commit 5323180db75d562a287cb2020b07c9422df13df6
author Atsushi Nemoto <anemo@mba.ocn.ne.jp> Sat Apr 14 02:37:26 2007 +0900
committer Ralf Baechle <ralf@linux-mips.org> Fri Apr 20 14:58:37 2007 +0100
tree 71039fd0a03f89ebb3172d75a9e594d4f9f56fd6
parent 9a9943575ade643368849e2c963094ac637867e0

[MIPS] Disallow CpU exception in kernel again.

The commit 4d40bff7110e9e1a97ff8c01bdd6350e9867cc10 ("Allow CpU
exception in kernel partially") was broken.  The commit was to fix
theoretical problem but broke usual case.  Revert it for now.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 7d76a85..6b356f6 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -757,11 +757,12 @@
 {
 	unsigned int cpid;
 
+	die_if_kernel("do_cpu invoked from kernel context!", regs);
+
 	cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;
 
 	switch (cpid) {
 	case 0:
-		die_if_kernel("do_cpu invoked from kernel context!", regs);
 		if (!cpu_has_llsc)
 			if (!simulate_llsc(regs))
 				return;
@@ -772,9 +773,6 @@
 		break;
 
 	case 1:
-		if (!test_thread_flag(TIF_ALLOW_FP_IN_KERNEL))
-			die_if_kernel("do_cpu invoked from kernel context!",
-				      regs);
 		if (used_math())	/* Using the FPU again.  */
 			own_fpu(1);
 		else {			/* First time FPU user.  */
@@ -782,19 +780,7 @@
 			set_used_math();
 		}
 
-		if (raw_cpu_has_fpu) {
-			if (test_thread_flag(TIF_ALLOW_FP_IN_KERNEL)) {
-				local_irq_disable();
-				if (cpu_has_fpu)
-					regs->cp0_status |= ST0_CU1;
-				/*
-				 * We must return without enabling
-				 * interrupts to ensure keep FPU
-				 * ownership until resume.
-				 */
-				return;
-			}
-		} else {
+		if (!raw_cpu_has_fpu) {
 			int sig;
 			sig = fpu_emulator_cop1Handler(regs,
 						&current->thread.fpu, 0);
@@ -836,7 +822,6 @@
 
 	case 2:
 	case 3:
-		die_if_kernel("do_cpu invoked from kernel context!", regs);
 		break;
 	}