From 7cd4e55c43e376027cf8b99f3069e49fb8b37c11 Mon Sep 17 00:00:00 2001
From: Justin Hibbits <jhibbits@FreeBSD.org>
Date: Fri, 15 Dec 2017 04:11:20 +0000
Subject: [PATCH] Handle the Facility Unavailable exception as a SIGILL

Currently Facility Unavailable is absent and once an application
tries to use or access a register from a feature disabled in the
CPU it causes a kernel panic.

A simple test-case is:

int main() { asm volatile ("tbegin.;"); }

which will use TM (Hardware Transactional Memory) feature which
is not supported by the kernel and so will trigger the following
kernel panic:

----

fatal user trap:

    exception       = 0xf60 (unknown)
    srr0            = 0x10000890
    srr1            = 0x800000000000f032
    lr              = 0x100004e4
    curthread       = 0x5f93000
    pid = 1021, comm = htm

panic: unknown trap
cpuid = 40
KDB: stack backtrace:
Uptime: 3m18s
Dumping 10 MB (3 chunks)
    chunk 0: 11MB (2648 pages) ... ok
    chunk 1: 1MB (24 pages) ... ok
    chunk 2: 1MB (2 pages)panic: IOMMU mapping error: -4

cpuid = 40
Uptime: 3m18s

----

Since Hardware Transactional Memory is not yet supported by FreeBSD, treat
this as an illegal instruction.

PR:		224350
Submitted by:	Gustavo Romero <gromero_AT_ibm_DOT_com>
MFC after:	2 weeks
---
 sys/powerpc/include/trap.h | 3 +++
 sys/powerpc/powerpc/trap.c | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/sys/powerpc/include/trap.h b/sys/powerpc/include/trap.h
index 22bb0d252be..a8164d0f72e 100644
--- a/sys/powerpc/include/trap.h
+++ b/sys/powerpc/include/trap.h
@@ -80,6 +80,9 @@
 #define	EXC_HEA		0x0e40		/* Hypervisor Emulation Assistance */
 #define	EXC_VSX		0x0f40		/* VSX Unavailable */
 
+/* Power ISA 2.07+: */
+#define	EXC_FAC		0x0f60		/* Facility Unavailable */
+
 /* The following are available on 4xx and 85xx */
 #define	EXC_CRIT	0x0100		/* Critical Input Interrupt */
 #define	EXC_PIT		0x1000		/* Programmable Interval Timer */
diff --git a/sys/powerpc/powerpc/trap.c b/sys/powerpc/powerpc/trap.c
index 7c119301003..c72b631cca4 100644
--- a/sys/powerpc/powerpc/trap.c
+++ b/sys/powerpc/powerpc/trap.c
@@ -135,6 +135,7 @@ static struct powerpc_exception powerpc_exceptions[] = {
 	{ EXC_PERF,	"performance monitoring" },
 	{ EXC_VEC,	"altivec unavailable" },
 	{ EXC_VSX,	"vsx unavailable" },
+	{ EXC_FAC,	"facility unavailable" },
 	{ EXC_ITMISS,	"instruction tlb miss" },
 	{ EXC_DLMISS,	"data load tlb miss" },
 	{ EXC_DSMISS,	"data store tlb miss" },
@@ -279,6 +280,11 @@ trap(struct trapframe *frame)
 			enable_fpu(td);
 			break;
 
+		case EXC_FAC:
+			sig = SIGILL;
+			ucode =	ILL_ILLOPC;
+			break;
+
 		case EXC_VECAST_E:
 		case EXC_VECAST_G4:
 		case EXC_VECAST_G5: