On Sun, May 17, 2009 at 3:18 PM, seshikanth varma <seshikanthvarma@xxxxxxxxx> wrote: > Hi All, > I am trying to understand the implementation of copy_from_user() and > copy_to_user() implementation in linux. I know the basics of asm format. But > i don't know what is > .section .fixup > .previous > .align 4 > Can u please point me to a detailed documentation of asm details involving > the above? Google for "inline assembly" and "assembly in C". > Thanks, > Seshikanth > > 320 * Tell gcc we read from memory instead of writing: this is because > 321 * we do not write to any memory gcc knows about, so there are no > 322 * aliasing issues. > 323 */ > 324#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) > \ > 325 __asm__ __volatile__( > \ > 326 "1: mov"itype" %"rtype"1,%2\n" > \ > 327 "2:\n" > \ > 328 ".section .fixup,\"ax\"\n" > \ > 329 "3: movl %3,%0\n" > \ > 330 " jmp 2b\n" > \ > 331 ".previous\n" > \ > 332 ".section __ex_table,\"a\"\n" > \ > 333 " .align 4\n" > \ > 334 " .long 1b,3b\n" > \ > 335 ".previous" > \ > 336 : "=r"(err) > \ > 337 : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err)) > 338 > 339 > > -- > Regards, > Seshikanth > -- Regards, Sandeep. “To learn is to change. Education is a process that changes the learner.” -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
