Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756909Ab3DWWme (ORCPT ); Tue, 23 Apr 2013 18:42:34 -0400 Received: from moutng.kundenserver.de ([212.227.126.187]:51561 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756477Ab3DWWmc (ORCPT ); Tue, 23 Apr 2013 18:42:32 -0400 Message-ID: <51770E4E.2040003@dawncrow.de> Date: Wed, 24 Apr 2013 00:42:22 +0200 From: =?ISO-8859-1?Q?Andr=E9_Hentschel?= User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Will Deacon CC: Russell King - ARM Linux , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCHv2] arm: Preserve TPIDRURW on context switch References: <517168BB.3070903@dawncrow.de> <20130422143616.GP14496@n2100.arm.linux.org.uk> <20130422151836.GA15665@mudshark.cambridge.arm.com> <5175A697.3080308@dawncrow.de> <20130423091536.GB17593@mudshark.cambridge.arm.com> In-Reply-To: <20130423091536.GB17593@mudshark.cambridge.arm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Provags-ID: V02:K0:g/AwBd7Mf9qxhry/6yVJQ9emKnGErp8ZHsSV6J2BSkE 1oT6jVcXnn8gjIBpEfe2S7YNCmbQPEXX5nSDIdCzIqjDasx5Zu tGYJDt3E4TQGSj0Mj3YlZ9OIt3ZKpMVIuo3Gbytl1YfB1/uU71 eJNwvJR+oWA8DxDXc7Mni2oKlIcdD5XMrg5kJKXAImyE/EJ+ol gbFcUHrw2ElBlIMz8V/Gm3uEh1KR+FzZt9zLm7YXHPZbIzsrSa bKXfbg+Vr4p//aq1LFLgNtcaA39e13MEhCcUHiN1NWn6mquYgu ZLEoh53gwxHAM8lLbHY2xUPCQG1Etwt8jhH0WW9VLhNIanU6Cv s5QQkJa2EeTvJp8nnIug= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7666 Lines: 221 Am 23.04.2013 11:15, schrieb Will Deacon: > On Mon, Apr 22, 2013 at 10:07:35PM +0100, Andr? Hentschel wrote: >> Am 22.04.2013 17:18, schrieb Will Deacon: >>> On Mon, Apr 22, 2013 at 03:36:16PM +0100, Russell King - ARM Linux wrote: >>>> On Fri, Apr 19, 2013 at 05:54:35PM +0200, Andr? Hentschel wrote: >>>>> From: =?UTF-8?q?Andr=C3=A9=20Hentschel?= >>>>> >>>>> There are more and more applications coming to WinRT, Wine could support them, >>>>> but mostly they expect to have the thread environment block (TEB) in TPIDRURW. >>>>> This register must be preserved per thread instead of being cleared. >>>>> >>>>> Signed-off-by: Andr? Hentschel >>>> >>>> This actually makes things less efficient all round, because you >>>> now use the value immediately after loading, which means it will cause >>>> pipeline stalls, certainly on older CPUs. >>>> >>>> Could you please rework the patch to try avoiding soo many modifications >>>> to the way things have been done here? >>> >>> copy_thread also needs updating so that the *register* value for the parent >>> is copied to the child, since the parent may have written the register >>> after the last context-switch, meaning that tp_value is out-of-date. >> >> Thank you both for reviewing. >> >> I guess you mostly mean "ldr r6, [r2, #TI_CPU_DOMAIN]". >> I just thought about old CPUs and remembered again that we at Wine >> need that patch only on v7 (and later). So is it ok to introduce a set_tls_v7 >> in tls.h and make use of CONFIG_CPU_V7 compile-time check in >> the changed files and in the copy_thread function? > > No, we should support this feature on any CPU with the TPIDRURW register, > otherwise it's going to get really confusing for userspace. Sure, remembered that today. >> Do i need any further flag checks in copy_thread or can i use the >> compile-time check to add unconditional code? > > You could introduce `get' tls functions, which don't do anything for CPUs > without the relevant registers. Before i have another round of testing and patch formatting/sending, what about the untested patch below? diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index cddda1f..bb5b48d 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -58,7 +58,7 @@ struct thread_info { struct cpu_context_save cpu_context; /* cpu context */ __u32 syscall; /* syscall number */ __u8 used_cp[16]; /* thread used copro */ - unsigned long tp_value; + unsigned long tp_value[2]; #ifdef CONFIG_CRUNCH struct crunch_state crunchstate; #endif diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h index 73409e6..1c10163 100644 --- a/arch/arm/include/asm/tls.h +++ b/arch/arm/include/asm/tls.h @@ -2,13 +2,30 @@ #define __ASMARM_TLS_H #ifdef __ASSEMBLY__ + .macro get_tls2_none, tp, tmp1 + .endm + + .macro get_tls2_v6k, tp, tmp1 + mrc p15, 0, \tmp1, c13, c0, 