nova: extent ec_ctrl in kernel and base-nova

The commit switches the kernel branch to r5 and updates the syscall bindings
in base-nova accordingly. Beside some cleanups, r5 extents the ec_ctrl syscall
to support following features:

* An EC may yield its current timeslice. The timeslice gets enqueued at the end
  of the run queue without refreshing the left budget of the quantum.
* An EC helps with the current SC another EC. Used in Genode to implement
  helping over a user-level lock to avoid live-lock situation. (Think of
  a limited priority-inheritance mechanism.)
* An EC requests a new scheduler decision. Used in Genode to transfer back the
  potentially helping SC to the helper EC.

Issue #986

base-nova/Makefile

@@ -9,7 +9,7 @@ VERBOSE     ?= @
 ECHO        = @echo
 GIT_URL     = https://github.com/alex-ab/NOVA.git
 GIT_REV     = HEAD
-GIT_BRANCH  = r4
+GIT_BRANCH  = r5
 CONTRIB_DIR = contrib
 PATCHES     = $(shell find patches -name '*.patch')
 

base-nova/include/32bit/nova/syscalls.h

@@ -210,9 +210,9 @@ namespace Nova {
 
 
 	ALWAYS_INLINE
-	inline uint8_t ec_ctrl(Ec_op op, unsigned para = ~0UL)
+	inline uint8_t ec_ctrl(Ec_op op, mword_t ec = ~0UL, mword_t para = ~0UL)
 	{
-		return syscall_0(NOVA_EC_CTRL, op, para);
+		return syscall_1(NOVA_EC_CTRL, op, ec, para);
 	}
 
 

base-nova/include/64bit/nova/syscalls.h

@@ -173,9 +173,9 @@ namespace Nova {
 
 
 	ALWAYS_INLINE
-	inline uint8_t ec_ctrl(Ec_op op, mword_t ec = ~0UL)
+	inline uint8_t ec_ctrl(Ec_op op, mword_t ec = ~0UL, mword_t para = ~0UL)
 	{
-		return syscall_0(NOVA_EC_CTRL, op, ec);
+		return syscall_1(NOVA_EC_CTRL, op, ec, para);
 	}
 
 

base-nova/include/nova/syscall-generic.h

@@ -150,7 +150,7 @@ namespace Nova {
 	/**
 	 * Ec operations
 	 */
-	enum Ec_op { EC_RECALL = 0U, EC_YIELD = 1U };
+	enum Ec_op { EC_RECALL = 0U, EC_YIELD = 1U, EC_DONATE_SC = 2U, EC_RESCHEDULE = 3U };
 
