From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751709AbbAMIfY (ORCPT ); Tue, 13 Jan 2015 03:35:24 -0500 Received: from mail-wi0-f174.google.com ([209.85.212.174]:43669 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751592AbbAMIfW (ORCPT ); Tue, 13 Jan 2015 03:35:22 -0500 MIME-Version: 1.0 In-Reply-To: <20150112183955.GO13360@arm.com> References: <1420986751-30364-1-git-send-email-r.peniaev@gmail.com> <1420986751-30364-2-git-send-email-r.peniaev@gmail.com> <20150112183955.GO13360@arm.com> Date: Tue, 13 Jan 2015 17:35:20 +0900 Message-ID: Subject: Re: [PATCH 1/2] ARM: entry-common: fix forgotten set of thread_info->syscall From: Roman Peniaev To: Will Deacon Cc: Russell King , Stefano Stabellini , Marc Zyngier , Catalin Marinas , Sekhar Nori , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "stable@vger.kernel.org" , Christoffer Dall Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 13, 2015 at 3:39 AM, Will Deacon wrote: > On Sun, Jan 11, 2015 at 02:32:30PM +0000, Roman Pen wrote: >> thread_info->syscall is used only for ptrace, but syscall number >> is also used by syscall_get_nr and returned to userspace by the >> following proc file access: >> >> $ cat /proc/self/syscall >> 0 0x3 0xbe928bd8 0x1000 0x0 0xac9e0 0x3 0xbe928bb4 0xb6f5dfbc >> ^ >> The first number is the syscall number, currently it is zero. >> Patch fixes this: >> >> $ cat /proc/self/syscall >> 3 0x3 0xbefc7bd8 0x1000 0x0 0xac9e0 0x3 0xbefc7bb4 0xb6e82fbc >> ^ >> Right, read syscall > > Yes, it seems that despite requiring CONFIG_HAVE_ARCH_TRACEHOOK, > the /proc code requires syscall_get_nr to work regardless of > TIF_SYSCALL_TRACE. > >> Signed-off-by: Roman Pen >> Cc: Russell King >> Cc: Marc Zyngier >> Cc: Catalin Marinas >> Cc: Christoffer Dall >> Cc: Stefano Stabellini >> Cc: Sekhar Nori >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Cc: stable@vger.kernel.org >> --- >> arch/arm/kernel/asm-offsets.c | 1 + >> arch/arm/kernel/entry-common.S | 1 + >> 2 files changed, 2 insertions(+) >> >> diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c >> index 2d2d608..6911bad 100644 >> --- a/arch/arm/kernel/asm-offsets.c >> +++ b/arch/arm/kernel/asm-offsets.c >> @@ -70,6 +70,7 @@ int main(void) >> DEFINE(TI_CPU, offsetof(struct thread_info, cpu)); >> DEFINE(TI_CPU_DOMAIN, offsetof(struct thread_info, cpu_domain)); >> DEFINE(TI_CPU_SAVE, offsetof(struct thread_info, cpu_context)); >> + DEFINE(TI_SYSCALL, offsetof(struct thread_info, syscall)); >> DEFINE(TI_USED_CP, offsetof(struct thread_info, used_cp)); >> DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value)); >> DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate)); >> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S >> index f8ccc21..89452ff 100644 >> --- a/arch/arm/kernel/entry-common.S >> +++ b/arch/arm/kernel/entry-common.S >> @@ -189,6 +189,7 @@ ENTRY(vector_swi) >> #endif >> >> local_restart: >> + str scno, [tsk, #TI_SYSCALL] @ set syscall number >> ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing >> stmdb sp!, {r4, r5} @ push fifth and sixth args > > Do we definitely want to update scno on syscall restarting? Good question. First thing to mention is __sys_trace will trace 'restart_syscall', not the real syscall we are going to restart. E.g. in test application we do infinite poll and then send STOP and CONT to this app: test-243 [002] ...1 1792.067726: sys_enter: NR 168 (0, 0, ffffffff, 0, 0, 0) test-243 [002] ...1 1802.299073: sys_exit: NR 168 = -516 test-243 [004] ...1 1814.716264: sys_enter: NR 0 (0, 0, ffffffff, 0, 0, 0) test-243 [004] ...1 2183.687225: sys_exit: NR 0 = -516 the poll was restarted and trace shows that we are in restart_syscall. Is that expected? And the second thing is that my next patch did some tweaks in 'syscall_trace_enter', where we take scno not from param we passed, but from thread_info->syscall we previously set. So, regarding your question, if I set scno only once - I will break previous behavior, and __sys_trace will trace the syscall we