[PATCH] ppc32: Even more preempt fixes

[PATCH] ppc32: Even more preempt fixes

[Benjamin Herrenschmidt]

Add a warning if enable_kernel_{fp,altivec} is called with preempt
enabled since this is always an error, and make sure the alignement
exception handler properly disables preempt when doing FP operations.

Please, apply,
Ben.

diff -urN linux-2.5/arch/ppc/kernel/align.c linuxppc-2.5-benh/arch/ppc/kernel/align.c
--- linux-2.5/arch/ppc/kernel/align.c	2004-03-30 08:55:49.000000000 +1000
+++ linuxppc-2.5-benh/arch/ppc/kernel/align.c	2004-03-30 13:00:44.000000000 +1000
@@ -325,14 +325,18 @@
 	 * the kernel with -msoft-float so it doesn't use the
 	 * fp regs for copying 8-byte objects. */
 	case LD+F+S:
+		preempt_disable();
 		enable_kernel_fp();
 		cvt_fd(&data.f, &current->thread.fpr[reg], &current->thread.fpscr);
 		/* current->thread.fpr[reg] = data.f; */
+		preempt_enable();
 		break;
 	case ST+F+S:
+		preempt_disable();
 		enable_kernel_fp();
 		cvt_df(&current->thread.fpr[reg], &data.f, &current->thread.fpscr);
 		/* data.f = current->thread.fpr[reg]; */
+		preempt_enable();
 		break;
 	default:
 		printk("align: can't handle flags=%x\n", flags);
diff -urN linux-2.5/arch/ppc/kernel/process.c linuxppc-2.5-benh/arch/ppc/kernel/process.c
--- linux-2.5/arch/ppc/kernel/process.c	2004-03-29 12:54:12.000000000 +1000
+++ linuxppc-2.5-benh/arch/ppc/kernel/process.c	2004-03-30 14:55:42.000000000 +1000
@@ -163,7 +163,8 @@
 void
 enable_kernel_altivec(void)
 {
-	preempt_disable();
+	WARN_ON(current_thread_info()->preempt_count == 0 && !irqs_disabled());
+
 #ifdef CONFIG_SMP
 	if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
 		giveup_altivec(current);
@@ -172,14 +173,15 @@
 #else
 	giveup_altivec(last_task_used_altivec);
 #endif /* __SMP __ */
-	preempt_enable();
 }
+EXPORT_SYMBOL(enable_kernel_altivec);
 #endif /* CONFIG_ALTIVEC */
 
 void
 enable_kernel_fp(void)
 {
-	preempt_disable();
+	WARN_ON(current_thread_info()->preempt_count == 0 && !irqs_disabled());
+
 #ifdef CONFIG_SMP
 	if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
 		giveup_fpu(current);
@@ -188,8 +190,8 @@
 #else
 	giveup_fpu(last_task_used_math);
 #endif /* CONFIG_SMP */
-	preempt_enable();
 }
+EXPORT_SYMBOL(enable_kernel_fp);
 
 int
 dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)