selftests/powerpc/ptrace: Update ptrace-perf watchpoint selftest

Now that ptrace and perf are no longer exclusive, update the
test to exercise interesting interactions.

An assembly file is used for the children to allow precise instruction
choice and addresses, while avoiding any compiler quirks.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-7-bgray@linux.ibm.com

tools/testing/selftests/powerpc/ptrace/Makefile

@@ -36,6 +36,7 @@ $(TM_TESTS): CFLAGS += -I../tm -mhtm
 CFLAGS += $(KHDR_INCLUDES) -fno-pie
 
 $(OUTPUT)/ptrace-gpr: ptrace-gpr.S
+$(OUTPUT)/ptrace-perf-hwbreak: ptrace-perf-asm.S
 $(OUTPUT)/ptrace-pkey $(OUTPUT)/core-pkey: LDLIBS += -pthread
 
 $(TEST_GEN_PROGS): ../harness.c ../utils.c ../lib/reg.S

tools/testing/selftests/powerpc/ptrace/ptrace-perf-asm.S

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <ppc-asm.h>
+
+.global same_watch_addr_load
+.global same_watch_addr_trap
+
+FUNC_START(same_watch_addr_child)
+	nop
+same_watch_addr_load:
+	ld 0,0(3)
+	nop
+same_watch_addr_trap:
+	trap
+	blr
+FUNC_END(same_watch_addr_child)
+
+
+.global perf_then_ptrace_load1
+.global perf_then_ptrace_load2
+.global perf_then_ptrace_trap
+
+FUNC_START(perf_then_ptrace_child)
+	nop
+perf_then_ptrace_load1:
+	ld 0,0(3)
+perf_then_ptrace_load2:
+	ld 0,0(4)
+	nop
+perf_then_ptrace_trap:
+	trap
+	blr
+FUNC_END(perf_then_ptrace_child)