Many changes compared to version 6, so I decided to send it out now. James Morse raised an important issue to which I do not have a solution yet. But would like to discuss it. --- https://lore.kernel.org/lkml/45a2f0b8-5bac-8b5d-d595-f92e9acb27ad@xxxxxxx > + /* Map relocation function va == pa */ > + rc = trans_pgd_map_page(&info, trans_ttbr0, __va(kern_reloc), > + kern_reloc, PAGE_KERNEL_EXEC); > + if (rc) > + return rc; James wrote: You can't do this with the page table helpers. We support platforms with no memory in range of TTBR0's VA space. See dd006da21646f You will need some idmapped memory to turn the MMU off on a system that booted at EL1. This will need to be in a set of page tables that the helpers can't easily touch - so it should only be a single page. (like the arch code's existing idmap - although that may have been overwritten). (I have a machine where this is a problem, if I get the time I will have a stab at making hibernate's safe page idmaped). --- As I understand, there are platforms where TTBR0 cannot include all physical memory for idmap. However, kexec must have at least one page idmapped (kimage->control_code_page) to be able to relocate kernel while MMU is enabled: I am still trying to fully understand the problem: CONFIG_ARM64_VA_BITS must be smaller than 48 and physical memory must start at a high address for this problem to occur. Why can't we simply decrease T0SZ to cover all physical memory? Changelog: v8: - Synced with mainline to keep series up-to-date v7: -- Addressed comments from James Morse - arm64: hibernate: pass the allocated pgdp to ttbr0 Removed "Fixes" tag, and added Added Reviewed-by: James Morse - arm64: hibernate: check pgd table allocation Sent out as a standalone patch so it can be sent to stable Series applies on mainline + this patch - arm64: hibernate: add trans_pgd public functions Remove second allocation of tmp_pg_dir in swsusp_arch_resume Added Reviewed-by: James Morse <james.morse@xxxxxxx> - arm64: kexec: move relocation function setup and clean up Fixed typo in commit log Changed kern_reloc to phys_addr_t types. Added explanation why kern_reloc is needed. Split into four patches: arm64: kexec: make dtb_mem always enabled arm64: kexec: remove unnecessary debug prints arm64: kexec: call kexec_image_info only once arm64: kexec: move relocation function setup - arm64: kexec: add expandable argument to relocation function Changed types of new arguments from unsigned long to phys_addr_t. Changed offset prefix to KEXEC_* Split into four patches: arm64: kexec: cpu_soft_restart change argument types arm64: kexec: arm64_relocate_new_kernel clean-ups arm64: kexec: arm64_relocate_new_kernel don't use x0 as temp arm64: kexec: add expandable argument to relocation function - arm64: kexec: configure trans_pgd page table for kexec Added invalid entries into EL2 vector table Removed KEXEC_EL2_VECTOR_TABLE_SIZE and KEXEC_EL2_VECTOR_TABLE_OFFSET Copy relocation functions and table into separate pages Changed types in kern_reloc_arg. Split into three patches: arm64: kexec: offset for relocation function arm64: kexec: kexec EL2 vectors arm64: kexec: configure trans_pgd page table for kexec - arm64: kexec: enable MMU during kexec relocation Split into two patches: arm64: kexec: enable MMU during kexec relocation arm64: kexec: remove head from relocation argument v6: - Sync with mainline tip - Added Acked's from Dave Young v5: - Addressed comments from Matthias Brugger: added review-by's, improved comments, and made cleanups to swsusp_arch_resume() in addition to create_safe_exec_page(). - Synced with mainline tip. v4: - Addressed comments from James Morse. - Split "check pgd table allocation" into two patches, and moved to the beginning of series for simpler backport of the fixes. Added "Fixes:" tags to commit logs. - Changed "arm64, hibernate:" to "arm64: hibernate:" - Added Reviewed-by's - Moved "add PUD_SECT_RDONLY" earlier in series to be with other clean-ups - Added "Derived from:" to arch/arm64/mm/trans_pgd.c - Removed "flags" from trans_info - Changed .trans_alloc_page assumption to return zeroed page. - Simplify changes to trans_pgd_map_page(), by keeping the old code. - Simplify changes to trans_pgd_create_copy, by keeping the old code. - Removed: "add trans_pgd_create_empty" - replace init_mm with NULL, and keep using non "__" version of populate functions. v3: - Split changes to create_safe_exec_page() into several patches for easier review as request by Mark Rutland. This is why this series has 3 more patches. - Renamed trans_table to tans_pgd as agreed with Mark. The header comment in trans_pgd.c explains that trans stands for transitional page tables. Meaning