminating Signals logic
//=============================================================================================

// Forward declare abort after the __typeof__ call to avoid ambiguities
libcfa_public void exit( int status, const char fmt[], ... ) __attribute__(( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
libcfa_public void abort( const char fmt[], ... ) __attribute__(( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ ));
libcfa_public void abort( bool signalAbort, const char fmt[], ... ) __attribute__(( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
libcfa_public void __abort( bool signalAbort, const char fmt[], va_list args ) __attribute__(( __nothrow__, __leaf__, __noreturn__ ));

extern "C" {
        libcfa_public void abort( void ) __attribute__(( __nothrow__, __leaf__, __noreturn__ )) {
                abort( false, "%s", "" );
        }

        libcfa_public void __cabi_abort( const char fmt[], ... ) __attribute__(( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ )) {
                va_list argp;
                va_start( argp, fmt );
                __abort( false, fmt, argp );
                va_end( argp );
        }

        libcfa_public void exit( int status ) __attribute__(( __nothrow__, __leaf__, __noreturn__ )) {
                __cabi_libc.exit( status );
        }
}

// See concurrency/kernel.cfa and concurrency/preemption.cfa for strong definition used in multi-processor mode.
void __kernel_abort_lock( void ) __attribute__(( __nothrow__, __leaf__, __weak__ )) {}
void __kernel_abort_msg( char buffer[], int size ) __attribute__(( __nothrow__, __leaf__, __weak__ )) {}
int __kernel_abort_lastframe( void ) __attribute__(( __nothrow__, __leaf__, __weak__ )) { return 4; }

enum { abort_text_size = 1024 };
static char abort_text[ abort_text_size ];

static void __cfaabi_backtrace( int start ) {
        enum { Frames = 50, };                                                          // maximum number of stack frames
        int last = __kernel_abort_lastframe();                          // skip last N stack frames

        void * array[Frames];
        size_t size = backtrace( array, Frames );
        char ** messages = backtrace_symbols( array, size ); // does not demangle names

        *index( messages[0], '(' ) = '\0';                                      // find executable name
        __cfaabi_bits_print_nolock( STDERR_FILENO, "Stack back trace for: %s\n", messages[0]);

        for ( unsigned int i = start; i < size - last && messages != 0p; i += 1 ) {
                char * name = 0p, * offset_begin = 0p, * offset_end = 0p;

                for ( char * p = messages[i]; *p; p += 1 ) {    // find parantheses and +offset
                        //__cfaabi_bits_print_nolock( "X %s\n", p);
                        if ( *p == '(' ) {
                                name = p;
                        } else if ( *p == '+' ) {
                                offset_begin = p;
                        } else if ( *p == ')' ) {
                                offset_end = p;
                                break;
                        }
                }

                // if line contains symbol, print it
                int frameNo = i - start;
                if ( name && offset_begin && offset_end && name < offset_begin ) {
                        *name++ = '\0';                                                         // delimit strings
                        *offset_begin++ = '\0';
                        *offset_end++ = '\0';

                        __cfaabi_bits_print_nolock( STDERR_FILENO, "(%i) %s : %s + %s %s\n", frameNo, messages[i], name, offset_begin, offset_end);
                } else {                                                                                // otherwise, print the whole line
                        __cfaabi_bits_print_nolock( STDERR_FILENO, "(%i) %s\n", frameNo, messages[i] );
                }
        }
        free( messages );
}

void exit( int status, const char fmt[], ... ) {
        va_list args;
        va_start( args, fmt );
        vfprintf( stderr, fmt, args );
        va_end( args );
        __cabi_libc.exit( status );
}

static volatile bool __abort_first = 0;

// Cannot forward va_list.
void __abort( bool signalAbort, const char fmt[], va_list args ) {
        // Multiple threads can come here from multiple paths
        // To make sure this is safe any concurrent/subsequent call to abort is redirected to libc-abort
        bool first = ! __atomic_test_and_set( &__abort_first, __ATOMIC_SEQ_CST);

        // Prevent preemption from kicking-in and messing with the abort
        __kernel_abort_lock();

        // first to abort ?
        if ( !first ) {
                // We aren't the first to abort just let C handle it
                signal( SIGABRT, SIG_DFL );     // restore default in case we came here through the function.
                __cabi_libc.abort();
        }

        int len = snprintf( abort_text, abort_text_size, "Cforall Runtime error (UNIX pid:%ld): ", (long int)getpid() ); // use UNIX pid (versus getPid)
        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );

        // print the cause of the error
        assert( fmt );
        len = vsnprintf( abort_text, abort_text_size, fmt, args );
        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );

        // add optional newline if missing at the end of the format text
        if ( fmt[strlen( fmt ) - 1] != '\n' ) {
                __cfaabi_bits_write( STDERR_FILENO, "\n", 1 );
        } // if

        // Give the kernel the chance to add some data in here
        __kernel_abort_msg( abort_text, abort_text_size );

        // print stack trace in handler
        __cfaabi_backtrace( signalAbort ? 4 : 2 );

        // Finally call abort
        __cabi_libc.abort();

}

void abort( const char fmt[], ... ) {
        va_list args;
        va_start( args, fmt );
        __abort( false, fmt, args );
        // CONTROL NEVER REACHES HERE!
        va_end( args );
}

void abort( bool signalAbort, const char fmt[], ... ) {
        va_list args;
        va_start( args, fmt );
        __abort( signalAbort, fmt, args );
        // CONTROL NEVER REACHES HERE!
        va_end( args );
}

void sigHandler_segv( __CFA_SIGPARMS__ ) {
                if ( sfp->si_addr == 0p ) {
                        abort( true, "Null pointer (0p) dereference.\n" );
                } else {
                        abort( true, "%s at memory location %p.\n"
                                   "Possible cause is reading outside the address space or writing to a protected area within the address space with an invalid pointer or subscript.\n",
                                   (sig == SIGSEGV ? "Segment fault" : "Bus error"), sfp->si_addr );
                }
}

void sigHandler_ill( __CFA_SIGPARMS__ ) {
        abort( true, "Executing illegal instruction at location %p.\n"
                        "Possible cause is stack corruption.\n",
                        sfp->si_addr );
}

void sigHandler_fpe( __CFA_SIGPARMS__ ) {
        const char * msg;

        choose( sfp->si_code ) {
          case FPE_INTDIV, FPE_FLTDIV: msg = "divide by zero";
          case FPE_FLTOVF: msg = "overflow";
          case FPE_FLTUND: msg = "underflow";
          case FPE_FLTRES: msg = "inexact result";
          case FPE_FLTINV: msg = "invalid operation";
          default: msg = "unknown";
        } // choose
        abort( true, "Computation error %s at location %p.\n", msg, sfp->si_addr );
}

void sigHandler_term( __CFA_SIGPARMS__ ) {
        abort( true, "Application interrupted by signal: %s.\n", strsignal( sig ) );
}

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