If the kernel disables transactional memory (TM) and userspace still
tries TM related actions (TM instructions or TM SPR accesses) TM aware
hardware will cause the kernel to take a facility unavailable
exception.
Add checks for the exception being caused by illegal TM access in
userspace.
Signed-off-by: Cyril Bur <cyril...@gmail.com>
---
arch/powerpc/kernel/traps.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 0eba74b..cd40130 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1372,6 +1372,13 @@ void vsx_unavailable_exception(struct pt_regs *regs)
}
#ifdef CONFIG_PPC64
+static void tm_unavailable(struct pt_regs *regs)
+{
+ pr_emerg("Unrecoverable TM Unavailable Exception "
+ "%lx at %lx\n", regs->trap, regs->nip);
+ die("Unrecoverable TM Unavailable Exception", regs, SIGABRT);
+}
+
void facility_unavailable_exception(struct pt_regs *regs)
{
static char *facility_strings[] = {
@@ -1451,6 +1458,23 @@ void facility_unavailable_exception(struct pt_regs *regs)
return;
}
+ /*
+ * TM Unavailable
+ *
+ * If
+ * - firmware bits say don't do TM or
+ * - CONFIG_PPC_TRANSACTIONAL_MEM was not set and
+ * - hardware is actually TM aware
+ * Then userspace can spam the console (even with the use of
+ * _ratelimited), just send the SIGILL.
+ */
+ if (status == FSCR_TM_LG) {
+ if (!cpu_has_feature(CPU_FTR_TM))
+ goto out;
+ tm_unavailable(regs);
+ return;
+ }
+
if ((status < ARRAY_SIZE(facility_strings)) &&
facility_strings[status])
facility = facility_strings[status];
@@ -1463,6 +1487,7 @@ void facility_unavailable_exception(struct pt_regs *regs)
"%sFacility '%s' unavailable, exception at 0x%lx, MSR=%lx\n",
hv ? "Hypervisor " : "", facility, regs->nip, regs->msr);
+out:
if (user_mode(regs)) {
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
return;
--
2.9.3
