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Date:      Wed, 25 Jul 2018 18:11:37 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r336722 - head/sys/arm/arm
Message-ID:  <201807251811.w6PIBbkp028000@repo.freebsd.org>
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Author: jhb
Date: Wed Jul 25 18:11:37 2018
New Revision: 336722
URL: https://svnweb.freebsd.org/changeset/base/336722

Log:
  Raise a proper SIGTRAP / TRAP_TRACE signal for a PT_STEP step on arm.
  
  Previously, a step by PT_STEP resulted in no signal being raised to
  the debugger so that a step was silently completed with the program
  continuing to execute after the step.  Fix by raising a SIGTRAP
  signal with TRAP_TRACE as the signal code.
  
  To simplify the error handling cases (if ptrace_clear_single_step()
  fails, etc.) move the handling of PTRACE_BREAKPOINT into the
  gdb_trapper() function.  If ptrace_clear_single_step() fails,
  gdb_trapper() won't claim the fault, and the default case of
  SIGILL / ILL_OPC will be used.
  
  Differential Revision:	https://reviews.freebsd.org/D16100

Modified:
  head/sys/arm/arm/undefined.c

Modified: head/sys/arm/arm/undefined.c
==============================================================================
--- head/sys/arm/arm/undefined.c	Wed Jul 25 17:45:56 2018	(r336721)
+++ head/sys/arm/arm/undefined.c	Wed Jul 25 18:11:37 2018	(r336722)
@@ -144,6 +144,7 @@ gdb_trapper(u_int addr, u_int insn, struct trapframe *
 {
 	struct thread *td;
 	ksiginfo_t ksi;
+	int error;
 
 	td = (curthread == NULL) ? &thread0 : curthread;
 
@@ -162,6 +163,27 @@ gdb_trapper(u_int addr, u_int insn, struct trapframe *
 #endif
 #endif
 	}
+
+	if (code == FAULT_USER) {
+		/* TODO: No support for ptrace from Thumb-2 */
+		if ((frame->tf_spsr & PSR_T) == 0 &&
+		    insn == PTRACE_BREAKPOINT) {
+			PROC_LOCK(td->td_proc);
+			_PHOLD(td->td_proc);
+			error = ptrace_clear_single_step(td);
+			_PRELE(td->td_proc);
+			PROC_UNLOCK(td->td_proc);
+			if (error == 0) {
+				ksiginfo_init_trap(&ksi);
+				ksi.ksi_signo = SIGTRAP;
+				ksi.ksi_code = TRAP_TRACE;
+				ksi.ksi_addr = (u_int32_t *)addr;
+				trapsignal(td, &ksi);
+				return (0);
+			}
+		}
+	}
+	
 	return 1;
 }
 
@@ -191,7 +213,6 @@ undefinedinstruction(struct trapframe *frame)
 	int fault_code;
 	int coprocessor;
 	struct undefined_handler *uh;
-	int error;
 #ifdef VERBOSE_ARM32
 	int s;
 #endif
@@ -304,26 +325,6 @@ undefinedinstruction(struct trapframe *frame)
 	    if (uh->uh_handler(fault_pc, fault_instruction, frame,
 			       fault_code) == 0)
 		    break;
-
-	if (fault_code & FAULT_USER) {
-		/* TODO: No support for ptrace from Thumb-2 */
-		if ((frame->tf_spsr & PSR_T) == 0 &&
-		    fault_instruction == PTRACE_BREAKPOINT) {
-			PROC_LOCK(td->td_proc);
-			_PHOLD(td->td_proc);
-			error = ptrace_clear_single_step(td);
-			_PRELE(td->td_proc);
-			PROC_UNLOCK(td->td_proc);
-			if (error != 0) {
-				ksiginfo_init_trap(&ksi);
-				ksi.ksi_signo = SIGILL;
-				ksi.ksi_code = ILL_ILLOPC;
-				ksi.ksi_addr = (u_int32_t *)(intptr_t) fault_pc;
-				trapsignal(td, &ksi);
-			}
-			return;
-		}
-	}
 
 	if (uh == NULL && (fault_code & FAULT_USER)) {
 		/* Fault has not been handled */

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