powerpc/ftrace: Skip instruction patching if the instructions are the same

To simplify upcoming changes to ftrace, add a check to skip actual
instruction patching if the old and new instructions are the same. We
still validate that the instruction is what we expect, but don't
actually patch the same instruction again.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241030070850.1361304-8-hbathini@linux.ibm.com

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index fe0546f..7195172 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -82,7 +82,7 @@ static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_
 {
        int ret = ftrace_validate_inst(ip, old);
 
-       if (!ret)
+       if (!ret && !ppc_inst_equal(old, new))
                ret = patch_instruction((u32 *)ip, new);
 
        return ret;