2019-04-18 09:11:45

by Thomas Gleixner

Subject: [patch V2 25/29] livepatch: Simplify stack trace retrieval

Replace the indirection through struct stack_trace by using the storage
array based interfaces.

Signed-off-by: Thomas Gleixner <[email protected]>
---
kernel/livepatch/transition.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)

--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -202,15 +202,15 @@ void klp_update_patch_state(struct task_
* Determine whether the given stack trace includes any references to a
* to-be-patched or to-be-unpatched function.
*/
-static int klp_check_stack_func(struct klp_func *func,
- struct stack_trace *trace)
+static int klp_check_stack_func(struct klp_func *func, unsigned long *entries,
+ unsigned int nr_entries)
{
unsigned long func_addr, func_size, address;
struct klp_ops *ops;
int i;

- for (i = 0; i < trace->nr_entries; i++) {
- address = trace->entries[i];
+ for (i = 0; i < nr_entries; i++) {
+ address = entries[i];

if (klp_target_state == KLP_UNPATCHED) {
/*
@@ -254,29 +254,25 @@ static int klp_check_stack_func(struct k
static int klp_check_stack(struct task_struct *task, char *err_buf)
{
static unsigned long entries[MAX_STACK_ENTRIES];
- struct stack_trace trace;
struct klp_object *obj;
struct klp_func *func;
- int ret;
+ int ret, nr_entries;

- trace.skip = 0;
- trace.nr_entries = 0;
- trace.max_entries = MAX_STACK_ENTRIES;
- trace.entries = entries;
- ret = save_stack_trace_tsk_reliable(task, &trace);
+ ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
WARN_ON_ONCE(ret == -ENOSYS);
- if (ret) {
+ if (ret < 0) {
snprintf(err_buf, STACK_ERR_BUF_SIZE,
"%s: %s:%d has an unreliable stack\n",
__func__, task->comm, task->pid);
return ret;
}
+ nr_entries = ret;

klp_for_each_object(klp_transition_patch, obj) {
if (!obj->patched)
continue;
klp_for_each_func(obj, func) {
- ret = klp_check_stack_func(func, &trace);
+ ret = klp_check_stack_func(func, entries, nr_entries);
if (ret) {
snprintf(err_buf, STACK_ERR_BUF_SIZE,
"%s: %s:%d is sleeping on function %s\n",

2019-04-23 08:19:49

by Miroslav Benes

Subject: Re: [patch V2 25/29] livepatch: Simplify stack trace retrieval

On Thu, 18 Apr 2019, Thomas Gleixner wrote:

> Replace the indirection through struct stack_trace by using the storage
> array based interfaces.
>
> Signed-off-by: Thomas Gleixner <[email protected]>

Acked-by: Miroslav Benes <[email protected]>

Feel free to take it through tip or let us know to pick it up.

Miroslav