lwn.git/arch/arm64/kernel/hibernate.c, branch standardize-docs

arm64: hibernate: preserve kdump image around hibernation

2017-04-05T17:28:50+00:00

Since arch_kexec_protect_crashkres() removes a mapping for crash dump kernel image, the loaded data won't be preserved around hibernation. In this patch, helper functions, crash_prepare_suspend()/ crash_post_resume(), are additionally called before/after hibernation so that the relevant memory segments will be mapped again and preserved just as the others are. In addition, to minimize the size of hibernation image, crash_is_nosave() is added to pfn_is_nosave() in order to recognize only the pages that hold loaded crash dump kernel image as saveable. Hibernation excludes any pages that are marked as Reserved and yet "nosave." Signed-off-by: AKASHI Takahiro Reviewed-by: James Morse Signed-off-by: Catalin Marinas

arm64: Use __pa_symbol for kernel symbols

2017-01-12T15:05:39+00:00

__pa_symbol is technically the marcro that should be used for kernel symbols. Switch to this as a pre-requisite for DEBUG_VIRTUAL which will do bounds checking. Reviewed-by: Mark Rutland Tested-by: Mark Rutland Signed-off-by: Laura Abbott Signed-off-by: Will Deacon

arm64: add missing printk newlines

2017-01-10T12:35:27+00:00

A few printk calls in arm64 omit a trailing newline, even though there is no subsequent KERN_CONT printk associated with them, and we actually want a newline. This can result in unrelated lines being appended, rather than appearing on a new line. Additionally, timestamp prefixes may appear in-line. This makes the logs harder to read than necessary. Avoid this by adding a trailing newline. These were found with a shortlist generated by: $ git grep 'pr$intk\|_.*$(.*)' -- arch/arm64 | grep -v pr_fmt | grep -v '\\n"' Signed-off-by: Mark Rutland CC: James Morse Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon

treewide: Fix printk() message errors

2016-12-14T09:54:27+00:00

This patch fix spelling typos in printk and kconfig. Signed-off-by: Masanari Iida Acked-by: Randy Dunlap Signed-off-by: Jiri Kosina

Revert "arm64: hibernate: Refuse to hibernate if the boot cpu is offline"

2016-08-26T10:21:25+00:00

Now that we use the MPIDR to resume on the same CPU that we hibernated on, we no longer need to refuse to hibernate if the boot cpu is offline. (Which we can't possibly know if kexec causes logical CPUs to be renumbered). This reverts commit 1fe492ce6482b77807b25d29690a48c46456beee. Signed-off-by: James Morse Acked-by: Catalin Marinas Signed-off-by: Will Deacon

arm64: hibernate: Resume when hibernate image created on non-boot CPU

2016-08-26T10:21:25+00:00

disable_nonboot_cpus() assumes that the lowest numbered online CPU is the boot CPU, and that this is the correct CPU to run any power management code on. On arm64 CPU0 can be taken offline. For hibernate/resume this means we may hibernate on a CPU other than CPU0. If the system is rebooted with kexec 'CPU0' will be assigned to a different CPU. This complicates hibernate/resume as now we can't trust the CPU numbers. We currently forbid hibernate if CPU0 has been hotplugged out to avoid this situation without kexec. Save the MPIDR of the CPU we hibernated on in the hibernate arch-header, use hibernate_resume_nonboot_cpu_disable() to direct which CPU we should resume on based on the MPIDR of the CPU we hibernated on. This allows us to hibernate/resume on any CPU, even if the logical numbers have been shuffled by kexec. Signed-off-by: James Morse Cc: Mark Rutland Cc: Lorenzo Pieralisi Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon

