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.Martin@xxxxxxx>
---
There will probably also be a call to discover the signal frame size
(MINSIGSTKSZ equivalent) for the current configuration, something like
* PR_GET_MINSIGSTKSZ
This series doesn't add this yet: only the PR_SVE_{SET,GET}_VL prctls
are provided.
arch/arm64/include/asm/fpsimd.h | 19 +++++++++++++++++++
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, 52 insertions(+)
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 88bcf69..e13259e 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__
@@ -110,12 +111,30 @@ extern unsigned int sve_get_vl(void);
extern void fpsimd_sync_to_sve(struct task_struct *task);
#ifdef CONFIG_ARM64_SVE
+
extern void fpsimd_sync_to_fpsimd(struct task_struct *task);
extern void fpsimd_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 fpsimd_sync_to_fpsimd(struct task_struct *task) { }
static void __maybe_unused fpsimd_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 747c65a..6f0f300 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -190,4 +190,8 @@ int cpu_enable_pan(void *__unused);
int cpu_enable_uao(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 2c113e4..bdacfcd 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -468,6 +468,19 @@ void fpsimd_sync_from_fpsimd_zeropad(struct task_struct *task)
__fpsimd_sync_from_fpsimd_zeropad(task, sve_vq_from_vl(vl));
}
+/* 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;
+}
+
#endif /* CONFIG_ARM64_SVE */
#ifdef CONFIG_KERNEL_MODE_NEON
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 842914e..5f50385 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -103,6 +103,12 @@
#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
@@ -2261,6 +2267,12 @@ 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
--
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