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Date:      Thu, 30 Jul 2020 14:05:24 +0000 (UTC)
From:      Andriy Gapon <avg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r363697 - in stable/12/sys/cddl/dev: dtrace/arm fbt/arm
Message-ID:  <202007301405.06UE5Ovs037292@repo.freebsd.org>
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Author: avg
Date: Thu Jul 30 14:05:24 2020
New Revision: 363697
URL: https://svnweb.freebsd.org/changeset/base/363697

Log:
  MFC r363383: dtrace/fbt: fix return probe arguments on arm
  
  arg0 should be an offset of the return point within the function, arg1
  should be the return value.  Previously the return probe had arguments as
  if for the entry probe.
  
  Tested on armv7.
  
  andrew noted that the same problem seems to be present on arm64, mips,
  and riscv.
  I am not sure if I will get around to fixing those.  So, platform users
  or anyone looking to make a contribution please be aware of this
  opportunity.

Modified:
  stable/12/sys/cddl/dev/dtrace/arm/dtrace_subr.c
  stable/12/sys/cddl/dev/fbt/arm/fbt_isa.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/cddl/dev/dtrace/arm/dtrace_subr.c
==============================================================================
--- stable/12/sys/cddl/dev/dtrace/arm/dtrace_subr.c	Thu Jul 30 14:01:54 2020	(r363696)
+++ stable/12/sys/cddl/dev/dtrace/arm/dtrace_subr.c	Thu Jul 30 14:05:24 2020	(r363697)
@@ -248,7 +248,7 @@ dtrace_invop_start(struct trapframe *frame)
 	register_t *r0, *sp;
 	int data, invop, reg, update_sp;
 
-	invop = dtrace_invop(frame->tf_pc, frame, frame->tf_pc);
+	invop = dtrace_invop(frame->tf_pc, frame, frame->tf_r0);
 	switch (invop & DTRACE_INVOP_MASK) {
 	case DTRACE_INVOP_PUSHM:
 		sp = (register_t *)frame->tf_svc_sp;

Modified: stable/12/sys/cddl/dev/fbt/arm/fbt_isa.c
==============================================================================
--- stable/12/sys/cddl/dev/fbt/arm/fbt_isa.c	Thu Jul 30 14:01:54 2020	(r363696)
+++ stable/12/sys/cddl/dev/fbt/arm/fbt_isa.c	Thu Jul 30 14:05:24 2020	(r363697)
@@ -56,9 +56,12 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uin
 	register_t fifthparam;
 
 	for (; fbt != NULL; fbt = fbt->fbtp_hashnext) {
-		if ((uintptr_t)fbt->fbtp_patchpoint == addr) {
-			cpu->cpu_dtrace_caller = addr;
+		if ((uintptr_t)fbt->fbtp_patchpoint != addr)
+			continue;
 
+		cpu->cpu_dtrace_caller = addr;
+
+		if (fbt->fbtp_roffset == 0) {
 			/* Get 5th parameter from stack */
 			DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
 			fifthparam = *(register_t *)frame->tf_svc_sp;
@@ -67,11 +70,13 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uin
 			dtrace_probe(fbt->fbtp_id, frame->tf_r0,
 			    frame->tf_r1, frame->tf_r2,
 			    frame->tf_r3, fifthparam);
-
-			cpu->cpu_dtrace_caller = 0;
-
-			return (fbt->fbtp_rval | (fbt->fbtp_savedval << DTRACE_INVOP_SHIFT));
+		} else {
+			dtrace_probe(fbt->fbtp_id, fbt->fbtp_roffset, rval,
+			    0, 0, 0);
 		}
+
+		cpu->cpu_dtrace_caller = 0;
+		return (fbt->fbtp_rval | (fbt->fbtp_savedval << DTRACE_INVOP_SHIFT));
 	}
 
 	return (0);
@@ -178,6 +183,7 @@ again:
 		fbt->fbtp_rval = DTRACE_INVOP_B;
 	else
 		fbt->fbtp_rval = DTRACE_INVOP_POPM;
+	fbt->fbtp_roffset = (uintptr_t)instr - (uintptr_t)symval->value;
 	fbt->fbtp_savedval = *instr;
 	fbt->fbtp_patchval = FBT_BREAKPOINT;
 	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];

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