From 2d2123bc7c7f843aa9db87720de159a049839862 Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Tue, 31 Oct 2017 15:51:14 +0000 Subject: arm64/sve: Add prctl controls for userspace vector length management MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch adds two arm64-specific prctls, to permit userspace to control its vector length: * PR_SVE_SET_VL: set the thread's SVE vector length and vector length inheritance mode. * PR_SVE_GET_VL: get the same information. Although these prctls resemble instruction set features in the SVE architecture, they provide additional control: the vector length inheritance mode is Linux-specific and nothing to do with the architecture, and the architecture does not permit EL0 to set its own vector length directly. Both can be used in portable tools without requiring the use of SVE instructions. Signed-off-by: Dave Martin Reviewed-by: Catalin Marinas Cc: Alex Bennée [will: Fixed up prctl constants to avoid clash with PDEATHSIG] Signed-off-by: Will Deacon --- kernel/sys.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'kernel/sys.c') diff --git a/kernel/sys.c b/kernel/sys.c index 9aebc2935013..c541916b38c6 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) (-EINVAL) +#endif +#ifndef SVE_GET_VL +# define SVE_GET_VL() (-EINVAL) +#endif /* * this is where the system-wide overflow UID and GID are defined, for @@ -2385,6 +2391,12 @@ 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(arg2); + break; + case PR_SVE_GET_VL: + error = SVE_GET_VL(); + break; default: error = -EINVAL; break; -- cgit v1.2.3