This patch adds a do-nothing skeleton for the arm64 Scalable Vector
Extension control prctls.
These prctls are only avilable with
CONFIG_ARM64=y
CONFIG_ARM64_SVE=y
Otherwise they will compile out and return -EINVAL if attempted
from userspace.
The backend functions sve_{set,get}_task_vl() will be fleshed out
with actual functionality in subsequent patches.
Signed-off-by: Dave Martin <dave.mar...@arm.com>
---
arch/arm64/include/asm/fpsimd.h | 16 ++++++++++++++++
arch/arm64/include/asm/processor.h | 4 ++++
arch/arm64/kernel/fpsimd.c | 13 +++++++++++++
include/uapi/linux/prctl.h | 4 ++++
kernel/sys.c | 12 ++++++++++++
5 files changed, 49 insertions(+)
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 71b94ee..7dba890 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -17,6 +17,7 @@
#define __ASM_FP_H
#include <asm/ptrace.h>
+#include <asm/errno.h>
#ifndef __ASSEMBLY__
@@ -107,12 +108,27 @@ extern void fpsimd_sync_to_sve(struct task_struct *task);
extern void sve_sync_to_fpsimd(struct task_struct *task);
extern void sve_sync_from_fpsimd_zeropad(struct task_struct *task);
+extern int sve_set_task_vl(struct task_struct *task,
+ unsigned long vector_length, unsigned long flags);
+extern int sve_get_task_vl(struct task_struct *task);
+
#else /* ! CONFIG_ARM64_SVE */
static void __maybe_unused sve_sync_to_fpsimd(struct task_struct *task) { }
static void __maybe_unused sve_sync_from_fpsimd_zeropad(
struct task_struct *task) { }
+static int __maybe_unused sve_set_task_vl(struct task_struct *task,
+ unsigned long vector_length, unsigned long flags)
+{
+ return -EINVAL;
+}
+
+static int __maybe_unused sve_get_task_vl(struct task_struct *task)
+{
+ return -EINVAL;
+}
+
#endif /* ! CONFIG_ARM64_SVE */
#endif
diff --git a/arch/arm64/include/asm/processor.h
b/arch/arm64/include/asm/processor.h
index c97b8bd..865c279 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -189,4 +189,8 @@ static inline void spin_lock_prefetch(const void *ptr)
int cpu_enable_pan(void *__unused);
int cpu_enable_cache_maint_trap(void *__unused);
+#define SVE_SET_VL(task, vector_length, flags) \
+ sve_set_task_vl(task, vector_length, flags)
+#define SVE_GET_VL(task) sve_get_task_vl(task)
+
#endif /* __ASM_PROCESSOR_H */
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index ee59325..4102d13 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -204,6 +204,19 @@ void do_sve_acc(unsigned int esr, struct pt_regs *regs)
task_fpsimd_load(current);
}
+/* PR_SVE_SET_VL */
+int sve_set_task_vl(struct task_struct *task,
+ unsigned long vector_length, unsigned long flags)
+{
+ return -EINVAL;
+}
+
+/* PR_SVE_GET_VL */
+int sve_get_task_vl(struct task_struct *task)
+{
+ return -EINVAL;
+}
+
#else /* ! CONFIG_ARM64_SVE */
/* Dummy declarations for usage protected with IS_ENABLED(CONFIG_ARM64_SVE): */
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index a8d0759..e32e2da 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -197,4 +197,8 @@ struct prctl_mm_map {
# define PR_CAP_AMBIENT_LOWER 3
# define PR_CAP_AMBIENT_CLEAR_ALL 4
+/* arm64 Scalable Vector Extension controls */
+#define PR_SVE_SET_VL 48 /* set task vector length */
+#define PR_SVE_GET_VL 49 /* get task vector length */
+
#endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 7ff6d1b..ea5d37e 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -110,6 +110,12 @@
#ifndef SET_FP_MODE
# define SET_FP_MODE(a,b) (-EINVAL)
#endif
+#ifndef SVE_SET_VL
+# define SVE_SET_VL(a,b,c) (-EINVAL)
+#endif
+#ifndef SVE_GET_VL
+# define SVE_GET_VL(a) (-EINVAL)
+#endif
/*
* this is where the system-wide overflow UID and GID are defined, for
@@ -2290,6 +2296,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2,
unsigned long, arg3,
case PR_GET_FP_MODE:
error = GET_FP_MODE(me);
break;
+ case PR_SVE_SET_VL:
+ error = SVE_SET_VL(me, arg2, arg3);
+ break;
+ case PR_SVE_GET_VL:
+ error = SVE_GET_VL(me);
+ break;
default:
error = -EINVAL;
break;
--
2.1.4
