minix/kernel/system/do_sigreturn.c
Ben Gras b00f287449 Restore user-owned bits from PSW after a signal handler, instead of
copying complete PSW after signal handler.

This fixes a psw corruption bug reported by Jens de Smit <jst260@few.vu.nl>.
2007-05-08 15:43:00 +00:00

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 "../system.h"
#include <string.h>
#include <signal.h>
#include <ibm/cpu.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;
int proc;
if (! isokendpt(m_ptr->SIG_ENDPT, &proc)) return(EINVAL);
if (iskerneln(proc)) return(EPERM);
rp = proc_addr(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));
/* 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 (_MINIX_CHIP == _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. */
#if _MINIX_CHIP == _CHIP_POWERPC
memcpy(&rp->p_reg, &sc.sc_regs, sizeof(struct stackframe_s));
#else
memcpy(&rp->p_reg, &sc.sc_regs, sizeof(struct sigregs));
#endif
return(OK);
}
#endif /* USE_SIGRETURN */