svn commit: r283887 - head/sys/arm/arm

[Andrew Turner]

Author: andrew
Date: Mon Jun  1 18:13:32 2015
New Revision: 283887
URL: https://svnweb.freebsd.org/changeset/base/283887

Log:
  Clear the C bit of the saved program state register when also clearing the
  return value. We use this bit to signal when a syscall has failed, and
  without this getcontext/setcontext may fail.
  
  MFC after:	1 week

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

Modified: head/sys/arm/arm/machdep.c
==============================================================================
--- head/sys/arm/arm/machdep.c	Mon Jun  1 18:08:56 2015	(r283886)
+++ head/sys/arm/arm/machdep.c	Mon Jun  1 18:13:32 2015	(r283887)
@@ -741,10 +741,13 @@ get_mcontext(struct thread *td, mcontext
 	struct trapframe *tf = td->td_frame;
 	__greg_t *gr = mcp->__gregs;
 
-	if (clear_ret & GET_MC_CLEAR_RET)
+	if (clear_ret & GET_MC_CLEAR_RET) {
 		gr[_REG_R0] = 0;
-	else
+		gr[_REG_CPSR] = tf->tf_spsr & ~PSR_C;
+	} else {
 		gr[_REG_R0]   = tf->tf_r0;
+		gr[_REG_CPSR] = tf->tf_spsr;
+	}
 	gr[_REG_R1]   = tf->tf_r1;
 	gr[_REG_R2]   = tf->tf_r2;
 	gr[_REG_R3]   = tf->tf_r3;
@@ -760,7 +763,6 @@ get_mcontext(struct thread *td, mcontext
 	gr[_REG_SP]   = tf->tf_usr_sp;
 	gr[_REG_LR]   = tf->tf_usr_lr;
 	gr[_REG_PC]   = tf->tf_pc;
-	gr[_REG_CPSR] = tf->tf_spsr;
 
 	return (0);
 }