restarted. And I think this is what we need, because according to the 'syscall_trace_enter' code we do 'secure_computing' and 'audit_syscall_entry', which definitely expect original syscall, not the 'restart_syscall'. -- Roman From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 In-Reply-To: <20150112183955.GO13360@arm.com> References: <1420986751-30364-1-git-send-email-r.peniaev@gmail.com> <1420986751-30364-2-git-send-email-r.peniaev@gmail.com> <20150112183955.GO13360@arm.com> Date: Tue, 13 Jan 2015 17:35:20 +0900 Message-ID: Subject: Re: [PATCH 1/2] ARM: entry-common: fix forgotten set of thread_info->syscall From: Roman Peniaev To: Will Deacon Cc: Russell King , Stefano Stabellini , Marc Zyngier , Catalin Marinas , Sekhar Nori , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "stable@vger.kernel.org" , Christoffer Dall Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: On Tue, Jan 13, 2015 at 3:39 AM, Will Deacon wrote: > On Sun, Jan 11, 2015 at 02:32:30PM +0000, Roman Pen wrote: >> thread_info->syscall is used only for ptrace, but syscall number >> is also used by syscall_get_nr and returned to userspace by the >> following proc file access: >> >> $ cat /proc/self/syscall >> 0 0x3 0xbe928bd8 0x1000 0x0 0xac9e0 0x3 0xbe928bb4 0xb6f5dfbc >> ^ >> The first number is the syscall number, currently it is zero. >> Patch fixes this: >> >> $ cat /proc/self/syscall >> 3 0x3 0xbefc7bd8 0x1000 0x0 0xac9e0 0x3 0xbefc7bb4 0xb6e82fbc >> ^ >> Right, read syscall > > Yes, it seems that despite requiring CONFIG_HAVE_ARCH_TRACEHOOK, > the /proc code requires syscall_get_nr to work regardless of > TIF_SYSCALL_TRACE. > >> Signed-off-by: Roman Pen >> Cc: Russell King >> Cc: Marc Zyngier >> Cc: Catalin Marinas >> Cc: Christoffer Dall >> Cc: Stefano Stabellini >> Cc: Sekhar Nori >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Cc: stable@vger.kernel.org >> --- >> arch/arm/kernel/asm-offsets.c | 1 + >> arch/arm/kernel/entry-common.S | 1 + >> 2 files changed, 2 insertions(+) >> >> diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c >> index 2d2d608..6911bad 100644 >> --- a/arch/arm/kernel/asm-offsets.c >> +++ b/arch/arm/kernel/asm-offsets.c >> @@ -70,6 +70,7 @@ int main(void) >> DEFINE(TI_CPU, offsetof(struct thread_info, cpu)); >> DEFINE(TI_CPU_DOMAIN, offsetof(struct thread_info, cpu_domain)); >> DEFINE(TI_CPU_SAVE, offsetof(struct thread_info, cpu_context)); >> + DEFINE(TI_SYSCALL, offsetof(struct thread_info, syscall)); >> DEFINE(TI_USED_CP, offsetof(struct thread_info, used_cp)); >> DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value)); >> DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate)); >> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S >> index f8ccc21..89452ff 100644 >> --- a/arch/arm/kernel/entry-common.S >> +++ b/arch/arm/kernel/entry-common.S >> @@ -189,6 +189,7 @@ ENTRY(vector_swi) >> #endif >> >> local_restart: >> + str scno, [tsk, #TI_SYSCALL] @ set syscall number >> ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing >> stmdb sp!, {r4, r5} @ push fifth and sixth args > > Do we definitely want to update scno on syscall restarting? Good question. First thing to mention is __sys_trace will trace 'restart_syscall', not the real syscall we are going to restart. E.g. in test application we do infinite poll and then send STOP and CONT to this app: test-243 [002] ...1 1792.067726: sys_enter: NR 168 (0, 0, ffffffff, 0, 0, 0) test-243 [002] ...1 1802.299073: sys_exit: NR 168 = -516 test-243 [004] ...1 1814.716264: sys_enter: NR 0 (0, 0, ffffffff, 0, 0, 0) test-243 [004] ...1 2183.687225: sys_exit: NR 0 = -516 the poll was restarted and trace shows that we are in restart_syscall. Is that expected? And the second thing is that my next patch did some tweaks in 'syscall_trace_enter', where we take scno not from param we passed, but from thread_info->syscall we previously set. So, regarding your question, if I set scno only once - I will break previous behavior, and __sys_trace will trace the syscall we restarted. And I