 
 	class Descriptor

base-nova/patches/yield.patch

@@ -1,116 +0,0 @@
-diff --git a/include/sc.hpp b/include/sc.hpp
-index b849a1f..b480050 100644
---- a/include/sc.hpp
-+++ b/include/sc.hpp
-@@ -54,7 +54,7 @@ class Sc : public Kobject, public Refcount
- 
-         static unsigned prio_top CPULOCAL;
- 
--        void ready_enqueue (uint64);
-+        void ready_enqueue (uint64, bool use_left = true);
-         void ready_dequeue (uint64);
- 
-         static void free (Rcu_elem * a) {
-@@ -90,7 +90,7 @@ class Sc : public Kobject, public Refcount
-         static void rke_handler();
- 
-         NORETURN
--        static void schedule (bool = false);
-+        static void schedule (bool = false, bool = true);
- 
-         ALWAYS_INLINE
-         static inline void *operator new (size_t) { return cache.alloc(); }
-diff --git a/include/syscall.hpp b/include/syscall.hpp
-index 59e4489..5d61f1e 100644
---- a/include/syscall.hpp
-+++ b/include/syscall.hpp
-@@ -138,6 +138,9 @@ class Sys_ec_ctrl : public Sys_regs
-     public:
-         ALWAYS_INLINE
-         inline unsigned long ec() const { return ARG_1 >> 8; }
-+
-+        ALWAYS_INLINE
-+        inline unsigned op() const { return flags() & 0x3; }
- };
- 
- class Sys_sc_ctrl : public Sys_regs
-diff --git a/src/sc.cpp b/src/sc.cpp
-index 53ff07b..bc4dfa2 100644
---- a/src/sc.cpp
-+++ b/src/sc.cpp
-@@ -52,7 +52,7 @@ Sc::Sc (Pd *own, Ec *e, unsigned c, Sc *x) : Kobject (SC, static_cast<Space_obj
-     trace (TRACE_SYSCALL, "SC:%p created (EC:%p CPU:%#x P:%#x Q:%#x) - xCPU", this, e, c, prio, budget / (Lapic::freq_bus / 1000));
- }
- 
--void Sc::ready_enqueue (uint64 t)
-+void Sc::ready_enqueue (uint64 t, bool use_left)
- {
-     assert (prio < priorities);
-     assert (cpu == Cpu::id);
-@@ -68,13 +68,13 @@ void Sc::ready_enqueue (uint64 t)
-         next = list[prio];
-         prev = list[prio]->prev;
-         next->prev = prev->next = this;
--        if (left)
-+        if (use_left && left)
-             list[prio] = this;
-     }
- 
-     trace (TRACE_SCHEDULE, "ENQ:%p (%02u) PRIO:%#x TOP:%#x %s", this, left, prio, prio_top, prio > current->prio ? "reschedule" : "");
- 
--    if (prio > current->prio || (this != current && prio == current->prio && left))
-+    if (prio > current->prio || (this != current && prio == current->prio && (use_left && left)))
-         Cpu::hazard |= HZD_SCHED;
- 
-     if (!left)
-@@ -106,7 +106,7 @@ void Sc::ready_dequeue (uint64 t)
-     tsc = t;
- }
- 
--void Sc::schedule (bool suspend)
-+void Sc::schedule (bool suspend, bool use_left)
- {
-     Counter::print<1,16> (++Counter::schedule, Console_vga::COLOR_LIGHT_CYAN, SPN_SCH);
- 
-@@ -123,7 +123,7 @@ void Sc::schedule (bool suspend)
-         delete current;
-     else
-     if (EXPECT_TRUE (!suspend))
--        current->ready_enqueue (t);
-+        current->ready_enqueue (t, use_left);
- 
-     Sc *sc = list[prio_top];
-     assert (sc);
-diff --git a/src/syscall.cpp b/src/syscall.cpp
-index 975d4dc..6e792b0 100644
---- a/src/syscall.cpp
-+++ b/src/syscall.cpp
-@@ -409,6 +412,9 @@ void Ec::sys_ec_ctrl()
- {
-     Sys_ec_ctrl *r = static_cast<Sys_ec_ctrl *>(current->sys_regs());
- 
-+    switch (r->op()) {
-+        case 0:
-+{
-     Capability cap = Space_obj::lookup (r->ec());
-     if (EXPECT_FALSE (cap.obj()->type() != Kobject::EC || !(cap.prm() & 1UL << 0))) {
-         trace (TRACE_ERROR, "%s: Bad EC CAP (%#lx)", __func__, r->ec());
-@@ -423,6 +429,18 @@ void Ec::sys_ec_ctrl()
- 
-         if (Cpu::id != ec->cpu && Ec::remote (ec->cpu) == ec)
-             Lapic::send_ipi (ec->cpu, VEC_IPI_RKE);
-+
-+    }
-+}
-+            break;
-+
-+        case 1:
-+            current->cont = sys_finish<Sys_regs::SUCCESS>;
-+            Sc::schedule (false, false);
-+            break;
-+
-+        default:
-+      	     sys_finish<Sys_regs::BAD_PAR>();
-     }
- 
-     sys_finish<Sys_regs::SUCCESS>();