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linux/arch/s390/boot/decompressor.h

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s390: remove decompressor's head.S Decompressor's head.S provided "data mover" sole purpose of which has been to safely move uncompressed kernel at 0x100000 and jump to it. With current bzImage layout entire decompressor's code guaranteed to be in a safe location under 0x100000, and hence could not be overwritten during kernel move. For that reason head.S could be replaced with simple memmove function. To do so introduce early boot code phase which is executed from arch/s390/boot/head.S after "verify_facilities" and takes care of optional kernel image decompression and transition to it. Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-07-19 04:11:28 -07:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BOOT_COMPRESSED_DECOMPRESSOR_H
#define BOOT_COMPRESSED_DECOMPRESSOR_H
s390/boot: Rework deployment of the kernel image 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>
2024-03-22 06:39:57 -07:00
#ifndef CONFIG_KERNEL_UNCOMPRESSED
s390: rescue initrd as early as possible To avoid multi-stage initrd rescue operation and to simplify assumptions during early memory allocations move initrd at some final safe destination as early as possible. This would also allow us to drop .bss usage restrictions for some files. Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-04-11 02:56:55 -07:00
unsigned long mem_safe_offset(void);
s390/boot: Rework deployment of the kernel image 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>
2024-03-22 06:39:57 -07:00
void deploy_kernel(void *output);
#endif
s390/decompressor: rework uncompressed image info collection The kernel decompressor has to know several bits of information about uncompressed image. Currently this info is collected by running "nm" on uncompressed vmlinux + "sed" and producing sizes.h file. This method worked well, but it has several disadvantages. Obscure symbols name pattern matching is fragile. Adding new values makes pattern even longer. Logic is spread across code and make file. Limited ability to adjust symbols values (currently magic lma value of 0x100000 is always subtracted). Apart from that same pieces of information (and more) would be needed for early memory detection and features like KASLR outside of boot/compressed/ folder where sizes.h is generated. To overcome limitations new "struct vmlinux_info" has been introduced to include values needed for the decompressor and the rest of the boot code. The only static instance of vmlinux_info is produced during vmlinux link step by filling in struct fields by the linker (like it is done with input_data in boot/compressed/vmlinux.scr.lds.S). This way individual values could be adjusted with all the knowledge linker has and arithmetic it supports. Later .vmlinux.info section (which contains struct vmlinux_info) is transplanted into the decompressor image and dropped from uncompressed image altogether. While doing that replace "compressed/vmlinux.scr.lds.S" linker script (whose purpose is to rename .data section in piggy.o to .rodata.compressed) with plain objcopy command. And simplify decompressor's linker script. Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-07-19 07:51:25 -07:00
s390: remove decompressor's head.S Decompressor's head.S provided "data mover" sole purpose of which has been to safely move uncompressed kernel at 0x100000 and jump to it. With current bzImage layout entire decompressor's code guaranteed to be in a safe location under 0x100000, and hence could not be overwritten during kernel move. For that reason head.S could be replaced with simple memmove function. To do so introduce early boot code phase which is executed from arch/s390/boot/head.S after "verify_facilities" and takes care of optional kernel image decompression and transition to it. Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-07-19 04:11:28 -07:00
#endif /* BOOT_COMPRESSED_DECOMPRESSOR_H */
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