powerpc: Add ppc_inst_as_u64()

The code patching code wants to get the value of a struct ppc_inst as
a u64 when the instruction is prefixed, so we can pass the u64 down to
__put_user_asm() and write it with a single store.

The optprobes code wants to load a struct ppc_inst as an immediate
into a register so it is useful to have it as a u64 to use the
existing helper function.

Currently this is a bit awkward because the value differs based on the
CPU endianness, so add a helper to do the conversion.

This fixes the usage in arch_prepare_optimized_kprobe() which was
previously incorrect on big endian.

Fixes: 650b55b707fd ("powerpc: Add prefixed instructions to instruction data type")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Jordan Niethe <jniethe5@gmail.com>
Link: https://lore.kernel.org/r/20200526072630.2487363-1-mpe@ellerman.id.au

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index 5b756ba77ed2..45f3ec868258 100644
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -113,6 +113,15 @@ static inline struct ppc_inst *ppc_inst_next(void *location, struct ppc_inst *va
 	return location + ppc_inst_len(tmp);
 }
 
+static inline u64 ppc_inst_as_u64(struct ppc_inst x)
+{
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+	return (u64)ppc_inst_suffix(x) << 32 | ppc_inst_val(x);
+#else
+	return (u64)ppc_inst_val(x) << 32 | ppc_inst_suffix(x);
+#endif
+}
+
 int probe_user_read_inst(struct ppc_inst *inst,
 			 struct ppc_inst __user *nip);