Turn ARCH_USE_MEMREMAP_PROT into a generic Kconfig symbol, and fix the
dependency expression to reflect that AMD_MEM_ENCRYPT depends on it,
instead of the other way around. This will permit ARCH_USE_MEMREMAP_PROT
to be selected by other architectures.
Note that the encryption related early memremap routines in
arch/x86/mm/ioremap.c cannot be built for 32-bit x86 without triggering
the following warning:
arch/x86//mm/ioremap.c: In function 'early_memremap_encrypted':
>> arch/x86/include/asm/pgtable_types.h:193:27: warning: conversion from
'long long unsigned int' to 'long unsigned int' changes
value from '9223372036854776163' to '355' [-Woverflow]
#define __PAGE_KERNEL_ENC (__PAGE_KERNEL | _PAGE_ENC)
^~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86//mm/ioremap.c:713:46: note: in expansion of macro '__PAGE_KERNEL_ENC'
return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_ENC);
which essentially means they are 64-bit only anyway. However, we cannot
make them dependent on CONFIG_ARCH_HAS_MEM_ENCRYPT, since that is always
defined, even for i386 (and changing that results in a slew of build errors)
So instead, build those routines only if CONFIG_AMD_MEM_ENCRYPT is
defined.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190202094119.13230-9-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
show_ldttss() shifts desc.base2 by 24 bit, but base2 is 8 bits of a
bitfield in a u16.
Due to the really great idea of integer promotion in C99 base2 is promoted
to an int, because that's the standard defined behaviour when all values
which can be represented by base2 fit into an int.
Now if bit 7 is set in desc.base2 the result of the shift left by 24 makes
the resulting integer negative and the following conversion to unsigned
long legitmately sign extends first causing the upper bits 32 bits to be
set in the result.
Fix this by casting desc.base2 to unsigned long before the shift.
Detected by CoverityScan, CID#1475635 ("Unintended sign extension")
[ tglx: Reworded the changelog a bit as I actually had to lookup
the standard (again) to decode the original one. ]
Fixes: a1a371c468 ("x86/fault: Decode page fault OOPSes better")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: kernel-janitors@vger.kernel.org
Link: https://lkml.kernel.org/r/20181222191116.21831-1-colin.king@canonical.com
Merge more updates from Andrew Morton:
- procfs updates
- various misc bits
- lib/ updates
- epoll updates
- autofs
- fatfs
- a few more MM bits
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (58 commits)
mm/page_io.c: fix polled swap page in
checkpatch: add Co-developed-by to signature tags
docs: fix Co-Developed-by docs
drivers/base/platform.c: kmemleak ignore a known leak
fs: don't open code lru_to_page()
fs/: remove caller signal_pending branch predictions
mm/: remove caller signal_pending branch predictions
arch/arc/mm/fault.c: remove caller signal_pending_branch predictions
kernel/sched/: remove caller signal_pending branch predictions
kernel/locking/mutex.c: remove caller signal_pending branch predictions
mm: select HAVE_MOVE_PMD on x86 for faster mremap
mm: speed up mremap by 20x on large regions
mm: treewide: remove unused address argument from pte_alloc functions
initramfs: cleanup incomplete rootfs
scripts/gdb: fix lx-version string output
kernel/kcov.c: mark write_comp_data() as notrace
kernel/sysctl: add panic_print into sysctl
panic: add options to print system info when panic happens
bfs: extra sanity checking and static inode bitmap
exec: separate MM_ANONPAGES and RLIMIT_STACK accounting
...
Patch series "Add support for fast mremap".
This series speeds up the mremap(2) syscall by copying page tables at
the PMD level even for non-THP systems. There is concern that the extra
'address' argument that mremap passes to pte_alloc may do something
subtle architecture related in the future that may make the scheme not
work. Also we find that there is no point in passing the 'address' to
pte_alloc since its unused. This patch therefore removes this argument
tree-wide resulting in a nice negative diff as well. Also ensuring
along the way that the enabled architectures do not do anything funky
with the 'address' argument that goes unnoticed by the optimization.
Build and boot tested on x86-64. Build tested on arm64. The config
enablement patch for arm64 will be posted in the future after more
testing.
