linux-toradex.git/arch/mips/kernel/vdso.c, branch v6.19

MIPS: vdso: Switch to generic storage implementation

2025-02-21T08:54:02+00:00

The generic storage implementation provides the same features as the
custom one. However it can be shared between architectures, making
maintenance easier.

Co-developed-by: Nam Cao 
Signed-off-by: Nam Cao 
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-13-13a4669dfc8c@linutronix.de

mips: vdso: prefer do_mmap() to mmap_region()

2025-01-26T04:22:37+00:00

Patch series "mm: update mips to use do_mmap(), make mmap_region()
internal".

Currently the only user of mmap_region() outside of the memory management
code is the MIPS VDSO implementation.

This uses mmap_region() to map a 'delay slot emulation page' at the top of
the stack which is read-only and executable.

This mapping requires that an already-acquired mmap write lock is utilised
and that uffd and populate logic is ignored. This rules out vm_mmap(),
however do_mmap() fits the bill.

Adapt this code to use do_mmap() and then once done, make mmap_region()
internal and userland testable, and avoid any other uses of mmap_region(),
which is absolutely and strictly an internal mm function which bypasses a
great number of checks and logic.


This patch (of 2):

mmap_region() is an internal memory management implementation detail that
is not intended to be used outside of the memory management subsystem.

Map the delay slot emulation page using do_mmap() which makes use of the
already-held mmap write lock and bypasses unneeded populate and
userfaultfd logic.

This should have the precise same behaviour as the existing logic.

Link: https://lkml.kernel.org/r/cover.1735819274.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/ef076e381570f709e5c2c142dc030ec5b3309a0e.1735819274.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes 
Reviewed-by: Liam R. Howlett 
Cc: Jann Horn 
Cc: Thomas Bogendoerfer 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

MIPS: vdso: Remove timekeeper includes

2024-10-15T15:50:29+00:00

Since the generic VDSO clock mode storage is used, this header file is
unused and can be removed.

This avoids including a non-VDSO header while building the VDSO,
which can lead to compilation errors.

Signed-off-by: Thomas Weißschuh 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/20241010-vdso-generic-arch_update_vsyscall-v1-9-7fe5a3ea4382@linutronix.de

MIPS: vdso: Use generic union vdso_data_store

2024-02-20T19:56:01+00:00

There is already a generic union definition for vdso_data_store in the vdso
datapage header.

Use this definition to prevent code duplication.

Signed-off-by: Anna-Maria Behnsen 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Vincenzo Frascino 
Reviewed-by: Kees Cook 
Link: https://lore.kernel.org/r/20240219153939.75719-10-anna-maria@linutronix.de

treewide: use get_random_u32_below() instead of deprecated function

2022-11-18T01:15:15+00:00

This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook 
Reviewed-by: Greg Kroah-Hartman 
Acked-by: Darrick J. Wong  # for xfs
Reviewed-by: SeongJae Park  # for damon
Reviewed-by: Jason Gunthorpe  # for infiniband
Reviewed-by: Russell King (Oracle)  # for arm
Acked-by: Ulf Hansson  # for mmc
Signed-off-by: Jason A. Donenfeld

treewide: use prandom_u32_max() when possible, part 1

2022-10-11T23:42:55+00:00

Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:

@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)

@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@

-       RAND = get_random_u32();
        ... when != RAND
-       RAND %= (E);
+       RAND = prandom_u32_max(E);

// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@

        ((T)get_random_u32()@p & (LITERAL))

// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@

value = None
if literal.startswith('0x'):
        value = int(literal, 16)
elif literal[0] in '123456789':
        value = int(literal, 10)
if value is None:
        print("I don't know how to handle %s" % (literal))
        cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
        print("Skipping 0x%x for cleanup elsewhere" % (value))
        cocci.include_match(False)
elif value & (value + 1) != 0:
        print("Skipping 0x%x because it's not a power of two minus one" % (value))
        cocci.include_match(False)
elif literal.startswith('0x'):
        coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
        coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))

// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@

-       (FUNC()@p & (LITERAL))
+       prandom_u32_max(RESULT)

@collapse_ret@
type T;
identifier VAR;
expression E;
@@

 {
-       T VAR;
-       VAR = (E);
-       return VAR;
+       return E;
 }

@drop_var@
type T;
identifier VAR;
@@

 {
-       T VAR;
        ... when != VAR
 }

Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Kees Cook 
Reviewed-by: Yury Norov 
Reviewed-by: KP Singh 
Reviewed-by: Jan Kara  # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder  # for drbd
Acked-by: Jakub Kicinski 
Acked-by: Heiko Carstens  # for s390
Acked-by: Ulf Hansson  # for mmc
Acked-by: Darrick J. Wong  # for xfs
Signed-off-by: Jason A. Donenfeld

MIPS: vdso: Utilize __pa() for gic_pfn

2022-07-11T08:32:07+00:00

The GIC user offset is mapped into every process' virtual address and is
therefore part of the hot-path of arch_setup_additional_pages(). Utilize
__pa() such that we are more optimal even when CONFIG_DEBUG_VIRTUAL is
enabled, and while at it utilize PFN_DOWN() instead of open-coding the
right shift by PAGE_SHIFT.

Reported-by: Greg Ungerer 
Suggested-by: Serge Semin 
Fixes: dfad83cb7193 ("MIPS: Add support for CONFIG_DEBUG_VIRTUAL")
Signed-off-by: Florian Fainelli 
Acked-by: Greg Ungerer 
Tested-by: Greg Ungerer 
Signed-off-by: Thomas Bogendoerfer

MIPS: Add support for CONFIG_DEBUG_VIRTUAL

2021-04-06T12:34:02+00:00

Provide hooks to intercept bad usages of virt_to_phys() and
__pa_symbol() throughout the kernel. To make this possible, we need to
rename the current implement of virt_to_phys() into
__virt_to_phys_nodebug() and wrap it around depending on
CONFIG_DEBUG_VIRTUAL.

A similar thing is needed for __pa_symbol() which is now aliased to
__phys_addr_symbol() whose implementation is either the direct return of
RELOC_HIDE or goes through the debug version.

Signed-off-by: Florian Fainelli 
Signed-off-by: Thomas Bogendoerfer

MIPS: vdso: Use vma page protection for remapping

2020-11-19T12:26:38+00:00

MIPS protection bits are setup during runtime so using defines like
PAGE_READONLY ignores these runtime changes. To fix this we simply
use the page protection of the setup vma.

Signed-off-by: Thomas Bogendoerfer

mmap locking API: use coccinelle to convert mmap_sem rwsem call sites

2020-06-09T16:39:14+00:00

This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.

The change is generated using coccinelle with the following rule:

// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .

@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)

Signed-off-by: Michel Lespinasse 
Signed-off-by: Andrew Morton 
Reviewed-by: Daniel Jordan 
Reviewed-by: Laurent Dufour 
Reviewed-by: Vlastimil Babka 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jason Gunthorpe 
Cc: Jerome Glisse 
Cc: John Hubbard 
Cc: Liam Howlett 
Cc: Matthew Wilcox 
Cc: Peter Zijlstra 
Cc: Ying Han 
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds