> Date: Sat, 10 Sep 2016 11:14:53 -0700 > From: Philip Guenther <guent...@gmail.com> > > On Sat, 10 Sep 2016, Mark Kettenis wrote: > > ok kettenis@, but it is probably time to rewrite the comment above > > thie function as well. > > Like this?
Yeah, nothing worth keeping in the bits you removed. > Index: trap.c > =================================================================== > RCS file: /cvs/src/sys/arch/sparc64/sparc64/trap.c,v > retrieving revision 1.89 > diff -u -p -r1.89 trap.c > --- trap.c 10 Sep 2016 18:02:15 -0000 1.89 > +++ trap.c 10 Sep 2016 18:06:52 -0000 > @@ -1186,27 +1186,6 @@ out: > * `in' registers within the syscall trap code (because of the automatic > * `save' effect of each trap). They are, however, the %o registers of the > * thing that made the system call, and are named that way here. > - * > - * 32-bit system calls on a 64-bit system are a problem. Each system call > - * argument is stored in the smaller of the argument's true size or a > - * `register_t'. Now on a 64-bit machine all normal types can be stored in a > - * `register_t'. (The only exceptions would be 128-bit `quad's or 128-bit > - * extended precision floating point values, which we don't support.) For > - * 32-bit syscalls, 64-bit integers like `off_t's, double precision floating > - * point values, and several other types cannot fit in a 32-bit `register_t'. > - * These will require reading in two `register_t' values for one argument. > - * > - * In order to calculate the true size of the arguments and therefore whether > - * any argument needs to be split into two slots, the system call args > - * structure needs to be built with the appropriately sized register_t. > - * Otherwise the emul needs to do some magic to split oversized arguments. > - * > - * We can handle most this stuff for normal syscalls by using either a 32-bit > - * or 64-bit array of `register_t' arguments. Unfortunately ktrace always > - * expects arguments to be `register_t's, so it loses badly. What's worse, > - * ktrace may need to do size translations to massage the argument array > - * appropriately according to the emulation that is doing the ktrace. > - * > */ > void > syscall(tf, code, pc) > @@ -1248,10 +1227,10 @@ syscall(tf, code, pc) > * of the user's stack frame (see <machine/frame.h>). > * > * Check for ``special'' codes that alter this, namely syscall and > - * __syscall. The latter takes a quad syscall number, so that other > - * arguments are at their natural alignments. Adjust the number > - * of ``easy'' arguments as appropriate; we will copy the hard > - * ones later as needed. > + * __syscall. These both pass a syscall number in the first argument > + * register, so the other arguments are just shifted down, possibly > + * pushing one off the end into the extension area. This happens > + * with mmap() and mquery() used via __syscall(). > */ > ap = &tf->tf_out[0]; > nap = 6; >
