arm64/sme: Implement vector length configuration prctl()s

As for SVE provide a prctl() interface which allows processes to
configure their SME vector length.

Signed-off-by: Mark Brown <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 32cd682258d9ab4d545954488c36e0303796e3a3..38fd6aab7febf2f9008da57e654c481da471f6f8 100644 (file)
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -288,6 +288,8 @@ static inline int sme_max_virtualisable_vl(void)
 }
 
 extern unsigned int sme_get_vl(void);
+extern int sme_set_current_vl(unsigned long arg);
+extern int sme_get_current_vl(void);
 
 #else
 
@@ -299,6 +301,8 @@ static inline void sme_setup(void) { }
 static inline unsigned int sme_get_vl(void) { return 0; }
 static inline int sme_max_vl(void) { return 0; }
 static inline int sme_max_virtualisable_vl(void) { return 0; }
+static inline int sme_set_current_vl(unsigned long arg) { return -EINVAL; }
+static inline int sme_get_current_vl(void) { return -EINVAL; }
 
 #endif /* ! CONFIG_ARM64_SME */
 

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index abf34a9c2eabd93963de186bfcfdf42fd29649d1..7a57cbff8a03bcc53c91009d523a92424757cfed 100644 (file)
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -355,9 +355,11 @@ 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 e1317b7c452519b0a65f87bfb62646e9933679e4..4e6b58dcd6f90eccc1d04dbbd3b64d42e423c8dc 100644 (file)
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -82,6 +82,7 @@ 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 754a96563f6f8d809de782e9eb6f60b029ad38e2..39f44fcb9b99f82431357498fe7ea3dd6ed5eba2 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -149,6 +149,8 @@ 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;
@@ -807,6 +809,36 @@ int sve_get_current_vl(void)
        return vec_prctl_status(ARM64_VEC_SVE, 0);
 }
 
+#ifdef CONFIG_ARM64_SME
+/* 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);
+}
+#endif /* CONFIG_ARM64_SME */
+
 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 e998764f0262522903f04101f945a73a2f724a36..a5e06dcbba136d618c6dcf61f0cbb6e3bfe9ea2c 100644 (file)
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -272,6 +272,15 @@ struct prctl_mm_map {
 # define PR_SCHED_CORE_SCOPE_THREAD_GROUP      1
 # define PR_SCHED_CORE_SCOPE_PROCESS_GROUP     2
 
+/* 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 */
+
 #define PR_SET_VMA             0x53564d41
 # define PR_SET_VMA_ANON_NAME          0
 

diff --git a/kernel/sys.c b/kernel/sys.c
index 374f83e952397ec90f322697f444124520c82945..b911fa6d81ab7a19bc3d40dfb796e361adbbcc8d 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -117,6 +117,12 @@
 #ifndef SVE_GET_VL
 # define SVE_GET_VL()          (-EINVAL)
 #endif
+#ifndef SME_SET_VL
+# define SME_SET_VL(a)         (-EINVAL)
+#endif
+#ifndef SME_GET_VL
+# define SME_GET_VL()          (-EINVAL)
+#endif
 #ifndef PAC_RESET_KEYS
 # define PAC_RESET_KEYS(a, b)  (-EINVAL)
 #endif
@@ -2541,6 +2547,12 @@ 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;