[crypto] Use generic implementations of slow-path big integer functions

In the original big integer implementation, big integers were entirely
opaque to the caller and only the architecture-dependent code knew any
details of the internal structure.

This has long since ceased to be the case: for the sake of arithmetic
efficiency, many portions of the codebase now presume that big
integers are represented as an array of elements, with each element
being a native-endian unsigned value (with the precise type being
chosen by the architecture-specific header file) and with the least
significant element being first in the array.

The functions bigint_init(), bigint_done(), bigint_is_zero(),
bigint_is_geq(), and bigint_max_bit_set() are never used on fast code
paths, and most architectures use a generic C implementation of these
functions.

Provide generic implementations of these slow-path functions to be
used on all architectures.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Author: mcb30

src/arch/arm32/include/bits/bigint.h

@@ -10,33 +10,10 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stdint.h>
 #include <string.h>
-#include <strings.h>
 
 /** Element of a big integer */
 typedef uint32_t bigint_element_t;
 
-/**
- * Initialise big integer
- *
- * @v value0		Element 0 of big integer to initialise
- * @v size		Number of elements
- * @v data		Raw data
- * @v len		Length of raw data
- */
-static inline __attribute__ (( always_inline )) void
-bigint_init_raw ( uint32_t *value0, unsigned int size,
-		  const void *data, size_t len ) {
-	size_t pad_len = ( sizeof ( bigint_t ( size ) ) - len );
-	uint8_t *value_byte = ( ( void * ) value0 );
-	const uint8_t *data_byte = ( data + len );
-
-	/* Copy raw data in reverse order, padding with zeros */
-	while ( len-- )
-		*(value_byte++) = *(--data_byte);
-	while ( pad_len-- )
-		*(value_byte++) = 0;
-}
-
 /**
  * Add big integers
  *
@@ -182,76 +159,6 @@ bigint_shr_raw ( uint32_t *value0, unsigned int size ) {
 	return carry;
 }
 
-/**
- * Test if big integer is equal to zero
- *
- * @v value0		Element 0 of big integer
- * @v size		Number of elements
- * @ret is_zero		Big integer is equal to zero
- */
-static inline __attribute__ (( always_inline, pure )) int
-bigint_is_zero_raw ( const uint32_t *value0, unsigned int size ) {
-	const uint32_t *value = value0;
-	uint32_t value_i;
-
-	do {
-		value_i = *(value++);
-		if ( value_i )
-			break;
-	} while ( --size );
-
-	return ( value_i == 0 );
-}
-
-/**
- * Compare big integers
- *
- * @v value0		Element 0 of big integer
- * @v reference0	Element 0 of reference big integer
- * @v size		Number of elements
- * @ret geq		Big integer is greater than or equal to the reference
- */
-static inline __attribute__ (( always_inline, pure )) int
-bigint_is_geq_raw ( const uint32_t *value0, const uint32_t *reference0,
-		    unsigned int size ) {
-	const uint32_t *value = ( value0 + size );
-	const uint32_t *reference = ( reference0 + size );
-	uint32_t value_i;
-	uint32_t reference_i;
-
-	do {
-		value_i = *(--value);
-		reference_i = *(--reference);
-		if ( value_i != reference_i )
-			break;
-	} while ( --size );
-
-	return ( value_i >= reference_i );
-}
-
-/**
- * Find highest bit set in big integer
- *
- * @v value0		Element 0 of big integer
- * @v size		Number of elements
- * @ret max_bit		Highest bit set + 1 (or 0 if no bits set)
- */
-static inline __attribute__ (( always_inline )) int
-bigint_max_set_bit_raw ( const uint32_t *value0, unsigned int size ) {
-	const uint32_t *value = ( value0 + size );
-	int max_bit = ( 8 * sizeof ( bigint_t ( size ) ) );
-	uint32_t value_i;
-
-	do {
-		value_i = *(--value);
-		max_bit -= ( 32 - fls ( value_i ) );
-		if ( value_i )
-			break;
-	} while ( --size );
-
-	return max_bit;
-}
-
 /**
  * Grow big integer
  *
@@ -284,25 +191,6 @@ bigint_shrink_raw ( const uint32_t *source0, unsigned int source_size __unused,
 	memcpy ( dest0, source0, sizeof ( bigint_t ( dest_size ) ) );
 }
 
