2 files changed, 111 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index aad85a24134a..e44cac0da346 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -334,6 +334,16 @@ extern int set_endian(struct task_struct *tsk, unsigned int val);
 extern int get_unalign_ctl(struct task_struct *tsk, unsigned long adr);
 extern int set_unalign_ctl(struct task_struct *tsk, unsigned int val);
 
+#ifdef CONFIG_PPC_BOOK3S_64
+
+#define PPC_GET_DEXCR_ASPECT(tsk, asp) get_dexcr_prctl((tsk), (asp))
+#define PPC_SET_DEXCR_ASPECT(tsk, asp, val) set_dexcr_prctl((tsk), (asp), (val))
+
+int get_dexcr_prctl(struct task_struct *tsk, unsigned long asp);
+int set_dexcr_prctl(struct task_struct *tsk, unsigned long asp, unsigned long val);
+
+#endif
+
 extern void load_fp_state(struct thread_fp_state *fp);
 extern void store_fp_state(struct thread_fp_state *fp);
 extern void load_vr_state(struct thread_vr_state *vr);
diff --git a/arch/powerpc/kernel/dexcr.c b/arch/powerpc/kernel/dexcr.c
index d5cd77421088..3a0358e91c60 100644
--- a/arch/powerpc/kernel/dexcr.c
+++ b/arch/powerpc/kernel/dexcr.c
@@ -21,3 +21,104 @@ static int __init init_task_dexcr(void)
 	return 0;
 }
 early_initcall(init_task_dexcr)
+
+/* Allow thread local configuration of these by default */
+#define DEXCR_PRCTL_EDITABLE ( \
+	DEXCR_PR_IBRTPD | \
+	DEXCR_PR_SRAPD | \
+	DEXCR_PR_NPHIE)
+
+static int prctl_to_aspect(unsigned long which, unsigned int *aspect)
+{
+	switch (which) {
+	case PR_PPC_DEXCR_SBHE:
+		*aspect = DEXCR_PR_SBHE;
+		break;
+	case PR_PPC_DEXCR_IBRTPD:
+		*aspect = DEXCR_PR_IBRTPD;
+		break;
+	case PR_PPC_DEXCR_SRAPD:
+		*aspect = DEXCR_PR_SRAPD;
+		break;
+	case PR_PPC_DEXCR_NPHIE:
+		*aspect = DEXCR_PR_NPHIE;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+int get_dexcr_prctl(struct task_struct *task, unsigned long which)
+{
+	unsigned int aspect;
+	int ret;
+
+	ret = prctl_to_aspect(which, &aspect);
+	if (ret)
+		return ret;
+
+	if (aspect & DEXCR_PRCTL_EDITABLE)
+		ret |= PR_PPC_DEXCR_CTRL_EDITABLE;
+
+	if (aspect & mfspr(SPRN_DEXCR))
+		ret |= PR_PPC_DEXCR_CTRL_SET;
+	else
+		ret |= PR_PPC_DEXCR_CTRL_CLEAR;
+
+	if (aspect & task->thread.dexcr_onexec)
+		ret |= PR_PPC_DEXCR_CTRL_SET_ONEXEC;
+	else
+		ret |= PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC;
+
+	return ret;
+}
+
+int set_dexcr_prctl(struct task_struct *task, unsigned long which, unsigned long ctrl)
+{
+	unsigned long dexcr;
+	unsigned int aspect;
+	int err = 0;
+
+	err = prctl_to_aspect(which, &aspect);
+	if (err)
+		return err;
+
+	if (!(aspect & DEXCR_PRCTL_EDITABLE))
+		return -EPERM;
+
+	if (ctrl & ~PR_PPC_DEXCR_CTRL_MASK)
+		return -EINVAL;
+
+	if (ctrl & PR_PPC_DEXCR_CTRL_SET && ctrl & PR_PPC_DEXCR_CTRL_CLEAR)
+		return -EINVAL;
+
+	if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC && ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)
+		return -EINVAL;
+
+	/*
+	 * We do not want an unprivileged process being able to disable
+	 * a setuid process's hash check instructions
+	 */
+	if (aspect == DEXCR_PR_NPHIE &&
+	    ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC &&
+	    !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	dexcr = mfspr(SPRN_DEXCR);
+
+	if (ctrl & PR_PPC_DEXCR_CTRL_SET)
+		dexcr |= aspect;
+	else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR)
+		dexcr &= ~aspect;
+
+	if (ctrl & PR_PPC_DEXCR_CTRL_SET_ONEXEC)
+		task->thread.dexcr_onexec |= aspect;
+	else if (ctrl & PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC)
+		task->thread.dexcr_onexec &= ~aspect;
+
+	mtspr(SPRN_DEXCR, dexcr);
+
+	return 0;
+}