initial
This commit is contained in:
Martin Slachta
+407
@@ -0,0 +1,407 @@
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#include <errno.h>
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#include <getopt.h>
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#include <linux/perf_event.h>
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#include <signal.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/ptrace.h>
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#include <sys/syscall.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "../public/tracy/Tracy.hpp"
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#include "../public/common/TracyVersion.hpp"
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#include "../public/client/TracyCallstack.hpp"
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#include "GitRef.hpp"
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namespace tracy {
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extern uint32_t ___tracy_magic_pid_override;
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extern char ___tracy_magic_process_name[64];
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}
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static volatile sig_atomic_t s_shouldQuit = 0;
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static pid_t s_targetPid = 0;
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static bool s_isForked = false;
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static void SignalHandler( int sig )
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{
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s_shouldQuit = 1;
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if( s_isForked && s_targetPid != 0 )
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{
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// We launched the target under ptrace, so forward the signal to wake
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// a blocking waitpid and let the child exit. kill() is async-signal-safe.
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kill( s_targetPid, SIGINT );
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}
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}
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static bool ReadProcessName( pid_t pid, char* buf, size_t bufSize )
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{
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char path[64];
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snprintf( path, sizeof( path ), "/proc/%d/comm", (int)pid );
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FILE* f = fopen( path, "r" );
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if( !f ) return false;
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if( !fgets( buf, bufSize, f ) )
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{
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fclose( f );
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return false;
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}
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fclose( f );
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// Remove trailing newline
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size_t len = strlen( buf );
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while( len > 0 && ( buf[len-1] == '\n' || buf[len-1] == '\r' ) ) len--;
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buf[len] = '\0';
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return len > 0;
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}
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static bool CheckPerfPermissions()
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{
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FILE* f = fopen( "/proc/sys/kernel/perf_event_paranoid", "r" );
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if( !f )
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{
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fprintf( stderr, "Warning: Cannot read /proc/sys/kernel/perf_event_paranoid\n" );
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return true; // Assume OK
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}
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int paranoid = 2;
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if( fscanf( f, "%d", ¶noid ) != 1 ) paranoid = 2;
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fclose( f );
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if( paranoid > 1 && geteuid() != 0 )
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{
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fprintf( stderr, "Warning: perf_event_paranoid = %d. Profiling another process may require:\n", paranoid );
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fprintf( stderr, " - Running as root, or\n" );
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fprintf( stderr, " - Setting /proc/sys/kernel/perf_event_paranoid to -1 or 0, or\n" );
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fprintf( stderr, " - Granting CAP_PERFMON + CAP_SYS_PTRACE capabilities\n" );
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}
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return true;
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}
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static bool ProcessIsAlive( pid_t pid )
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{
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return kill( pid, 0 ) == 0;
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}
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// Try opening one perf event against the target so we fail fast with a clear
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// message instead of starting the profiler and silently producing no samples.
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static bool PreflightPerfEventOpen( pid_t pid )
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{
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perf_event_attr pe = {};
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pe.type = PERF_TYPE_SOFTWARE;
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pe.size = sizeof( perf_event_attr );
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pe.config = PERF_COUNT_SW_CPU_CLOCK;
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pe.disabled = 1;
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pe.exclude_kernel = 1;
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pe.exclude_hv = 1;
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const long fd = syscall( __NR_perf_event_open, &pe, pid, 0, -1, 0 );
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if( fd < 0 )
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{
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const int err = errno;
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if( err == EACCES || err == EPERM )
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{
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fprintf( stderr, "Cannot open perf events for pid %d: %s\n", (int)pid, strerror( err ) );
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fprintf( stderr, "Profiling another process requires one of:\n" );
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fprintf( stderr, " - running as root, or\n" );
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fprintf( stderr, " - /proc/sys/kernel/perf_event_paranoid <= 0, or\n" );
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fprintf( stderr, " - CAP_PERFMON + CAP_SYS_PTRACE capabilities\n" );
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return false;
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}
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if( err == ESRCH )
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{
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fprintf( stderr, "Target process %d no longer exists.\n", (int)pid );
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return false;
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}
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// Other errors may still be recoverable in the real setup path.
