linux-stable.git/kernel/resource.c, branch v6.11.2

x86/kaslr: Expose and use the end of the physical memory address space

2024-08-20T11:44:57+00:00

iounmap() on x86 occasionally fails to unmap because the provided valid
ioremap address is not below high_memory. It turned out that this
happens due to KASLR.

KASLR uses the full address space between PAGE_OFFSET and vaddr_end to
randomize the starting points of the direct map, vmalloc and vmemmap
regions.  It thereby limits the size of the direct map by using the
installed memory size plus an extra configurable margin for hot-plug
memory.  This limitation is done to gain more randomization space
because otherwise only the holes between the direct map, vmalloc,
vmemmap and vaddr_end would be usable for randomizing.

The limited direct map size is not exposed to the rest of the kernel, so
the memory hot-plug and resource management related code paths still
operate under the assumption that the available address space can be
determined with MAX_PHYSMEM_BITS.

request_free_mem_region() allocates from (1 << MAX_PHYSMEM_BITS) - 1
downwards.  That means the first allocation happens past the end of the
direct map and if unlucky this address is in the vmalloc space, which
causes high_memory to become greater than VMALLOC_START and consequently
causes iounmap() to fail for valid ioremap addresses.

MAX_PHYSMEM_BITS cannot be changed for that because the randomization
does not align with address bit boundaries and there are other places
which actually require to know the maximum number of address bits.  All
remaining usage sites of MAX_PHYSMEM_BITS have been analyzed and found
to be correct.

Cure this by exposing the end of the direct map via PHYSMEM_END and use
that for the memory hot-plug and resource management related places
instead of relying on MAX_PHYSMEM_BITS. In the KASLR case PHYSMEM_END
maps to a variable which is initialized by the KASLR initialization and
otherwise it is based on MAX_PHYSMEM_BITS as before.

To prevent future hickups add a check into add_pages() to catch callers
trying to add memory above PHYSMEM_END.

Fixes: 0483e1fa6e09 ("x86/mm: Implement ASLR for kernel memory regions")
Reported-by: Max Ramanouski 
Reported-by: Alistair Popple 
Signed-off-by: Thomas Gleixner 
Tested-By: Max Ramanouski 
Tested-by: Alistair Popple 
Reviewed-by: Dan Williams 
Reviewed-by: Alistair Popple 
Reviewed-by: Kees Cook 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/87ed6soy3z.ffs@tglx

resource: Export find_resource_space()

2024-05-28T16:14:14+00:00

PCI bridge window logic needs to find out in advance to the actual
allocation if there is an empty space big enough to fit the window.

Export find_resource_space() for the purpose. Also move the struct
resource_constraint into generic header to be able to use the new
interface.

Link: https://lore.kernel.org/r/20240507102523.57320-7-ilpo.jarvinen@linux.intel.com
Tested-by: Lidong Wang 
Signed-off-by: Ilpo Järvinen 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Mika Westerberg

resource: Handle simple alignment inside __find_resource_space()

2024-05-28T16:14:14+00:00

allocate_resource() accepts ->alignf() callback to perform custom alignment
beyond constraint->align. If alignf is NULL, simple_align_resource() is
used which only returns avail->start (no change).

Using avail->start directly is natural and can be done with a conditional
in __find_resource_space() instead which avoids unnecessarily using
callback. It makes the code inside __find_resource_space() more obvious and
removes the need for the caller to provide constraint->alignf
unnecessarily.

This is preparation for exporting find_resource_space().

Link: https://lore.kernel.org/r/20240507102523.57320-6-ilpo.jarvinen@linux.intel.com
Tested-by: Lidong Wang 
Signed-off-by: Ilpo Järvinen 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Mika Westerberg

resource: Use typedef for alignf callback

2024-05-28T16:14:14+00:00

To make it simpler to declare resource constraint alignf callbacks, add
typedef for it and document it.

Suggested-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20240507102523.57320-5-ilpo.jarvinen@linux.intel.com
Tested-by: Lidong Wang 
Signed-off-by: Ilpo Järvinen 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Mika Westerberg

resource: Document find_resource_space() and resource_constraint

2024-05-28T16:14:13+00:00

Document find_resource_space() and the struct resource_constraint as they
are going to be exposed outside of resource.c.

Link: https://lore.kernel.org/r/20240507102523.57320-4-ilpo.jarvinen@linux.intel.com
Tested-by: Lidong Wang 
Signed-off-by: Ilpo Järvinen 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Mika Westerberg

resource: Rename find_resource() to find_resource_space()

2024-05-28T16:14:13+00:00

Rename find_resource() to find_resource_space() to better describe what the
function does. This is a preparation for exposing it beyond resource.c,
which is needed by PCI core. Also rename the __ variant to match the names.

