* [PATCH v4 1/3] um/kconfig: introduce CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
2020-07-19 21:02 [PATCH v4 0/3] um: allow static linking for non-glibc libc implementations Ignat Korchagin
@ 2020-07-19 21:02 ` Ignat Korchagin
2020-07-19 21:02 ` [PATCH v4 2/3] um: some fixes to build UML with musl Ignat Korchagin
2020-07-19 21:02 ` [PATCH v4 3/3] um: allow static linking for non-glibc implementations Ignat Korchagin
2 siblings, 0 replies; 4+ messages in thread
From: Ignat Korchagin @ 2020-07-19 21:02 UTC (permalink / raw)
To: jdike, richard, anton.ivanov, brendanhiggins, masahiroy,
linux-um, linux-kernel
Cc: Ignat Korchagin, kernel-team
For statically linked UML build it is important to take into account the
standard C-library implementation. Some implementations, notably glibc have
caveats: even when linked statically, the final program might require some
runtime dependencies, if certain functions are used within the code.
Consider the following program:
int main(void)
{
getpwent();
return 0;
}
Compiling this program and linking statically with glibc produces the following
warning from the linker:
/usr/sbin/ld: /tmp/ccuthw1o.o: in function `main':
test.c:(.text+0x5): warning: Using 'getpwent' in statically linked
applications requires at runtime the shared libraries from the glibc version
used for linking
We will use the flag to detect such C-library implementation build time and
possibly disable static linking for UML to avoid producing a binary with
unexpected behaviour and dependencies.
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
---
init/Kconfig | 6 ++++++
scripts/cc-can-link.sh | 5 +++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 0498af567f70..0a1ec56c9f33 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -57,6 +57,12 @@ config CC_CAN_LINK_STATIC
default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT
default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static)
+config CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
+ bool
+ depends on UML && CC_CAN_LINK_STATIC
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static -Xlinker --fatal-warnings) if 64BIT
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static -Xlinker --fatal-warnings)
+
config CC_HAS_ASM_GOTO
def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
diff --git a/scripts/cc-can-link.sh b/scripts/cc-can-link.sh
index 6efcead31989..e5011a46103e 100755
--- a/scripts/cc-can-link.sh
+++ b/scripts/cc-can-link.sh
@@ -2,10 +2,11 @@
# SPDX-License-Identifier: GPL-2.0
cat << "END" | $@ -x c - -o /dev/null >/dev/null 2>&1
-#include <stdio.h>
+#include <sys/types.h>
+#include <pwd.h>
int main(void)
{
- printf("");
+ getpwent();
return 0;
}
END
--
2.20.1
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH v4 2/3] um: some fixes to build UML with musl
2020-07-19 21:02 [PATCH v4 0/3] um: allow static linking for non-glibc libc implementations Ignat Korchagin
2020-07-19 21:02 ` [PATCH v4 1/3] um/kconfig: introduce CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS Ignat Korchagin
@ 2020-07-19 21:02 ` Ignat Korchagin
2020-07-19 21:02 ` [PATCH v4 3/3] um: allow static linking for non-glibc implementations Ignat Korchagin
2 siblings, 0 replies; 4+ messages in thread
From: Ignat Korchagin @ 2020-07-19 21:02 UTC (permalink / raw)
To: jdike, richard, anton.ivanov, brendanhiggins, masahiroy,
linux-um, linux-kernel
Cc: Ignat Korchagin, kernel-team
musl toolchain and headers are a bit more strict. These fixes enable building
UML with musl as well as seem not to break on glibc.
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
---
arch/um/drivers/daemon_user.c | 1 +
arch/um/drivers/pcap_user.c | 12 ++++++------
arch/um/drivers/slip_user.c | 2 +-
arch/um/drivers/vector_user.c | 4 +---
arch/um/os-Linux/util.c | 2 +-
arch/x86/um/user-offsets.c | 2 +-
6 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/arch/um/drivers/daemon_user.c b/arch/um/drivers/daemon_user.c
index 3695821d06a2..785baedc3555 100644
--- a/arch/um/drivers/daemon_user.c
+++ b/arch/um/drivers/daemon_user.c
@@ -7,6 +7,7 @@
*/
#include <stdint.h>
+#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
diff --git a/arch/um/drivers/pcap_user.c b/arch/um/drivers/pcap_user.c
index bbd20638788a..52ddda3e3b10 100644
--- a/arch/um/drivers/pcap_user.c
+++ b/arch/um/drivers/pcap_user.c
@@ -32,7 +32,7 @@ static int pcap_user_init(void *data, void *dev)
return 0;
}
-static int pcap_open(void *data)
+static int pcap_user_open(void *data)
{
struct pcap_data *pri = data;
__u32 netmask;
@@ -44,14 +44,14 @@ static int pcap_open(void *data)
if (pri->filter != NULL) {
err = dev_netmask(pri->dev, &netmask);
if (err < 0) {
- printk(UM_KERN_ERR "pcap_open : dev_netmask failed\n");
+ printk(UM_KERN_ERR "pcap_user_open : dev_netmask failed\n");
return -EIO;
}
pri->compiled = uml_kmalloc(sizeof(struct bpf_program),
UM_GFP_KERNEL);
if (pri->compiled == NULL) {
- printk(UM_KERN_ERR "pcap_open : kmalloc failed\n");
+ printk(UM_KERN_ERR "pcap_user_open : kmalloc failed\n");
return -ENOMEM;
}
@@ -59,14 +59,14 @@ static int pcap_open(void *data)
(struct bpf_program *) pri->compiled,
pri->filter, pri->optimize, netmask);
