Changes in Makefile

faabed29 - kbuild: introduce hostprogs-always-y and userprogs-always-y

Sat, 01 Aug 2020 12:27:18 +0000

kbuild: introduce hostprogs-always-y and userprogs-always-yTo build host programs, you need to add the program names to 'hostprogs'to use the necessary build rule, but it is not enough to build thembecause there is no dependency.There are two types of host programs: built as the prerequisite ofanother (e.g. gen_crc32table in lib/Makefile), or always built whenKbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile).The latter is typical in Makefiles under scripts/, which contains hostprograms globally used during the kernel build. To build them, you needto add them to both 'hostprogs' and 'always-y'.This commit adds hostprogs-always-y as a shorthand.The same applies to user programs. net/bpfilter/Makefile buildsbpfilter_umh on demand, hence always-y is unneeded. In contrast,programs under samples/ are added to both 'userprogs' and 'always-y'so they are always built when Kbuild visits the Makefiles.userprogs-always-y works as a shorthand.Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda List of files: /linux-6.15/samples/pidfd/Makefile

60fb0b12 - samples: pidfd: build sample program for target architecture

Wed, 29 Apr 2020 03:45:23 +0000

samples: pidfd: build sample program for target architectureThis userspace program includes UAPI headers exported to usr/include/.'make headers' always works for the target architecture (i.e. the samearchitecture as the kernel), so the sample program should be built forthe target as well. Kbuild now supports 'userprogs' for that.I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because$(CC) may not provide libc.Signed-off-by: Masahiro Yamada Acked-by: Sam Ravnborg List of files: /linux-6.15/samples/pidfd/Makefile

5f2fb52f - kbuild: rename hostprogs-y/always to hostprogs/always-y

Sat, 01 Feb 2020 16:49:24 +0000

kbuild: rename hostprogs-y/always to hostprogs/always-yIn old days, the "host-progs" syntax was used for specifying hostprograms. It was renamed to the current "hostprogs-y" in 2004.It is typically useful in scripts/Makefile because it allows Kbuild toselectively compile host programs based on the kernel configuration.This commit renames like follows: always -> always-y hostprogs-y -> hostprogsSo, scripts/Makefile will look like this: always-$(CONFIG_BUILD_BIN2C) += ... always-$(CONFIG_KALLSYMS) += ... ... hostprogs := $(always-y) $(always-m)I think this makes more sense because a host program is always a hostprogram, irrespective of the kernel configuration. We want to specifywhich ones to compile by CONFIG options, so always-y will be handier.The "always", "hostprogs-y", "hostprogs-m" will be kept for backwardcompatibility for a while.Signed-off-by: Masahiro Yamada List of files: /linux-6.15/samples/pidfd/Makefile

43c6afee - samples: show race-free pidfd metadata access

Sun, 07 Apr 2019 19:18:11 +0000

samples: show race-free pidfd metadata accessThis is a sample program showing userspace how to get race-free accessto process metadata from a pidfd. It is rather easy to do and userspacecan actually simply reuse code that currently parses a process's statusfile in procfs.The program can easily be extended into a generic helper suitable forinclusion in a libc to make it even easier for userspace to gain metadataaccess.Since this came up in a discussion because this API is going to be usedin various service managers: A lot of programs will have a whitelistseccomp filter that returns for all new syscalls. Thismeans that programs might get confused if CLONE_PIDFD works but thelater pidfd_send_signal() syscall doesn't. Hence, here's a ahead oftime check that pidfd_send_signal() is supported:bool pidfd_send_signal_supported(){ int procfd = open("/proc/self", O_DIRECTORY | O_RDONLY | O_CLOEXEC); if (procfd < 0) return false; /* * A process is always allowed to signal itself so * pidfd_send_signal() should never fail this test. If it does * it must mean it is not available, blocked by an LSM, seccomp, * or other. */ return pidfd_send_signal(procfd, 0, NULL, 0) == 0;}Signed-off-by: Christian Brauner Co-developed-by: Jann Horn Signed-off-by: Jann Horn Reviewed-by: Oleg Nesterov Cc: Arnd Bergmann Cc: "Eric W. Biederman" Cc: Kees Cook Cc: Thomas Gleixner Cc: David Howells Cc: "Michael Kerrisk (man-pages)" Cc: Andy Lutomirsky Cc: Andrew Morton Cc: Aleksa Sarai Cc: Linus Torvalds Cc: Al Viro List of files: /linux-6.15/samples/pidfd/Makefile