-/**
- * Finalise big integer
- *
- * @v value0		Element 0 of big integer to finalise
- * @v size		Number of elements
- * @v out		Output buffer
- * @v len		Length of output buffer
- */
-static inline __attribute__ (( always_inline )) void
-bigint_done_raw ( const uint32_t *value0, unsigned int size __unused,
-		  void *out, size_t len ) {
-	const uint8_t *value_byte = ( ( const void * ) value0 );
-	uint8_t *out_byte = ( out + len );
-
-	/* Copy raw data in reverse order */
-	while ( len-- )
-		*(--out_byte) = *(value_byte++);
-}
-
 /**
  * Multiply big integer elements
  *

src/arch/arm64/include/bits/bigint.h

@@ -11,33 +11,10 @@ FILE_SECBOOT ( PERMITTED );
 
 #include <stdint.h>
 #include <string.h>
-#include <strings.h>
 
 /** Element of a big integer */
 typedef uint64_t bigint_element_t;
 
-/**
- * Initialise big integer
- *
- * @v value0		Element 0 of big integer to initialise
- * @v size		Number of elements
- * @v data		Raw data
- * @v len		Length of raw data
- */
-static inline __attribute__ (( always_inline )) void
-bigint_init_raw ( uint64_t *value0, unsigned int size,
-		  const void *data, size_t len ) {
-	size_t pad_len = ( sizeof ( bigint_t ( size ) ) - len );
-	uint8_t *value_byte = ( ( void * ) value0 );
-	const uint8_t *data_byte = ( data + len );
-
-	/* Copy raw data in reverse order, padding with zeros */
-	while ( len-- )
-		*(value_byte++) = *(--data_byte);
-	while ( pad_len-- )
-		*(value_byte++) = 0;
-}
-
 /**
  * Add big integers
  *
@@ -183,76 +160,6 @@ bigint_shr_raw ( uint64_t *value0, unsigned int size ) {
 	return ( low & 1 );
 }
 
-/**
- * Test if big integer is equal to zero
- *
- * @v value0		Element 0 of big integer
- * @v size		Number of elements
- * @ret is_zero		Big integer is equal to zero
- */
-static inline __attribute__ (( always_inline, pure )) int
-bigint_is_zero_raw ( const uint64_t *value0, unsigned int size ) {
-	const uint64_t *value = value0;
-	uint64_t value_i;
-
-	do {
-		value_i = *(value++);
-		if ( value_i )
-			break;
-	} while ( --size );
-
-	return ( value_i == 0 );
-}
-
-/**
- * Compare big integers
- *
- * @v value0		Element 0 of big integer
- * @v reference0	Element 0 of reference big integer
- * @v size		Number of elements
- * @ret geq		Big integer is greater than or equal to the reference
- */
-static inline __attribute__ (( always_inline, pure )) int
-bigint_is_geq_raw ( const uint64_t *value0, const uint64_t *reference0,
-		    unsigned int size ) {
-	const uint64_t *value = ( value0 + size );
-	const uint64_t *reference = ( reference0 + size );
-	uint64_t value_i;
-	uint64_t reference_i;
-
-	do {
-		value_i = *(--value);
-		reference_i = *(--reference);
-		if ( value_i != reference_i )
-			break;
-	} while ( --size );
-
-	return ( value_i >= reference_i );
-}
-
-/**
- * Find highest bit set in big integer
- *
- * @v value0		Element 0 of big integer
- * @v size		Number of elements
- * @ret max_bit		Highest bit set + 1 (or 0 if no bits set)
- */
-static inline __attribute__ (( always_inline )) int
-bigint_max_set_bit_raw ( const uint64_t *value0, unsigned int size ) {
-	const uint64_t *value = ( value0 + size );
-	int max_bit = ( 8 * sizeof ( bigint_t ( size ) ) );
-	uint64_t value_i;
-
-	do {
-		value_i = *(--value);
-		max_bit -= ( 64 - fls ( value_i ) );
-		if ( value_i )
-			break;
-	} while ( --size );
-
-	return max_bit;
-}
-
 /**
  * Grow big integer
  *
@@ -285,25 +192,6 @@ bigint_shrink_raw ( const uint64_t *source0, unsigned int source_size __unused,
 	memcpy ( dest0, source0, sizeof ( bigint_t ( dest_size ) ) );
 }
 
-/**
- * Finalise big integer
- *
- * @v value0		Element 0 of big integer to finalise
- * @v size		Number of elements
- * @v out		Output buffer
- * @v len		Length of output buffer
- */
-static inline __attribute__ (( always_inline )) void
-bigint_done_raw ( const uint64_t *value0, unsigned int size __unused,
-		  void *out, size_t len ) {
-	const uint8_t *value_byte = ( ( const void * ) value0 );
-	uint8_t *out_byte = ( out + len );
-
-	/* Copy raw data in reverse order */
-	while ( len-- )
-		*(--out_byte) = *(value_byte++);
-}
-
 /**
  * Multiply big integer elements
  *