linux/lib/xz, branch v6.7

arch: Remove Itanium (IA-64) architecture

2023-09-11T08:13:17Z

The Itanium architecture is obsolete, and an informal survey [0] reveals that any residual use of Itanium hardware in production is mostly HP-UX or OpenVMS based. The use of Linux on Itanium appears to be limited to enthusiasts that occasionally boot a fresh Linux kernel to see whether things are still working as intended, and perhaps to churn out some distro packages that are rarely used in practice. None of the original companies behind Itanium still produce or support any hardware or software for the architecture, and it is listed as 'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers that contributed on behalf of those companies (nor anyone else, for that matter) have been willing to support or maintain the architecture upstream or even be responsible for applying the odd fix. The Intel firmware team removed all IA-64 support from the Tianocore/EDK2 reference implementation of EFI in 2018. (Itanium is the original architecture for which EFI was developed, and the way Linux supports it deviates significantly from other architectures.) Some distros, such as Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have dropped support years ago. While the argument is being made [1] that there is a 'for the common good' angle to being able to build and run existing projects such as the Grid Community Toolkit [2] on Itanium for interoperability testing, the fact remains that none of those projects are known to be deployed on Linux/ia64, and very few people actually have access to such a system in the first place. Even if there were ways imaginable in which Linux/ia64 could be put to good use today, what matters is whether anyone is actually doing that, and this does not appear to be the case. There are no emulators widely available, and so boot testing Itanium is generally infeasible for ordinary contributors. GCC still supports IA-64 but its compile farm [3] no longer has any IA-64 machines. GLIBC would like to get rid of IA-64 [4] too because it would permit some overdue code cleanups. In summary, the benefits to the ecosystem of having IA-64 be part of it are mostly theoretical, whereas the maintenance overhead of keeping it supported is real. So let's rip off the band aid, and remove the IA-64 arch code entirely. This follows the timeline proposed by the Debian/ia64 maintainer [5], which removes support in a controlled manner, leaving IA-64 in a known good state in the most recent LTS release. Other projects will follow once the kernel support is removed. [0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/ [1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/ [2] https://gridcf.org/gct-docs/latest/index.html [3] https://cfarm.tetaneutral.net/machines/list/ [4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/ [5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/ Acked-by: Tony Luck Signed-off-by: Ard Biesheuvel

lib/xz, lib/decompress_unxz.c: Fix spelling in comments

2021-10-19T15:44:30Z

uncompressible -> incompressible non-splitted -> non-split Link: https://lore.kernel.org/r/20211010213145.17462-6-xiang@kernel.org Signed-off-by: Lasse Collin Signed-off-by: Gao Xiang

lib/xz: Add MicroLZMA decoder

2021-10-19T15:44:30Z

MicroLZMA is a yet another header format variant where the first byte of a raw LZMA stream (without the end of stream marker) has been replaced with a bitwise-negation of the lc/lp/pb properties byte. MicroLZMA was created to be used in EROFS but can be used by other things too where wasting minimal amount of space for headers is important. This is implemented using most of the LZMA2 code as is so the amount of new code is small. The API has a few extra features compared to the XZ decoder. On the other hand, the API lacks XZ_BUF_ERROR support which is important to take into account when using this API. MicroLZMA doesn't support BCJ filters. In theory they could be added later as there are many unused/reserved values for the first byte of the compressed stream but in practice it is somewhat unlikely to happen due to a few implementation reasons. Link: https://lore.kernel.org/r/20211010213145.17462-5-xiang@kernel.org Signed-off-by: Lasse Collin Signed-off-by: Gao Xiang

lib/xz: Move s->lzma.len = 0 initialization to lzma_reset()

