linux/scripts, branch v5.18-rc5

objtool: Enable unreachable warnings for CLANG LTO

2022-04-19T19:58:48Z

With IBT support in, objtool is now fully capable of following vmlinux code flow in LTO mode. Start reporting unreachable warnings for Clang LTO as well. Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls") Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/7b12df54bceeb0761fe9fc8269ea0c00501214a9.1650300597.git.jpoimboe@redhat.com

Merge tag 'hardening-v5.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2022-04-13T00:29:40Z

Pull hardening fixes from Kees Cook: - latent_entropy: Use /dev/urandom instead of small GCC seed (Jason Donenfeld) - uapi/stddef.h: add missed include guards (Tadeusz Struk) * tag 'hardening-v5.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: gcc-plugins: latent_entropy: use /dev/urandom uapi/linux/stddef.h: Add include guards

gcc-plugins: latent_entropy: use /dev/urandom

2022-04-12T18:31:40Z

While the latent entropy plugin mostly doesn't derive entropy from get_random_const() for measuring the call graph, when __latent_entropy is applied to a constant, then it's initialized statically to output from get_random_const(). In that case, this data is derived from a 64-bit seed, which means a buffer of 512 bits doesn't really have that amount of compile-time entropy. This patch fixes that shortcoming by just buffering chunks of /dev/urandom output and doling it out as requested. At the same time, it's important that we don't break the use of -frandom-seed, for people who want the runtime benefits of the latent entropy plugin, while still having compile-time determinism. In that case, we detect whether gcc's set_random_seed() has been called by making a call to get_random_seed(noinit=true) in the plugin init function, which is called after set_random_seed() is called but before anything that calls get_random_seed(noinit=false), and seeing if it's zero or not. If it's not zero, we're in deterministic mode, and so we just generate numbers with a basic xorshift prng. Note that we don't detect if -frandom-seed is being used using the documented local_tick variable, because it's assigned via: local_tick = (unsigned) tv.tv_sec * 1000 + tv.tv_usec / 1000; which may well overflow and become -1 on its own, and so isn't reliable: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105171 [kees: The 256 byte rnd_buf size was chosen based on average (250), median (64), and std deviation (575) bytes of used entropy for a defconfig x86_64 build] Fixes: 38addce8b600 ("gcc-plugins: Add latent_entropy plugin") Cc: stable@vger.kernel.org Cc: PaX Team Signed-off-by: Jason A. Donenfeld Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220405222815.21155-1-Jason@zx2c4.com

modpost: restore the warning message for missing symbol versions

2022-04-02T18:11:51Z

This log message was accidentally chopped off. I was wondering why this happened, but checking the ML log, Mark precisely followed my suggestion [1]. I just used "..." because I was too lazy to type the sentence fully. Sorry for the confusion. [1]: https://lore.kernel.org/all/CAK7LNAR6bXXk9-ZzZYpTqzFqdYbQsZHmiWspu27rtsFxvfRuVA@mail.gmail.com/ Fixes: 4a6795933a89 ("kbuild: modpost: Explicitly warn about unprototyped symbols") Signed-off-by: Masahiro Yamada Acked-by: Mark Brown Reviewed-by: Nick Desaulniers

kbuild: fix empty ${PYTHON} in scripts/link-vmlinux.sh

2022-04-01T15:04:42Z

The two commits d8d2d38275c1 ("kbuild: remove PYTHON variable") a8cccdd95473 ("init: lto: ensure initcall ordering") were applied in the same development cycle, into two different trees. After they were merged together, this ${PYTHON} expands to an empty string. Therefore, ${srctree}/scripts/jobserver-exec is executed directly. (it has the executable bit set) This is working but let's fix the code into the intended form. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers Reviewed-by: Sedat Dilek

kconfig: remove stale comment about removed kconfig_print_symbol()

2022-04-01T15:04:17Z

This comment is about kconfig_print_symbol(), which was removed by commit 6ce45a91a982 ("kconfig: refactor conf_write_symbol()"). Signed-off-by: Masahiro Yamada