The changes were obtained by applying the following Coccinelle script.
(thanks Julia for answering all Coccinelle questions!).
Following fix ups were done manually:
* Removal of address argument from pte_fragment_alloc
* Removal of pte_alloc_one_fast definitions from m68k and microblaze.
// Options: --include-headers --no-includes
// Note: I split the 'identifier fn' line, so if you are manually
// running it, please unsplit it so it runs for you.
virtual patch
@pte_alloc_func_def depends on patch exists@
identifier E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
type T2;
@@
fn(...
- , T2 E2
)
{ ... }
@pte_alloc_func_proto_noarg depends on patch exists@
type T1, T2, T3, T4;
identifier fn =~ "^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1, T2);
+ T3 fn(T1);
|
- T3 fn(T1, T2, T4);
+ T3 fn(T1, T2);
)
@pte_alloc_func_proto depends on patch exists@
identifier E1, E2, E4;
type T1, T2, T3, T4;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
(
- T3 fn(T1 E1, T2 E2);
+ T3 fn(T1 E1);
|
- T3 fn(T1 E1, T2 E2, T4 E4);
+ T3 fn(T1 E1, T2 E2);
)
@pte_alloc_func_call depends on patch exists@
expression E2;
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
@@
fn(...
-, E2
)
@pte_alloc_macro depends on patch exists@
identifier fn =~
"^(__pte_alloc|pte_alloc_one|pte_alloc|__pte_alloc_kernel|pte_alloc_one_kernel)$";
identifier a, b, c;
expression e;
position p;
@@
(
- #define fn(a, b, c) e
+ #define fn(a, b) e
|
- #define fn(a, b) e
+ #define fn(a) e
)
Link: http://lkml.kernel.org/r/20181108181201.88826-2-joelaf@google.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Suggested-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge misc updates from Andrew Morton:
- large KASAN update to use arm's "software tag-based mode"
- a few misc things
- sh updates
- ocfs2 updates
- just about all of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (167 commits)
kernel/fork.c: mark 'stack_vm_area' with __maybe_unused
memcg, oom: notify on oom killer invocation from the charge path
mm, swap: fix swapoff with KSM pages
include/linux/gfp.h: fix typo
mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm
hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
memory_hotplug: add missing newlines to debugging output
mm: remove __hugepage_set_anon_rmap()
include/linux/vmstat.h: remove unused page state adjustment macro
mm/page_alloc.c: allow error injection
mm: migrate: drop unused argument of migrate_page_move_mapping()
blkdev: avoid migration stalls for blkdev pages
mm: migrate: provide buffer_migrate_page_norefs()
mm: migrate: move migrate_page_lock_buffers()
mm: migrate: lock buffers before migrate_page_move_mapping()
mm: migration: factor out code to compute expected number of page references
mm, page_alloc: enable pcpu_drain with zone capability
kmemleak: add config to select auto scan
mm/page_alloc.c: don't call kasan_free_pages() at deferred mem init
...
Pull DMA mapping updates from Christoph Hellwig:
"A huge update this time, but a lot of that is just consolidating or
removing code:
- provide a common DMA_MAPPING_ERROR definition and avoid indirect
calls for dma_map_* error checking
- use direct calls for the DMA direct mapping case, avoiding huge
retpoline overhead for high performance workloads
- merge the swiotlb dma_map_ops into dma-direct
- provide a generic remapping DMA consistent allocator for
architectures that have devices that perform DMA that is not cache
coherent. Based on the existing arm64 implementation and also used
for csky now.
- improve the dma-debug infrastructure, including dynamic allocation
of entries (Robin Murphy)
- default to providing chaining scatterlist everywhere, with opt-outs
for the few architectures (alpha, parisc, most arm32 variants) that
can't cope with it
- misc sparc32 dma-related cleanups
- remove the dma_mark_clean arch hook used by swiotlb on ia64 and
replace it with the generic noncoherent infrastructure
- fix the return type of dma_set_max_seg_size (Niklas Söderlund)
- move the dummy dma ops for not DMA capable devices from arm64 to
common code (Robin Murphy)
- ensure dma_alloc_coherent returns zeroed memory to avoid kernel
data leaks through userspace. We already did this for most common
architectures, but this ensures we do it everywhere.
