source: libcfa/src/interpose.cfa @ e10714a

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Last change on this file since e10714a was e10714a, checked in by Peter A. Buhr <pabuhr@…>, 16 months ago

update interpose code, and document 32-bit interpose bug in glibc

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1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// interpose.c --
8//
9// Author           : Thierry Delisle
10// Created On       : Wed Mar 29 16:10:31 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Mar 27 21:09:03 2023
13// Update Count     : 196
14//
15
16#include <stdio.h>
17#include <unistd.h>                                                                             // _exit, getpid
18extern "C" {
19#include <dlfcn.h>                                                                              // dlopen, dlsym
20#include <execinfo.h>                                                                   // backtrace, messages
21}
22
23#include "bits/defs.hfa"
24#include "bits/signal.hfa"                                                              // sigHandler_?
25#include "startup.hfa"                                                                  // STARTUP_PRIORITY_CORE
26#include <assert.h>
27
28//=============================================================================================
29// Interposing helpers
30//=============================================================================================
31
32static void preload_libgcc(void) {
33        dlopen( "libgcc_s.so.1", RTLD_NOW );
34        if ( const char * error = dlerror() ) abort( "interpose_symbol : internal error pre-loading libgcc, %s\n", error );
35}
36
37typedef void (* generic_fptr_t)(void);
38
39static generic_fptr_t do_interpose_symbol( void * library, const char symbol[], const char version[] ) {
40        union { generic_fptr_t fptr; void * ptr; } originalFunc;
41
42        #if defined( _GNU_SOURCE )
43        if ( version ) {
44                originalFunc.ptr = dlvsym( library, symbol, version );
45        } else {
46                originalFunc.ptr = dlsym( library, symbol );
47        } // if
48        #else
49        originalFunc.ptr = dlsym( library, symbol );
50        #endif // _GNU_SOURCE
51
52        if ( ! originalFunc.ptr ) {                                                     // == nullptr
53                abort( "interpose_symbol : internal error, %s\n", dlerror() );
54        } // if
55        return originalFunc.fptr;
56}
57
58static generic_fptr_t interpose_symbol( const char symbol[], const char version[] ) {
59        void * library;
60
61        #if defined( RTLD_NEXT )
62        library = RTLD_NEXT;
63        #else
64        // missing RTLD_NEXT => must hard-code library name, assuming libstdc++
65        library = dlopen( "libc.so.6", RTLD_LAZY );
66        if ( ! library ) {                                                                      // == nullptr
67                abort( "interpose_symbol : failed to open libc, %s\n", dlerror() );
68        } // if
69        #endif // RTLD_NEXT
70
71        return do_interpose_symbol( library, symbol, version );
72}
73
74#define INTERPOSE_LIBC( x, ver ) __cabi_libc.x = (typeof(__cabi_libc.x))interpose_symbol( #x, ver )
75
76//=============================================================================================
77// Interposition Startup logic
78//=============================================================================================
79
80static void sigHandler_segv( __CFA_SIGPARMS__ );
81static void sigHandler_ill ( __CFA_SIGPARMS__ );
82static void sigHandler_fpe ( __CFA_SIGPARMS__ );
83static void sigHandler_abrt( __CFA_SIGPARMS__ );
84static void sigHandler_term( __CFA_SIGPARMS__ );
85
86static struct {
87        void (* exit)( int ) __attribute__(( __noreturn__ ));
88        void (* abort)( void ) __attribute__(( __noreturn__ ));
89} __cabi_libc;
90
91libcfa_public int cfa_main_returned;
92
93extern "C" {
94        void __cfathreadabi_interpose_startup( generic_fptr_t (*do_interpose_symbol)( void * library, const char symbol[], const char version[] ) ) __attribute__((weak));
95        void __cfaabi_interpose_startup( void ) {
96                const char *version = 0p;
97                cfa_main_returned = 0;
98
99                preload_libgcc();
100
101                #pragma GCC diagnostic push
102                #pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
103                INTERPOSE_LIBC( abort, version );
104                INTERPOSE_LIBC( exit , version );
105                #pragma GCC diagnostic pop
106
107                if(__cfathreadabi_interpose_startup) __cfathreadabi_interpose_startup( do_interpose_symbol );
108
109                // SKULLDUGGERY: In Ubuntu 22.04, someone augmented signal.h to allow SIGSTKSZ to be "sysconf(_SC_SIGSTKSZ)" in
110                // sigstksz.h, as well as 8192 in sigstack.h. HOWEVER, they forgot to provide a mechanism to tell signal.h to
111                // use sigstack.h rather than sigstksz.h. (I'm not happy.) By undefining _GNU_SOURCE before signal.h and
112                // redefining it afterwards, you can get 8192, but then nothing works correctly inside of signal.h without
113                // _GNU_SOURCE defined.  So what is needed is a way to get signal.h to use sigstack.h WITH _GNU_SOURCE defined.
114                // Basically something is wrong with features.h and its use in signal.h.
