kernel.git/arch/x86/kernel/setup.c, branch linux-5.8.y

x86/setup: Add an initrdmem= option to specify initrd physical address

2020-04-27T07:28:16Z

Add the initrdmem option: initrdmem=ss[KMG],nn[KMG] which is used to specify the physical address of the initrd, almost always an address in FLASH. Also add code for x86 to use the existing phys_init_start and phys_init_size variables in the kernel. This is useful in cases where a kernel and an initrd is placed in FLASH, but there is no firmware file system structure in the FLASH. One such situation occurs when unused FLASH space on UEFI systems has been reclaimed by, e.g., taking it from the Management Engine. For example, on many systems, the ME is given half the FLASH part; not only is 2.75M of an 8M part unused; but 10.75M of a 16M part is unused. This space can be used to contain an initrd, but need to tell Linux where it is. This space is "raw": due to, e.g., UEFI limitations: it can not be added to UEFI firmware volumes without rebuilding UEFI from source or writing a UEFI device driver. It can be referenced only as a physical address and size. At the same time, if a kernel can be "netbooted" or loaded from GRUB or syslinux, the option of not using the physical address specification should be available. Then, it is easy to boot the kernel and provide an initrd; or boot the the kernel and let it use the initrd in FLASH. In practice, this has proven to be very helpful when integrating Linux into FLASH on x86. Hence, the most flexible and convenient path is to enable the initrdmem command line option in a way that it is the last choice tried. For example, on the DigitalLoggers Atomic Pi, an image into FLASH can be burnt in with a built-in command line which includes: initrdmem=0xff968000,0x200000 which specifies a location and size. [ bp: Massage commit message, make it passive. ] [akpm@linux-foundation.org: coding style fixes] Signed-off-by: Ronald G. Minnich Signed-off-by: Andrew Morton Signed-off-by: Borislav Petkov Reviewed-by: H. Peter Anvin (Intel) Link: http://lkml.kernel.org/r/CAP6exYLK11rhreX=6QPyDQmW7wPHsKNEFtXE47pjx41xS6O7-A@mail.gmail.com Link: https://lkml.kernel.org/r/20200426011021.1cskg0AGd%akpm@linux-foundation.org

mm: hugetlb: optionally allocate gigantic hugepages using cma

2020-04-10T22:36:21Z

Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the run-time allocation of gigantic pages. However it actually works only at early stages of the system loading, when the majority of memory is free. After some time the memory gets fragmented by non-movable pages, so the chances to find a contiguous 1GB block are getting close to zero. Even dropping caches manually doesn't help a lot. At large scale rebooting servers in order to allocate gigantic hugepages is quite expensive and complex. At the same time keeping some constant percentage of memory in reserved hugepages even if the workload isn't using it is a big waste: not all workloads can benefit from using 1 GB pages. The following solution can solve the problem: 1) On boot time a dedicated cma area* is reserved. The size is passed as a kernel argument. 2) Run-time allocations of gigantic hugepages are performed using the cma allocator and the dedicated cma area In this case gigantic hugepages can be allocated successfully with a high probability, however the memory isn't completely wasted if nobody is using 1GB hugepages: it can be used for pagecache, anon memory, THPs, etc. * On a multi-node machine a per-node cma area is allocated on each node. Following gigantic hugetlb allocation are using the first available numa node if the mask isn't specified by a user. Usage: 1) configure the kernel to allocate a cma area for hugetlb allocations: pass hugetlb_cma=10G as a kernel argument 2) allocate hugetlb pages as usual, e.g. echo 10 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages If the option isn't enabled or the allocation of the cma area failed, the current behavior of the system is preserved. x86 and arm-64 are covered by this patch, other architectures can be trivially added later. The patch contains clean-ups and fixes proposed and implemented by Aslan Bakirov and Randy Dunlap. It also contains ideas and suggestions proposed by Rik van Riel, Michal Hocko and Mike Kravetz. Thanks! Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Tested-by: Andreas Schaufler Acked-by: Mike Kravetz Acked-by: Michal Hocko Cc: Aslan Bakirov Cc: Randy Dunlap Cc: Rik van Riel Cc: Joonsoo Kim Link: http://lkml.kernel.org/r/20200407163840.92263-3-guro@fb.com Signed-off-by: Linus Torvalds

