svn commit: r354783 - head/sys/powerpc/powerpc

[Justin Hibbits]

Author: jhibbits
Date: Sun Nov 17 01:01:02 2019
New Revision: 354783
URL: https://svnweb.freebsd.org/changeset/base/354783

Log:
  powerpc: Return SIGILL if DSCR does not exist in m{f,t}spr emulation
  
  Guard against programs written for one powerpc target running on another,
  and panicking the system due to not having the DSCR register.

Modified:
  head/sys/powerpc/powerpc/exec_machdep.c

Modified: head/sys/powerpc/powerpc/exec_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/exec_machdep.c	Sun Nov 17 00:52:58 2019	(r354782)
+++ head/sys/powerpc/powerpc/exec_machdep.c	Sun Nov 17 01:01:02 2019	(r354783)
@@ -1086,15 +1086,17 @@ emulate_mfspr(int spr, int reg, struct trapframe *fram
 	td = curthread;
 
 	if (spr == SPR_DSCR || spr == SPR_DSCRP) {
+		if (!(cpu_features2 & PPC_FEATURE2_DSCR))
+			return (SIGILL);
 		// If DSCR was never set, get the default DSCR
 		if ((td->td_pcb->pcb_flags & PCB_CDSCR) == 0)
 			td->td_pcb->pcb_dscr = mfspr(SPR_DSCRP);
 
 		frame->fixreg[reg] = td->td_pcb->pcb_dscr;
 		frame->srr0 += 4;
-		return 0;
+		return (0);
 	} else
-		return SIGILL;
+		return (SIGILL);
 }
 
 static int
@@ -1104,13 +1106,15 @@ emulate_mtspr(int spr, int reg, struct trapframe *fram
 	td = curthread;
 
 	if (spr == SPR_DSCR || spr == SPR_DSCRP) {
+		if (!(cpu_features2 & PPC_FEATURE2_DSCR))
+			return (SIGILL);
 		td->td_pcb->pcb_flags |= PCB_CDSCR;
 		td->td_pcb->pcb_dscr = frame->fixreg[reg];
 		mtspr(SPR_DSCRP, frame->fixreg[reg]);
 		frame->srr0 += 4;
-		return 0;
+		return (0);
 	} else
-		return SIGILL;
+		return (SIGILL);
 }
 
 #define XFX 0xFC0007FF