@@ -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);
@@ -19,3 +19,102 @@ 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;
+}
@@ -306,4 +306,20 @@ struct prctl_mm_map {
# define PR_RISCV_V_VSTATE_CTRL_NEXT_MASK 0xc
# define PR_RISCV_V_VSTATE_CTRL_MASK 0x1f
+/* PowerPC Dynamic Execution Control Register (DEXCR) controls */
+#define PR_PPC_GET_DEXCR 71
+#define PR_PPC_SET_DEXCR 72
+/* DEXCR aspect to act on */
+# define PR_PPC_DEXCR_SBHE 0 /* Speculative branch hint enable */
+# define PR_PPC_DEXCR_IBRTPD 1 /* Indirect branch recurrent target prediction disable */
+# define PR_PPC_DEXCR_SRAPD 2 /* Subroutine return address prediction disable */
+# define PR_PPC_DEXCR_NPHIE 3 /* Non-privileged hash instruction enable */
+/* Action to apply / return */
+# define PR_PPC_DEXCR_CTRL_EDITABLE (1UL << 0) /* This aspect can be modified with PR_PPC_SET_DEXCR */
+# define PR_PPC_DEXCR_CTRL_SET (1UL << 1) /* Set the aspect for this process */
+# define PR_PPC_DEXCR_CTRL_CLEAR (1UL << 2) /* Clear the aspect for this process */
+# define PR_PPC_DEXCR_CTRL_SET_ONEXEC (1UL << 3) /* Set the aspect on exec */
+# define PR_PPC_DEXCR_CTRL_CLEAR_ONEXEC (1UL << 4) /* Clear the aspect on exec */
+# define PR_PPC_DEXCR_CTRL_MASK 0x1f
+
#endif /* _LINUX_PRCTL_H */
@@ -146,6 +146,12 @@
#ifndef RISCV_V_GET_CONTROL
# define RISCV_V_GET_CONTROL() (-EINVAL)
#endif
+#ifndef PPC_GET_DEXCR_ASPECT
+# define PPC_GET_DEXCR_ASPECT(a, b) (-EINVAL)
+#endif
+#ifndef PPC_SET_DEXCR_ASPECT
+# define PPC_SET_DEXCR_ASPECT(a, b, c) (-EINVAL)
+#endif
/*
* this is where the system-wide overflow UID and GID are defined, for
@@ -2726,6 +2732,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
case PR_GET_MDWE:
error = prctl_get_mdwe(arg2, arg3, arg4, arg5);
break;
+ case PR_PPC_GET_DEXCR:
+ if (arg3 || arg4 || arg5)
+ return -EINVAL;
+ error = PPC_GET_DEXCR_ASPECT(me, arg2);
+ break;
+ case PR_PPC_SET_DEXCR:
+ if (arg4 || arg5)
+ return -EINVAL;
+ error = PPC_SET_DEXCR_ASPECT(me, arg2, arg3);
+ break;
case PR_SET_VMA:
error = prctl_set_vma(arg2, arg3, arg4, arg5);
break;
Now that we track a DEXCR on a per-task basis, individual tasks are free to configure it as they like. The interface is a pair of getter/setter prctl's that work on a single aspect at a time (multiple aspects at once is more difficult if there are different rules applied for each aspect, now or in future). The getter shows the current state of the process config, and the setter allows setting/clearing the aspect. Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> --- I'm intentionally trying to avoid saying 'enabling' or 'disabling' the aspect, as that could be confusing when the aspects themselves may 'enable' or 'disable' their feature when the aspect is set. --- arch/powerpc/include/asm/processor.h | 10 +++ arch/powerpc/kernel/dexcr.c | 99 ++++++++++++++++++++++++++++ include/uapi/linux/prctl.h | 16 +++++ kernel/sys.c | 16 +++++ 4 files changed, 141 insertions(+)