2 @ get user r/w TLS register + str \tmp1, [\tp, #4] + .endm + + .macro get_tls2_v6, tp, tmp1 + ldr \tmp1, =elf_hwcap + ldr \tmp1, [\tmp1, #0] + tst \tmp1, #HWCAP_TLS @ hardware TLS available? + mrcne p15, 0, \tmp1, c13, c0, 2 @ get user r/w TLS register + strne \tmp1, [\tp, #4] + .endm + + .macro set_tls_none, tp, tmp1, tmp2 .endm .macro set_tls_v6k, tp, tmp1, tmp2 - mcr p15, 0, \tp, c13, c0, 3 @ set TLS register - mov \tmp1, #0 - mcr p15, 0, \tmp1, c13, c0, 2 @ clear user r/w TLS register + ldrd \tmp1, \tmp2, [\tp] + mcr p15, 0, \tmp1, c13, c0, 3 @ set user r/o TLS register + mcr p15, 0, \tmp2, c13, c0, 2 @ set user r/w TLS register .endm .macro set_tls_v6, tp, tmp1, tmp2 @@ -16,33 +33,39 @@ ldr \tmp1, [\tmp1, #0] mov \tmp2, #0xffff0fff tst \tmp1, #HWCAP_TLS @ hardware TLS available? - mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register - movne \tmp1, #0 - mcrne p15, 0, \tmp1, c13, c0, 2 @ clear user r/w TLS register - streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0 + ldrdne \tmp1, \tmp2, [\tp] + ldreq \tmp1, [\tp] + mcrne p15, 0, \tmp1, c13, c0, 3 @ yes, set user r/o TLS register + mcrne p15, 0, \tmp2, c13, c0, 2 @ set user r/w TLS register + streq \tmp1, [\tmp2, #-15] @ set TLS value at 0xffff0ff0 .endm .macro set_tls_software, tp, tmp1, tmp2 - mov \tmp1, #0xffff0fff - str \tp, [\tmp1, #-15] @ set TLS value at 0xffff0ff0 + ldr \tmp1, [\tp] + mov \tmp2, #0xffff0fff + str \tmp1, [\tmp2, #-15] @ set TLS value at 0xffff0ff0 .endm #endif #ifdef CONFIG_TLS_REG_EMUL #define tls_emu 1 #define has_tls_reg 1 +#define get_tls2 get_tls2_none #define set_tls set_tls_none #elif defined(CONFIG_CPU_V6) #define tls_emu 0 #define has_tls_reg (elf_hwcap & HWCAP_TLS) +#define get_tls2 get_tls2_v6 #define set_tls set_tls_v6 #elif defined(CONFIG_CPU_32v6K) #define tls_emu 0 #define has_tls_reg 1 +#define get_tls2 get_tls2_v6k #define set_tls set_tls_v6k #else #define tls_emu 0 #define has_tls_reg 0 +#define get_tls2 get_tls2_none #define set_tls set_tls_software #endif diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 0f82098..097686b 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -728,7 +728,7 @@ ENTRY(__switch_to) UNWIND(.fnstart ) UNWIND(.cantunwind ) add ip, r1, #TI_CPU_SAVE - ldr r3, [r2, #TI_TP_VALUE] + add r3, r1, #TI_TP_VALUE ARM( stmia ip!, {r4 - sl, fp, sp, lr} ) @ Store most regs on stack THUMB( stmia ip!, {r4 - sl, fp} ) @ Store most regs on stack THUMB( str sp, [ip], #4 ) @@ -736,6 +736,8 @@ ENTRY(__switch_to) #ifdef CONFIG_CPU_USE_DOMAINS ldr r6, [r2, #TI_CPU_DOMAIN] #endif + get_tls2 r3, r4 + add r3, r2, #TI_TP_VALUE set_tls r3, r4, r5 #if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) ldr r7, [r2, #TI_TASK] diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 047d3e4..6138eb1 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -395,7 +395,8 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start, clear_ptrace_hw_breakpoint(p); if (clone_flags & CLONE_SETTLS) - thread->tp_value = childregs->ARM_r3; + thread->tp_value[0] = childregs->ARM_r3; + thread->tp_value[1] = current_thread_info()->tp_value[1]; thread_notify(THREAD_NOTIFY_COPY, thread); diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index 03deeff..2bc1514 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -849,7 +849,7 @@ long arch_ptrace(struct task_struct *child, long request, #endif case PTRACE_GET_THREAD_AREA: - ret = put_user(task_thread_info(child)->tp_value, + ret = put_user(task_thread_info(child)->tp_value[0], datap); break; diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index 1c08911..f9d6259 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -588,7 +588,7 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs) return regs->ARM_r0; case NR(set_tls): - thread->tp_value = regs->ARM_r0; + thread->tp_value[0] = regs->ARM_r0; if (tls_emu) return 0; if (has_tls_reg) { @@ -706,7 +706,7 @@ static int get_tp_trap(struct pt_regs *regs, unsigned int instr) int reg = (instr >> 12) & 15; if (reg == 15) return 1; - regs->uregs[reg] = current_thread_info()->tp_value; + regs->uregs[reg] = current_thread_info()->tp_value[0]; regs->ARM_pc += 4; return 0; } -- 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/