Merge tag 'docs-5.18-2' of git://git.lwn.net/linux

2022-03-31T19:10:42Z

Pull more documentation updates from Jonathan Corbet: "Some late-arriving documentation improvements. This is mostly build-system fixes from Mauro and Akira; I also took the liberty of dropping in my 'messy diffstat' document" * tag 'docs-5.18-2' of git://git.lwn.net/linux: docs: Add a document on how to fix a messy diffstat docs: sphinx/requirements: Limit jinja2<3.1 Documentation: kunit: Fix cross-referencing warnings scripts/kernel-doc: change the line number meta info scripts/get_abi: change the file/line number meta info docs: kernel_include.py: add sphinx build dependencies docs: kernel_abi.py: add sphinx build dependencies docs: kernel_feat.py: add build dependencies scripts/get_feat.pl: allow output the parsed file names docs: kfigure.py: Don't warn of missing PDF converter in 'make htmldocs' Documentation: Fix duplicate statement about raw_spinlock_t type

Merge tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2022-03-31T18:59:03Z

Pull Kbuild updates from Masahiro Yamada: - Add new environment variables, USERCFLAGS and USERLDFLAGS to allow additional flags to be passed to user-space programs. - Fix missing fflush() bugs in Kconfig and fixdep - Fix a minor bug in the comment format of the .config file - Make kallsyms ignore llvm's local labels, .L* - Fix UAPI compile-test for cross-compiling with Clang - Extend the LLVM= syntax to support LLVM= form for using a particular version of LLVm, and LLVM= form for using custom LLVM in a particular directory path. - Clean up Makefiles * tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kbuild: Make $(LLVM) more flexible kbuild: add --target to correctly cross-compile UAPI headers with Clang fixdep: use fflush() and ferror() to ensure successful write to files arch: syscalls: simplify uapi/kapi directory creation usr/include: replace extra-y with always-y certs: simplify empty certs creation in certs/Makefile certs: include certs/signing_key.x509 unconditionally kallsyms: ignore all local labels prefixed by '.L' kconfig: fix missing '# end of' for empty menu kconfig: add fflush() before ferror() check kbuild: replace $(if A,A,B) with $(or A,B) kbuild: Add environment variables for userprogs flags kbuild: unify cmd_copy and cmd_shipped

fixdep: use fflush() and ferror() to ensure successful write to files

2022-03-31T03:03:46Z

Currently, fixdep checks the return value from (v)printf(), but it does not ensure the complete write to the .cmd file. printf() just writes data to the internal buffer, which usually succeeds. (Of course, it may fail for another reason, for example when the file descriptor is closed, but that is another story.) When the buffer (4k?) is full, an actual write occurs, and printf() may really fail. One of typical cases is "No space left on device" when the disk is full. The data remaining in the buffer will be pushed out to the file when the program exits, but we never know if it is successful. One straight-forward fix would be to add the following code at the end of the program. ret = fflush(stdout); if (ret < 0) { /* error handling */ } However, it is tedious to check the return code in all the call sites of printf(), fflush(), fclose(), and whatever can cause actual writes to the end device. Doing that lets the program bail out at the first failure but is usually not worth the effort. Instead, let's check the error status from ferror(). This is 'sticky', so you need to check it just once. You still need to call fflush(). Signed-off-by: Masahiro Yamada Reviewed-by: David Laight Reviewed-by: Nick Desaulniers

scripts/kernel-doc: change the line number meta info

2022-03-28T19:53:46Z

In order to make it more standard and ReST compatible, change the meta-tag used with --enable-lineno from: #define LINENO to .. LINENO In practice, no functional changes. Signed-off-by: Mauro Carvalho Chehab Link: https://lore.kernel.org/r/40725032b5a4a33db740bf1de397523af958ff8a.1648290305.git.mchehab@kernel.org Signed-off-by: Jonathan Corbet