sparc64: Like x86 we should check current->mm during perf backtrace generation.

[ Upstream commit 08280e6c4c2e8049ac61d9e8e3536ec1df629c0d ]

If the MM is not active, only report the top-level PC.  Do not try to
access the address space.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 614da62..5331ae1 100644 (file)
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -1422,8 +1422,6 @@ static void perf_callchain_user_64(struct perf_callchain_entry *entry,
 {
        unsigned long ufp;
 
-       perf_callchain_store(entry, regs->tpc);
-
        ufp = regs->u_regs[UREG_I6] + STACK_BIAS;
        do {
                struct sparc_stackf *usf, sf;
@@ -1444,8 +1442,6 @@ static void perf_callchain_user_32(struct perf_callchain_entry *entry,
 {
        unsigned long ufp;
 
-       perf_callchain_store(entry, regs->tpc);
-
        ufp = regs->u_regs[UREG_I6] & 0xffffffffUL;
        do {
                struct sparc_stackf32 *usf, sf;
@@ -1464,6 +1460,11 @@ static void perf_callchain_user_32(struct perf_callchain_entry *entry,
 void
 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 {
+       perf_callchain_store(entry, regs->tpc);
+
+       if (!current->mm)
+               return;
+
        flushw_user();
        if (test_thread_flag(TIF_32BIT))
                perf_callchain_user_32(entry, regs);