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-rw-r--r--arch/um/include/linux/time-internal.h2
-rw-r--r--arch/um/kernel/skas/syscall.c11
2 files changed, 13 insertions, 0 deletions
diff --git a/arch/um/include/linux/time-internal.h b/arch/um/include/linux/time-internal.h
index b22226634ff6..138908b999d7 100644
--- a/arch/um/include/linux/time-internal.h
+++ b/arch/um/include/linux/time-internal.h
@@ -83,6 +83,8 @@ extern void time_travel_not_configured(void);
#define time_travel_del_event(...) time_travel_not_configured()
#endif /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
+extern unsigned long tt_extra_sched_jiffies;
+
/*
* Without CONFIG_UML_TIME_TRAVEL_SUPPORT this is a linker error if used,
* which is intentional since we really shouldn't link it in that case.
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index b09e85279d2b..a5beaea2967e 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -31,6 +31,17 @@ void handle_syscall(struct uml_pt_regs *r)
goto out;
syscall = UPT_SYSCALL_NR(r);
+
+ /*
+ * If no time passes, then sched_yield may not actually yield, causing
+ * broken spinlock implementations in userspace (ASAN) to hang for long
+ * periods of time.
+ */
+ if ((time_travel_mode == TT_MODE_INFCPU ||
+ time_travel_mode == TT_MODE_EXTERNAL) &&
+ syscall == __NR_sched_yield)
+ tt_extra_sched_jiffies += 1;
+
if (syscall >= 0 && syscall < __NR_syscalls) {
unsigned long ret = EXECUTE_SYSCALL(syscall, regs);