they are used in transition between two kernels. v2: - Fixed hibernate bug reported by James Morse - Addressed comments from James Morse: * More incremental changes to trans_table * Removed TRANS_FORCEMAP * Added kexec reboot data for image with 380M in size. Enable MMU during kexec relocation in order to improve reboot performance. If kexec functionality is used for a fast system update, with a minimal downtime, the relocation of kernel + initramfs takes a significant portion of reboot. The reason for slow relocation is because it is done without MMU, and thus not benefiting from D-Cache. Performance data ---------------- For this experiment, the size of kernel plus initramfs is small, only 25M. If initramfs was larger, than the improvements would be greater, as time spent in relocation is proportional to the size of relocation. Previously: kernel shutdown 0.022131328s relocation 0.440510736s kernel startup 0.294706768s Relocation was taking: 58.2% of reboot time Now: kernel shutdown 0.032066576s relocation 0.022158152s kernel startup 0.296055880s Now: Relocation takes 6.3% of reboot time Total reboot is x2.16 times faster. With bigger userland (fitImage 380M), the reboot time is improved by 3.57s, and is reduced from 3.9s down to 0.33s Previous approaches and discussions ----------------------------------- https://lore.kernel.org/lkml/20191016200034.1342308-1-pasha.tatashin@xxxxxxxxxx version 7 of this series https://lore.kernel.org/lkml/20191004185234.31471-1-pasha.tatashin@xxxxxxxxxx version 6 of this series https://lore.kernel.org/lkml/20190923203427.294286-1-pasha.tatashin@xxxxxxxxxx version 5 of this series https://lore.kernel.org/lkml/20190909181221.309510-1-pasha.tatashin@xxxxxxxxxx version 4 of this series https://lore.kernel.org/lkml/20190821183204.23576-1-pasha.tatashin@xxxxxxxxxx version 3 of this series https://lore.kernel.org/lkml/20190817024629.26611-1-pasha.tatashin@xxxxxxxxxx version 2 of this series https://lore.kernel.org/lkml/20190801152439.11363-1-pasha.tatashin@xxxxxxxxxx version 1 of this series https://lore.kernel.org/lkml/20190709182014.16052-1-pasha.tatashin@xxxxxxxxxx reserve space for kexec to avoid relocation, involves changes to generic code to optimize a problem that exists on arm64 only: https://lore.kernel.org/lkml/20190716165641.6990-1-pasha.tatashin@xxxxxxxxxx The first attempt to enable MMU, some bugs that prevented performance improvement. The page tables unnecessary configured idmap for the whole physical space. https://lore.kernel.org/lkml/20190731153857.4045-1-pasha.tatashin@xxxxxxxxxx No linear copy, bug with EL2 reboots. Pavel Tatashin (25): kexec: quiet down kexec reboot kexec: add machine_kexec_post_load() arm64: kexec: remove unnecessary debug prints arm64: kexec: make dtb_mem always enabled arm64: hibernate: pass the allocated pgdp to ttbr0 arm64: hibernate: use get_safe_page directly arm64: hibernate: remove gotos as they are not needed arm64: hibernate: rename dst to page in create_safe_exec_page arm64: hibernate: add PUD_SECT_RDONLY arm64: hibernate: add trans_pgd public functions arm64: hibernate: move page handling function to new trans_pgd.c arm64: trans_pgd: make trans_pgd_map_page generic arm64: trans_pgd: pass allocator trans_pgd_create_copy arm64: trans_pgd: pass NULL instead of init_mm to *_populate functions arm64: kexec: move relocation function setup arm64: kexec: call kexec_image_info only once arm64: kexec: cpu_soft_restart change argument types arm64: kexec: arm64_relocate_new_kernel clean-ups arm64: kexec: arm64_relocate_new_kernel don't use x0 as temp arm64: kexec: add expandable argument to relocation function arm64: kexec: offset for relocation function arm64: kexec: kexec EL2 vectors arm64: kexec: configure trans_pgd page table for kexec arm64: kexec: enable MMU during kexec relocation arm64: kexec: remove head from relocation argument arch/arm64/Kconfig | 4 + arch/arm64/include/asm/kexec.h | 47 ++++- arch/arm64/include/asm/pgtable-hwdef.h | 1 + arch/arm64/include/asm/trans_pgd.h | 34 ++++ arch/arm64/kernel/asm-offsets.c | 14 ++ arch/arm64/kernel/cpu-reset.S | 8 +- arch/arm64/kernel/cpu-reset.h | 14 +- arch/arm64/kernel/hibernate.c | 255 ++++--------------------- arch/arm64/kernel/machine_kexec.c | 186 ++++++++++++++---- arch/arm64/kernel/relocate_kernel.S | 233 ++++++++++++---------- arch/arm64/mm/Makefile | 1 + arch/arm64/mm/trans_pgd.c | 244 +++++++++++++++++++++++ kernel/kexec.c | 4 + kernel/kexec_core.c | 8 +- kernel/kexec_file.c | 4 + kernel/kexec_internal.h | 2 + 16 files changed, 690 insertions(+), 369 deletions(-) create mode 100644 arch/arm64/include/asm/trans_pgd.h create mode 100644 arch/arm64/mm/trans_pgd.c -- 2.24.0
