From 261aa2b9b790868a16a6cee0f19c73221ddc81d5 Mon Sep 17 00:00:00 2001
From: Patrick Williams <iawillia@us.ibm.com>
Date: Tue, 22 Jun 2010 16:41:25 -0500
Subject: Program exception handling and emulated instruction for mfsprg3.

---
 src/include/kernel/ppcarch.H | 14 +++++++++++
 src/kernel/exception.C       | 58 ++++++++++++++++++++++++++++++++++++++++++++
 src/kernel/makefile          |  2 +-
 src/kernel/start.S           |  2 +-
 src/lib/syscall_task.C       |  9 ++++++-
 5 files changed, 82 insertions(+), 3 deletions(-)
 create mode 100644 src/include/kernel/ppcarch.H
 create mode 100644 src/kernel/exception.C

diff --git a/src/include/kernel/ppcarch.H b/src/include/kernel/ppcarch.H
new file mode 100644
index 000000000..f6b80ea6f
--- /dev/null
+++ b/src/include/kernel/ppcarch.H
@@ -0,0 +1,14 @@
+#ifndef __KERNEL_PPCARCH_H
+#define __KERNEL_PPCARCH_H
+
+#include <kernel/types.h>
+
+__attribute__((always_inline))
+inline uint64_t ppc_getSRR1() 
+{
+    register uint64_t srr1 = 0;
+    asm volatile("mfsrr1 %0" : "=r" (srr1));
+    return srr1;
+} 
+
+#endif
diff --git a/src/kernel/exception.C b/src/kernel/exception.C
new file mode 100644
index 000000000..98d36c35c
--- /dev/null
+++ b/src/kernel/exception.C
@@ -0,0 +1,58 @@
+#include <kernel/types.h>
+#include <kernel/console.H>
+#include <kernel/task.H>
+#include <kernel/taskmgr.H>
+#include <kernel/ppcarch.H>
+
+namespace Systemcalls { void TaskEnd(task_t*); }
+namespace ExceptionHandles
+{
+    bool HvEmulation(task_t*);
+}
+
+const uint64_t EXCEPTION_SRR1_MASK 	= 0x00000000783F0000;
+const uint64_t EXCEPTION_SRR1_HVEMUL	= 0x0000000000080000;
+
+extern "C"
+void kernel_execute_prog_ex()
+{
+    task_t* t = TaskManager::getCurrentTask();
+    uint64_t exception = ppc_getSRR1() & EXCEPTION_SRR1_MASK;
+
+    bool handled = false;
+    switch(exception)
+    {
+	case EXCEPTION_SRR1_HVEMUL:
+	    handled = ExceptionHandles::HvEmulation(t);
+	    break;
+    }
+    if (!handled)
+    {
+	printk("Program exception, killing task %d\n", t->tid);
+	Systemcalls::TaskEnd(t);
+    }
+}
+
+namespace ExceptionHandles
+{
+    bool HvEmulation(task_t* t)
+    {
+	/*printk("NIP = %llx : Inst = %lx\n",
+	       t->context.nip,
+	       (*(uint32_t*)t->context.nip));*/
+
+	uint32_t instruction = *(uint32_t*)t->context.nip;
+
+	    // check for mfsprg3
+	if ((instruction & 0xfc1fffff) == 0x7c1342a6)
+	{
+	    t->context.gprs[(instruction & 0x03E00000) >> 21] = 
+		    (uint64_t) t;
+	    t->context.nip = (void*) (((uint64_t)t->context.nip)+4);
+	    return true;
+	}
+
+	return false;
+    }
+
+}
diff --git a/src/kernel/makefile b/src/kernel/makefile
index 629c39bcb..4bdc0d02d 100644
--- a/src/kernel/makefile
+++ b/src/kernel/makefile
@@ -2,7 +2,7 @@ OBJDIR = ../../obj
 include ../../config.mk
 
 OBJS = start.o kernel.o console.o pagemgr.o heapmgr.o taskmgr.o cpumgr.o
-OBJS += syscall.o scheduler.o spinlock.o
+OBJS += syscall.o scheduler.o spinlock.o exception.o
 OBJECTS = $(addprefix ${OBJDIR}/, ${OBJS})
 
 all: ${OBJECTS}
diff --git a/src/kernel/start.S b/src/kernel/start.S
index 93cc0156e..774c62f67 100644
--- a/src/kernel/start.S
+++ b/src/kernel/start.S
@@ -103,7 +103,7 @@ UNIMPL_INTERRUPT(inst_storage, 0x400)
 UNIMPL_INTERRUPT(inst_segment, 0x480)
 UNIMPL_INTERRUPT(external, 0x500)
 UNIMPL_INTERRUPT(alignment, 0x600)
-UNIMPL_INTERRUPT(program, 0x700)
+STD_INTERRUPT(prog_ex, 0x700)
 UNIMPL_INTERRUPT(fp_unavail, 0x800)
 STD_INTERRUPT(decrementer, 0x900)
 UNIMPL_INTERRUPT(hype_decrementer, 0x980)
diff --git a/src/lib/syscall_task.C b/src/lib/syscall_task.C
index d07ea3f19..405e4f202 100644
--- a/src/lib/syscall_task.C
+++ b/src/lib/syscall_task.C
@@ -1,6 +1,7 @@
 #include <sys/task.h>
 #include <sys/syscall.h>
 #include <kernel/task.H>
+#include <kernel/taskmgr.H>
 
 using namespace Systemcalls;
 
@@ -23,5 +24,11 @@ void task_end()
 
 tid_t task_gettid()
 {
-    return (tid_t)_syscall0(TASK_GETTID);
+    // Even though we have a syscall for GETTID, we can implement this as a 
+    // direct access to SPRG3.  On processor that do not support unprivilaged
+    // access to this SPR, we implement it as an emulated instruction in the
+    // exception handler.
+
+    return TaskManager::getCurrentTask()->tid;
+    //return (tid_t)_syscall0(TASK_GETTID);
 }
-- 
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