arm64: hibernate: Support DEBUG_PAGEALLOC

2016-08-25T17:00:30+00:00

DEBUG_PAGEALLOC removes the valid bit of page table entries to prevent any access to unallocated memory. Hibernate uses this as a hint that those pages don't need to be saved/restored. This patch adds the kernel_page_present() function it uses. hibernate.c copies the resume kernel's linear map for use during restore. Add _copy_pte() to fill-in the holes made by DEBUG_PAGEALLOC in the resume kernel, so we can restore data the original kernel had at these addresses. Finally, DEBUG_PAGEALLOC means the linear-map alias of KERNEL_START to KERNEL_END may have holes in it, so we can't lazily clean this whole area to the PoC. Only clean the new mmuoff region, and the kernel/kvm idmaps. This reverts commit da24eb1f3f9e2c7b75c5f8c40d8e48e2c4789596. Reported-by: Will Deacon Signed-off-by: James Morse Cc: Catalin Marinas Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon

arm64: Create sections.h

2016-08-25T17:00:29+00:00

Each time new section markers are added, kernel/vmlinux.ld.S is updated, and new extern char __start_foo[] definitions are scattered through the tree. Create asm/include/sections.h to collect these definitions (and include the existing asm-generic version). Signed-off-by: James Morse Reviewed-by: Mark Rutland Tested-by: Mark Rutland Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon

arm64: hibernate: handle allocation failures

2016-08-12T18:08:33+00:00

In create_safe_exec_page(), we create a copy of the hibernate exit text, along with some page tables to map this via TTBR0. We then install the new tables in TTBR0. In swsusp_arch_resume() we call create_safe_exec_page() before trying a number of operations which may fail (e.g. copying the linear map page tables). If these fail, we bail out of swsusp_arch_resume() and return an error code, but leave TTBR0 as-is. Subsequently, the core hibernate code will call free_basic_memory_bitmaps(), which will free all of the memory allocations we made, including the page tables installed in TTBR0. Thus, we may have TTBR0 pointing at dangling freed memory for some period of time. If the hibernate attempt was triggered by a user requesting a hibernate test via the reboot syscall, we may return to userspace with the clobbered TTBR0 value. Avoid these issues by reorganising swsusp_arch_resume() such that we have no failure paths after create_safe_exec_page(). We also add a check that the zero page allocation succeeded, matching what we have for other allocations. Fixes: 82869ac57b5d ("arm64: kernel: Add support for hibernate/suspend-to-disk") Signed-off-by: Mark Rutland Acked-by: James Morse Cc: Lorenzo Pieralisi Cc: Will Deacon Cc: # 4.7+ Signed-off-by: Catalin Marinas

arm64: hibernate: avoid potential TLB conflict

2016-08-12T17:46:29+00:00

In create_safe_exec_page we install a set of global mappings in TTBR0, then subsequently invalidate TLBs. While TTBR0 points at the zero page, and the TLBs should be free of stale global entries, we may have stale ASID-tagged entries (e.g. from the EFI runtime services mappings) for the same VAs. Per the ARM ARM these ASID-tagged entries may conflict with newly-allocated global entries, and we must follow a Break-Before-Make approach to avoid issues resulting from this. This patch reworks create_safe_exec_page to invalidate TLBs while the zero page is still in place, ensuring that there are no potential conflicts when the new TTBR0 value is installed. As a single CPU is online while this code executes, we do not need to perform broadcast TLB maintenance, and can call local_flush_tlb_all(), which also subsumes some barriers. The remaining assembly is converted to use write_sysreg() and isb(). Other than this, we safely manipulate TTBRs in the hibernate dance. The code we install as part of the new TTBR0 mapping (the hibernated kernel's swsusp_arch_suspend_exit) installs a zero page into TTBR1, invalidates TLBs, then installs its preferred value. Upon being restored to the middle of swsusp_arch_suspend, the new image will call __cpu_suspend_exit, which will call cpu_uninstall_idmap, installing the zero page in TTBR0 and invalidating all TLB entries. Fixes: 82869ac57b5d ("arm64: kernel: Add support for hibernate/suspend-to-disk") Signed-off-by: Mark Rutland Acked-by: James Morse Tested-by: James Morse Cc: Lorenzo Pieralisi Cc: Will Deacon Cc: # 4.7+ Signed-off-by: Catalin Marinas