[PATCH v6 13/28] powerpc: Add a probe_user_read_inst() function

[Jordan Niethe]

Introduce a probe_user_read_inst() function to use in cases where
probe_user_read() is used for getting an instruction. This will be more
useful for prefixed instructions.

Signed-off-by: Jordan Niethe <jniet...@gmail.com>
---
v6: - New to series
---
 arch/powerpc/include/asm/inst.h |  3 +++
 arch/powerpc/lib/Makefile       |  2 +-
 arch/powerpc/lib/inst.c         | 18 ++++++++++++++++++
 arch/powerpc/mm/fault.c         |  2 +-
 4 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 arch/powerpc/lib/inst.c

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index 552e953bf04f..3e9a58420151 100644
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -37,4 +37,7 @@ static inline bool ppc_inst_equal(struct ppc_inst x, struct 
ppc_inst y)
        return ppc_inst_val(x) == ppc_inst_val(y);
 }
 
+int probe_user_read_inst(struct ppc_inst *inst,
+                        struct ppc_inst *nip);
+
 #endif /* _ASM_INST_H */
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index b8de3be10eb4..546591848219 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -16,7 +16,7 @@ CFLAGS_code-patching.o += -DDISABLE_BRANCH_PROFILING
 CFLAGS_feature-fixups.o += -DDISABLE_BRANCH_PROFILING
 endif
 
-obj-y += alloc.o code-patching.o feature-fixups.o pmem.o
+obj-y += alloc.o code-patching.o feature-fixups.o pmem.o inst.o
 
 ifndef CONFIG_KASAN
 obj-y  +=      string.o memcmp_$(BITS).o
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);
+       return err;
+}
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 7a68a3b32615..4983197d4a8e 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -281,7 +281,7 @@ static bool bad_stack_expansion(struct pt_regs *regs, 
unsigned long address,
                    access_ok(nip, sizeof(*nip))) {
                        struct ppc_inst inst;
 
-                       if (!probe_user_read(&inst, nip, sizeof(inst)))
+                       if (!probe_user_read_inst(&inst, (struct ppc_inst 
__user *)nip))
                                return !store_updates_sp(inst);
                        *must_retry = true;
                }
-- 
2.17.1