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, 2 insertions, 2 deletions

diff --git a/arch/powerpc/lib/test_emulate_step.c b/arch/powerpc/lib/test_emulate_step.c
index c9a1a343123d..e25e92750416 100644
--- a/arch/powerpc/lib/test_emulate_step.c
+++ b/arch/powerpc/lib/test_emulate_step.c
@@ -1147,7 +1147,7 @@ static int __init emulate_compute_instr(struct pt_regs *regs,
 
 	if (analyse_instr(&op, regs, instr) != 1 ||
 	    GETTYPE(op.type) != COMPUTE) {
-		pr_info("emulation failed, instruction = 0x%08x\n", ppc_inst_val(instr));
+		pr_info("execution failed, instruction = %s\n", ppc_inst_as_str(instr));
 		return -EFAULT;
 	}
 
@@ -1167,7 +1167,7 @@ static int __init execute_compute_instr(struct pt_regs *regs,
 	/* Patch the NOP with the actual instruction */
 	patch_instruction_site(&patch__exec_instr, instr);
 	if (exec_instr(regs)) {
-		pr_info("execution failed, instruction = 0x%08x\n", ppc_inst_val(instr));
+		pr_info("execution failed, instruction = %s\n", ppc_inst_as_str(instr));
 		return -EFAULT;
 	}