x86, 386 removal: Remove support for IRQ 13 FPU error reporting

Remove support for FPU error reporting via IRQ 13, as opposed to
exception 16 (#MF).  One last remnant of i386 gone.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Alan Cox <alan@linux.intel.com>

arch/x86/kernel/cpu/proc.c

@@ -26,11 +26,6 @@ static void show_cpuinfo_core(struct seq_file *m, struct cpuinfo_x86 *c,
 #ifdef CONFIG_X86_32
 static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 {
-	/*
-	 * We use exception 16 if we have hardware math and we've either seen
-	 * it or the CPU claims it is internal
-	 */
-	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
 		   "hlt_bug\t\t: %s\n"
@@ -45,7 +40,7 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",
-		   fpu_exception ? "yes" : "no",
+		   c->hard_math ? "yes" : "no",
 		   c->cpuid_level,
 		   c->wp_works_ok ? "yes" : "no");
 }

arch/x86/kernel/irqinit.c

@@ -42,39 +42,6 @@
  * (these are usually mapped into the 0x30-0xff vector range)
  */
 
-#ifdef CONFIG_X86_32
-/*
- * Note that on a 486, we don't want to do a SIGFPE on an irq13
- * as the irq is unreliable, and exception 16 works correctly
- * (ie as explained in the intel literature). On a 386, you
- * can't use exception 16 due to bad IBM design, so we have to
- * rely on the less exact irq13.
- *
- * Careful.. Not only is IRQ13 unreliable, but it is also
- * leads to races. IBM designers who came up with it should
- * be shot.
- */
-
-static irqreturn_t math_error_irq(int cpl, void *dev_id)
-{
-	outb(0, 0xF0);
-	if (ignore_fpu_irq || !boot_cpu_data.hard_math)
-		return IRQ_NONE;
-	math_error(get_irq_regs(), 0, X86_TRAP_MF);
-	return IRQ_HANDLED;
-}
-
-/*
- * New motherboards sometimes make IRQ 13 be a PCI interrupt,
- * so allow interrupt sharing.
- */
-static struct irqaction fpu_irq = {
-	.handler = math_error_irq,
-	.name = "fpu",
-	.flags = IRQF_NO_THREAD,
-};
-#endif
-
 /*
  * IRQ2 is cascade interrupt to second interrupt controller
  */
@@ -242,13 +209,6 @@ void __init native_init_IRQ(void)
 		setup_irq(2, &irq2);
 
 #ifdef CONFIG_X86_32
-	/*
-	 * External FPU? Set up irq13 if so, for
-	 * original braindamaged IBM FERR coupling.
-	 */
-	if (boot_cpu_data.hard_math && !cpu_has_fpu)
-		setup_irq(FPU_IRQ, &fpu_irq);
-
 	irq_ctx_init(smp_processor_id());
 #endif
 }

arch/x86/kernel/traps.c

@@ -69,9 +69,6 @@
 
 asmlinkage int system_call(void);
 
-/* Do we ignore FPU interrupts ? */
-char ignore_fpu_irq;
-
 /*
  * The IDT has to be page-aligned to simplify the Pentium
  * F0 0F bug workaround.
@@ -564,9 +561,6 @@ void math_error(struct pt_regs *regs, int error_code, int trapnr)
 
 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 {
-#ifdef CONFIG_X86_32
-	ignore_fpu_irq = 1;
-#endif
 	exception_enter(regs);
 	math_error(regs, error_code, X86_TRAP_MF);
 	exception_exit(regs);