Re: [PATCH v8 13/30] powerpc: Add a probe_user_read_inst() function

On Wed, May 13, 2020 at 10:52 PM Michael Ellerman [off-list ref] wrote:

Jordan Niethe [off-list ref] writes:

quoted

diff --git a/arch/powerpc/lib/inst.c b/arch/powerpc/lib/inst.c
new file mode 100644
index 000000000000..eaf786afad2b
--- /dev/null
+++ b/arch/powerpc/lib/inst.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright 2020, IBM Corporation.
+ */
+
+#include <linux/uaccess.h>
+#include <asm/inst.h>
+
+int probe_user_read_inst(struct ppc_inst *inst,
+                      struct ppc_inst *nip)
+{
+     unsigned int val;
+     int err;
+
+     err = probe_user_read(&val, nip, sizeof(val));
+     *inst = ppc_inst(val);

We shouldn't be storing to *inst if the read failed?

Good point.

I changed it to:

+       if (!err)
+               *inst = ppc_inst(val);
+

Similarly for probe_kernel_read_inst().

Thanks.

cheers