mips _lwp_makecontext: Align sp.

PR kern/59327: user stack pointer is not aligned properly

Author: riastradh

lib/libc/arch/mips/gen/_lwp.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: _lwp.c,v 1.10 2025/04/24 23:56:50 riastradh Exp $	*/
+/*	$NetBSD: _lwp.c,v 1.11 2025/04/25 01:18:24 riastradh Exp $	*/
 
 /*
  * Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -31,11 +31,12 @@
 
 #include <sys/cdefs.h>
 #if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: _lwp.c,v 1.10 2025/04/24 23:56:50 riastradh Exp $");
+__RCSID("$NetBSD: _lwp.c,v 1.11 2025/04/25 01:18:24 riastradh Exp $");
 #endif /* LIBC_SCCS and not lint */
 
 #include "namespace.h"
 
+#include <sys/param.h>
 #include <sys/types.h>
 
 #include <lwp.h>
@@ -69,7 +70,7 @@ _lwp_makecontext(ucontext_t *u, void (*start)(void *),
 	gr[_REG_T9] = (uintptr_t) start; /* required for .abicalls */
 	gr[_REG_RA] = (uintptr_t) _lwp_exit;
 	gr[_REG_A0] = (uintptr_t) arg;
-	gr[_REG_SP] = (uintptr_t) sp;
+	gr[_REG_SP] = (uintptr_t) sp & ~STACK_ALIGNBYTES;
 	u->uc_mcontext._mc_tlsbase =
 	    (uintptr_t)tcb + TLS_TP_OFFSET + sizeof(struct tls_tcb);
 	u->uc_flags |= _UC_TLSBASE;

tests/kernel/t_signal_and_sp.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: t_signal_and_sp.c,v 1.16 2025/04/25 00:59:27 riastradh Exp $	*/
+/*	$NetBSD: t_signal_and_sp.c,v 1.17 2025/04/25 01:18:24 riastradh Exp $	*/
 
 /*
  * Copyright (c) 2024 The NetBSD Foundation, Inc.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: t_signal_and_sp.c,v 1.16 2025/04/25 00:59:27 riastradh Exp $");
+__RCSID("$NetBSD: t_signal_and_sp.c,v 1.17 2025/04/25 01:18:24 riastradh Exp $");
 
 #include <sys/wait.h>
 
@@ -496,10 +496,6 @@ ATF_TC_BODY(threadsp, tc)
 	atf_tc_expect_signal(SIGBUS, "PR kern/59327:"
 	    " user stack pointer is not aligned properly");
 #endif
-#ifdef __mips__
-	atf_tc_expect_fail("PR kern/59327:"
-	    " user stack pointer is not aligned properly");
-#endif
 
 	RZ(pthread_create(&t, NULL, &threadspfunc, NULL));