403 lines
11 KiB
C
403 lines
11 KiB
C
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/* go-callers.c -- get callers for Go.
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Copyright 2012 The Go Authors. All rights reserved.
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Use of this source code is governed by a BSD-style
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license that can be found in the LICENSE file. */
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#include "config.h"
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#include "backtrace.h"
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#include "runtime.h"
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#include "array.h"
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/* This is set to non-zero when calling backtrace_full. This is used
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to avoid getting hanging on a recursive lock in dl_iterate_phdr on
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older versions of glibc when a SIGPROF signal arrives while
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collecting a backtrace. */
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uint32 __go_runtime_in_callers;
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/* Argument passed to callback function. */
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struct callers_data
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{
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Location *locbuf;
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int skip;
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int index;
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int max;
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int keep_thunks;
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int saw_sigtramp;
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};
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/* Whether to skip a particular function name in the traceback. This
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is mostly to keep the output similar to the gc output for
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runtime.Caller(N).
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See also similar code in runtime/mprof.go that strips out such
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functions for block/mutex/memory profiles. */
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bool
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runtime_skipInCallback(const char *function, struct callers_data *arg)
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{
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const char *p;
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/* Skip thunks and recover functions. There is no equivalent to
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these functions in the gc toolchain. */
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p = function + __builtin_strlen (function);
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while (p > function && p[-1] >= '0' && p[-1] <= '9')
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--p;
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if (p - function > 7 && __builtin_strncmp (p - 7, "..thunk", 7) == 0)
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return true;
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if (p - function > 3 && __builtin_strcmp (p - 3, "..r") == 0)
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return true;
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if (p - function > 6 && __builtin_strncmp (p - 6, "..stub", 6) == 0)
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return true;
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/* Skip runtime.deferreturn and runtime.sighandler as the gc
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compiler has no corresponding function. */
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if (p - function == sizeof ("runtime.deferreturn") - 1
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&& __builtin_strcmp (function, "runtime.deferreturn") == 0)
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return true;
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if (p - function == sizeof ("runtime.sighandler") - 1
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&& __builtin_strcmp (function, "runtime.sighandler") == 0)
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return true;
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/* Skip the signal handler functions that remain on the stack for us
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but not for gc. */
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if ((p - function == sizeof ("runtime.sigtramp") - 1
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&& __builtin_strcmp (function, "runtime.sigtramp") == 0)
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|| (p - function == sizeof ("runtime.sigtrampgo") - 1
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&& __builtin_strcmp (function, "runtime.sigtrampgo") == 0))
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{
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/* Also try to skip the signal handler function. */
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if (arg != NULL)
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arg->saw_sigtramp = 1;
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return true;
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}
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return false;
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}
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/* Callback function for backtrace_full. Just collect the locations.
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Return zero to continue, non-zero to stop. */
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static int
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callback (void *data, uintptr_t pc, const char *filename, int lineno,
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const char *function)
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{
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struct callers_data *arg = (struct callers_data *) data;
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Location *loc;
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/* Skip an unnamed function above sigtramp. It is likely the signal
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handler function. */
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if (arg->saw_sigtramp)
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{
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arg->saw_sigtramp = 0;
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if (function == NULL)
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return 0;
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}
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/* Skip split stack functions. */
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if (function != NULL)
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{
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const char *p;
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p = function;
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if (__builtin_strncmp (p, "___", 3) == 0)
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++p;
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if (__builtin_strncmp (p, "__morestack_", 12) == 0)
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return 0;
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}
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else if (filename != NULL)
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{
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const char *p;
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p = strrchr (filename, '/');
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if (p == NULL)
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p = filename;
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if (__builtin_strncmp (p, "/morestack.S", 12) == 0)
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return 0;
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}
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if (function != NULL
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&& !arg->keep_thunks
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&& runtime_skipInCallback (function, arg))
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return 0;
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if (arg->skip > 0)
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{
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--arg->skip;
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return 0;
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}
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loc = &arg->locbuf[arg->index];
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/* On the call to backtrace_full the pc value was most likely
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decremented if there was a normal call, since the pc referred to
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the instruction where the call returned and not the call itself.
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This was done so that the line number referred to the call
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instruction. To make sure the actual pc from the call stack is
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used, it is incremented here.
