crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()

Herbert notes that DIV_ROUND_UP() may overflow unnecessarily if an ecdsa
implementation's ->key_size() callback returns an unusuall

crypto: ecdsa - Harden against integer overflows in DIV_ROUND_UP()

Herbert notes that DIV_ROUND_UP() may overflow unnecessarily if an ecdsa
implementation's ->key_size() callback returns an unusually large value.
Herbert instead suggests (for a division by 8):

X / 8 + !!(X & 7)

Based on this formula, introduce a generic DIV_ROUND_UP_POW2() macro and
use it in lieu of DIV_ROUND_UP() for ->key_size() return values.

Additionally, use the macro in ecc_digits_from_bytes(), whose "nbytes"
parameter is a ->key_size() return value in some instances, or a
user-specified ASN.1 length in the case of ecdsa_get_signature_rs().

Link: https://lore.kernel.org/r/[email protected]/
Signed-off-by: Lukas Wunner <[email protected]>
Signed-off-by: Lukas Wunner <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

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math.h: Add unsigned 8 bits fractional numbers type

Some users may be requiring only rather small numbers as both
numerator and denominator: add signed and unsigned 8 bits
structs {s8,u8}_fract.

Si

math.h: Add unsigned 8 bits fractional numbers type

Some users may be requiring only rather small numbers as both
numerator and denominator: add signed and unsigned 8 bits
structs {s8,u8}_fract.

Signed-off-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jonathan Cameron <[email protected]>

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drm/i915: Move abs_diff() to math.h

abs_diff() belongs to math.h. Move it there. This will allow others to
use it.

[[email protected]: add abs_diff() documentation]
Link: https:

drm/i915: Move abs_diff() to math.h

abs_diff() belongs to math.h. Move it there. This will allow others to
use it.

[[email protected]: add abs_diff() documentation]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix comment, per Randy]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Andy Shevchenko <[email protected]>
Reviewed-by: Jiri Slaby <[email protected]> # tty/serial
Acked-by: Jani Nikula <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Andi Shyti <[email protected]>
Reviewed-by: Philipp Zabel <[email protected]> # gpu/ipu-v3
Cc: Alexey Dobriyan <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Imre Deak <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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include/linux/math.h: fix mult_frac() multiple argument evaluation bug

mult_frac() evaluates _all_ arguments multiple times in the body.

Clarify comment while I'm at it.

Link: https://lkml.kernel.

include/linux/math.h: fix mult_frac() multiple argument evaluation bug

mult_frac() evaluates _all_ arguments multiple times in the body.

Clarify comment while I'm at it.

Link: https://lkml.kernel.org/r/f9f9fdbb-ec8e-4f5e-a998-2a58627a1a43@p183
Signed-off-by: Alexey Dobriyan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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math.h: Introduce data types for fractional numbers

Introduce a macro to produce data types like

struct TYPE_fract {
__TYPE numerator;
__TYPE denominator;
};

to be used in the code wherever

math.h: Introduce data types for fractional numbers

Introduce a macro to produce data types like

struct TYPE_fract {
__TYPE numerator;
__TYPE denominator;
};

to be used in the code wherever it's needed.

In the following changes convert some users to it.

Signed-off-by: Andy Shevchenko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Cameron <[email protected]>

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kernel.h: split out mathematical helpers

kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out
mathematical helpers.

kernel.h: split out mathematical helpers

kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out
mathematical helpers.

At the same time convert users in header and lib folder to use new
header. Though for time being include new header back to kernel.h to
avoid twisted indirected includes for existing users.

[[email protected]: fix powerpc build]
Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Andy Shevchenko <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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