2021-10-19T15:44:30Z

It's a more logical place even if the resetting needs to be done only once per LZMA2 stream (if lzma_reset() called in the middle of an LZMA2 stream, .len will already be 0). Link: https://lore.kernel.org/r/20211010213145.17462-4-xiang@kernel.org Signed-off-by: Lasse Collin Signed-off-by: Gao Xiang

lib/xz: Validate the value before assigning it to an enum variable

2021-10-19T15:44:30Z

This might matter, for example, if the underlying type of enum xz_check was a signed char. In such a case the validation wouldn't have caught an unsupported header. I don't know if this problem can occur in the kernel on any arch but it's still good to fix it because some people might copy the XZ code to their own projects from Linux instead of the upstream XZ Embedded repository. This change may increase the code size by a few bytes. An alternative would have been to use an unsigned int instead of enum xz_check but using an enumeration looks cleaner. Link: https://lore.kernel.org/r/20211010213145.17462-3-xiang@kernel.org Signed-off-by: Lasse Collin Signed-off-by: Gao Xiang

lib/xz: Avoid overlapping memcpy() with invalid input with in-place decompression

2021-10-19T15:44:30Z

With valid files, the safety margin described in lib/decompress_unxz.c ensures that these buffers cannot overlap. But if the uncompressed size of the input is larger than the caller thought, which is possible when the input file is invalid/corrupt, the buffers can overlap. Obviously the result will then be garbage (and usually the decoder will return an error too) but no other harm will happen when such an over-run occurs. This change only affects uncompressed LZMA2 chunks and so this should have no effect on performance. Link: https://lore.kernel.org/r/20211010213145.17462-2-xiang@kernel.org Signed-off-by: Lasse Collin Signed-off-by: Gao Xiang

lib/decompressors: fix spelling mistakes

2021-07-01T18:06:05Z

Fix some spelling mistakes in comments: sentinal ==> sentinel compresed ==> compressed dependeny ==> dependency immediatelly ==> immediately dervied ==> derived splitted ==> split nore ==> not independed ==> independent asumed ==> assumed Link: https://lkml.kernel.org/r/20210604085656.12257-1-thunder.leizhen@huawei.com Signed-off-by: Zhen Lei Cc: Jiri Kosina Cc: Thomas Bogendoerfer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Revert "lib: Revert use of fallthrough pseudo-keyword in lib/"

2020-11-18T20:15:17Z

This reverts commit 6a9dc5fd6170 ("lib: Revert use of fallthrough pseudo-keyword in lib/") Now that we can build arch/powerpc/boot/ free of -Wimplicit-fallthrough, re-enable these fixes for lib/. Signed-off-by: Nick Desaulniers Tested-by: Nathan Chancellor Reviewed-by: Nathan Chancellor Reviewed-by: Gustavo A. R. Silva Reviewed-by: Miguel Ojeda Link: https://github.com/ClangBuiltLinux/linux/issues/236 Signed-off-by: Gustavo A. R. Silva

lib: Revert use of fallthrough pseudo-keyword in lib/

2020-08-24T21:17:44Z

The following build error for powerpc64 was reported by Nathan Chancellor: "$ scripts/config --file arch/powerpc/configs/powernv_defconfig -e KERNEL_XZ $ make -skj"$(nproc)" ARCH=powerpc CROSS_COMPILE=powerpc64le-linux- distclean powernv_defconfig zImage ... In file included from arch/powerpc/boot/../../../lib/decompress_unxz.c:234, from arch/powerpc/boot/decompress.c:38: arch/powerpc/boot/../../../lib/xz/xz_dec_stream.c: In function 'dec_main': arch/powerpc/boot/../../../lib/xz/xz_dec_stream.c:586:4: error: 'fallthrough' undeclared (first use in this function) 586 | fallthrough; | ^~~~~~~~~~~ This will end up affecting distribution configurations such as Debian and OpenSUSE according to my testing. I am not sure what the solution is, the PowerPC wrapper does not set -D__KERNEL__ so I am not sure that compiler_attributes.h can be safely included." In order to avoid these sort of problems, it seems that the best solution is to use /* fall through */ comments instead of the fallthrough pseudo-keyword macro in lib/, for now. Reported-by: Nathan Chancellor Fixes: df561f6688fe ("treewide: Use fallthrough pseudo-keyword") Signed-off-by: Gustavo A. R. Silva Reviewed-and-tested-by: Nathan Chancellor Signed-off-by: Linus Torvalds

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59Z

Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva