powerpc: Add a ppc_inst_as_str() helper

There are quite a few places where instructions are printed, this is
done using a '%x' format specifier. With the introduction of prefixed
instructions, this does not work well. Currently in these places,
ppc_inst_val() is used for the value for %x so only the first word of
prefixed instructions are printed.

When the instructions are word instructions, only a single word should
be printed. For prefixed instructions both the prefix and suffix should
be printed. To accommodate both of these situations, instead of a '%x'
specifier use '%s' and introduce a helper, __ppc_inst_as_str() which
returns a char *. The char * __ppc_inst_as_str() returns is buffer that
is passed to it by the caller.

It is cumbersome to require every caller of __ppc_inst_as_str() to now
declare a buffer. To make it more convenient to use __ppc_inst_as_str(),
wrap it in a macro that uses a compound statement to allocate a buffer
on the caller's stack before calling it.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
[mpe: Drop 0x prefix to match most existings uses, especially xmon]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200602052728.18227-1-jniethe5@gmail.com

1 files changed, 19 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index 45f3ec868258..cc73c1267572 100644
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -122,6 +122,25 @@ static inline u64 ppc_inst_as_u64(struct ppc_inst x)
 #endif
 }
 
+#define PPC_INST_STR_LEN sizeof("00000000 00000000")
+
+static inline char *__ppc_inst_as_str(char str[PPC_INST_STR_LEN], struct ppc_inst x)
+{
+	if (ppc_inst_prefixed(x))
+		sprintf(str, "%08x %08x", ppc_inst_val(x), ppc_inst_suffix(x));
+	else
+		sprintf(str, "%08x", ppc_inst_val(x));
+
+	return str;
+}
+
+#define ppc_inst_as_str(x)		\
+({					\
+	char __str[PPC_INST_STR_LEN];	\
+	__ppc_inst_as_str(__str, x);	\
+	__str;				\
+})
+
 int probe_user_read_inst(struct ppc_inst *inst,
 			 struct ppc_inst __user *nip);