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fprintf( stderr, "Warning: perf_event_open preflight failed: %s\n", strerror( err ) );
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return true;
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}
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close( (int)fd );
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return true;
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}
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static void PrintUsage( const char* progName )
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{
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printf( "tracy-monitor %i.%i.%i / %s\n\n", tracy::Version::Major, tracy::Version::Minor, tracy::Version::Patch, tracy::GitRef );
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printf( "Usage: %s [OPTIONS] program [arguments...]\n", progName );
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printf( " %s [OPTIONS] -p PID\n", progName );
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printf( "\n" );
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printf( "Options:\n" );
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printf( " -p PID Attach to existing process (PID)\n" );
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printf( " -h Show this help message\n" );
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printf( "\n" );
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printf( "Examples:\n" );
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printf( " %s ./my_program arg1 arg2\n", progName );
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printf( " %s -p 1234\n", progName );
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printf( "\n" );
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printf( "The monitor captures sampling profiling data from an external process\n" );
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printf( "and streams it to a Tracy server for visualization.\n" );
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printf( "\n" );
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printf( "In launch mode, the target program is started under ptrace control to\n" );
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printf( "ensure profiling begins before the first instruction executes.\n" );
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printf( "\n" );
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printf( "In attach mode (-p), the target must already be running.\n" );
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}
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static int RunAttached( pid_t pid )
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{
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if( !ProcessIsAlive( pid ) )
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{
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fprintf( stderr, "Process %d does not exist or is not accessible.\n", (int)pid );
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return 1;
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}
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s_targetPid = pid;
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char procName[64] = {};
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if( ReadProcessName( pid, procName, sizeof( procName ) ) )
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{
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memcpy( tracy::___tracy_magic_process_name, procName, sizeof( tracy::___tracy_magic_process_name ) );
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}
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printf( "Attaching to process %d", (int)pid );
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if( tracy::___tracy_magic_process_name[0] ) printf( " (%s)", tracy::___tracy_magic_process_name );
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printf( "...\n" );
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fflush( stdout );
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if( !PreflightPerfEventOpen( pid ) ) return 1;
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tracy::InitExternalImageCache( pid );
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tracy::___tracy_magic_pid_override = (uint32_t)pid;
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tracy::StartupProfiler();
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printf( "Profiling started. Waiting for Tracy server connection...\n" );
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// Wait for the target process to exit, or for a signal
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while( !s_shouldQuit && ProcessIsAlive( pid ) )
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{
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usleep( 100000 ); // 100ms poll
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}
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if( s_shouldQuit )
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{
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printf( "\nShutting down profiler...\n" );
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}
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else
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{
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printf( "Target process %d exited.\n", (int)pid );
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}
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tracy::ShutdownProfiler();
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return 0;
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}
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static int RunForked( int argc, char** argv )
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{
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pid_t childPid = fork();
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if( childPid < 0 )
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{
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fprintf( stderr, "Unable to fork: %s\n", strerror( errno ) );
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return 2;
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}
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if( childPid == 0 )
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{
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// Child process: request ptrace stop at exec, then exec the target
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if( ptrace( PTRACE_TRACEME, 0, nullptr, nullptr ) < 0 )
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{
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fprintf( stderr, "ptrace(TRACEME) failed: %s\n", strerror( errno ) );
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_exit( 2 );
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}
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execvp( argv[0], argv );
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fprintf( stderr, "Unable to exec '%s': %s\n", argv[0], strerror( errno ) );
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_exit( 2 );
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}
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// Parent: wait for the child to stop at the exec boundary (SIGTRAP)
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s_targetPid = childPid;
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s_isForked = true;
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int status;
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for(;;)
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{
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if( waitpid( childPid, &status, 0 ) >= 0 ) break;
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if( errno == EINTR ) continue;
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fprintf( stderr, "waitpid failed: %s\n", strerror( errno ) );
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kill( childPid, SIGKILL );
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waitpid( childPid, nullptr, 0 );
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return 2;
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}
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if( !WIFSTOPPED( status ) )
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{
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// Child exited or was killed before reaching the post-exec SIGTRAP.
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if( s_shouldQuit )
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{
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fprintf( stderr, "\nInterrupted before target started.\n" );
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}
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else if( WIFEXITED( status ) )
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{
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fprintf( stderr, "Target exited before profiling began (status %d) -- exec failed?\n", WEXITSTATUS( status ) );
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}
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else if( WIFSIGNALED( status ) )
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{
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fprintf( stderr, "Target killed by signal %d before profiling began.\n", WTERMSIG( status ) );
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}
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else
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{
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fprintf( stderr, "Child process did not stop as expected (status=0x%x).\n", status );
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}
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return 2;
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}
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// The child has exec'd but is stopped. Its address space is now the target program.
