From patchwork Thu Jan 12 11:26:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 18867 Received: (qmail 73155 invoked by alias); 12 Jan 2017 11:26:42 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 73036 invoked by uid 89); 12 Jan 2017 11:26:41 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-5.1 required=5.0 tests=BAYES_00, RP_MATCHES_RCVD, SPF_PASS autolearn=ham version=3.3.2 spammy=synchronisation, 1057, 1109 X-Spam-User: qpsmtpd, 2 recipients X-HELO: foss.arm.com From: Dave Martin To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Marc Zyngier , Alan Hayward , Christoffer Dall , linux-arch@vger.kernel.org, libc-alpha@sourceware.org, Florian Weimer , Joseph Myers , Szabolcs Nagy , Torvald Riegel , gdb@sourceware.org, Yao Qi Subject: [RFC PATCH 08/10] arm64/sve: ptrace: Wire up vector length control and reporting Date: Thu, 12 Jan 2017 11:26:07 +0000 Message-Id: <1484220369-23970-9-git-send-email-Dave.Martin@arm.com> In-Reply-To: <1484220369-23970-1-git-send-email-Dave.Martin@arm.com> References: <1484220369-23970-1-git-send-email-Dave.Martin@arm.com> This patch adds support for manipulating a task's vector length at runtime via ptrace. As a simplification, we turn the task back into an FPSIMD-only task when changing the vector length. If the register data is written too, we then turn the task back into an SVE task, with changed task_struct layout for the SVE data, before the actual data writing is done. Because the vector length is now variable, sve_get() now needs to return the real maximum for user_sve_header.max_vl, since .vl may be less than this (that's the whole point). Signed-off-by: Dave Martin --- arch/arm64/include/asm/fpsimd.h | 1 + arch/arm64/include/uapi/asm/ptrace.h | 5 +++++ arch/arm64/kernel/ptrace.c | 25 +++++++++++++++---------- 3 files changed, 21 insertions(+), 10 deletions(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index 1ec2363..0f1b068 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -105,6 +105,7 @@ extern void sve_load_state(void const *state, u32 const *pfpsr, extern unsigned int sve_get_vl(void); extern int sve_set_vector_length(struct task_struct *task, unsigned long vl, unsigned long flags); +extern int sve_max_vl; /* * FPSIMD/SVE synchronisation helpers for ptrace: diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h index 48b57a0..bcb542d 100644 --- a/arch/arm64/include/uapi/asm/ptrace.h +++ b/arch/arm64/include/uapi/asm/ptrace.h @@ -64,6 +64,8 @@ #ifndef __ASSEMBLY__ +#include + /* * User structures for general purpose, floating point and debug registers. */ @@ -108,6 +110,9 @@ struct user_sve_header { #define SVE_PT_REGS_FPSIMD 0 #define SVE_PT_REGS_SVE SVE_PT_REGS_MASK +#define SVE_PT_VL_THREAD PR_SVE_SET_VL_THREAD +#define SVE_PT_VL_INHERIT PR_SVE_SET_VL_INHERIT + /* * The remainder of the SVE state follows struct user_sve_header. The diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 32debb8..7e40039 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -741,14 +741,15 @@ static int sve_get(struct task_struct *target, BUG_ON(!sve_vl_valid(header.vl)); vq = sve_vq_from_vl(header.vl); - /* Until runtime or per-task vector length changing is supported: */ - header.max_vl = header.vl; + BUG_ON(!sve_vl_valid(sve_max_vl)); + header.max_vl = sve_max_vl; header.flags = test_tsk_thread_flag(target, TIF_SVE) ? SVE_PT_REGS_SVE : SVE_PT_REGS_FPSIMD; header.size = SVE_PT_SIZE(vq, header.flags); - header.max_size = SVE_PT_SIZE(vq, SVE_PT_REGS_SVE); + header.max_size = SVE_PT_SIZE(sve_vq_from_vl(header.max_vl), + SVE_PT_REGS_SVE); ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &header, 0, sizeof(header)); @@ -830,14 +831,18 @@ static int sve_set(struct task_struct *target, if (ret) goto out; - if (header.vl != target->thread.sve_vl) - return -EINVAL; - - BUG_ON(!sve_vl_valid(header.vl)); - vq = sve_vq_from_vl(header.vl); + /* + * Apart from PT_SVE_REGS_MASK, all PT_SVE_* flags are consumed by + * sve_set_vector_length(), which will also validate them for us: + */ + ret = sve_set_vector_length(target, header.vl, + header.flags & ~SVE_PT_REGS_MASK); + if (ret) + goto out; - if (header.flags & ~SVE_PT_REGS_MASK) - return -EINVAL; + /* Actual VL set may be less than the user asked for: */ + BUG_ON(!sve_vl_valid(target->thread.sve_vl)); + vq = sve_vq_from_vl(target->thread.sve_vl); /* Registers: FPSIMD-only case */