Commit ce5e3f90 authored by Arvind Sankar's avatar Arvind Sankar Committed by Ard Biesheuvel
Browse files

efi/printf: Add 64-bit and 8-bit integer support 



Support 'll' qualifier for long long by copying the decimal printing
code from lib/vsprintf.c. For simplicity, the 32-bit code is used on
64-bit architectures as well.

Support 'hh' qualifier for signed/unsigned char type integers.

Signed-off-by: default avatarArvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200518190716.751506-8-nivedita@alum.mit.edu


Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 29a28066

drivers/firmware/efi/libstub/vsprintf.c

+143 −27
Original line number Diff line number Diff line
@@ -7,10 +7,7 @@ 
 * ----------------------------------------------------------------------- */



/*

 * Oh, it's a waste of space, but oh-so-yummy for debugging.  This

 * version of printf() does not include 64-bit support.  "Live with

 * it."

 *

 * Oh, it's a waste of space, but oh-so-yummy for debugging.

 */



#include <stdarg.h>
@@ -28,6 +25,86 @@ static int skip_atoi(const char **s) 
	return i;

}



/*

 * put_dec_full4 handles numbers in the range 0 <= r < 10000.

 * The multiplier 0xccd is round(2^15/10), and the approximation

 * r/10 == (r * 0xccd) >> 15 is exact for all r < 16389.

 */

static

void put_dec_full4(char *buf, unsigned int r)

{

	int i;



	for (i = 0; i < 3; i++) {

		unsigned int q = (r * 0xccd) >> 15;

		*buf++ = '0' + (r - q * 10);

		r = q;

	}

	*buf++ = '0' + r;

}



/* put_dec is copied from lib/vsprintf.c with small modifications */



/*

 * Call put_dec_full4 on x % 10000, return x / 10000.

 * The approximation x/10000 == (x * 0x346DC5D7) >> 43

 * holds for all x < 1,128,869,999.  The largest value this

 * helper will ever be asked to convert is 1,125,520,955.

 * (second call in the put_dec code, assuming n is all-ones).

 */

static

unsigned int put_dec_helper4(char *buf, unsigned int x)

{

	unsigned int q = (x * 0x346DC5D7ULL) >> 43;



	put_dec_full4(buf, x - q * 10000);

	return q;

}



/* Based on code by Douglas W. Jones found at

 * <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>

 * (with permission from the author).

 * Performs no 64-bit division and hence should be fast on 32-bit machines.

 */

static

int put_dec(char *buf, unsigned long long n)

{

	unsigned int d3, d2, d1, q, h;

	char *p = buf;



	d1  = ((unsigned int)n >> 16); /* implicit "& 0xffff" */

	h   = (n >> 32);

	d2  = (h      ) & 0xffff;

	d3  = (h >> 16); /* implicit "& 0xffff" */



	/* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0

	     = 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */

	q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((unsigned int)n & 0xffff);

	q = put_dec_helper4(p, q);

	p += 4;



	q += 7671 * d3 + 9496 * d2 + 6 * d1;

	q = put_dec_helper4(p, q);

	p += 4;



	q += 4749 * d3 + 42 * d2;

	q = put_dec_helper4(p, q);

	p += 4;



	q += 281 * d3;

	q = put_dec_helper4(p, q);

	p += 4;



	put_dec_full4(p, q);

	p += 4;



	/* strip off the extra 0's we printed */

	while (p > buf && p[-1] == '0')

		--p;



	return p - buf;

}



#define ZEROPAD	1		/* pad with zero */

#define SIGN	2		/* unsigned/signed long */

#define PLUS	4		/* show plus */
@@ -36,13 +113,7 @@ static int skip_atoi(const char **s) 
#define SMALL	32		/* Must be 32 == 0x20 */

#define SPECIAL	64		/* 0x */



#define __do_div(n, base) ({ \

int __res; \

__res = ((unsigned long) n) % (unsigned) base; \

n = ((unsigned long) n) / (unsigned) base; \

__res; })



static char *number(char *str, long num, int base, int size, int precision,

static char *number(char *str, long long num, int base, int size, int precision,

		    int type)

{

	/* we are called with base 8, 10 or 16, only, thus don't need "G..."  */
@@ -57,8 +128,6 @@ static char *number(char *str, long num, int base, int size, int precision, 
	locase = (type & SMALL);

	if (type & LEFT)

		type &= ~ZEROPAD;

	if (base < 2 || base > 16)

		return NULL;

	c = (type & ZEROPAD) ? '0' : ' ';

	sign = 0;

	if (type & SIGN) {
@@ -83,9 +152,28 @@ static char *number(char *str, long num, int base, int size, int precision, 
	i = 0;

	if (num == 0)

		tmp[i++] = '0';

	else

		while (num != 0)

			tmp[i++] = (digits[__do_div(num, base)] | locase);

	else {

		switch (base) {

		case 10:

			i += put_dec(&tmp[i], num);

			break;

		case 8:

			while (num != 0) {

				tmp[i++] = '0' + (num & 07);

				num = (unsigned long long)num >> 3;

			}

			break;

		case 16:

			while (num != 0) {

				tmp[i++] = digits[num & 0xf] | locase;

				num = (unsigned long long)num >> 4;

			}

			break;

		default:

			unreachable();

		}

	}



	if (i > precision)

		precision = i;

	size -= precision;
@@ -117,7 +205,7 @@ static char *number(char *str, long num, int base, int size, int precision, 
int vsprintf(char *buf, const char *fmt, va_list args)

{

	int len;

	unsigned long num;

	unsigned long long num;

	int i, base;

	char *str;

	const char *s;
@@ -127,7 +215,7 @@ int vsprintf(char *buf, const char *fmt, va_list args) 
	int field_width;	/* width of output field */

	int precision;		/* min. # of digits for integers; max

				   number of chars for from string */

	int qualifier;		/* 'h' or 'l' for integer fields */

	int qualifier;		/* 'h', 'hh', 'l' or 'll' for integer fields */



	for (str = buf; *fmt; ++fmt) {

		if (*fmt != '%') {
@@ -191,6 +279,10 @@ int vsprintf(char *buf, const char *fmt, va_list args) 
		if (*fmt == 'h' || *fmt == 'l') {

			qualifier = *fmt;

			++fmt;

			if (qualifier == *fmt) {

				qualifier -= 'a'-'A';

				++fmt;

			}

		}



		/* default base */
@@ -260,17 +352,41 @@ int vsprintf(char *buf, const char *fmt, va_list args) 
				--fmt;

			continue;

		}

		if (qualifier == 'l') {

			num = va_arg(args, unsigned long);

		} else if (qualifier == 'h') {

			num = (unsigned short)va_arg(args, int);

			if (flags & SIGN)

				num = (short)num;

		} else if (flags & SIGN) {

		if (flags & SIGN) {

			switch (qualifier) {

			case 'L':

				num = va_arg(args, long long);

				break;

			case 'l':

				num = va_arg(args, long);

				break;

			case 'h':

				num = (short)va_arg(args, int);

				break;

			case 'H':

				num = (signed char)va_arg(args, int);

				break;

			default:

				num = va_arg(args, int);

			}

		} else {

			switch (qualifier) {

			case 'L':

				num = va_arg(args, unsigned long long);

				break;

			case 'l':

				num = va_arg(args, unsigned long);

				break;

			case 'h':

				num = (unsigned short)va_arg(args, int);

				break;

			case 'H':

				num = (unsigned char)va_arg(args, int);

				break;

			default:

				num = va_arg(args, unsigned int);

			}

		}

		str = number(str, num, base, field_width, precision, flags);

	}

	*str = '\0';

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