Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755296AbbETQTK (ORCPT ); Wed, 20 May 2015 12:19:10 -0400 Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.217]:12297 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754189AbbETQTI (ORCPT ); Wed, 20 May 2015 12:19:08 -0400 X-RZG-AUTH: :ImkWY2CseuihIZy6ZWWciR6unPh5JPSWE7VxbdUCFBN5njG7Q28CH4RMeHzjXw== X-RZG-CLASS-ID: mo00 Message-ID: <555CB3D5.7000307@dawncrow.de> Date: Wed, 20 May 2015 18:18:29 +0200 From: =?windows-1252?Q?Andr=E9_Hentschel?= User-Agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: "linux-arch@vger.kernel.org" CC: Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "gregkh@linuxfoundation.org" , Will Deacon , Catalin Marinas , Nathan Lynch Subject: [PATCH v2] arm64: Preserve the user r/w register tpidr_el0 on context switch and fork in compat mode Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4051 Lines: 127 From: Andr? Hentschel Since commit a4780adeefd042482f624f5e0d577bf9cdcbb760 the user writeable TLS register on ARM is preserved per thread. This patch does it analogous to the ARM patch, but for compat mode on ARM64. Signed-off-by: Andr? Hentschel Cc: Will Deacon Cc: Catalin Marinas --- This patch is against Linux 4.1-rc1 (b787f68c36d49bb1d9236f403813641efa74a031) v2: Trying to address suggestions by Will Deacon @Will Deacon: The macro you suggested is not helpful it seems, instead i introduced static functions. They also could be macros i guess, but it seems much cleaner to me to use functions as it only affects one file. Should the final version be send to rmk's patchtracker or will someone else pick it up? arch/arm64/include/asm/processor.h | 3 +++ arch/arm64/kernel/process.c | 41 +++++++++++++++++++++++++++++--------- 2 files changed, 35 insertions(+), 9 deletions(-) diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index d2c37a1..466a851 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -79,6 +79,9 @@ struct cpu_context { struct thread_struct { struct cpu_context cpu_context; /* cpu context */ unsigned long tp_value; +#ifdef CONFIG_COMPAT + unsigned long tp_compat; +#endif struct fpsimd_state fpsimd_state; unsigned long fault_address; /* fault info */ unsigned long fault_code; /* ESR_EL1 value */ diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index c6b1f3b..630f44b 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -58,6 +58,22 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif +static unsigned long get_tp_compat(struct thread_struct *p) +{ +#ifdef CONFIG_COMPAT + return p->tp_compat; +#else + return 0; +#endif +} + +static void set_tp_compat(struct thread_struct *p, unsigned long tpidr) +{ +#ifdef CONFIG_COMPAT + p->tp_compat = tpidr; +#endif +} + void soft_restart(unsigned long addr) { setup_mm_for_reboot(); @@ -219,6 +235,7 @@ static void tls_thread_flush(void) if (is_compat_task()) { current->thread.tp_value = 0; + set_tp_compat(¤t->thread, 0); /* * We need to ensure ordering between the shadow state and the @@ -259,17 +276,22 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context)); if (likely(!(p->flags & PF_KTHREAD))) { + unsigned long tpidr; *childregs = *current_pt_regs(); childregs->regs[0] = 0; + /* + * Read the current TLS pointer from tpidr_el0 as it may be + * out-of-sync with the saved value. + */ + asm("mrs %0, tpidr_el0" : "=r" (tpidr)); if (is_compat_thread(task_thread_info(p))) { + set_tp_compat(&p->thread, tpidr); + if (stack_start) childregs->compat_sp = stack_start; } else { - /* - * Read the current TLS pointer from tpidr_el0 as it may be - * out-of-sync with the saved value. - */ - asm("mrs %0, tpidr_el0" : "=r" (tls)); + tls = tpidr; + if (stack_start) { /* 16-byte aligned stack mandatory on AArch64 */ if (stack_start & 15) @@ -302,13 +324,14 @@ static void tls_thread_switch(struct task_struct *next) { unsigned long tpidr, tpidrro; - if (!is_compat_task()) { - asm("mrs %0, tpidr_el0" : "=r" (tpidr)); + asm("mrs %0, tpidr_el0" : "=r" (tpidr)); + if (is_compat_task()) + set_tp_compat(¤t->thread, tpidr); + else current->thread.tp_value = tpidr; - } if (is_compat_thread(task_thread_info(next))) { - tpidr = 0; + tpidr = get_tp_compat(&next->thread); tpidrro = next->thread.tp_value; } else { tpidr = next->thread.tp_value; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/