115
116                #undef SIGSTKSZ
117                #define SIGSTKSZ 8192
118
119                // As a precaution (and necessity), errors that result in termination are delivered on a separate stack because
120                // task stacks might be very small (4K) and the signal delivery corrupts memory to the point that a clean
121                // shutdown is impossible. Also, when a stack overflow encounters the non-accessible sentinel page (debug only)
122                // and generates a segment fault, the signal cannot be delivered on the sentinel page. Finally, calls to abort
123                // print a stack trace that uses substantial stack space.
124
125                #define MINSTKSZ SIGSTKSZ * 8
126                static char stack[MINSTKSZ] __attribute__(( aligned (16) ));
127                static stack_t ss;
128
129                ss.ss_sp = stack;
130                ss.ss_size = MINSTKSZ;
131                ss.ss_flags = 0;
132                if ( sigaltstack( &ss, 0p ) == -1 ) {
133                        abort( "__cfaabi_interpose_startup : internal error, sigaltstack error(%d) %s.", errno, strerror( errno ) );
134                } // if
135
136                // Failure handler
137                 // internal errors
138                __cfaabi_sigaction( SIGSEGV, sigHandler_segv, SA_SIGINFO | SA_ONSTACK ); // Invalid memory reference (default: Core)
139                __cfaabi_sigaction( SIGBUS , sigHandler_segv, SA_SIGINFO | SA_ONSTACK ); // Bus error, bad memory access (default: Core)
140                __cfaabi_sigaction( SIGILL , sigHandler_ill , SA_SIGINFO | SA_ONSTACK ); // Illegal Instruction (default: Core)
141                __cfaabi_sigaction( SIGFPE , sigHandler_fpe , SA_SIGINFO | SA_ONSTACK ); // Floating-point exception (default: Core)
142
143                // handlers to outside errors
144                // reset in-case they insist and send it over and over
145                __cfaabi_sigaction( SIGTERM, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Termination signal (default: Term)
146                __cfaabi_sigaction( SIGINT , sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Interrupt from keyboard (default: Term)
147                __cfaabi_sigaction( SIGHUP , sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Hangup detected on controlling terminal or death of controlling process (default: Term)
148                __cfaabi_sigaction( SIGQUIT, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Quit from keyboard (default: Core)
149                __cfaabi_sigaction( SIGABRT, sigHandler_term, SA_SIGINFO | SA_ONSTACK | SA_RESETHAND ); // Abort signal from abort(3) (default: Core)
150        }
151}
152
153//=============================================================================================
154// Terminating Signals logic
155//=============================================================================================
156
157// Forward declare abort after the __typeof__ call to avoid ambiguities
158libcfa_public void exit( int status, const char fmt[], ... ) __attribute__(( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
159libcfa_public void abort( const char fmt[], ... ) __attribute__(( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ ));
160libcfa_public void abort( bool signalAbort, const char fmt[], ... ) __attribute__(( format(printf, 2, 3), __nothrow__, __leaf__, __noreturn__ ));
161libcfa_public void __abort( bool signalAbort, const char fmt[], va_list args ) __attribute__(( __nothrow__, __leaf__, __noreturn__ ));
162
163extern "C" {
164        libcfa_public void abort( void ) __attribute__(( __nothrow__, __leaf__, __noreturn__ )) {
165                abort( false, "%s", "" );
166        }
167
168        libcfa_public void __cabi_abort( const char fmt[], ... ) __attribute__(( format(printf, 1, 2), __nothrow__, __leaf__, __noreturn__ )) {
169                va_list argp;
170                va_start( argp, fmt );
171                __abort( false, fmt, argp );
172                va_end( argp );
173        }
174
175        libcfa_public void exit( int status ) __attribute__(( __nothrow__, __leaf__, __noreturn__ )) {
176                __cabi_libc.exit( status );
177        }
178}
179
180// See concurrency/kernel.cfa and concurrency/preemption.cfa for strong definition used in multi-processor mode.
