[PATCH] Fix PR 17206

Yao Qi
2014-07-28T11:34:41Z

As reported in PR 17206, an internal error is triggered when command
until is executed. In infcmd.c:until_next_command, step_range_end is
set to 'pc',

if (!func)
{
struct bound_minimal_symbol msymbol = lookup_minimal_symbol_by_pc (pc);

if (msymbol.minsym == NULL)
error (_("Execution is not within a known function."));

tp->control.step_range_start = BMSYMBOL_VALUE_ADDRESS (msymbol);
tp->control.step_range_end = pc;
}

and later in infrun.c:resume, the assert below is triggered in PR
17206.

if (tp->control.may_range_step)
{
/* If we're resuming a thread with the PC out of the step
range, then we're doing some nested/finer run control
operation, like stepping the thread out of the dynamic
linker or the displaced stepping scratch pad. We
shouldn't have allowed a range step then. */
gdb_assert (pc_in_thread_step_range (pc, tp));
}

In until_next_command, we set step range to [XXX, pc), so pc isn't
within the range. pc_in_thread_step_range returns false and the
assert is triggered. AFAICS, the range we want in until_next_command
is [XXX, pc] instead of [XXX, pc), because we want to program step
until greater than pc. This patch is to set step_range_end to
'pc + 1'.

Regression tested on x86_64-linux, both native and gdbserver.

gdb:

2014-07-28 Yao Qi <yao@codesourcery.com>

PR gdb/17206
* infcmd.c (until_next_command): Set step_range_end to PC + 1.
---
gdb/infcmd.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 76ec560..50cc04b 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -1359,7 +1359,9 @@ until_next_command (int from_tty)
error (_("Execution is not within a known function."));

tp->control.step_range_start = BMSYMBOL_VALUE_ADDRESS (msymbol);
- tp->control.step_range_end = pc;
+ /* The upper-bound of step_range is exclusive. In order to make PC
+ within the range, set the step_range_end with PC + 1. */
+ tp->control.step_range_end = pc + 1;
}
else
{
--
1.9.0