Link: https://lore.kernel.org/r/20240507102523.57320-3-ilpo.jarvinen@linux.intel.com
Tested-by: Lidong Wang 
Signed-off-by: Ilpo Järvinen 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Mika Westerberg

Merge tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-01-09T19:46:20+00:00

Pull non-MM updates from Andrew Morton:
 "Quite a lot of kexec work this time around. Many singleton patches in
  many places. The notable patch series are:

   - nilfs2 folio conversion from Matthew Wilcox in 'nilfs2: Folio
     conversions for file paths'.

   - Additional nilfs2 folio conversion from Ryusuke Konishi in 'nilfs2:
     Folio conversions for directory paths'.

   - IA64 remnant removal in Heiko Carstens's 'Remove unused code after
     IA-64 removal'.

   - Arnd Bergmann has enabled the -Wmissing-prototypes warning
     everywhere in 'Treewide: enable -Wmissing-prototypes'. This had
     some followup fixes:

      - Nathan Chancellor has cleaned up the hexagon build in the series
        'hexagon: Fix up instances of -Wmissing-prototypes'.

      - Nathan also addressed some s390 warnings in 's390: A couple of
        fixes for -Wmissing-prototypes'.

      - Arnd Bergmann addresses the same warnings for MIPS in his series
        'mips: address -Wmissing-prototypes warnings'.

   - Baoquan He has made kexec_file operate in a top-down-fitting manner
     similar to kexec_load in the series 'kexec_file: Load kernel at top
     of system RAM if required'

   - Baoquan He has also added the self-explanatory 'kexec_file: print
     out debugging message if required'.

   - Some checkstack maintenance work from Tiezhu Yang in the series
     'Modify some code about checkstack'.

   - Douglas Anderson has disentangled the watchdog code's logging when
     multiple reports are occurring simultaneously. The series is
     'watchdog: Better handling of concurrent lockups'.

   - Yuntao Wang has contributed some maintenance work on the crash code
     in 'crash: Some cleanups and fixes'"

* tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (157 commits)
  crash_core: fix and simplify the logic of crash_exclude_mem_range()
  x86/crash: use SZ_1M macro instead of hardcoded value
  x86/crash: remove the unused image parameter from prepare_elf_headers()
  kdump: remove redundant DEFAULT_CRASH_KERNEL_LOW_SIZE
  scripts/decode_stacktrace.sh: strip unexpected CR from lines
  watchdog: if panicking and we dumped everything, don't re-enable dumping
  watchdog/hardlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
  watchdog/softlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
  watchdog/hardlockup: adopt softlockup logic avoiding double-dumps
  kexec_core: fix the assignment to kimage->control_page
  x86/kexec: fix incorrect end address passed to kernel_ident_mapping_init()
  lib/trace_readwrite.c:: replace asm-generic/io with linux/io
  nilfs2: cpfile: fix some kernel-doc warnings
  stacktrace: fix kernel-doc typo
  scripts/checkstack.pl: fix no space expression between sp and offset
  x86/kexec: fix incorrect argument passed to kexec_dprintk()
  x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs
  nilfs2: add missing set_freezable() for freezable kthread
  kernel: relay: remove relay_file_splice_read dead code, doesn't work
  docs: submit-checklist: remove all of "make namespacecheck"
  ...

resource: add walk_system_ram_res_rev()

2023-12-11T01:21:44+00:00

This function, being a variant of walk_system_ram_res() introduced in
commit 8c86e70acead ("resource: provide new functions to walk through
resources"), walks through a list of all the resources of System RAM in
reversed order, i.e., from higher to lower.

It will be used in kexec_file code to load kernel, initrd etc when
preparing kexec reboot.

Link: https://lkml.kernel.org/r/ZVTA6z/06cLnWKUz@MiWiFi-R3L-srv
Signed-off-by: AKASHI Takahiro 
Signed-off-by: Baoquan He 
Cc: Eric Biederman 
Signed-off-by: Andrew Morton

kernel/resource: Increment by align value in get_free_mem_region()

2023-12-05T01:19:03+00:00

Currently get_free_mem_region() searches for available capacity
in increments equal to the region size being requested. This can
cause the search to take giant steps through the resource leaving
needless gaps and missing available space.

Specifically 'cxl create-region' fails with ERANGE even though capacity
of the given size and CXL's expected 256M x InterleaveWays alignment can
be satisfied.

Replace the total-request-size increment with a next alignment increment
so that the next possible address is always examined for availability.

Fixes: 14b80582c43e ("resource: Introduce alloc_free_mem_region()")
Reported-by: Dmytro Adamenko 
Reported-by: Dan Williams 
Signed-off-by: Alison Schofield 
Reviewed-by: Dave Jiang 
Link: https://lore.kernel.org/r/20231113221324.1118092-1-alison.schofield@intel.com
Cc: Jason Gunthorpe 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Dan Williams

resource: Unify next_resource() and next_resource_skip_children()

2023-10-05T11:58:07+00:00

We have the next_resource() is used once and no user for the
next_resource_skip_children() outside of the for_each_resource().

Unify them by adding skip_children parameter to the next_resource().

Signed-off-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20230912165312.402422-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman