linux-stable.git/arch/openrisc/kernel/dma.c, branch linux-rolling-stable

mm/pagewalk: split walk_page_range_novma() into kernel/user parts

2025-07-10T05:42:05+00:00

walk_page_range_novma() is rather confusing - it supports two modes, one
used often, the other used only for debugging.

The first mode is the common case of traversal of kernel page tables,
which is what nearly all callers use this for.

Secondly it provides an unusual debugging interface that allows for the
traversal of page tables in a userland range of memory even for that
memory which is not described by a VMA.

It is far from certain that such page tables should even exist, but
perhaps this is precisely why it is useful as a debugging mechanism.

As a result, this is utilised by ptdump only.  Historically, things were
reversed - ptdump was the only user, and other parts of the kernel evolved
to use the kernel page table walking here.

Since we have some complicated and confusing locking rules for the novma
case, it makes sense to separate the two usages into their own functions.

Doing this also provide self-documentation as to the intent of the caller
- are they doing something rather unusual or are they simply doing a
standard kernel page table walk?

We therefore establish two separate functions - walk_page_range_debug()
for this single usage, and walk_kernel_page_table_range() for general
kernel page table walking.

The walk_page_range_debug() function is currently used to traverse both
userland and kernel mappings, so we maintain this and in the case of
kernel mappings being traversed, we have walk_page_range_debug() invoke
walk_kernel_page_table_range() internally.

We additionally make walk_page_range_debug() internal to mm.

Link: https://lkml.kernel.org/r/20250605135104.90720-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes 
Acked-by: Mike Rapoport (Microsoft) 
Acked-by: Qi Zheng 
Reviewed-by: Oscar Salvador 
Reviewed-by: Suren Baghdasaryan 
Reviewed-by: Vlastimil Babka 
Acked-by: David Hildenbrand 
Cc: Albert Ou 
Cc: Alexandre Ghiti 
Cc: Barry Song 
Cc: Huacai Chen 
Cc: Jann Horn 
Cc: Jonas Bonn 
Cc: Liam Howlett 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: WANG Xuerui 
Signed-off-by: Andrew Morton

openrisc: Introduce new utility functions to flush and invalidate caches

2025-04-20T06:06:54+00:00

According to the OpenRISC architecture manual, the dcache and icache may
not be present. When these caches are present, the invalidate and flush
registers may be absent. The current implementation does not perform
checks to verify their presence before utilizing cache registers, or
invalidating and flushing cache blocks.

Introduce new functions to detect the presence of cache components and
related special-purpose registers.

There are a few places where a range of addresses have to be flushed or
invalidated and the implementation is duplicated. Introduce new utility
functions and macros that generalize this implementation and reduce
duplication.

Signed-off-by: Sahil Siddiq 
Signed-off-by: Stafford Horne

openrisc: Fix pagewalk usage in arch_dma_{clear, set}_uncached

2022-10-08T05:11:29+00:00

Since commit 8782fb61cc848 ("mm: pagewalk: Fix race between unmap and page
walker"), walk_page_range() on kernel ranges won't work anymore,
walk_page_range_novma() must be used instead.

Note: I don't have an openrisc development setup, so this is completely
untested.

Fixes: 8782fb61cc848 ("mm: pagewalk: Fix race between unmap and page walker")
Signed-off-by: Jann Horn 
Signed-off-by: Stafford Horne

openrisc: fix SMP tlb flush NULL pointer dereference

2021-11-03T11:48:29+00:00

Throughout the OpenRISC kernel port VMA is passed as NULL when flushing
kernel tlb entries.  Somehow this was missed when I was testing
c28b27416da9 ("openrisc: Implement proper SMP tlb flushing") and now the
SMP kernel fails to completely boot.

In OpenRISC VMA is used only to determine which cores need to have their
TLB entries flushed.

This patch updates the logic to flush tlbs on all cores when the VMA is
passed as NULL.  Also, we update places VMA is passed as NULL to use
flush_tlb_kernel_range instead.  Now, the only place VMA is passed as
NULL is in the implementation of flush_tlb_kernel_range.

Fixes: c28b27416da9 ("openrisc: Implement proper SMP tlb flushing")
Reported-by: Jan Henrik Weinstock 
Signed-off-by: Stafford Horne

dma-mapping: merge into

2020-10-06T05:07:06+00:00

Move more nitty gritty DMA implementation details into the common
internal header.

Signed-off-by: Christoph Hellwig

openrisc: fix boot oops when DEBUG_VM is enabled

2020-06-26T07:27:36+00:00

Since v5.8-rc1 OpenRISC Linux fails to boot when DEBUG_VM is enabled.
This has been bisected to commit 42fc541404f2 ("mmap locking API: add
mmap_assert_locked() and mmap_assert_write_locked()").

The added locking checks exposed the issue that OpenRISC was not taking
this mmap lock when during page walks for DMA operations.  This patch
locks and unlocks the mmap lock for page walking.

Link: http://lkml.kernel.org/r/20200617090247.1680188-1-shorne@gmail.com
Fixes: 42fc541404f2 ("mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()"
Signed-off-by: Stafford Horne 
Reviewed-by: Michel Lespinasse 
Cc: Jonas Bonn 
Cc: Stefan Kristiansson 
Cc: Jason Gunthorpe 
Cc: Steven Price 
Cc: Thomas Hellstrom 
Cc: Robin Murphy 
Cc: Vlastimil Babka 
Cc: Daniel Jordan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

openrisc: use the generic in-place uncached DMA allocator

2020-03-16T09:48:16+00:00

Switch openrisc to use the dma-direct allocator and just provide the
hooks for setting memory uncached or cached.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Stafford Horne 
Reviewed-by: Robin Murphy

dma-mapping: drop the dev argument to arch_sync_dma_for_*

2019-11-20T19:31:38+00:00

These are pure cache maintainance routines, so drop the unused
struct device argument.

Signed-off-by: Christoph Hellwig 
Suggested-by: Daniel Vetter

pagewalk: separate function pointers from iterator data

2019-09-07T07:28:04+00:00

The mm_walk structure currently mixed data and code.  Split out the
operations vectors into a new mm_walk_ops structure, and while we are
changing the API also declare the mm_walk structure inside the
walk_page_range and walk_page_vma functions.

Based on patch from Linus Torvalds.

Link: https://lore.kernel.org/r/20190828141955.22210-3-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Thomas Hellstrom 
Reviewed-by: Steven Price 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe

mm: split out a new pagewalk.h header from mm.h

2019-09-07T07:28:04+00:00

Add a new header for the two handful of users of the walk_page_range /
walk_page_vma interface instead of polluting all users of mm.h with it.

Link: https://lore.kernel.org/r/20190828141955.22210-2-hch@lst.de
Signed-off-by: Christoph Hellwig 
Reviewed-by: Thomas Hellstrom 
Reviewed-by: Steven Price 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Jason Gunthorpe