/**
* strnlen_user: - Get the size of a string in user space.
* @s: The string to measure.
* @n: The maximum valid length
*
* Get the size of a NUL-terminated string in user space.
*
* Returns the size of the string INCLUDING the terminating NUL.
* On exception, returns 0.
* If the string is too long, returns a value greater than @n.
*/
long strnlen_user(const char __user *s, long n)
{
unsigned long mask = -__addr_ok(s);
unsigned long res, tmp;
might_fault();
__asm__ __volatile__(
" testl %0, %0\n"
" jz 3f\n"
" andl %0,%%ecx\n"
"0: repne; scasb\n"
" setne %%al\n"
" subl %%ecx,%0\n"
" addl %0,%%eax\n"
"1:\n"
".section .fixup,\"ax\"\n"
"2: xorl %%eax,%%eax\n"
" jmp 1b\n"
"3: movb $1,%%al\n"
" jmp 1b\n"
".previous\n"
".section __ex_table,\"a\"\n"
" .align 4\n"
" .long 0b,2b\n"
".previous"
:"=&r" (n), "=&D" (s), "=&a" (res), "=&c" (tmp)
:"0" (n), "1" (s), "2" (0), "3" (mask)
:"cc");
return res & mask;
}
long strnlen_user(const char __user *s, long n)
{
unsigned long mask = -__addr_ok(s);
unsigned long res;
__asm__ __volatile__(
" and %0, %5\n"
" mv r1, %1\n"
" beqz %0, strnlen_exit\n"
" and3 r0, %1, #3\n"
" bnez r0, strnlen_byte_loop\n"
" cmpui %0, #4\n"
" bc strnlen_byte_loop\n"
" sll3 r3, %6, #7\n"
"strnlen_word_loop:\n"
"0: ld r0, @%1+\n"
" not r2, r0\n"
" sub r0, %6\n"
" and r2, r3\n"
" and r2, r0\n"
" bnez r2, strnlen_last_bytes_fixup\n"
" addi %0, #-4\n"
" beqz %0, strnlen_exit\n"
" bgtz %0, strnlen_word_loop\n"
"strnlen_last_bytes:\n"
" mv %0, %4\n"
"strnlen_last_bytes_fixup:\n"
" addi %1, #-4\n"
"strnlen_byte_loop:\n"
"1: ldb r0, @%1\n"
" addi %0, #-1\n"
" beqz r0, strnlen_exit\n"
long strnlen_user(const char __user *s, long n)
{
unsigned long mask = -__addr_ok(s);
unsigned long res;
__asm__ __volatile__(
" and %0, %5\n"
" mv r1, %1\n"
" beqz %0, strnlen_exit\n"
" and3 r0, %1, #3\n"
" bnez r0, strnlen_byte_loop\n"
" cmpui %0, #4\n"
" bc strnlen_byte_loop\n"
" sll3 r3, %6, #7\n"
"strnlen_word_loop:\n"
"0: ld r0, @%1+\n"
" not r2, r0\n"
" sub r0, %6\n"
" and r2, r3\n"
" and r2, r0\n"
" bnez r2, strnlen_last_bytes_fixup\n"
" addi %0, #-4\n"
" beqz %0, strnlen_exit\n"
" bgtz %0, strnlen_word_loop\n"
"strnlen_last_bytes:\n"
" mv %0, %4\n"
"strnlen_last_bytes_fixup:\n"
" addi %1, #-4\n"
"strnlen_byte_loop:\n"
"1: ldb r0, @%1\n"
" addi %0, #-1\n"
" beqz r0, strnlen_exit\n"
" addi %1, #1\n"
" bnez %0, strnlen_byte_loop\n"
"strnlen_exit:\n"
" sub %1, r1\n"
" add3 %0, %1, #1\n"
" .fillinsn\n"
"9:\n"
".section .fixup,\"ax\"\n"
" .balign 4\n"
"4: addi %1, #-4\n"
" .fillinsn\n"
"5: ldi %0, #0\n"
" seth r1, #high(9b)\n"
" or3 r1, r1, #low(9b)\n"
" jmp r1\n"
".previous\n"
".section __ex_table,\"a\"\n"
" .balign 4\n"
" .long 0b,4b\n"
" .long 1b,5b\n"
".previous"
: "=&r" (res), "=r" (s)
: "0" (n), "1" (s), "r" (n & 3), "r" (mask), "r"(0x01010101)
: "r0", "r1", "r2", "r3", "cbit");
/* NOTE: strnlen_user() algorithm:
* {
* char *p;
* for (p = s; n-- && *p != '\0'; ++p)
* ;
* return p - s + 1;
* }
*/
/* NOTE: If a null char. exists, return 0.
* if ((x - 0x01010101) & ~x & 0x80808080)\n"
* return 0;\n"
*/
return res & mask;
}