if (err < 0) {
- printk(UM_KERN_ERR "pcap_open : pcap_compile failed - "
+ printk(UM_KERN_ERR "pcap_user_open : pcap_compile failed - "
"'%s'\n", pcap_geterr(pri->pcap));
goto out;
}
err = pcap_setfilter(pri->pcap, pri->compiled);
if (err < 0) {
- printk(UM_KERN_ERR "pcap_open : pcap_setfilter "
+ printk(UM_KERN_ERR "pcap_user_open : pcap_setfilter "
"failed - '%s'\n", pcap_geterr(pri->pcap));
goto out;
}
@@ -127,7 +127,7 @@ int pcap_user_read(int fd, void *buffer, int len, struct pcap_data *pri)
const struct net_user_info pcap_user_info = {
.init = pcap_user_init,
- .open = pcap_open,
+ .open = pcap_user_open,
.close = NULL,
.remove = pcap_remove,
.add_address = NULL,
diff --git a/arch/um/drivers/slip_user.c b/arch/um/drivers/slip_user.c
index 8016d32b6809..482a19c5105c 100644
--- a/arch/um/drivers/slip_user.c
+++ b/arch/um/drivers/slip_user.c
@@ -9,7 +9,7 @@
#include <errno.h>
#include <fcntl.h>
#include <string.h>
-#include <sys/termios.h>
+#include <termios.h>
#include <sys/wait.h>
#include <net_user.h>
#include <os.h>
diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index c4a0f26b2824..45d4164ad355 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -18,9 +18,7 @@
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/un.h>
-#include <net/ethernet.h>
#include <netinet/ip.h>
-#include <netinet/ether.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <sys/wait.h>
@@ -332,7 +330,7 @@ static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id)
}
switch (id) {
case ID_BESS:
- if (connect(fd, remote_addr, sizeof(struct sockaddr_un)) < 0) {
+ if (connect(fd, (const struct sockaddr *) remote_addr, sizeof(struct sockaddr_un)) < 0) {
printk(UM_KERN_ERR "bess open:cannot connect to %s %i", remote_addr->sun_path, -errno);
goto unix_cleanup;
}
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index ecf2f390fad2..07327425d06e 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -10,7 +10,7 @@
#include <signal.h>
#include <string.h>
#include <termios.h>
-#include <wait.h>
+#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include <init.h>
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index c51dd8363d25..bae61554abcc 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -2,7 +2,7 @@
#include <stdio.h>
#include <stddef.h>
#include <signal.h>
-#include <sys/poll.h>
+#include <poll.h>
#include <sys/mman.h>
#include <sys/user.h>
#define __FRAME_OFFSETS
--
2.20.1
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH v4 3/3] um: allow static linking for non-glibc implementations
2020-07-19 21:02 [PATCH v4 0/3] um: allow static linking for non-glibc libc implementations Ignat Korchagin
2020-07-19 21:02 ` [PATCH v4 1/3] um/kconfig: introduce CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS Ignat Korchagin
2020-07-19 21:02 ` [PATCH v4 2/3] um: some fixes to build UML with musl Ignat Korchagin
@ 2020-07-19 21:02 ` Ignat Korchagin
2 siblings, 0 replies; 4+ messages in thread
From: Ignat Korchagin @ 2020-07-19 21:02 UTC (permalink / raw)
To: jdike, richard, anton.ivanov, brendanhiggins, masahiroy,
linux-um, linux-kernel
Cc: Ignat Korchagin, kernel-team
It is possible to produce a statically linked UML binary with UML_NET_VECTOR,
UML_NET_VDE and UML_NET_PCAP options enabled using alternative libc
implementations, which do not rely on NSS, such as musl.
Allow static linking in this case.
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
---
arch/um/Kconfig | 6 +++---
arch/um/drivers/Kconfig | 6 +++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 9318dc6d1a0c..d888b859c167 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -62,12 +62,12 @@ config NR_CPUS
source "arch/$(HEADER_ARCH)/um/Kconfig"
-config FORBID_STATIC_LINK
- bool
+config MAY_HAVE_RUNTIME_DEPS
+ bool
config STATIC_LINK
bool "Force a static link"
- depends on !FORBID_STATIC_LINK
+ depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
help
This option gives you the ability to force a static link of UML.
Normally, UML is linked as a shared binary. This is inconvenient for
diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
index 9160ead56e33..2e7b8e0e7194 100644
--- a/arch/um/drivers/Kconfig
+++ b/arch/um/drivers/Kconfig
@@ -234,7 +234,7 @@ config UML_NET_DAEMON
config UML_NET_VECTOR
bool "Vector I/O high performance network devices"
depends on UML_NET
- select FORBID_STATIC_LINK
+ select MAY_HAVE_RUNTIME_DEPS
help
This User-Mode Linux network driver uses multi-message send
and receive functions. The host running the UML guest must have
@@ -246,7 +246,7 @@ config UML_NET_VECTOR
config UML_NET_VDE
bool "VDE transport (obsolete)"
depends on UML_NET
- select FORBID_STATIC_LINK
+ select MAY_HAVE_RUNTIME_DEPS
help
This User-Mode Linux network transport allows one or more running
UMLs on a single host to communicate with each other and also
@@ -294,7 +294,7 @@ config UML_NET_MCAST
config UML_NET_PCAP
bool "pcap transport (obsolete)"
depends on UML_NET
- select FORBID_STATIC_LINK
+ select MAY_HAVE_RUNTIME_DEPS
help
The pcap transport makes a pcap packet stream on the host look
like an ethernet device inside UML. This is useful for making
--
2.20.1
^ permalink raw reply [flat|nested] 4+ messages in thread