dma_zalloc_coherent has been deprecated and can hopefully be
removed after -rc1 with a coccinelle script"
* tag 'dma-mapping-4.21' of git://git.infradead.org/users/hch/dma-mapping: (73 commits)
dma-mapping: fix inverted logic in dma_supported
dma-mapping: deprecate dma_zalloc_coherent
dma-mapping: zero memory returned from dma_alloc_*
sparc/iommu: fix ->map_sg return value
sparc/io-unit: fix ->map_sg return value
arm64: default to the direct mapping in get_arch_dma_ops
PCI: Remove unused attr variable in pci_dma_configure
ia64: only select ARCH_HAS_DMA_COHERENT_TO_PFN if swiotlb is enabled
dma-mapping: bypass indirect calls for dma-direct
vmd: use the proper dma_* APIs instead of direct methods calls
dma-direct: merge swiotlb_dma_ops into the dma_direct code
dma-direct: use dma_direct_map_page to implement dma_direct_map_sg
dma-direct: improve addressability error reporting
swiotlb: remove dma_mark_clean
swiotlb: remove SWIOTLB_MAP_ERROR
ACPI / scan: Refactor _CCA enforcement
dma-mapping: factor out dummy DMA ops
dma-mapping: always build the direct mapping code
dma-mapping: move dma_cache_sync out of line
dma-mapping: move various slow path functions out of line
...
Pull x86 mm updates from Ingo Molnar:
"The main changes in this cycle were:
- Update and clean up x86 fault handling, by Andy Lutomirski.
- Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
and related fallout, by Dan Williams.
- CPA cleanups and reorganization by Peter Zijlstra: simplify the
flow and remove a few warts.
- Other misc cleanups"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
x86/mm/dump_pagetables: Use DEFINE_SHOW_ATTRIBUTE()
x86/mm/cpa: Rename @addrinarray to @numpages
x86/mm/cpa: Better use CLFLUSHOPT
x86/mm/cpa: Fold cpa_flush_range() and cpa_flush_array() into a single cpa_flush() function
x86/mm/cpa: Make cpa_data::numpages invariant
x86/mm/cpa: Optimize cpa_flush_array() TLB invalidation
x86/mm/cpa: Simplify the code after making cpa->vaddr invariant
x86/mm/cpa: Make cpa_data::vaddr invariant
x86/mm/cpa: Add __cpa_addr() helper
x86/mm/cpa: Add ARRAY and PAGES_ARRAY selftests
x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()
x86/mm: Validate kernel_physical_mapping_init() PTE population
generic/pgtable: Introduce set_pte_safe()
generic/pgtable: Introduce {p4d,pgd}_same()
generic/pgtable: Make {pmd, pud}_same() unconditionally available
x86/fault: Clean up the page fault oops decoder a bit
x86/fault: Decode page fault OOPSes better
x86/vsyscall/64: Use X86_PF constants in the simulated #PF error code
x86/oops: Show the correct CS value in show_regs()
x86/fault: Don't try to recover from an implicit supervisor access
...