x86/setup: Fix static memory detection

2020-03-19T10:58:13Z

When booting x86 images in qemu, the following warning is seen randomly if DEBUG_LOCKDEP is enabled. WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:1119 lockdep_register_key+0xc0/0x100 static_obj() returns true if an address is between _stext and _end. On x86, this includes the brk memory space. Problem is that this memory block is not static on x86; its unused portions are released after init and can be allocated. This results in the observed warning if a lockdep object is allocated from this memory. Solve the problem by implementing arch_is_kernel_initmem_freed() for x86 and have it return true if an address is within the released memory range. The same problem was solved for s390 with commit 7a5da02de8d6e ("locking/lockdep: check for freed initmem in static_obj()"), which introduced arch_is_kernel_initmem_freed(). Signed-off-by: Guenter Roeck Signed-off-by: Borislav Petkov Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200131021159.9178-1-linux@roeck-us.net

Merge tag 'mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx

2020-01-31T00:11:50Z

Pull x86 MPX removal from Dave Hansen: "MPX requires recompiling applications, which requires compiler support. Unfortunately, GCC 9.1 is expected to be be released without support for MPX. This means that there was only a relatively small window where folks could have ever used MPX. It failed to gain wide adoption in the industry, and Linux was the only mainstream OS to ever support it widely. Support for the feature may also disappear on future processors. This set completes the process that we started during the 5.4 merge window when the MPX prctl()s were removed. XSAVE support is left in place, which allows MPX-using KVM guests to continue to function" * tag 'mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx: x86/mpx: remove MPX from arch/x86 mm: remove arch_bprm_mm_init() hook x86/mpx: remove bounds exception code x86/mpx: remove build infrastructure x86/alternatives: add missing insn.h include

Merge tag 'tty-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2020-01-29T18:13:27Z

Pull tty/serial driver updates from Greg KH: "Here are the big set of tty and serial driver updates for 5.6-rc1 Included in here are: - dummy_con cleanups (touches lots of arch code) - sysrq logic cleanups (touches lots of serial drivers) - samsung driver fixes (wasn't really being built) - conmakeshash move to tty subdir out of scripts - lots of small tty/serial driver updates All of these have been in linux-next for a while with no reported issues" * tag 'tty-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (140 commits) tty: n_hdlc: Use flexible-array member and struct_size() helper tty: baudrate: SPARC supports few more baud rates tty: baudrate: Synchronise baud_table[] and baud_bits[] tty: serial: meson_uart: Add support for kernel debugger serial: imx: fix a race condition in receive path serial: 8250_bcm2835aux: Document struct bcm2835aux_data serial: 8250_bcm2835aux: Use generic remapping code serial: 8250_bcm2835aux: Allocate uart_8250_port on stack serial: 8250_bcm2835aux: Suppress register_port error on -EPROBE_DEFER serial: 8250_bcm2835aux: Suppress clk_get error on -EPROBE_DEFER serial: 8250_bcm2835aux: Fix line mismatch on driver unbind serial_core: Remove unused member in uart_port vt: Correct comment documenting do_take_over_console() vt: Delete comment referencing non-existent unbind_con_driver() arch/xtensa/setup: Drop dummy_con initialization arch/x86/setup: Drop dummy_con initialization arch/unicore32/setup: Drop dummy_con initialization arch/sparc/setup: Drop dummy_con initialization arch/sh/setup: Drop dummy_con initialization arch/s390/setup: Drop dummy_con initialization ...

Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-01-28T17:03:40Z

Pull EFI updates from Ingo Molnar: "The main changes in this cycle were: - Cleanup of the GOP [graphics output] handling code in the EFI stub - Complete refactoring of the mixed mode handling in the x86 EFI stub - Overhaul of the x86 EFI boot/runtime code - Increase robustness for mixed mode code - Add the ability to disable DMA at the root port level in the EFI stub - Get rid of RWX mappings in the EFI memory map and page tables, where possible - Move the support code for the old EFI memory mapping style into its only user, the SGI UV1+ support code. - plus misc fixes, updates, smaller cleanups. ... and due to interactions with the RWX changes, another round of PAT cleanups make a guest appearance via the EFI tree - with no side effects intended" * 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits) efi/x86: Disable instrumentation in the EFI runtime handling code efi/libstub/x86: Fix EFI server boot failure efi/x86: Disallow efi=old_map in mixed mode x86/boot/compressed: Relax sed symbol type regex for LLVM ld.lld efi/x86: avoid KASAN false positives when accessing the 1: 1 mapping efi: Fix handling of multiple efi_fake_mem= entries efi: Fix efi_memmap_alloc() leaks efi: Add tracking for dynamically allocated memmaps efi: Add a flags parameter to efi_memory_map efi: Fix comment for efi_mem_type() wrt absent physical addresses efi/arm: Defer probe of PCIe backed efifb on DT systems efi/x86: Limit EFI old memory map to SGI UV machines efi/x86: Avoid RWX mappings for all of DRAM efi/x86: Don't map the entire kernel text RW for mixed mode x86/mm: Fix NX bit clearing issue in kernel_map_pages_in_pgd efi/libstub/x86: Fix unused-variable warning efi/libstub/x86: Use mandatory 16-byte stack alignment in mixed mode efi/libstub/x86: Use const attribute for efi_is_64bit() efi: Allow disabling PCI busmastering on bridges during boot efi/x86: Allow translating 64-bit arguments for mixed mode calls ...

x86/mpx: remove MPX from arch/x86

2020-01-23T18:41:20Z

From: Dave Hansen MPX is being removed from the kernel due to a lack of support in the toolchain going forward (gcc). This removes all the remaining (dead at this point) MPX handling code remaining in the tree. The only remaining code is the XSAVE support for MPX state which is currently needd for KVM to handle VMs which might use MPX. Cc: Peter Zijlstra (Intel) Cc: Andy Lutomirski Cc: x86@kernel.org Cc: Linus Torvalds Cc: Andrew Morton Signed-off-by: Dave Hansen

arch/x86/setup: Drop dummy_con initialization

2020-01-14T14:29:19Z

con_init in tty/vt.c will now set conswitchp to dummy_con if it's unset. Drop it from arch setup code. Signed-off-by: Arvind Sankar Link: https://lore.kernel.org/r/20191218214506.49252-24-nivedita@alum.mit.edu Signed-off-by: Greg Kroah-Hartman

x86/boot: Explicitly include realmode.h to handle RM reservations

2019-12-10T09:15:47Z

Explicitly include asm/realmode.h, which provides reserve_real_mode(), instead of picking it up by an indirect include of asm/acpi.h. acpi.h will soon stop including realmode.h so that changing realmode.h doesn't require a full kernel rebuild. Signed-off-by: Sean Christopherson Link: https://lkml.kernel.org/r/20191126165417.22423-3-sean.j.christopherson@intel.com Signed-off-by: Ingo Molnar

mm, x86/mm: Untangle address space layout definitions from basic pgtable type definitions

2019-12-10T09:12:55Z

- Untangle the somewhat incestous way of how VMALLOC_START is used all across the kernel, but is, on x86, defined deep inside one of the lowest level page table headers. It doesn't help that vmalloc.h only includes a single asm header: #include /* pgprot_t */ So there was no existing cross-arch way to decouple address layout definitions from page.h details. I used this: #ifndef VMALLOC_START # include #endif This way every architecture that wants to simplify page.h can do so. - Also on x86 we had a couple of LDT related inline functions that used the late-stage address space layout positions - but these could be uninlined without real trouble - the end result is cleaner this way as well. Signed-off-by: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Borislav Petkov Cc: Linus Torvalds Cc: Andrew Morton Cc: Rik van Riel Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar