mirror of
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197 lines
5.2 KiB
C
197 lines
5.2 KiB
C
/* 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 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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};
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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 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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/* Skip thunks and recover functions. There is no equivalent to
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these functions in the gc toolchain, so returning them here means
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significantly different results for runtime.Caller(N). */
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if (function != NULL && !arg->keep_thunks)
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{
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const char *p;
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p = __builtin_strchr (function, '.');
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if (p != NULL && __builtin_strncmp (p + 1, "$thunk", 6) == 0)
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return 0;
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p = __builtin_strrchr (function, '$');
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if (p != NULL && __builtin_strcmp(p, "$recover") == 0)
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return 0;
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}
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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, "kickoff") == 0
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|| __builtin_strcmp (function, "runtime_mstart") == 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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/* 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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/* 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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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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runtime_xadd (&runtime_in_callers, 1);
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backtrace_full (__go_get_backtrace_state (), 0, callback, error_callback,
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&data);
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runtime_xadd (&runtime_in_callers, -1);
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return data.index;
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}
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int Callers (int, struct __go_open_array)
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__asm__ (GOSYM_PREFIX "runtime.Callers");
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int
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Callers (int 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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locbuf = (Location *) runtime_mal (pc.__count * sizeof (Location));
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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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