diff options
| author | Bob Moore <robert.moore@intel.com> | 2008-11-12 15:15:29 +0800 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2008-12-29 22:38:36 -0500 |
| commit | fc37445733aeae4fd1a20385850620354263b1d5 (patch) | |
| tree | a989d6bf8dcc2011f25e365532c3855a48f11c62 /drivers/acpi/dispatcher | |
| parent | 96411a630412f057d365aa1e9de7d23c069d627a (diff) | |
ACPICA: Add a mechanism to escape infinite AML While() loops
Add a loop counter to force exit from AML While loops if the
count becomes too large. This can occur in poorly written AML
when the hardware does not respond within a while loop and the
loop does not implement a timeout. The maximum loop count is
configurable. A new exception code is returned when a loop is
broken, AE_AML_INFINITE_LOOP. Bob Moore, Alexey Starikovskiy.
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi/dispatcher')
| -rw-r--r-- | drivers/acpi/dispatcher/dsopcode.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/drivers/acpi/dispatcher/dsopcode.c b/drivers/acpi/dispatcher/dsopcode.c index 5cd406676c2c..50c892a49fa3 100644 --- a/drivers/acpi/dispatcher/dsopcode.c +++ b/drivers/acpi/dispatcher/dsopcode.c @@ -1262,13 +1262,31 @@ acpi_ds_exec_end_control_op(struct acpi_walk_state * walk_state, ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op)); - if (walk_state->control_state->common.value) { + control_state = walk_state->control_state; + if (control_state->common.value) { - /* Predicate was true, go back and evaluate it again! */ + /* Predicate was true, the body of the loop was just executed */ + /* + * This loop counter mechanism allows the interpreter to escape + * possibly infinite loops. This can occur in poorly written AML + * when the hardware does not respond within a while loop and the + * loop does not implement a timeout. + */ + control_state->control.loop_count++; + if (control_state->control.loop_count > + ACPI_MAX_LOOP_ITERATIONS) { + status = AE_AML_INFINITE_LOOP; + break; + } + + /* + * Go back and evaluate the predicate and maybe execute the loop + * another time + */ status = AE_CTRL_PENDING; walk_state->aml_last_while = - walk_state->control_state->control.aml_predicate_start; + control_state->control.aml_predicate_start; break; } |