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f913a66004
Currently several approaches for finding unused memory in decompressor are utilized. While "safe_addr" grows towards higher addresses, vmem code allocates paging structures top down. The former requires careful ordering. In addition to that ipl report handling code verifies potential intersections with secure boot certificates on its own. Neither of two approaches are memory holes aware and consistent with each other in low memory conditions. To solve that, existing approaches are generalized and combined together, as well as online memory ranges are now taken into consideration. physmem_info has been extended to contain reserved memory ranges. New set of functions allow to handle reserves and find unused memory. All reserves and memory allocations are "typed". In case of out of memory condition decompressor fails with detailed info on current reserved ranges and usable online memory. Linux version 6.2.0 ... Kernel command line: ... mem=100M Our of memory allocating 100000 bytes 100000 aligned in range 0:5800000 Reserved memory ranges: 0000000000000000 0000000003e33000 DECOMPRESSOR 0000000003f00000 00000000057648a3 INITRD 00000000063e0000 00000000063e8000 VMEM 00000000063eb000 00000000063f4000 VMEM 00000000063f7800 0000000006400000 VMEM 0000000005800000 0000000006300000 KASAN Usable online memory ranges (info source: sclp read info [3]): 0000000000000000 0000000006400000 Usable online memory total: 6400000 Reserved: 61b10a3 Free: 24ef5d Call Trace: (sp:000000000002bd58 [<0000000000012a70>] physmem_alloc_top_down+0x60/0x14c) sp:000000000002bdc8 [<0000000000013756>] _pa+0x56/0x6a sp:000000000002bdf0 [<0000000000013bcc>] pgtable_populate+0x45c/0x65e sp:000000000002be90 [<00000000000140aa>] setup_vmem+0x2da/0x424 sp:000000000002bec8 [<0000000000011c20>] startup_kernel+0x428/0x8b4 sp:000000000002bf60 [<00000000000100f4>] startup_normal+0xd4/0xd4 physmem_alloc_range allows to find free memory in specified range. It should be used for one time allocations only like finding position for amode31 and vmlinux. physmem_alloc_top_down can be used just like physmem_alloc_range, but it also allows multiple allocations per type and tries to merge sequential allocations together. Which is useful for paging structures allocations. If sequential allocations cannot be merged together they are "chained", allowing easy per type reserved ranges enumeration and migration to memblock later. Extra "struct reserved_range" allocated for chaining are not tracked or reserved but rely on the fact that both physmem_alloc_range and physmem_alloc_top_down search for free memory only below current top down allocator position. All reserved ranges should be transferred to memblock before memblock allocations are enabled. The startup code has been reordered to delay any memory allocations until online memory ranges are detected and occupied memory ranges are marked as reserved to be excluded from follow-up allocations. Ipl report certificates are a special case, ipl report certificates list is checked together with other memory reserves until certificates are saved elsewhere. KASAN required memory for shadow memory allocation and mapping is reserved as 1 large chunk which is later passed to KASAN early initialization code. Acked-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.