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Diffstat (limited to 'arch/sh/kernel/process_32.c')
-rw-r--r--arch/sh/kernel/process_32.c42
1 files changed, 32 insertions, 10 deletions
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 0673c4746be..d8af889366a 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -134,7 +134,10 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
regs.regs[5] = (unsigned long)fn;
regs.pc = (unsigned long)kernel_thread_helper;
- regs.sr = (1 << 30);
+ regs.sr = SR_MD;
+#if defined(CONFIG_SH_FPU)
+ regs.sr |= SR_FD;
+#endif
/* Ok, create the new process.. */
pid = do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
@@ -142,6 +145,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
return pid;
}
+EXPORT_SYMBOL(kernel_thread);
/*
* Free current thread data structures etc..
@@ -186,6 +190,16 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
return fpvalid;
}
+EXPORT_SYMBOL(dump_fpu);
+
+/*
+ * This gets called before we allocate a new thread and copy
+ * the current task into it.
+ */
+void prepare_to_copy(struct task_struct *tsk)
+{
+ unlazy_fpu(tsk, task_pt_regs(tsk));
+}
asmlinkage void ret_from_fork(void);
@@ -195,16 +209,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs;
-#if defined(CONFIG_SH_FPU) || defined(CONFIG_SH_DSP)
+#if defined(CONFIG_SH_DSP)
struct task_struct *tsk = current;
#endif
-#if defined(CONFIG_SH_FPU)
- unlazy_fpu(tsk, regs);
- p->thread.fpu = tsk->thread.fpu;
- copy_to_stopped_child_used_math(p);
-#endif
-
#if defined(CONFIG_SH_DSP)
if (is_dsp_enabled(tsk)) {
/* We can use the __save_dsp or just copy the struct:
@@ -224,6 +232,8 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
} else {
childregs->regs[15] = (unsigned long)childregs;
ti->addr_limit = KERNEL_DS;
+ ti->status &= ~TS_USEDFPU;
+ p->fpu_counter = 0;
}
if (clone_flags & CLONE_SETTLS)
@@ -288,9 +298,13 @@ static void ubc_set_tracing(int asid, unsigned long pc)
__notrace_funcgraph struct task_struct *
__switch_to(struct task_struct *prev, struct task_struct *next)
{
-#if defined(CONFIG_SH_FPU)
+ struct thread_struct *next_t = &next->thread;
+
unlazy_fpu(prev, task_pt_regs(prev));
-#endif
+
+ /* we're going to use this soon, after a few expensive things */
+ if (next->fpu_counter > 5)
+ prefetch(&next_t->fpu.hard);
#ifdef CONFIG_MMU
/*
@@ -321,6 +335,14 @@ __switch_to(struct task_struct *prev, struct task_struct *next)
#endif
}
+ /*
+ * If the task has used fpu the last 5 timeslices, just do a full
+ * restore of the math state immediately to avoid the trap; the
+ * chances of needing FPU soon are obviously high now
+ */
+ if (next->fpu_counter > 5)
+ fpu_state_restore(task_pt_regs(next));
+
return prev;
}