microblaze_mmu_v2: Update process creation for MMU

Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 58 insertions, 0 deletions

diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 685ad71ced50..00b12c6d5326 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -126,9 +126,54 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         else
                 childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;
 
+#ifndef CONFIG_MMU
         memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
         ti->cpu_context.r1 = (unsigned long)childregs;
         ti->cpu_context.msr = (unsigned long)childregs->msr;
+#else
+
+        /* if creating a kernel thread then update the current reg (we don't
+         * want to use the parent's value when restoring by POP_STATE) */
+        if (kernel_mode(regs))
+                /* save new current on stack to use POP_STATE */
+                childregs->CURRENT_TASK = (unsigned long)p;
+        /* if returning to user then use the parent's value of this register */
+
+        /* if we're creating a new kernel thread then just zeroing all
+         * the registers. That's OK for a brand new thread.*/
+        /* Pls. note that some of them will be restored in POP_STATE */
+        if (kernel_mode(regs))
+                memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
+        /* if this thread is created for fork/vfork/clone, then we want to
+         * restore all the parent's context */
+        /* in addition to the registers which will be restored by POP_STATE */
+        else {
+                ti->cpu_context = *(struct cpu_context *)regs;
+                childregs->msr |= MSR_UMS;
+        }
+
+        /* FIXME STATE_SAVE_PT_OFFSET; */
+        ti->cpu_context.r1  = (unsigned long)childregs - STATE_SAVE_ARG_SPACE;
+        /* we should consider the fact that childregs is a copy of the parent
+         * regs which were saved immediately after entering the kernel state
+         * before enabling VM. This MSR will be restored in switch_to and
+         * RETURN() and we want to have the right machine state there
+         * specifically this state must have INTs disabled before and enabled
+         * after performing rtbd
+         * compose the right MSR for RETURN(). It will work for switch_to also
+         * excepting for VM and UMS
+         * don't touch UMS , CARRY and cache bits
+         * right now MSR is a copy of parent one */
+        childregs->msr |= MSR_BIP;
+        childregs->msr &= ~MSR_EIP;
+        childregs->msr |= MSR_IE;
+        childregs->msr &= ~MSR_VM;
+        childregs->msr |= MSR_VMS;
+        childregs->msr |= MSR_EE; /* exceptions will be enabled*/
+
+        ti->cpu_context.msr = (childregs->msr|MSR_VM);
+        ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
+#endif
         ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 
         if (clone_flags & CLONE_SETTLS)
@@ -137,6 +182,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
         return 0;
 }
 
+#ifndef CONFIG_MMU
 /*
  * Return saved PC of a blocked thread.
  */
@@ -151,6 +197,7 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
         else
                 return ctx->r14;
 }
+#endif
 
 static void kernel_thread_helper(int (*fn)(void *), void *arg)
 {
@@ -189,3 +236,14 @@ void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
         regs->r1 = usp;
         regs->pt_mode = 0;
 }
+
+#ifdef CONFIG_MMU
+#include <linux/elfcore.h>
+/*
+ * Set up a thread for executing a new program
+ */
+int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
+{
+        return 0; /* MicroBlaze has no separate FPU registers */
+}
+#endif /* CONFIG_MMU */