As for SVE provide a prctl() interface which allows processes to
configure their SME vector length.
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
arch/arm64/include/asm/processor.h | 4 +++-
arch/arm64/include/asm/thread_info.h | 1 +
arch/arm64/kernel/fpsimd.c | 30 ++++++++++++++++++++++++++++
include/uapi/linux/prctl.h | 9 +++++++++
kernel/sys.c | 6 ++++++
5 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 575a1fe719b7..a62d2f8045bf 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -354,9 +354,11 @@ extern void __init minsigstksz_setup(void);
*/
#include <asm/fpsimd.h>
-/* Userspace interface for PR_SVE_{SET,GET}_VL prctl()s: */
+/* Userspace interface for PR_S[MV]E_{SET,GET}_VL prctl()s: */
#define SVE_SET_VL(arg) sve_set_current_vl(arg)
#define SVE_GET_VL() sve_get_current_vl()
+#define SME_SET_VL(arg) sme_set_current_vl(arg)
+#define SME_GET_VL() sme_get_current_vl()
/* PR_PAC_RESET_KEYS prctl */
#define PAC_RESET_KEYS(tsk, arg) ptrauth_prctl_reset_keys(tsk, arg)
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index d5c8ac81ce11..5c4355204f4a 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -81,6 +81,7 @@ int arch_dup_task_struct(struct task_struct *dst,
#define TIF_SVE_VL_INHERIT 24 /* Inherit SVE vl_onexec across exec */
#define TIF_SSBD 25 /* Wants SSB mitigation */
#define TIF_TAGGED_ADDR 26 /* Allow tagged user addresses */
+#define TIF_SME_VL_INHERIT 28 /* Inherit SME vl_onexec across exec */
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 13df5920fe1e..9511428c2e81 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -145,6 +145,8 @@ static unsigned int vec_vl_inherit_flag(enum vec_type type)
switch (type) {
case ARM64_VEC_SVE:
return TIF_SVE_VL_INHERIT;
+ case ARM64_VEC_SME:
+ return TIF_SME_VL_INHERIT;
default:
WARN_ON_ONCE(1);
return 0;
@@ -800,6 +802,34 @@ int sve_get_current_vl(void)
return vec_prctl_status(ARM64_VEC_SVE, 0);
}
+/* PR_SME_SET_VL */
+int sme_set_current_vl(unsigned long arg)
+{
+ unsigned long vl, flags;
+ int ret;
+
+ vl = arg & PR_SME_VL_LEN_MASK;
+ flags = arg & ~vl;
+
+ if (!system_supports_sme() || is_compat_task())
+ return -EINVAL;
+
+ ret = vec_set_vector_length(current, ARM64_VEC_SME, vl, flags);
+ if (ret)
+ return ret;
+
+ return vec_prctl_status(ARM64_VEC_SME, flags);
+}
+
+/* PR_SME_GET_VL */
+int sme_get_current_vl(void)
+{
+ if (!system_supports_sme() || is_compat_task())
+ return -EINVAL;
+
+ return vec_prctl_status(ARM64_VEC_SME, 0);
+}
+
static void vec_probe_vqs(struct vl_info *info,
DECLARE_BITMAP(map, SVE_VQ_MAX))
{
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 43bd7f713c39..b3212d73c198 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -269,4 +269,13 @@ struct prctl_mm_map {
# define PR_SCHED_CORE_SHARE_FROM 3 /* pull core_sched cookie to pid */
# define PR_SCHED_CORE_MAX 4
+/* arm64 Scalable Matrix Extension controls */
+/* Flag values must be in sync with SVE versions */
+#define PR_SME_SET_VL 63 /* set task vector length */
+# define PR_SME_SET_VL_ONEXEC (1 << 18) /* defer effect until exec */
+#define PR_SME_GET_VL 64 /* get task vector length */
+/* Bits common to PR_SME_SET_VL and PR_SME_GET_VL */
+# define PR_SME_VL_LEN_MASK 0xffff
+# define PR_SME_VL_INHERIT (1 << 17) /* inherit across exec */
+
#endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 8fdac0d90504..bf45194ce03b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2463,6 +2463,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
case PR_SVE_GET_VL:
error = SVE_GET_VL();
break;
+ case PR_SME_SET_VL:
+ error = SME_SET_VL(arg2);
+ break;
+ case PR_SME_GET_VL:
+ error = SME_GET_VL();
+ break;
case PR_GET_SPECULATION_CTRL:
if (arg3 || arg4 || arg5)
return -EINVAL;
--
2.20.1