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In the case of a signal, the pc was not decremented by
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backtrace_full but still incremented here. That doesn't really
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hurt anything since the line number is right and the pc refers to
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the same instruction. */
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loc->pc = pc + 1;
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/* The libbacktrace library says that these strings might disappear,
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but with the current implementation they won't. We can't easily
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allocate memory here, so for now assume that we can save a
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pointer to the strings. */
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loc->filename = runtime_gostringnocopy ((const byte *) filename);
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loc->function = runtime_gostringnocopy ((const byte *) function);
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loc->lineno = lineno;
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++arg->index;
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/* There is no point to tracing past certain runtime functions.
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Stopping the backtrace here can avoid problems on systems that
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don't provide proper unwind information for makecontext, such as
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Solaris (http://gcc.gnu.org/PR52583 comment #21). */
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if (function != NULL)
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{
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if (__builtin_strcmp (function, "makecontext") == 0)
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return 1;
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if (filename != NULL)
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{
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const char *p;
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p = strrchr (filename, '/');
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if (p == NULL)
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p = filename;
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if (__builtin_strcmp (p, "/proc.c") == 0)
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{
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if (__builtin_strcmp (function, "runtime_mstart") == 0)
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return 1;
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}
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else if (__builtin_strcmp (p, "/proc.go") == 0)
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{
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if (__builtin_strcmp (function, "runtime.kickoff") == 0
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|| __builtin_strcmp (function, "runtime.main") == 0)
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return 1;
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}
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}
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}
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return arg->index >= arg->max;
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}
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/* Syminfo callback. */
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void
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__go_syminfo_fnname_callback (void *data,
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uintptr_t pc __attribute__ ((unused)),
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const char *symname,
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uintptr_t address __attribute__ ((unused)),
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uintptr_t size __attribute__ ((unused)))
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{
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String* strptr = (String*) data;
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if (symname != NULL)
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*strptr = runtime_gostringnocopy ((const byte *) symname);
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}
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/* Error callback. */
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static void
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error_callback (void *data __attribute__ ((unused)),
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const char *msg, int errnum)
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{
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if (errnum == -1)
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{
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/* No debug info available. Carry on as best we can. */
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return;
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}
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if (errnum != 0)
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runtime_printf ("%s errno %d\n", msg, errnum);
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runtime_throw (msg);
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}
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/* Return whether we are already collecting a stack trace. This is
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called from the signal handler. */
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bool alreadyInCallers(void)
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__attribute__ ((no_split_stack));
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bool alreadyInCallers(void)
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__asm__ (GOSYM_PREFIX "runtime.alreadyInCallers");
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bool
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alreadyInCallers()
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{
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return runtime_atomicload(&__go_runtime_in_callers) > 0;
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}
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/* Gather caller PC's. */
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int32
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runtime_callers (int32 skip, Location *locbuf, int32 m, bool keep_thunks)
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{
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struct callers_data data;
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struct backtrace_state* state;
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int32 i;
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data.locbuf = locbuf;
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data.skip = skip + 1;
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data.index = 0;
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data.max = m;
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data.keep_thunks = keep_thunks;
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data.saw_sigtramp = 0;
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runtime_xadd (&__go_runtime_in_callers, 1);
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state = __go_get_backtrace_state ();
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backtrace_full (state, 0, callback, error_callback, &data);
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runtime_xadd (&__go_runtime_in_callers, -1);
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/* For some reason GCC sometimes loses the name of a thunk function
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at the top of the stack. If we are skipping thunks, skip that
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one too. */
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if (!keep_thunks
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&& data.index > 2
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&& locbuf[data.index - 2].function.len == 0
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&& locbuf[data.index - 1].function.str != NULL
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&& __builtin_strcmp ((const char *) locbuf[data.index - 1].function.str,
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"runtime.kickoff") == 0)
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{
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locbuf[data.index - 2] = locbuf[data.index - 1];
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--data.index;
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}
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/* Try to use backtrace_syminfo to fill in any missing function
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names. This can happen when tracing through an object which has
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no debug info; backtrace_syminfo will look at the symbol table to
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get the name. This should only happen when tracing through code
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that is not written in Go and is not part of libgo. */
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for (i = 0; i < data.index; ++i)
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{
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if (locbuf[i].function.len == 0 && locbuf[i].pc != 0)
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backtrace_syminfo (state, locbuf[i].pc, __go_syminfo_fnname_callback,
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error_callback, &locbuf[i].function);
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}
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return data.index;
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}
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intgo Callers (intgo, struct __go_open_array)
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__asm__ (GOSYM_PREFIX "runtime.Callers");
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intgo
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Callers (intgo skip, struct __go_open_array pc)
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{
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Location *locbuf;
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int ret;
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int i;
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if (pc.__count == 0)
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return 0;
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/* Note that calling mallocgc here assumes that we are not going to
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store any allocated Go pointers in the slice. */
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locbuf = (Location *) runtime_mallocgc (pc.__count * sizeof (Location),
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nil, false);
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/* In the Go 1 release runtime.Callers has an off-by-one error,
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which we can not correct because it would break backward
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compatibility. Normally we would add 1 to SKIP here, but we
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don't so that we are compatible. */
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ret = runtime_callers (skip, locbuf, pc.__count, false);
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for (i = 0; i < ret; i++)
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((uintptr *) pc.__values)[i] = locbuf[i].pc;
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return ret;
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}
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struct callersRaw_data
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{
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uintptr* pcbuf;
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int index;
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int max;
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};
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// Callback function for backtrace_simple. Just collect pc's.
