um: Support time travel mode

[linux-2.6-microblaze.git] / arch / um / kernel / skas / syscall.c

diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index b783ac8..44bb107 100644 (file)
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -10,12 +10,23 @@
 #include <sysdep/ptrace.h>
 #include <sysdep/ptrace_user.h>
 #include <sysdep/syscalls.h>
+#include <shared/timer-internal.h>
 
 void handle_syscall(struct uml_pt_regs *r)
 {
        struct pt_regs *regs = container_of(r, struct pt_regs, regs);
        int syscall;
 
+       /*
+        * If we have infinite CPU resources, then make every syscall also a
+        * preemption point, since we don't have any other preemption in this
+        * case, and kernel threads would basically never run until userspace
+        * went to sleep, even if said userspace interacts with the kernel in
+        * various ways.
+        */
+       if (time_travel_mode == TT_MODE_INFCPU)
+               schedule();
+
        /* Initialize the syscall number and default return value. */
        UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
        PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);