minix/kernel/system/do_sigreturn.c

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/* The system call that is implemented in this file:
* m_type: SYS_SIGRETURN
*
* The parameters for this system call are:
* m2_i1: SIG_PROC # process returning from handler
* m2_p1: SIG_CTXT_PTR # pointer to sigcontext structure
*
*/
#include "../system.h"
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#include <string.h>
#include <signal.h>
#include <sys/sigcontext.h>
#if USE_SIGRETURN
/*===========================================================================*
* do_sigreturn *
*===========================================================================*/
PUBLIC int do_sigreturn(m_ptr)
message *m_ptr; /* pointer to request message */
{
/* 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;
phys_bytes src_phys;
if (! isokprocn(m_ptr->SIG_PROC)) return(EINVAL);
if (iskerneln(m_ptr->SIG_PROC)) return(EPERM);
rp = proc_addr(m_ptr->SIG_PROC);
/* Copy in the sigcontext structure. */
src_phys = umap_local(rp, D, (vir_bytes) m_ptr->SIG_CTXT_PTR,
(vir_bytes) sizeof(struct sigcontext));
if (src_phys == 0) return(EFAULT);
phys_copy(src_phys, vir2phys(&sc), (phys_bytes) sizeof(struct sigcontext));
/* Make sure that this is not just a jump buffer. */
if ((sc.sc_flags & SC_SIGCONTEXT) == 0) return(EINVAL);
/* Fix up only certain key registers if the compiler doesn't use
* register variables within functions containing setjmp.
*/
if (sc.sc_flags & SC_NOREGLOCALS) {
rp->p_reg.retreg = sc.sc_retreg;
rp->p_reg.fp = sc.sc_fp;
rp->p_reg.pc = sc.sc_pc;
rp->p_reg.sp = sc.sc_sp;
return(OK);
}
sc.sc_psw = rp->p_reg.psw;
#if (CHIP == INTEL)
/* 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;
#if _WORD_SIZE == 4
sc.sc_fs = rp->p_reg.fs;
sc.sc_gs = rp->p_reg.gs;
#endif
#endif
/* Restore the registers. */
memcpy(&rp->p_reg, &sc.sc_regs, sizeof(struct sigregs));
return(OK);
}
#endif /* USE_SIGRETURN */