svn commit: r256822 - in head/sys/cddl: contrib/opensolaris/uts/intel/dtrace dev/dtrace/amd64

[Mark Johnston]

Author: markj
Date: Mon Oct 21 04:15:55 2013
New Revision: 256822
URL: http://svnweb.freebsd.org/changeset/base/256822

Log:
  When fetching function arguments out of a frame on amd64, explicitly select
  the register based on the argument index rather than relying on the fields
  in struct reg to be in the right order. This assumption is incorrect on
  FreeBSD and generally led to bogus argument values for the sixth argument
  of PID and USDT probes; the first five are passed directly to dtrace_probe()
  via the fasttrap trap handler and so were correctly handled.
  
  MFC after:	2 weeks

Modified:
  head/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
  head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c

Modified: head/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c	Mon Oct 21 04:00:23 2013	(r256821)
+++ head/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c	Mon Oct 21 04:15:55 2013	(r256822)
@@ -272,7 +272,20 @@ fasttrap_anarg(struct reg *rp, int funct
 		 * registers.
 		 */
 		if (argno < 6)
-			return ((&rp->r_rdi)[argno]);
+			switch (argno) {
+			case 0:
+				return (rp->r_rdi);
+			case 1:
+				return (rp->r_rsi);
+			case 2:
+				return (rp->r_rdx);
+			case 3:
+				return (rp->r_rcx);
+			case 4:
+				return (rp->r_r8);
+			case 5:
+				return (rp->r_r9);
+			}
 
 		stack = (uintptr_t *)rp->r_rsp;
 		DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);

Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
==============================================================================
--- head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c	Mon Oct 21 04:00:23 2013	(r256821)
+++ head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c	Mon Oct 21 04:15:55 2013	(r256822)
@@ -367,7 +367,27 @@ dtrace_getarg(int arg, int aframes)
 			    sizeof (uintptr_t));
 
 			if (arg <= inreg) {
-				stack = (uintptr_t *)&rp->r_rdi;
+				switch (arg) {
+				case 0:
+					stack = (uintptr_t *)&rp->r_rdi;
+					break;
+				case 1:
+					stack = (uintptr_t *)&rp->r_rsi;
+					break;
+				case 2:
+					stack = (uintptr_t *)&rp->r_rdx;
+					break;
+				case 3:
+					stack = (uintptr_t *)&rp->r_rcx;
+					break;
+				case 4:
+					stack = (uintptr_t *)&rp->r_r8;
+					break;
+				case 5:
+					stack = (uintptr_t *)&rp->r_r9;
+					break;
+				}
+				arg = 0;
 			} else {
 				stack = (uintptr_t *)(rp->r_rsp);
 				arg -= inreg;