Re: [PATCH v15 1/6] x86/boot: Copy kstrtoull() to boot/string.c instead of using simple_strtoull()

Chao Fan
2019-01-10T01:17:03Z

On Wed, Jan 09, 2019 at 01:48:53PM +0100, Borislav Petkov wrote:
>On Mon, Jan 07, 2019 at 11:22:38AM +0800, Chao Fan wrote:
>> Copy kstrtoull() and necessary functions from lib/kstrtox.c to
>> boot/string.c so that code in boot/ can use kstrtoull() and the old
>> simple_strtoull() can be replaced.
>>
>> In boot/string.c, using div_u64() from math64.h directly will cause the
>> dividend handled as 64-bit value and bring ld error. The solution is to
>> separate the dividend to upper and lower in boot/string.o. So copy the
>> useful div_u64() and div_u64_rem() to boot/string.c also. To avoid
>> redefinition in i386, rename them as __div_u64() and __div_u64_rem().
>>
>> Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
>> ---
>> arch/x86/boot/string.c | 137 +++++++++++++++++++++++++++++++++++++++++
>> arch/x86/boot/string.h | 2 +
>> 2 files changed, 139 insertions(+)
>
>...
>
>> +static inline char _tolower(const char c)
>> +{
>> + return c | 0x20;
>> +}
>> +
>> +const char *_parse_integer_fixup_radix(const char *s, unsigned int *base)
>
>static

Will add it.

>
>> +{
>> + if (*base == 0) {
>> + if (s[0] == '0') {
>> + if (_tolower(s[1]) == 'x' && isxdigit(s[2]))
>> + *base = 16;
>> + else
>> + *base = 8;
>> + } else
>> + *base = 10;
>> + }
>> + if (*base == 16 && s[0] == '0' && _tolower(s[1]) == 'x')
>> + s += 2;
>> + return s;
>> +}
>> +
>> +/*
>> + * Convert non-negative integer string representation in explicitly given radix
>> + * to an integer.
>> + * Return number of characters consumed maybe or-ed with overflow bit.
>> + * If overflow occurs, result integer (incorrect) is still returned.
>> + *
>> + * Don't you dare use this function.
>> + */
>> +unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long *p)
>
>static

Will add it.

Thanks,
Chao Fan

>
>> +{
>> + unsigned long long res;
>> + unsigned int rv;
>> +
>> + res = 0;
>> + rv = 0;
>> + while (1) {
>> + unsigned int c = *s;
>> + unsigned int lc = c | 0x20; /* don't tolower() this line */
>> + unsigned int val;
>> +
>> + if ('0' <= c && c <= '9')
>> + val = c - '0';
>> + else if ('a' <= lc && lc <= 'f')
>> + val = lc - 'a' + 10;
>> + else
>> + break;
>> +
>> + if (val >= base)
>> + break;
>> + /*
>> + * Check for overflow only if we are within range of
>> + * it in the max base we support (16)
>> + */
>> + if (unlikely(res & (~0ull << 60))) {
>> + if (res > __div_u64(ULLONG_MAX - val, base))
>> + rv |= KSTRTOX_OVERFLOW;
>> + }
>> + res = res * base + val;
>> + rv++;
>> + s++;
>> + }
>> + *p = res;
>> + return rv;
>> +}
>
>
>--
>Regards/Gruss,
> Boris.
>
>Good mailing practices for 400: avoid top-posting and trim the reply.
>
>