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// Return zero to continue, non-zero to stop.
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static int callback_raw (void *data, uintptr_t pc)
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{
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struct callersRaw_data *arg = (struct callersRaw_data *) data;
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/* On the call to backtrace_simple the pc value was most likely
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decremented if there was a normal call, since the pc referred to
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the instruction where the call returned and not the call itself.
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This was done so that the line number referred to the call
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instruction. To make sure the actual pc from the call stack is
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used, it is incremented here.
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|
|
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In the case of a signal, the pc was not decremented by
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backtrace_full but still incremented here. That doesn't really
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hurt anything since the line number is right and the pc refers to
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the same instruction. */
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arg->pcbuf[arg->index] = pc + 1;
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arg->index++;
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return arg->index >= arg->max;
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}
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/* runtime_callersRaw is similar to runtime_callers() above, but
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it returns raw PC values as opposed to file/func/line locations. */
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int32
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runtime_callersRaw (uintptr *pcbuf, int32 m)
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{
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struct callersRaw_data data;
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struct backtrace_state* state;
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data.pcbuf = pcbuf;
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data.index = 0;
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data.max = m;
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runtime_xadd (&__go_runtime_in_callers, 1);
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state = __go_get_backtrace_state ();
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backtrace_simple (state, 0, callback_raw, error_callback, &data);
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runtime_xadd (&__go_runtime_in_callers, -1);
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return data.index;
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}
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/* runtime_pcInlineCallers returns the inline stack of calls for a PC.
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This is like runtime_callers, but instead of doing a backtrace,
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just finds the information for a single PC value. */
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int32 runtime_pcInlineCallers (uintptr, Location *, int32)
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__asm__ (GOSYM_PREFIX "runtime.pcInlineCallers");
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int32
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runtime_pcInlineCallers (uintptr pc, Location *locbuf, int32 m)
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{
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struct callers_data data;
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struct backtrace_state *state;
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int32 i;
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data.locbuf = locbuf;
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data.skip = 0;
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data.index = 0;
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data.max = m;
|
||
|
|
data.keep_thunks = false;
|
||
|
|
data.saw_sigtramp = 0;
|
||
|
|
runtime_xadd (&__go_runtime_in_callers, 1);
|
||
|
|
state = __go_get_backtrace_state ();
|
||
|
|
backtrace_pcinfo (state, pc, callback, error_callback, &data);
|
||
|
|
runtime_xadd (&__go_runtime_in_callers, -1);
|
||
|
|
|
||
|
|
/* Try to use backtrace_syminfo to fill in missing names. See
|
||
|
|
runtime_callers. */
|
||
|
|
for (i = 0; i < data.index; ++i)
|
||
|
|
{
|
||
|
|
if (locbuf[i].function.len == 0 && locbuf[i].pc != 0)
|
||
|
|
backtrace_syminfo (state, locbuf[i].pc, __go_syminfo_fnname_callback,
|
||
|
|
error_callback, &locbuf[i].function);
|
||
|
|
}
|
||
|
|
|
||
|
|
return data.index;
|
||
|
|
}
|