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// Read its process name and memory maps.
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char procName[64] = {};
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if( ReadProcessName( childPid, procName, sizeof( procName ) ) )
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{
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memcpy( tracy::___tracy_magic_process_name, procName, sizeof( tracy::___tracy_magic_process_name ) );
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}
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printf( "Profiling '%s' (pid %d)...\n",
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tracy::___tracy_magic_process_name[0] ? tracy::___tracy_magic_process_name : argv[0],
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(int)childPid );
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fflush( stdout );
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if( !PreflightPerfEventOpen( childPid ) )
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{
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kill( childPid, SIGKILL );
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waitpid( childPid, nullptr, 0 );
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return 1;
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}
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// Initialize the external image cache (target's /proc/pid/maps)
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tracy::InitExternalImageCache( childPid );
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// Set up the profiler to target the child
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tracy::___tracy_magic_pid_override = (uint32_t)childPid;
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tracy::StartupProfiler();
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// Detach ptrace and let the child run. If detach fails the child stays
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// stopped forever, so this has to be fatal.
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if( ptrace( PTRACE_DETACH, childPid, nullptr, nullptr ) < 0 )
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{
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fprintf( stderr, "ptrace(DETACH) failed: %s -- killing child.\n", strerror( errno ) );
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kill( childPid, SIGKILL );
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waitpid( childPid, nullptr, 0 );
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tracy::ShutdownProfiler();
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return 2;
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}
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printf( "Profiling started. Waiting for Tracy server connection...\n" );
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// Wait for child to exit, or for a signal
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for(;;)
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{
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if( s_shouldQuit ) break;
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int wstatus;
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pid_t ret = waitpid( childPid, &wstatus, WNOHANG );
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if( ret > 0 )
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{
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if( WIFEXITED( wstatus ) )
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{
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printf( "Target process exited with status %d.\n", WEXITSTATUS( wstatus ) );
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}
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else if( WIFSIGNALED( wstatus ) )
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{
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printf( "Target process killed by signal %d.\n", WTERMSIG( wstatus ) );
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}
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break;
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}
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else if( ret < 0 && errno != EINTR )
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{
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// Child already gone
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break;
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}
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usleep( 100000 );
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}
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if( s_shouldQuit && ProcessIsAlive( childPid ) )
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{
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printf( "\nForwarding signal to child and shutting down...\n" );
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kill( childPid, SIGINT );
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// Give it a moment to exit
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usleep( 500000 );
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if( ProcessIsAlive( childPid ) )
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{
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kill( childPid, SIGKILL );
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waitpid( childPid, nullptr, 0 );
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}
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}
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tracy::ShutdownProfiler();
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return 0;
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}
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int main( int argc, char** argv )
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{
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auto progName = argv[0];
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if( argc < 2 )
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{
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PrintUsage( progName );
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return 1;
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}
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// Install signal handlers for graceful shutdown
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struct sigaction sa = {};
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sa.sa_handler = SignalHandler;
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sigemptyset( &sa.sa_mask );
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sa.sa_flags = 0;
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sigaction( SIGINT, &sa, nullptr );
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sigaction( SIGTERM, &sa, nullptr );
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sigaction( SIGHUP, &sa, nullptr );
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sigaction( SIGQUIT, &sa, nullptr );
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pid_t attachPid = 0;
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bool wantAttach = false;
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static struct option longOptions[] = {
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{ "pid", required_argument, nullptr, 'p' },
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{ "help", no_argument, nullptr, 'h' },
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{ nullptr, 0, nullptr, 0 }
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};
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int c;
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while( ( c = getopt_long( argc, argv, "+p:h", longOptions, nullptr ) ) != -1 )
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{
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switch( c )
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{
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case 'p':
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attachPid = atoi( optarg );
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wantAttach = true;
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break;
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case 'h':
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PrintUsage( argv[0] );
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return 0;
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case '?':
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fprintf( stderr, "Unknown option. Use -h for help.\n" );
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return 1;
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}
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}
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argv += optind;
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argc -= optind;
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CheckPerfPermissions();
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if( wantAttach )
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{
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if( attachPid <= 0 )
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{
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fprintf( stderr, "Invalid PID specified.\n" );
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return 1;
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}
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return RunAttached( attachPid );
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}
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if( argc < 1 )
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{
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PrintUsage( progName ); // argv[0] was shifted, use original
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return 1;
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}
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return RunForked( argc, argv );
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}
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Block a user