think this is what we need, because according to the 'syscall_trace_enter' code we do 'secure_computing' and 'audit_syscall_entry', which definitely expect original syscall, not the 'restart_syscall'. -- Roman From mboxrd@z Thu Jan 1 00:00:00 1970 From: r.peniaev@gmail.com (Roman Peniaev) Date: Tue, 13 Jan 2015 17:35:20 +0900 Subject: [PATCH 1/2] ARM: entry-common: fix forgotten set of thread_info->syscall In-Reply-To: <20150112183955.GO13360@arm.com> References: <1420986751-30364-1-git-send-email-r.peniaev@gmail.com> <1420986751-30364-2-git-send-email-r.peniaev@gmail.com> <20150112183955.GO13360@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Jan 13, 2015 at 3:39 AM, Will Deacon wrote: > On Sun, Jan 11, 2015 at 02:32:30PM +0000, Roman Pen wrote: >> thread_info->syscall is used only for ptrace, but syscall number >> is also used by syscall_get_nr and returned to userspace by the >> following proc file access: >> >> $ cat /proc/self/syscall >> 0 0x3 0xbe928bd8 0x1000 0x0 0xac9e0 0x3 0xbe928bb4 0xb6f5dfbc >> ^ >> The first number is the syscall number, currently it is zero. >> Patch fixes this: >> >> $ cat /proc/self/syscall >> 3 0x3 0xbefc7bd8 0x1000 0x0 0xac9e0 0x3 0xbefc7bb4 0xb6e82fbc >> ^ >> Right, read syscall > > Yes, it seems that despite requiring CONFIG_HAVE_ARCH_TRACEHOOK, > the /proc code requires syscall_get_nr to work regardless of > TIF_SYSCALL_TRACE. > >> Signed-off-by: Roman Pen >> Cc: Russell King >> Cc: Marc Zyngier >> Cc: Catalin Marinas >> Cc: Christoffer Dall >> Cc: Stefano Stabellini >> Cc: Sekhar Nori >> Cc: linux-arm-kernel at lists.infradead.org >> Cc: linux-kernel at vger.kernel.org >> Cc: stable at vger.kernel.org >> --- >> arch/arm/kernel/asm-offsets.c | 1 + >> arch/arm/kernel/entry-common.S | 1 + >> 2 files changed, 2 insertions(+) >> >> diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c >> index 2d2d608..6911bad 100644 >> --- a/arch/arm/kernel/asm-offsets.c >> +++ b/arch/arm/kernel/asm-offsets.c >> @@ -70,6 +70,7 @@ int main(void) >> DEFINE(TI_CPU, offsetof(struct thread_info, cpu)); >> DEFINE(TI_CPU_DOMAIN, offsetof(struct thread_info, cpu_domain)); >> DEFINE(TI_CPU_SAVE, offsetof(struct thread_info, cpu_context)); >> + DEFINE(TI_SYSCALL, offsetof(struct thread_info, syscall)); >> DEFINE(TI_USED_CP, offsetof(struct thread_info, used_cp)); >> DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value)); >> DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate)); >> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S >> index f8ccc21..89452ff 100644 >> --- a/arch/arm/kernel/entry-common.S >> +++ b/arch/arm/kernel/entry-common.S >> @@ -189,6 +189,7 @@ ENTRY(vector_swi) >> #endif >> >> local_restart: >> + str scno, [tsk, #TI_SYSCALL] @ set syscall number >> ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing >> stmdb sp!, {r4, r5} @ push fifth and sixth args > > Do we definitely want to update scno on syscall restarting? Good question. First thing to mention is __sys_trace will trace 'restart_syscall', not the real syscall we are going to restart. E.g. in test application we do infinite poll and then send STOP and CONT to this app: test-243 [002] ...1 1792.067726: sys_enter: NR 168 (0, 0, ffffffff, 0, 0, 0) test-243 [002] ...1 1802.299073: sys_exit: NR 168 = -516 test-243 [004] ...1 1814.716264: sys_enter: NR 0 (0, 0, ffffffff, 0, 0, 0) test-243 [004] ...1 2183.687225: sys_exit: NR 0 = -516 the poll was restarted and trace shows that we are in restart_syscall. Is that expected? And the second thing is that my next patch did some tweaks in 'syscall_trace_enter', where we take scno not from param we passed, but from thread_info->syscall we previously set. So, regarding your question, if I set scno only once - I will break previous behavior, and __sys_trace will trace the syscall we restarted. And I think this is what we need, because according to the 'syscall_trace_enter' code we do 'secure_computing' and 'audit_syscall_entry', which definitely expect original syscall, not the 'restart_syscall'. -- Roman