From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754503AbYIZSHx (ORCPT ); Fri, 26 Sep 2008 14:07:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753484AbYIZSGP (ORCPT ); Fri, 26 Sep 2008 14:06:15 -0400 Received: from mail.windriver.com ([147.11.1.11]:37244 "EHLO mail.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753455AbYIZSGO (ORCPT ); Fri, 26 Sep 2008 14:06:14 -0400 From: Jason Wessel To: torvalds@linux-foundation.org Cc: linux-kernel@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net Subject: [PATCH 2/5] kgdb, x86, arm, mips, powerpc: ignore user space single stepping Date: Fri, 26 Sep 2008 13:05:17 -0500 Message-Id: <1222452320-16281-3-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.0.90.g436ed.dirty In-Reply-To: <1222452320-16281-2-git-send-email-jason.wessel@windriver.com> References: <1222452320-16281-1-git-send-email-jason.wessel@windriver.com> <1222452320-16281-2-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 26 Sep 2008 18:05:36.0737 (UTC) FILETIME=[7A1ACD10:01C92002] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On the x86 arch, user space single step exceptions should be ignored if they occur in the kernel space, such as ptrace stepping through a system call. First check if it is kgdb that is executing a single step, then ensure it is not an accidental traversal into the user space, while in kgdb, any other time the TIF_SINGLESTEP is set, kgdb should ignore the exception. On x86, arm, mips and powerpc, the kgdb_contthread usage was inconsistent with the way single stepping is implemented in the kgdb core. The arch specific stub should always set the kgdb_cpu_doing_single_step correctly if it is single stepping. This allows kgdb to correctly process an instruction steps if ptrace happens to be requesting an instruction step over a system call. Signed-off-by: Jason Wessel --- arch/arm/kernel/kgdb.c | 2 -- arch/mips/kernel/kgdb.c | 3 +-- arch/powerpc/kernel/kgdb.c | 5 ++--- arch/x86/kernel/kgdb.c | 18 +++++++++++------- kernel/kgdb.c | 8 ++++---- 5 files changed, 18 insertions(+), 18 deletions(-) diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index aaffaec..ba8ccfe 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -111,8 +111,6 @@ int kgdb_arch_handle_exception(int exception_vector, int signo, case 'D': case 'k': case 'c': - kgdb_contthread = NULL; - /* * Try to read optional parameter, pc unchanged if no parm. * If this was a compiled breakpoint, we need to move diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index 8f6d58e..6e152c8 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -236,8 +236,7 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, atomic_set(&kgdb_cpu_doing_single_step, -1); if (remcom_in_buffer[0] == 's') - if (kgdb_contthread) - atomic_set(&kgdb_cpu_doing_single_step, cpu); + atomic_set(&kgdb_cpu_doing_single_step, cpu); return 0; } diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index b4fdf2f..fe8f71d 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -347,9 +347,8 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, linux_regs->msr |= MSR_SE; #endif kgdb_single_step = 1; - if (kgdb_contthread) - atomic_set(&kgdb_cpu_doing_single_step, - raw_smp_processor_id()); + atomic_set(&kgdb_cpu_doing_single_step, + raw_smp_processor_id()); } return 0; } diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index f47f0eb..00f7896 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -378,10 +378,8 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, if (remcomInBuffer[0] == 's') { linux_regs->flags |= X86_EFLAGS_TF; kgdb_single_step = 1; - if (kgdb_contthread) { - atomic_set(&kgdb_cpu_doing_single_step, - raw_smp_processor_id()); - } + atomic_set(&kgdb_cpu_doing_single_step, + raw_smp_processor_id()); } get_debugreg(dr6, 6); @@ -466,9 +464,15 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd) case DIE_DEBUG: if (atomic_read(&kgdb_cpu_doing_single_step) == - raw_smp_processor_id() && - user_mode(regs)) - return single_step_cont(regs, args); + raw_smp_processor_id()) { + if (user_mode(regs)) + return single_step_cont(regs, args); + break; + } else if (test_thread_flag(TIF_SINGLESTEP)) + /* This means a user thread is single stepping + * a system call which should be ignored + */ + return NOTIFY_DONE; /* fall through */ default: if (user_mode(regs)) diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 949806a..25d955d 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -1462,7 +1462,7 @@ acquirelock: * Get the passive CPU lock which will hold all the non-primary * CPU in a spin state while the debugger is active */ - if (!kgdb_single_step || !kgdb_contthread) { + if (!kgdb_single_step) { for (i = 0; i < NR_CPUS; i++) atomic_set(&passive_cpu_wait[i], 1); } @@ -1475,7 +1475,7 @@ acquirelock: #ifdef CONFIG_SMP /* Signal the other CPUs to enter kgdb_wait() */ - if ((!kgdb_single_step || !kgdb_contthread) && kgdb_do_roundup) + if ((!kgdb_single_step) && kgdb_do_roundup) kgdb_roundup_cpus(flags); #endif @@ -1494,7 +1494,7 @@ acquirelock: kgdb_post_primary_code(ks->linux_regs, ks->ex_vector, ks->err_code); kgdb_deactivate_sw_breakpoints(); kgdb_single_step = 0; - kgdb_contthread = NULL; + kgdb_contthread = current; exception_level = 0; /* Talk to debugger with gdbserial protocol */ @@ -1508,7 +1508,7 @@ acquirelock: kgdb_info[ks->cpu].task = NULL; atomic_set(&cpu_in_kgdb[ks->cpu], 0); - if (!kgdb_single_step || !kgdb_contthread) { + if (!kgdb_single_step) { for (i = NR_CPUS-1; i >= 0; i--) atomic_set(&passive_cpu_wait[i], 0); /* -- 1.6.0.90.g436ed.dirty