On some distributions, on ppc64, ulimit -s returns 'unlimited': add a
reasonable default, and also make sure ulimit is invoked using the
default shell, which should ensure ulimit is actually implemented.

Also note that AUDIT_ARCH doesn't follow closely the naming reported
by 'uname -m': convert for i386 and ppc as needed.

While at it, move inclusion of seccomp.h after util.h, the former is
less generic (cosmetic/clang-tidy only).

Older kernel headers might lack a definition for AUDIT_ARCH_PPC64LE:
define that explicitly if it's not available.

Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
---
 Makefile   | 14 ++++++++++++--
 passt.c    |  2 +-
 seccomp.sh |  6 +++++-
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index c73a786..4647210 100644
--- a/Makefile
+++ b/Makefile
@@ -9,11 +9,21 @@
 # Copyright (c) 2021 Red Hat GmbH
 # Author: Stefano Brivio <sbrivio(a)redhat.com>
 
+RLIMIT_STACK_VAL := $(shell /bin/sh -c 'ulimit -s')
+ifeq ($(RLIMIT_STACK_VAL),unlimited)
+RLIMIT_STACK_VAL := 1024
+endif
+
+AUDIT_ARCH := $(shell uname -m | tr [a-z] [A-Z])
+AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/I[456]86/I386/')
+AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/PPC64/PPC/')
+AUDIT_ARCH := $(shell echo $(AUDIT_ARCH) | sed 's/PPCLE/PPC64LE/')
+
 CFLAGS += -Wall -Wextra -pedantic -std=c99 -D_XOPEN_SOURCE=700 -D_GNU_SOURCE
-CFLAGS += -DRLIMIT_STACK_VAL=$(shell ulimit -s)
 CFLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
 CFLAGS += -DNETNS_RUN_DIR=\"/run/netns\"
-CFLAGS += -DPASST_AUDIT_ARCH=AUDIT_ARCH_$(shell uname -m | tr [a-z] [A-Z])
+CFLAGS += -DPASST_AUDIT_ARCH=AUDIT_ARCH_$(AUDIT_ARCH)
+CFLAGS += -DRLIMIT_STACK_VAL=$(RLIMIT_STACK_VAL)
 CFLAGS += -DARCH=\"$(shell uname -m)\"
 
 # On gcc 11.2, with -O2 and -flto, tcp_hash() and siphash_20b(), if inlined,
diff --git a/passt.c b/passt.c
index 3581428..4f2b896 100644
--- a/passt.c
+++ b/passt.c
@@ -56,8 +56,8 @@
 #include <linux/capability.h>
 #include <linux/icmpv6.h>
 
-#include "seccomp.h"
 #include "util.h"
+#include "seccomp.h"
 #include "passt.h"
 #include "dhcp.h"
 #include "dhcpv6.h"
diff --git a/seccomp.sh b/seccomp.sh
index a055420..c710ce4 100755
--- a/seccomp.sh
+++ b/seccomp.sh
@@ -16,7 +16,11 @@
 TMP="$(mktemp)"
 OUT="seccomp.h"
 
-HEADER="/* This file was automatically generated by $(basename ${0}) */"
+HEADER="/* This file was automatically generated by $(basename ${0}) */
+
+#ifndef AUDIT_ARCH_PPC64LE
+#define AUDIT_ARCH_PPC64LE (AUDIT_ARCH_PPC64 | __AUDIT_ARCH_LE)
+#endif"
 
 # Prefix for each profile: check that 'arch' in seccomp_data is matching
 PRE='
-- 
2.33.0