sparc64: Properly truncate pt_regs framepointer in perf callback.

[ Upstream commit 9e8307ecaf9f8c8b5b3b22145021204c4e73114a ]

For 32-bit processes, we save the full 64-bits of the regs in pt_regs.

But unlike when the userspace actually does load and store
instructions, the top 32-bits don't get automatically truncated by the
cpu in kernel mode (because the kernel doesn't execute with PSTATE_AM
address masking enabled).

So we have to do it by hand.

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 87b5049306337487e1b8ed5037070b01c145aaf7..8c70d3e831dc7f40557fec682696e14fc92b5b3b 100644 (file)
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -1337,7 +1337,7 @@ static void perf_callchain_user_32(struct pt_regs *regs,
        callchain_store(entry, PERF_CONTEXT_USER);
        callchain_store(entry, regs->tpc);
 
-       ufp = regs->u_regs[UREG_I6];
+       ufp = regs->u_regs[UREG_I6] & 0xffffffffUL;
        do {
                struct sparc_stackf32 *usf, sf;
                unsigned long pc;