static struct btrace_function *
ftrace_new_switch (struct btrace_function *prev,
struct minimal_symbol *mfun,
struct symbol *fun)
{
struct btrace_function *bfun;
/* This is an unexplained function switch. The call stack will likely
be wrong at this point. */
bfun = ftrace_new_function (prev, mfun, fun);
ftrace_debug (bfun, "new switch");
return bfun;
}
static struct btrace_function *
ftrace_new_call (struct btrace_function *caller,
struct minimal_symbol *mfun,
struct symbol *fun)
{
struct btrace_function *bfun;
bfun = ftrace_new_function (caller, mfun, fun);
bfun->up = caller;
bfun->level += 1;
ftrace_debug (bfun, "new call");
return bfun;
}
static struct btrace_function *
ftrace_new_tailcall (struct btrace_function *caller,
struct minimal_symbol *mfun,
struct symbol *fun)
{
struct btrace_function *bfun;
bfun = ftrace_new_function (caller, mfun, fun);
bfun->up = caller;
bfun->level += 1;
bfun->flags |= BFUN_UP_LINKS_TO_TAILCALL;
ftrace_debug (bfun, "new tail call");
return bfun;
}
static struct btrace_function *
ftrace_new_gap (struct btrace_function *prev, int errcode)
{
struct btrace_function *bfun;
/* We hijack prev if it was empty. */
if (prev != NULL && prev->errcode == 0
&& VEC_empty (btrace_insn_s, prev->insn))
bfun = prev;
else
bfun = ftrace_new_function (prev, NULL, NULL);
bfun->errcode = errcode;
ftrace_debug (bfun, "new gap");
return bfun;
}
static struct btrace_function *
ftrace_update_function (struct btrace_function *bfun, CORE_ADDR pc)
{
struct bound_minimal_symbol bmfun;
struct minimal_symbol *mfun;
struct symbol *fun;
struct btrace_insn *last;
/* Try to determine the function we're in. We use both types of symbols
to avoid surprises when we sometimes get a full symbol and sometimes
only a minimal symbol. */
fun = find_pc_function (pc);
bmfun = lookup_minimal_symbol_by_pc (pc);
mfun = bmfun.minsym;
if (fun == NULL && mfun == NULL)
DEBUG_FTRACE ("no symbol at %s", core_addr_to_string_nz (pc));
/* If we didn't have a function or if we had a gap before, we create one. */
if (bfun == NULL || bfun->errcode != 0)
return ftrace_new_function (bfun, mfun, fun);
/* Check the last instruction, if we have one.
We do this check first, since it allows us to fill in the call stack
links in addition to the normal flow links. */
last = NULL;
if (!VEC_empty (btrace_insn_s, bfun->insn))
last = VEC_last (btrace_insn_s, bfun->insn);
if (last != NULL)
{
switch (last->iclass)
{
case BTRACE_INSN_RETURN:
{
const char *fname;
/* On some systems, _dl_runtime_resolve returns to the resolved
function instead of jumping to it. From our perspective,
however, this is a tailcall.
If we treated it as return, we wouldn't be able to find the
resolved function in our stack back trace. Hence, we would
lose the current stack back trace and start anew with an empty
back trace. When the resolved function returns, we would then
create a stack back trace with the same function names but
different frame id's. This will confuse stepping. */
fname = ftrace_print_function_name (bfun);
if (strcmp (fname, "_dl_runtime_resolve") == 0)
return ftrace_new_tailcall (bfun, mfun, fun);
return ftrace_new_return (bfun, mfun, fun);
}
case BTRACE_INSN_CALL:
/* Ignore calls to the next instruction. They are used for PIC. */
if (last->pc + last->size == pc)
break;
return ftrace_new_call (bfun, mfun, fun);
case BTRACE_INSN_JUMP:
{
CORE_ADDR start;
start = get_pc_function_start (pc);
/* If we can't determine the function for PC, we treat a jump at
the end of the block as tail call. */
if (start == 0 || start == pc)
return ftrace_new_tailcall (bfun, mfun, fun);
}
}
}
/* Check if we're switching functions for some other reason. */
if (ftrace_function_switched (bfun, mfun, fun))
{
DEBUG_FTRACE ("switching from %s in %s at %s",
ftrace_print_insn_addr (last),
ftrace_print_function_name (bfun),
ftrace_print_filename (bfun));
return ftrace_new_switch (bfun, mfun, fun);
}
return bfun;
}
static struct btrace_function *
ftrace_new_return (struct btrace_function *prev,
struct minimal_symbol *mfun,
struct symbol *fun)
{
struct btrace_function *bfun, *caller;
bfun = ftrace_new_function (prev, mfun, fun);
/* It is important to start at PREV's caller. Otherwise, we might find
PREV itself, if PREV is a recursive function. */
caller = ftrace_find_caller (prev->up, mfun, fun);
if (caller != NULL)
{
/* The caller of PREV is the preceding btrace function segment in this
function instance. */
gdb_assert (caller->segment.next == NULL);
caller->segment.next = bfun;
bfun->segment.prev = caller;
/* Maintain the function level. */
bfun->level = caller->level;
/* Maintain the call stack. */
bfun->up = caller->up;
bfun->flags = caller->flags;
ftrace_debug (bfun, "new return");
}
else
{
/* We did not find a caller. This could mean that something went
wrong or that the call is simply not included in the trace. */
/* Let's search for some actual call. */
caller = ftrace_find_call (prev->up);
if (caller == NULL)
{
/* There is no call in PREV's back trace. We assume that the
branch trace did not include it. */
/* Let's find the topmost call function - this skips tail calls. */
while (prev->up != NULL)
prev = prev->up;
/* We maintain levels for a series of returns for which we have
not seen the calls.
