minix/kernel/system/do_sigreturn.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

66 lines
1.9 KiB
C

/* The kernel call that is implemented in this file:
* m_type: SYS_SIGRETURN
*
* The parameters for this kernel call are:
* m2_i1: SIG_ENDPT # process returning from handler
* m2_p1: SIG_CTXT_PTR # pointer to sigcontext structure
*
*/
#include "kernel/system.h"
#include <string.h>
#include <machine/cpu.h>
#if USE_SIGRETURN
/*===========================================================================*
* do_sigreturn *
*===========================================================================*/
int do_sigreturn(struct proc * caller, message * m_ptr)
{
/* POSIX style signals require sys_sigreturn to put things in order before
* the signalled process can resume execution
*/
struct sigcontext sc;
register struct proc *rp;
int proc_nr, r;
if (! isokendpt(m_ptr->SIG_ENDPT, &proc_nr)) return(EINVAL);
if (iskerneln(proc_nr)) return(EPERM);
rp = proc_addr(proc_nr);
/* Copy in the sigcontext structure. */
if((r=data_copy(m_ptr->SIG_ENDPT, (vir_bytes) m_ptr->SIG_CTXT_PTR,
KERNEL, (vir_bytes) &sc, sizeof(struct sigcontext))) != OK)
return r;
/* Restore user bits of psw from sc, maintain system bits from proc. */
sc.sc_psw = (sc.sc_psw & X86_FLAGS_USER) |
(rp->p_reg.psw & ~X86_FLAGS_USER);
#if defined(__i386__)
/* Don't panic kernel if user gave bad selectors. */
sc.sc_cs = rp->p_reg.cs;
sc.sc_ds = rp->p_reg.ds;
sc.sc_es = rp->p_reg.es;
sc.sc_ss = rp->p_reg.ss;
sc.sc_fs = rp->p_reg.fs;
sc.sc_gs = rp->p_reg.gs;
#endif
/* Restore the registers. */
arch_proc_setcontext(rp, &sc.sc_regs, 1);
#if defined(__i386__)
if(sc.sc_flags & MF_FPU_INITIALIZED)
{
memcpy(rp->p_seg.fpu_state, &sc.sc_fpu_state, FPU_XFP_SIZE);
rp->p_misc_flags |= MF_FPU_INITIALIZED; /* Restore math usage flag. */
/* force reloading FPU */
release_fpu(rp);
}
#endif
return(OK);
}
#endif /* USE_SIGRETURN */