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-rw-r--r--kernel/kcsan/core.c28
-rw-r--r--kernel/kcsan/kcsan.h7
-rw-r--r--kernel/kcsan/report.c12
3 files changed, 40 insertions, 7 deletions
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 1866bafda4fd..9147ff6a12e5 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -291,6 +291,20 @@ static inline unsigned int get_delay(void)
0);
}
+void kcsan_save_irqtrace(struct task_struct *task)
+{
+#ifdef CONFIG_TRACE_IRQFLAGS
+ task->kcsan_save_irqtrace = task->irqtrace;
+#endif
+}
+
+void kcsan_restore_irqtrace(struct task_struct *task)
+{
+#ifdef CONFIG_TRACE_IRQFLAGS
+ task->irqtrace = task->kcsan_save_irqtrace;
+#endif
+}
+
/*
* Pull everything together: check_access() below contains the performance
* critical operations; the fast-path (including check_access) functions should
@@ -336,9 +350,11 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
flags = user_access_save();
if (consumed) {
+ kcsan_save_irqtrace(current);
kcsan_report(ptr, size, type, KCSAN_VALUE_CHANGE_MAYBE,
KCSAN_REPORT_CONSUMED_WATCHPOINT,
watchpoint - watchpoints);
+ kcsan_restore_irqtrace(current);
} else {
/*
* The other thread may not print any diagnostics, as it has
@@ -396,9 +412,14 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
goto out;
}
+ /*
+ * Save and restore the IRQ state trace touched by KCSAN, since KCSAN's
+ * runtime is entered for every memory access, and potentially useful
+ * information is lost if dirtied by KCSAN.
+ */
+ kcsan_save_irqtrace(current);
if (!kcsan_interrupt_watcher)
- /* Use raw to avoid lockdep recursion via IRQ flags tracing. */
- raw_local_irq_save(irq_flags);
+ local_irq_save(irq_flags);
watchpoint = insert_watchpoint((unsigned long)ptr, size, is_write);
if (watchpoint == NULL) {
@@ -539,7 +560,8 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
kcsan_counter_dec(KCSAN_COUNTER_USED_WATCHPOINTS);
out_unlock:
if (!kcsan_interrupt_watcher)
- raw_local_irq_restore(irq_flags);
+ local_irq_restore(irq_flags);
+ kcsan_restore_irqtrace(current);
out:
user_access_restore(ua_flags);
}
diff --git a/kernel/kcsan/kcsan.h b/kernel/kcsan/kcsan.h
index 763d6d08d94b..29480010dc30 100644
--- a/kernel/kcsan/kcsan.h
+++ b/kernel/kcsan/kcsan.h
@@ -9,6 +9,7 @@
#define _KERNEL_KCSAN_KCSAN_H
#include <linux/kcsan.h>
+#include <linux/sched.h>
/* The number of adjacent watchpoints to check. */
#define KCSAN_CHECK_ADJACENT 1
@@ -23,6 +24,12 @@ extern unsigned int kcsan_udelay_interrupt;
extern bool kcsan_enabled;
/*
+ * Save/restore IRQ flags state trace dirtied by KCSAN.
+ */
+void kcsan_save_irqtrace(struct task_struct *task);
+void kcsan_restore_irqtrace(struct task_struct *task);
+
+/*
* Initialize debugfs file.
*/
void kcsan_debugfs_init(void);
diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index ac5f8345bae9..9d07e175de0f 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -308,6 +308,9 @@ static void print_verbose_info(struct task_struct *task)
if (!task)
return;
+ /* Restore IRQ state trace for printing. */
+ kcsan_restore_irqtrace(task);
+
pr_err("\n");
debug_show_held_locks(task);
print_irqtrace_events(task);
@@ -606,10 +609,11 @@ void kcsan_report(const volatile void *ptr, size_t size, int access_type,
goto out;
/*
- * With TRACE_IRQFLAGS, lockdep's IRQ trace state becomes corrupted if
- * we do not turn off lockdep here; this could happen due to recursion
- * into lockdep via KCSAN if we detect a race in utilities used by
- * lockdep.
+ * Because we may generate reports when we're in scheduler code, the use
+ * of printk() could deadlock. Until such time that all printing code
+ * called in print_report() is scheduler-safe, accept the risk, and just
+ * get our message out. As such, also disable lockdep to hide the
+ * warning, and avoid disabling lockdep for the rest of the kernel.
*/
lockdep_off();