[tip:,sched/core] livepatch: Convert stack entries array to percpu
Commit Message
The following commit has been merged into the sched/core branch of tip:
Commit-ID: e92606fa172f63a26054885b9715be86c643229d
Gitweb: https://git.kernel.org/tip/e92606fa172f63a26054885b9715be86c643229d
Author: Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate: Mon, 13 Mar 2023 16:33:46 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 22 Mar 2023 17:09:28 +01:00
livepatch: Convert stack entries array to percpu
The entries array in klp_check_stack() is static local because it's too
big to be reasonably allocated on the stack. Serialized access is
enforced by the klp_mutex.
In preparation for calling klp_check_stack() without the mutex (from
cond_resched), convert it to a percpu variable.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230313233346.kayh4t2lpicjkpsv@treble
---
kernel/livepatch/transition.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
@@ -14,6 +14,8 @@
#include "transition.h"
#define MAX_STACK_ENTRIES 100
+DEFINE_PER_CPU(unsigned long[MAX_STACK_ENTRIES], klp_stack_entries);
+
#define STACK_ERR_BUF_SIZE 128
#define SIGNALS_TIMEOUT 15
@@ -240,12 +242,15 @@ static int klp_check_stack_func(struct klp_func *func, unsigned long *entries,
*/
static int klp_check_stack(struct task_struct *task, const char **oldname)
{
- static unsigned long entries[MAX_STACK_ENTRIES];
+ unsigned long *entries = this_cpu_ptr(klp_stack_entries);
struct klp_object *obj;
struct klp_func *func;
int ret, nr_entries;
- ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
+ /* Protect 'klp_stack_entries' */
+ lockdep_assert_preemption_disabled();
+
+ ret = stack_trace_save_tsk_reliable(task, entries, MAX_STACK_ENTRIES);
if (ret < 0)
return -EINVAL;
nr_entries = ret;