svn commit: r273570 - head/sys/cddl/dev/fbt/powerpc

[Justin Hibbits]

Author: jhibbits
Date: Fri Oct 24 03:33:01 2014
New Revision: 273570
URL: https://svnweb.freebsd.org/changeset/base/273570

Log:
  Three updates to PowerPC FBT:
  
  * Use a constant to define the number of stack frames in a probe exception.
  * Only allow function symbols in powerpc64 ('.' prefixed)
  * Set the fbtp_roffset for return probes, so the correct dtrace_probe call is
    made.
  
  MFC after:	1 week

Modified:
  head/sys/cddl/dev/fbt/powerpc/fbt_isa.c

Modified: head/sys/cddl/dev/fbt/powerpc/fbt_isa.c
==============================================================================
--- head/sys/cddl/dev/fbt/powerpc/fbt_isa.c	Thu Oct 23 23:20:04 2014	(r273569)
+++ head/sys/cddl/dev/fbt/powerpc/fbt_isa.c	Fri Oct 24 03:33:01 2014	(r273570)
@@ -48,6 +48,7 @@
 
 #define	FBT_ENTRY	"entry"
 #define	FBT_RETURN	"return"
+#define FBT_AFRAMES	7
 
 int
 fbt_invop(uintptr_t addr, uintptr_t *stack, uintptr_t rval)
@@ -116,9 +117,17 @@ fbt_provide_module_function(linker_file_
 	int j;
 	uint32_t *instr, *limit;
 
-	/* PowerPC64 uses '.' prefixes on symbol names, ignore it. */
+#ifdef __powerpc64__
+	/*
+	 * PowerPC64 uses '.' prefixes on symbol names, ignore it, but only
+	 * allow symbols with the '.' prefix, so that we don't get the function
+	 * descriptor instead.
+	 */
 	if (name[0] == '.')
 		name++;
+	else
+		return (0);
+#endif
 
 	if (strncmp(name, "dtrace_", 7) == 0 &&
 	    strncmp(name, "dtrace_safe_", 12) != 0) {
@@ -147,7 +156,7 @@ fbt_provide_module_function(linker_file_
 	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
 	fbt->fbtp_name = name;
 	fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
-	    name, FBT_ENTRY, 7, fbt);
+	    name, FBT_ENTRY, FBT_AFRAMES, fbt);
 	fbt->fbtp_patchpoint = instr;
 	fbt->fbtp_ctl = lf;
 	fbt->fbtp_loadcnt = lf->loadcnt;
@@ -210,7 +219,7 @@ again:
 
 	if (retfbt == NULL) {
 		fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
-		    name, FBT_RETURN, 7, fbt);
+		    name, FBT_RETURN, FBT_AFRAMES, fbt);
 	} else {
 		retfbt->fbtp_next = fbt;
 		fbt->fbtp_id = retfbt->fbtp_id;
@@ -229,6 +238,9 @@ again:
 	else
 		fbt->fbtp_rval = DTRACE_INVOP_JUMP;
 
+	fbt->fbtp_roffset =
+	    (uintptr_t)((uint8_t *)instr - (uint8_t *)symval->value);
+
 	fbt->fbtp_savedval = *instr;
 	fbt->fbtp_patchval = FBT_PATCHVAL;
 	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];