Wed Jun 24 04:47:10 2020 UTC ()
Fix core_dump_procinfo tests for powerpc, for which child process was
stalled indefinitely in trap instruction even after PT_CONTINUE.

For powerpc, program counter is not automatically incremented by trap
instruction. We cannot increment PC in the trap handler, which breaks
applications depending on this behavior, e.g., GDB.

Therefore, we need to pass (PC + 4) instead of (void *)1 (== PC) to
PT_CONTINUE when child process traps itself.


(rin)
diff -r1.1 -r1.2 src/tests/lib/libc/sys/t_ptrace_core_wait.h
cvs diff -r1.1 -r1.2 src/tests/lib/libc/sys/t_ptrace_core_wait.h (expand / switch to context diff)
--- src/tests/lib/libc/sys/t_ptrace_core_wait.h 2020/05/05 01:24:29 1.1
+++ src/tests/lib/libc/sys/t_ptrace_core_wait.h 2020/06/24 04:47:10 1.2
@@ -1,4 +1,4 @@
-/*	$NetBSD: t_ptrace_core_wait.h,v 1.1 2020/05/05 01:24:29 kamil Exp $	*/
+/*	$NetBSD: t_ptrace_core_wait.h,v 1.2 2020/06/24 04:47:10 rin Exp $	*/
 
 /*-
  * Copyright (c) 2016, 2017, 2018, 2019, 2020 The NetBSD Foundation, Inc.
@@ -207,7 +207,22 @@
 
 	DPRINTF("Before resuming the child process where it left off and "
 	    "without signal to be sent\n");
+#ifndef __powerpc__
 	SYSCALL_REQUIRE(ptrace(PT_CONTINUE, child, (void *)1, 0) != -1);
+#else
+	/*
+	 * For powerpc, program counter is not automatically incremented by
+	 * a trap instruction. We cannot increment PC in the trap handler,
+	 * which breaks applications depending on this behavior, e.g., GDB.
+	 * Therefore, we need to pass (PC + 4) instead of (void *)1 (== PC)
+	 * to PT_CONTINUE here.
+	 */
+	struct reg r;
+
+	SYSCALL_REQUIRE(ptrace(PT_GETREGS, child, &r, 0) != -1);
+	SYSCALL_REQUIRE(
+	    ptrace(PT_CONTINUE, child, (void *)(r.pc + 4), 0) != -1);
+#endif
 
 	DPRINTF("Before calling %s() for the child\n", TWAIT_FNAME);
 	TWAIT_REQUIRE_SUCCESS(wpid = TWAIT_GENERIC(child, &status, 0), child);