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path: root/arch/s390/boot/decompressor.c
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2025-01-26s390/boot: Improve decompression error reportingVasily Gorbik
Currently, decompression error messages can be very uninformative: [ 0.029853] startup: read error [ 0.040507] startup: -- System halted Improve these messages to make it clear that the error originates from the decompression code. Additionally, on decompression failures, if bootdebug is enabled, dump the message ring buffer before halting. This provides more context for diagnosing startup issues. Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Acked-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-04-17s390/boot: Rework deployment of the kernel imageAlexander Gordeev
Rework deployment of kernel image for both compressed and uncompressed variants as defined by CONFIG_KERNEL_UNCOMPRESSED kernel configuration variable. In case CONFIG_KERNEL_UNCOMPRESSED is disabled avoid uncompressing the kernel to a temporary buffer and copying it to the target address. Instead, uncompress it directly to the target destination. In case CONFIG_KERNEL_UNCOMPRESSED is enabled avoid moving the kernel to default 0x100000 location when KASLR is disabled or failed. Instead, use the uncompressed kernel image directly. In case KASLR is disabled or failed .amode31 section location in memory is not randomized and precedes the kernel image. In case CONFIG_KERNEL_UNCOMPRESSED is disabled that location overlaps the area used by the decompression algorithm. That is fine, since that area is not used after the decompression finished and the size of .amode31 section is not expected to exceed BOOT_HEAP_SIZE ever. There is no decompression in case CONFIG_KERNEL_UNCOMPRESSED is enabled. Therefore, rename decompress_kernel() to deploy_kernel(), which better describes both uncompressed and compressed cases. Introduce AMODE31_SIZE macro to avoid immediate value of 0x3000 (the size of .amode31 section) in the decompressor linker script. Modify the vmlinux linker script to force the size of .amode31 section to AMODE31_SIZE (the value of (_eamode31 - _samode31) could otherwise differ as result of compiler options used). Introduce __START_KERNEL macro that defines the kernel ELF image entry point and set it to the currrent value of 0x100000. Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2023-02-06Merge branch 'fixes' into featuresHeiko Carstens
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2023-01-31s390/decompressor: specify __decompress() buf len to avoid overflowVasily Gorbik
Historically calls to __decompress() didn't specify "out_len" parameter on many architectures including s390, expecting that no writes beyond uncompressed kernel image are performed. This has changed since commit 2aa14b1ab2c4 ("zstd: import usptream v1.5.2") which includes zstd library commit 6a7ede3dfccb ("Reduce size of dctx by reutilizing dst buffer (#2751)"). Now zstd decompression code might store literal buffer in the unwritten portion of the destination buffer. Since "out_len" is not set, it is considered to be unlimited and hence free to use for optimization needs. On s390 this might corrupt initrd or ipl report which are often placed right after the decompressor buffer. Luckily the size of uncompressed kernel image is already known to the decompressor, so to avoid the problem simply specify it in the "out_len" parameter. Link: https://github.com/facebook/zstd/commit/6a7ede3dfccb Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Tested-by: Alexander Egorenkov <egorenar@linux.ibm.com> Link: https://lore.kernel.org/r/patch-1.thread-41c676.git-41c676c2d153.your-ad-here.call-01675030179-ext-9637@work.hours Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2023-01-17Merge branch 'fixes' into featuresHeiko Carstens
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2023-01-13s390/boot: cleanup decompressor header filesAlexander Gordeev
Move declarations to appropriate header files. Instead of cryptic casting directly assign struct vmlinux_info type to _vmlinux_info linker script variable - wich it actually is. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2023-01-09s390: fix -Wundef warning for CONFIG_KERNEL_ZSTDMasahiro Yamada
Since commit 80b6093b55e3 ("kbuild: add -Wundef to KBUILD_CPPFLAGS for W=1 builds"), building with W=1 detects misuse of #(el)if. $ make W=1 ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- [snip] arch/s390/boot/decompressor.c:28:7: warning: "CONFIG_KERNEL_ZSTD" is not defined, evaluates to 0 [-Wundef] 28 | #elif CONFIG_KERNEL_ZSTD | ^~~~~~~~~~~~~~~~~~ This issue has been hidden because arch/s390/boot/Makefile overwrites KBUILD_CFLAGS, dropping -Wundef. CONFIG_KERNEL_ZSTD is a bool option. #elif defined() should be used. The line #ifdef CONFIG_KERNEL_BZIP2 is fine, but I changed it for consistency. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Link: https://lore.kernel.org/r/20230106161024.2373602-1-masahiroy@kernel.org Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2022-05-06s390/boot: get rid of startup archiveHeiko Carstens
The final kernel image is created by linking decompressor object files with a startup archive. The startup archive file however does not contain only optional code and data which can be discarded if not referenced. It also contains mandatory object data like head.o which must never be discarded, even if not referenced. Move the decompresser code and linker script to the boot directory and get rid of the startup archive so everything is kept during link time. Acked-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>