2022-11-28 03:35:15

by Benjamin Gray

Subject: [RFC PATCH 05/13] prctl: Define PowerPC DEXCR interface

Adds the definitions and generic handler for prctl control of the
PowerPC Dynamic Execution Control Register (DEXCR).

Signed-off-by: Benjamin Gray <[email protected]>
---
include/uapi/linux/prctl.h | 14 ++++++++++++++
kernel/sys.c | 16 ++++++++++++++++
2 files changed, 30 insertions(+)

diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index a5e06dcbba13..b4720e8de6f3 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -281,6 +281,20 @@ struct prctl_mm_map {
# define PR_SME_VL_LEN_MASK 0xffff
# define PR_SME_VL_INHERIT (1 << 17) /* inherit across exec */

+/* PowerPC Dynamic Execution Control Register (DEXCR) controls */
+#define PR_PPC_GET_DEXCR 65
+#define PR_PPC_SET_DEXCR 66
+/* 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_PRCTL (1 << 0)
+# define PR_PPC_DEXCR_SET_ASPECT (1 << 1)
+# define PR_PPC_DEXCR_FORCE_SET_ASPECT (1 << 2)
+# define PR_PPC_DEXCR_CLEAR_ASPECT (1 << 3)
+
#define PR_SET_VMA 0x53564d41
# define PR_SET_VMA_ANON_NAME 0

diff --git a/kernel/sys.c b/kernel/sys.c
index 5fd54bf0e886..55b8f7369059 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -139,6 +139,12 @@
#ifndef GET_TAGGED_ADDR_CTRL
# define GET_TAGGED_ADDR_CTRL() (-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
@@ -2623,6 +2629,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
error = sched_core_share_pid(arg2, arg3, arg4, arg5);
break;
#endif
+ 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;
--
2.38.1

2023-03-07 05:08:07

by Nicholas Piggin

Subject: Re: [RFC PATCH 05/13] prctl: Define PowerPC DEXCR interface

On Mon Nov 28, 2022 at 12:44 PM AEST, Benjamin Gray wrote:
> Adds the definitions and generic handler for prctl control of the
> PowerPC Dynamic Execution Control Register (DEXCR).

Assuming we'd go with the later prctl patches, this prep patch
is nice way to split out some of the mechanism.

Reviewed-by: Nicholas Piggin <[email protected]>

>
> Signed-off-by: Benjamin Gray <[email protected]>
> ---
> include/uapi/linux/prctl.h | 14 ++++++++++++++
> kernel/sys.c | 16 ++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> index a5e06dcbba13..b4720e8de6f3 100644
> --- a/include/uapi/linux/prctl.h
> +++ b/include/uapi/linux/prctl.h
> @@ -281,6 +281,20 @@ struct prctl_mm_map {
> # define PR_SME_VL_LEN_MASK 0xffff
> # define PR_SME_VL_INHERIT (1 << 17) /* inherit across exec */
>
> +/* PowerPC Dynamic Execution Control Register (DEXCR) controls */
> +#define PR_PPC_GET_DEXCR 65
> +#define PR_PPC_SET_DEXCR 66
> +/* 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_PRCTL (1 << 0)
> +# define PR_PPC_DEXCR_SET_ASPECT (1 << 1)
> +# define PR_PPC_DEXCR_FORCE_SET_ASPECT (1 << 2)
> +# define PR_PPC_DEXCR_CLEAR_ASPECT (1 << 3)
> +
> #define PR_SET_VMA 0x53564d41
> # define PR_SET_VMA_ANON_NAME 0
>
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 5fd54bf0e886..55b8f7369059 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -139,6 +139,12 @@
> #ifndef GET_TAGGED_ADDR_CTRL
> # define GET_TAGGED_ADDR_CTRL() (-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
> @@ -2623,6 +2629,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
> error = sched_core_share_pid(arg2, arg3, arg4, arg5);
> break;
> #endif
> + 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;
> --
> 2.38.1