From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Subject: [PATCH resend 02/15] arm64: add abstractions for FPSIMD state manipulation Date: Thu, 1 May 2014 17:49:34 +0200 Message-ID: <1398959381-8126-3-git-send-email-ard.biesheuvel@linaro.org> References: <1398959381-8126-1-git-send-email-ard.biesheuvel@linaro.org> Cc: catalin.marinas@arm.com, will.deacon@arm.com, steve.capper@linaro.org, Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org Return-path: Received: from mail-we0-f174.google.com ([74.125.82.174]:65373 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751833AbaEAPtw (ORCPT ); Thu, 1 May 2014 11:49:52 -0400 Received: by mail-we0-f174.google.com with SMTP id k48so3374361wev.33 for ; Thu, 01 May 2014 08:49:51 -0700 (PDT) In-Reply-To: <1398959381-8126-1-git-send-email-ard.biesheuvel@linaro.org> Sender: linux-crypto-owner@vger.kernel.org List-ID: There are two tacit assumptions in the FPSIMD handling code that will no longer hold after the next patch that optimizes away some FPSIMD state restores: . the FPSIMD registers of this CPU contain the userland FPSIMD state of task 'current'; . when switching to a task, its FPSIMD state will always be restored from memory. This patch adds the following functions to abstract away from straight FPSIMD register file saves and restores: - fpsimd_preserve_current_state -> ensure current's FPSIMD state is saved - fpsimd_restore_current_state -> ensure current's FPSIMD state is loaded - fpsimd_update_current_state -> replace current's FPSIMD state - fpsimd_flush_task_state -> invalidate live copies of a task's FPSIMD state Where necessary, the ptrace, signal handling and fork code are updated to use the above wrappers instead of poking into the FPSIMD registers directly. Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/fpsimd.h | 6 ++++++ arch/arm64/kernel/fpsimd.c | 33 +++++++++++++++++++++++++++++++++ arch/arm64/kernel/process.c | 2 +- arch/arm64/kernel/ptrace.c | 2 ++ arch/arm64/kernel/signal.c | 9 +++------ arch/arm64/kernel/signal32.c | 9 +++------ 6 files changed, 48 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index c43b4ac13008..9f9b8e438546 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -58,6 +58,12 @@ extern void fpsimd_load_state(struct fpsimd_state *state); extern void fpsimd_thread_switch(struct task_struct *next); extern void fpsimd_flush_thread(void); +extern void fpsimd_preserve_current_state(void); +extern void fpsimd_restore_current_state(void); +extern void fpsimd_update_current_state(struct fpsimd_state *state); + +extern void fpsimd_flush_task_state(struct task_struct *target); + #endif #endif diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 4aef42a04bdc..86ac6a9bc86a 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -87,6 +87,39 @@ void fpsimd_flush_thread(void) preempt_enable(); } +/* + * Save the userland FPSIMD state of 'current' to memory + */ +void fpsimd_preserve_current_state(void) +{ + fpsimd_save_state(¤t->thread.fpsimd_state); +} + +/* + * Load the userland FPSIMD state of 'current' from memory + */ +void fpsimd_restore_current_state(void) +{ + fpsimd_load_state(¤t->thread.fpsimd_state); +} + +/* + * Load an updated userland FPSIMD state for 'current' from memory + */ +void fpsimd_update_current_state(struct fpsimd_state *state) +{ + preempt_disable(); + fpsimd_load_state(state); + preempt_enable(); +} + +/* + * Invalidate live CPU copies of task t's FPSIMD state + */ +void fpsimd_flush_task_state(struct task_struct *t) +{ +} + #ifdef CONFIG_KERNEL_MODE_NEON /* diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 6391485f342d..c5693163408c 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -205,7 +205,7 @@ void release_thread(struct task_struct *dead_task) int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { - fpsimd_save_state(¤t->thread.fpsimd_state); + fpsimd_preserve_current_state(); *dst = *src; return 0; } diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 6a8928bba03c..f8700eca24e7 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -517,6 +517,7 @@ static int fpr_set(struct task_struct *target, const struct user_regset *regset, return ret; target->thread.fpsimd_state.user_fpsimd = newstate; + fpsimd_flush_task_state(target); return ret; } @@ -764,6 +765,7 @@ static int compat_vfp_set(struct task_struct *target, uregs->fpcr = fpscr & VFP_FPSCR_CTRL_MASK; } + fpsimd_flush_task_state(target); return ret; } diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 890a591f75dd..06448a77ff53 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -51,7 +51,7 @@ static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) int err; /* dump the hardware registers to the fpsimd_state structure */ - fpsimd_save_state(fpsimd); + fpsimd_preserve_current_state(); /* copy the FP and status/control registers */ err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs)); @@ -86,11 +86,8 @@ static int restore_fpsimd_context(struct fpsimd_context __user *ctx) __get_user_error(fpsimd.fpcr, &ctx->fpcr, err); /* load the hardware registers from the fpsimd_state structure */ - if (!err) { - preempt_disable(); - fpsimd_load_state(&fpsimd); - preempt_enable(); - } + if (!err) + fpsimd_update_current_state(&fpsimd); return err ? -EFAULT : 0; } diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c index b3fc9f5ec6d3..ac7e237d0bda 100644 --- a/arch/arm64/kernel/signal32.c +++ b/arch/arm64/kernel/signal32.c @@ -219,7 +219,7 @@ static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame) * Note that this also saves V16-31, which aren't visible * in AArch32. */ - fpsimd_save_state(fpsimd); + fpsimd_preserve_current_state(); /* Place structure header on the stack */ __put_user_error(magic, &frame->magic, err); @@ -282,11 +282,8 @@ static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame) * We don't need to touch the exception register, so * reload the hardware state. */ - if (!err) { - preempt_disable(); - fpsimd_load_state(&fpsimd); - preempt_enable(); - } + if (!err) + fpsimd_update_current_state(&fpsimd); return err ? -EFAULT : 0; } -- 1.8.3.2