Pull x86 fpu updates from Ingo Molnar:
"Misc preparatory changes for an upcoming FPU optimization that will
delay the loading of FPU registers to return-to-userspace"
* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/fpu: Don't export __kernel_fpu_{begin,end}()
x86/fpu: Update comment for __raw_xsave_addr()
x86/fpu: Add might_fault() to user_insn()
x86/pkeys: Make init_pkru_value static
x86/thread_info: Remove _TIF_ALLWORK_MASK
x86/process/32: Remove asm/math_emu.h include
x86/fpu: Use unsigned long long shift in xfeature_uncompacted_offset()
Pull EFI updates from Ingo Molnar:
"The main changes in this cycle were:
- Allocate the E820 buffer before doing the
GetMemoryMap/ExitBootServices dance so we don't run out of space
- Clear EFI boot services mappings when freeing the memory
- Harden efivars against callers that invoke it on non-EFI boots
- Reduce the number of memblock reservations resulting from extensive
use of the new efi_mem_reserve_persistent() API
- Other assorted fixes and cleanups"
* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/efi: Don't unmap EFI boot services code/data regions for EFI_OLD_MEMMAP and EFI_MIXED_MODE
efi: Reduce the amount of memblock reservations for persistent allocations
efi: Permit multiple entries in persistent memreserve data structure
efi/libstub: Disable some warnings for x86{,_64}
x86/efi: Move efi_<reserve/free>_boot_services() to arch/x86
x86/efi: Unmap EFI boot services code/data regions from efi_pgd
x86/mm/pageattr: Introduce helper function to unmap EFI boot services
efi/fdt: Simplify the get_fdt() flow
efi/fdt: Indentation fix
firmware/efi: Add NULL pointer checks in efivars API functions
Pull x86 pti updates from Thomas Gleixner:
"No point in speculating what's in this parcel:
- Drop the swap storage limit when L1TF is disabled so the full space
is available
- Add support for the new AMD STIBP always on mitigation mode
- Fix a bunch of STIPB typos"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/speculation: Add support for STIBP always-on preferred mode
x86/speculation/l1tf: Drop the swap storage limit restriction when l1tf=off
x86/speculation: Change misspelled STIPB to STIBP
While the dma-direct code is (relatively) clean and simple we actually
have to use the swiotlb ops for the mapping on many architectures due
to devices with addressing limits. Instead of keeping two
implementations around this commit allows the dma-direct
implementation to call the swiotlb bounce buffering functions and
thus share the guts of the mapping implementation. This also
simplified the dma-mapping setup on a few architectures where we
don't have to differenciate which implementation to use.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Tony Luck <tony.luck@intel.com>
A decoy address is used by set_mce_nospec() to update the cache attributes
for a page that may contain poison (multi-bit ECC error) while attempting
to minimize the possibility of triggering a speculative access to that
page.
When reserve_memtype() is handling a decoy address it needs to convert it
to its real physical alias. The conversion, AND'ing with __PHYSICAL_MASK,
is broken for a 32-bit physical mask and reserve_memtype() is passed the
last physical page. Gert reports triggering the:
BUG_ON(start >= end);
...assertion when running a 32-bit non-PAE build on a platform that has
a driver resource at the top of physical memory:
BIOS-e820: [mem 0x00000000fff00000-0x00000000ffffffff] reserved
Given that the decoy address scheme is only targeted at 64-bit builds and
assumes that the top of physical address space is free for use as a decoy
address range, simply bypass address sanitization in the 32-bit case.
Lastly, there was no need to crash the system when this failure occurred,
and no need to crash future systems if the assumptions of decoy addresses
are ever violated. Change the BUG_ON() to a WARN() with an error return.
Fixes: 510ee090ab ("x86/mm/pat: Prepare {reserve, free}_memtype() for...")
Reported-by: Gert Robben <t2@gert.gr>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Gert Robben <t2@gert.gr>
Cc: stable@vger.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: platform-driver-x86@vger.kernel.org
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/154454337985.789277.12133288391664677775.stgit@dwillia2-desk3.amr.corp.intel.com
Swap storage is restricted to max_swapfile_size (~16TB on x86_64) whenever
the system is deemed affected by L1TF vulnerability. Even though the limit
is quite high for most deployments it seems to be too restrictive for
deployments which are willing to live with the mitigation disabled.
We have a customer to deploy 8x 6,4TB PCIe/NVMe SSD swap devices which is
clearly out of the limit.
Drop the swap restriction when l1tf=off is specified. It also doesn't make
much sense to warn about too much memory for the l1tf mitigation when it is
forcefully disabled by the administrator.
[ tglx: Folded the documentation delta change ]
Fixes: 377eeaa8e1 ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: <linux-mm@kvack.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181113184910.26697-1-mhocko@kernel.org
Ideally, after kernel assumes control of the platform, firmware
shouldn't access EFI boot services code/data regions. But, it's noticed
that this is not so true in many x86 platforms. Hence, during boot,
kernel reserves EFI boot services code/data regions [1] and maps [2]
them to efi_pgd so that call to set_virtual_address_map() doesn't fail.
After returning from set_virtual_address_map(), kernel frees the
reserved regions [3] but they still remain mapped. Hence, introduce
kernel_unmap_pages_in_pgd() which will later be used to unmap EFI boot
services code/data regions.