181void __kernel_abort_lock( void ) __attribute__(( __nothrow__, __leaf__, __weak__ )) {}
182void __kernel_abort_msg( char buffer[], int size ) __attribute__(( __nothrow__, __leaf__, __weak__ )) {}
183int __kernel_abort_lastframe( void ) __attribute__(( __nothrow__, __leaf__, __weak__ )) { return 4; }
184
185enum { abort_text_size = 1024 };
186static char abort_text[ abort_text_size ];
187
188static void __cfaabi_backtrace( int start ) {
189        enum { Frames = 50, };                                                          // maximum number of stack frames
190        int last = __kernel_abort_lastframe();                          // skip last N stack frames
191
192        void * array[Frames];
193        size_t size = backtrace( array, Frames );
194        char ** messages = backtrace_symbols( array, size ); // does not demangle names
195
196        *index( messages[0], '(' ) = '\0';                                      // find executable name
197        __cfaabi_bits_print_nolock( STDERR_FILENO, "Stack back trace for: %s\n", messages[0]);
198
199        for ( unsigned int i = start; i < size - last && messages != 0p; i += 1 ) {
200                char * name = 0p, * offset_begin = 0p, * offset_end = 0p;
201
202                for ( char * p = messages[i]; *p; p += 1 ) {    // find parantheses and +offset
203                        //__cfaabi_bits_print_nolock( "X %s\n", p);
204                        if ( *p == '(' ) {
205                                name = p;
206                        } else if ( *p == '+' ) {
207                                offset_begin = p;
208                        } else if ( *p == ')' ) {
209                                offset_end = p;
210                                break;
211                        }
212                }
213
214                // if line contains symbol, print it
215                int frameNo = i - start;
216                if ( name && offset_begin && offset_end && name < offset_begin ) {
217                        *name++ = '\0';                                                         // delimit strings
218                        *offset_begin++ = '\0';
219                        *offset_end++ = '\0';
220
221                        __cfaabi_bits_print_nolock( STDERR_FILENO, "(%i) %s : %s + %s %s\n", frameNo, messages[i], name, offset_begin, offset_end);
222                } else {                                                                                // otherwise, print the whole line
223                        __cfaabi_bits_print_nolock( STDERR_FILENO, "(%i) %s\n", frameNo, messages[i] );
224                }
225        }
226        free( messages );
227}
228
229void exit( int status, const char fmt[], ... ) {
230        va_list args;
231        va_start( args, fmt );
232        vfprintf( stderr, fmt, args );
233        va_end( args );
234        __cabi_libc.exit( status );
235}
236
237static volatile bool __abort_first = 0;
238
239// Cannot forward va_list.
240void __abort( bool signalAbort, const char fmt[], va_list args ) {
241        // Multiple threads can come here from multiple paths
242        // To make sure this is safe any concurrent/subsequent call to abort is redirected to libc-abort
243        bool first = ! __atomic_test_and_set( &__abort_first, __ATOMIC_SEQ_CST);
244
245        // Prevent preemption from kicking-in and messing with the abort
246        __kernel_abort_lock();
247
248        // first to abort ?
249        if ( !first ) {
250                // We aren't the first to abort just let C handle it
251                signal( SIGABRT, SIG_DFL );     // restore default in case we came here through the function.
252                __cabi_libc.abort();
253        }
254
255        int len = snprintf( abort_text, abort_text_size, "Cforall Runtime error (UNIX pid:%ld) ", (long int)getpid() ); // use UNIX pid (versus getPid)
256        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
257
258        // print the cause of the error
259        assert( fmt );
260        len = vsnprintf( abort_text, abort_text_size, fmt, args );
261        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
262
263        // add optional newline if missing at the end of the format text
264        if ( fmt[strlen( fmt ) - 1] != '\n' ) {
265                __cfaabi_bits_write( STDERR_FILENO, "\n", 1 );
266        } // if
267
268        // Give the kernel the chance to add some data in here
269        __kernel_abort_msg( abort_text, abort_text_size );
270
271        // print stack trace in handler
272        __cfaabi_backtrace( signalAbort ? 4 : 2 );
273
274        // Finally call abort
275        __cabi_libc.abort();
276
277}
278
279void abort( const char fmt[], ... ) {
280        va_list args;
281        va_start( args, fmt );
282        __abort( false, fmt, args );
283        // CONTROL NEVER REACHES HERE!
284        va_end( args );
285}
286
287void abort( bool signalAbort, const char fmt[], ... ) {
288        va_list args;
289        va_start( args, fmt );
290        __abort( signalAbort, fmt, args );
291        // CONTROL NEVER REACHES HERE!
292        va_end( args );
293}
294
295void sigHandler_segv( __CFA_SIGPARMS__ ) {
296                if ( sfp->si_addr == 0p ) {
297                        abort( true, "Null pointer (0p) dereference.\n" );
298                } else {
299                        abort( true, "%s at memory location %p.\n"
300                                   "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",
301                                   (sig == SIGSEGV ? "Segment fault" : "Bus error"), sfp->si_addr );
302                }
303}
304
305void sigHandler_ill( __CFA_SIGPARMS__ ) {
306        abort( true, "Executing illegal instruction at location %p.\n"
307                        "Possible cause is stack corruption.\n",
308                        sfp->si_addr );
309}
310
311void sigHandler_fpe( __CFA_SIGPARMS__ ) {
312        const char * msg;
313
314        choose( sfp->si_code ) {
315          case FPE_INTDIV, FPE_FLTDIV: msg = "divide by zero";
316          case FPE_FLTOVF: msg = "overflow";
317          case FPE_FLTUND: msg = "underflow";
318          case FPE_FLTRES: msg = "inexact result";
319          case FPE_FLTINV: msg = "invalid operation";
320          default: msg = "unknown";
321        } // choose
322        abort( true, "Computation error %s at location %p.\n", msg, sfp->si_addr );
323}
324
325void sigHandler_term( __CFA_SIGPARMS__ ) {
326        abort( true, "Application interrupted by signal: %s.\n", strsignal( sig ) );
327}
328
329// Local Variables: //
330// mode: c //
331// tab-width: 4 //
332// End: //
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