minix/lib/libsys/taskcall.c
Ben Gras 2d72cbec41 SYSENTER/SYSCALL support
. add cpufeature detection of both
	. use it for both ipc and kernelcall traps, using a register
	  for call number
	. SYSENTER/SYSCALL does not save any context, therefore userland
	  has to save it
	. to accomodate multiple kernel entry/exit types, the entry
	  type is recorded in the process struct. hitherto all types
	  were interrupt (soft int, exception, hard int); now SYSENTER/SYSCALL
	  is new, with the difference that context is not fully restored
	  from proc struct when running the process again. this can't be
	  done as some information is missing.
	. complication: cases in which the kernel has to fully change
	  process context (i.e. sigreturn). in that case the exit type
	  is changed from SYSENTER/SYSEXIT to soft-int (i.e. iret) and
	  context is fully restored from the proc struct. this does mean
	  the PC and SP must change, as the sysenter/sysexit userland code
	  will otherwise try to restore its own context. this is true in the
	  sigreturn case.
	. override all usage by setting libc_ipc=1
2012-09-24 15:53:43 +02:00

20 lines
444 B
C

/* _taskcall() is the same as _syscall() except it returns negative error
* codes directly and not in errno. This is a better interface for PM and
* VFS.
*/
#include <lib.h>
#include <minix/syslib.h>
int _taskcall(who, syscallnr, msgptr)
endpoint_t who;
int syscallnr;
register message *msgptr;
{
int status;
msgptr->m_type = syscallnr;
status = sendrec(who, msgptr);
if (status != 0) return(status);
return(msgptr->m_type);
}