While at it modify kernel_map_pages_in_pgd() by:
1. Adding __init modifier because it's always used *only* during boot.
2. Add a warning if it's used after SMP is initialized because it uses
__flush_tlb_all() which flushes mappings only on current CPU.
Unmapping EFI boot services code/data regions will result in clearing
PAGE_PRESENT bit and it shouldn't bother L1TF cases because it's already
handled by protnone_mask() at arch/x86/include/asm/pgtable-invert.h.
[1] efi_reserve_boot_services()
[2] efi_map_region() -> __map_region() -> kernel_map_pages_in_pgd()
[3] efi_free_boot_services()
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arend van Spriel <arend.vanspriel@broadcom.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Snowberg <eric.snowberg@oracle.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jon Hunter <jonathanh@nvidia.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: YiFei Zhu <zhuyifei1999@gmail.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20181129171230.18699-5-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The IBPB speculation barrier is issued from switch_mm() when the kernel
switches to a user space task with a different mm than the user space task
which ran last on the same CPU.
An additional optimization is to avoid IBPB when the incoming task can be
ptraced by the outgoing task. This optimization only works when switching
directly between two user space tasks. When switching from a kernel task to
a user space task the optimization fails because the previous task cannot
be accessed anymore. So for quite some scenarios the optimization is just
adding overhead.
The upcoming conditional IBPB support will issue IBPB only for user space
tasks which have the TIF_SPEC_IB bit set. This requires to handle the
following cases:
1) Switch from a user space task (potential attacker) which has
TIF_SPEC_IB set to a user space task (potential victim) which has
TIF_SPEC_IB not set.
2) Switch from a user space task (potential attacker) which has
TIF_SPEC_IB not set to a user space task (potential victim) which has
TIF_SPEC_IB set.
This needs to be optimized for the case where the IBPB can be avoided when
only kernel threads ran in between user space tasks which belong to the
same process.
The current check whether two tasks belong to the same context is using the
tasks context id. While correct, it's simpler to use the mm pointer because
it allows to mangle the TIF_SPEC_IB bit into it. The context id based
mechanism requires extra storage, which creates worse code.
When a task is scheduled out its TIF_SPEC_IB bit is mangled as bit 0 into
the per CPU storage which is used to track the last user space mm which was
running on a CPU. This bit can be used together with the TIF_SPEC_IB bit of
the incoming task to make the decision whether IBPB needs to be issued or
not to cover the two cases above.
As conditional IBPB is going to be the default, remove the dubious ptrace
check for the IBPB always case and simply issue IBPB always when the
process changes.
Move the storage to a different place in the struct as the original one
created a hole.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181125185005.466447057@linutronix.de
- Make the oops messages a bit less scary (don't mention 'HW errors')
- Turn 'PROT USER' (which is visually easily confused with PROT_USER)
into individual bit descriptors: "[PROT] [USER]".
This also makes "[normal kernel read fault]" more apparent.
- De-abbreviate variables to make the code easier to read
- Use vertical alignment where appropriate.
- Add comment about string size limits and the helper function.
- Remove unnecessary line breaks.
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
One of Linus' favorite hobbies seems to be looking at OOPSes and
decoding the error code in his head. This is not one of my favorite
hobbies :)
Teach the page fault OOPS hander to decode the error code. If it's
a !USER fault from user mode, print an explicit note to that effect
and print out the addresses of various tables that might cause such
an error.
With this patch applied, if I intentionally point the LDT at 0x0 and
run the x86 selftests, I get:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
HW error: normal kernel read fault
This was a system access from user code
IDT: 0xfffffe0000000000 (limit=0xfff) GDT: 0xfffffe0000001000 (limit=0x7f)
LDTR: 0x50 -- base=0x0 limit=0xfff7
TR: 0x40 -- base=0xfffffe0000003000 limit=0x206f
PGD 800000000456e067 P4D 800000000456e067 PUD 4623067 PMD 0
SMP PTI
CPU: 0 PID: 153 Comm: ldt_gdt_64 Not tainted 4.19.0+ #1317
Hardware name: ...
RIP: 0033:0x401454
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/11212acb25980cd1b3030875cd9502414fbb214d.1542841400.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