We start at the preceding function's level in case this has
already been a return for which we have not seen the call.
We start at level 0 otherwise, to handle tail calls correctly. */
bfun->level = min (0, prev->level) - 1;
/* Fix up the call stack for PREV. */
ftrace_fixup_caller (prev, bfun, BFUN_UP_LINKS_TO_RET);
ftrace_debug (bfun, "new return - no caller");
}
else
{
/* There is a call in PREV's back trace to which we should have
returned. Let's remain at this level. */
bfun->level = prev->level;
ftrace_debug (bfun, "new return - unknown caller");
}
}
return bfun;
}
static struct btrace_function *
ftrace_update_function (struct gdbarch *gdbarch,
struct btrace_function *bfun, CORE_ADDR pc)
{
struct bound_minimal_symbol bmfun;
struct minimal_symbol *mfun;
struct symbol *fun;
struct btrace_insn *last;
/* Try to determine the function we're in. We use both types of symbols
to avoid surprises when we sometimes get a full symbol and sometimes
only a minimal symbol. */
fun = find_pc_function (pc);
bmfun = lookup_minimal_symbol_by_pc (pc);
mfun = bmfun.minsym;
if (fun == NULL && mfun == NULL)
DEBUG_FTRACE ("no symbol at %s", core_addr_to_string_nz (pc));
/* If we didn't have a function before, we create one. */
if (bfun == NULL)
return ftrace_new_function (bfun, mfun, fun);
/* Check the last instruction, if we have one.
We do this check first, since it allows us to fill in the call stack
links in addition to the normal flow links. */
last = NULL;
if (!VEC_empty (btrace_insn_s, bfun->insn))
last = VEC_last (btrace_insn_s, bfun->insn);
if (last != NULL)
{
CORE_ADDR lpc;
lpc = last->pc;
/* Check for returns. */
if (gdbarch_insn_is_ret (gdbarch, lpc))
return ftrace_new_return (gdbarch, bfun, mfun, fun);
/* Check for calls. */
if (gdbarch_insn_is_call (gdbarch, lpc))
{
int size;
size = gdb_insn_length (gdbarch, lpc);
/* Ignore calls to the next instruction. They are used for PIC. */
if (lpc + size != pc)
return ftrace_new_call (bfun, mfun, fun);
}
}
/* Check if we're switching functions for some other reason. */
if (ftrace_function_switched (bfun, mfun, fun))
{
DEBUG_FTRACE ("switching from %s in %s at %s",
ftrace_print_insn_addr (last),
ftrace_print_function_name (bfun),
ftrace_print_filename (bfun));
if (last != NULL)
{
CORE_ADDR start, lpc;
start = get_pc_function_start (pc);
/* If we can't determine the function for PC, we treat a jump at
the end of the block as tail call. */
if (start == 0)
start = pc;
lpc = last->pc;
/* Jumps indicate optimized tail calls. */
if (start == pc && gdbarch_insn_is_jump (gdbarch, lpc))
return ftrace_new_tailcall (bfun, mfun, fun);
}
return ftrace_new_switch (bfun, mfun, fun);
}
return bfun;
}
