Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757809AbXKYWAp (ORCPT ); Sun, 25 Nov 2007 17:00:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757366AbXKYWAR (ORCPT ); Sun, 25 Nov 2007 17:00:17 -0500 Received: from mx1.redhat.com ([66.187.233.31]:59993 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756358AbXKYWAO (ORCPT ); Sun, 25 Nov 2007 17:00:14 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Andrew Morton , Linus Torvalds Cc: linux-kernel@vger.kernel.org X-Fcc: ~/Mail/linus Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Subject: [PATCH 05/27] x86: single_step moved In-Reply-To: Roland McGrath's message of Sunday, 25 November 2007 13:55:07 -0800 <20071125215507.4B89226F8C5@magilla.localdomain> References: <20071125215507.4B89226F8C5@magilla.localdomain> X-Shopping-List: (1) Heretical gold baskets (2) Political lieutenant sycophants (3) Pernicious skeptical detectors (4) Serious nutrition friction Message-Id: <20071125215939.3EA2826F8C5@magilla.localdomain> Date: Sun, 25 Nov 2007 13:59:39 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8312 Lines: 321 This moves the single-step support code from ptrace_64.c into a new file step.c, verbatim. This paves the way for consolidating this code between 64-bit and 32-bit versions. Signed-off-by: Roland McGrath --- arch/x86/kernel/Makefile_64 | 2 + arch/x86/kernel/ptrace_64.c | 134 ----------------------------------------- arch/x86/kernel/step.c | 140 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 142 insertions(+), 134 deletions(-) diff --git a/arch/x86/kernel/Makefile_64 b/arch/x86/kernel/Makefile_64 index 203a9d8..d35ee6f 100644 --- a/arch/x86/kernel/Makefile_64 +++ b/arch/x86/kernel/Makefile_64 @@ -13,6 +13,8 @@ obj-y := process_64.o signal_64.o entry_64.o traps_64.o irq_64.o \ pci-dma_64.o pci-nommu_64.o alternative.o hpet.o tsc_64.o bugs_64.o \ i8253.o +obj-y += step.o + obj-$(CONFIG_IA32_EMULATION) += tls.o obj-$(CONFIG_STACKTRACE) += stacktrace.o diff --git a/arch/x86/kernel/ptrace_64.c b/arch/x86/kernel/ptrace_64.c index c2e1a13..52479b1 100644 --- a/arch/x86/kernel/ptrace_64.c +++ b/arch/x86/kernel/ptrace_64.c @@ -80,140 +80,6 @@ static inline long put_stack_long(struct task_struct *task, int offset, return 0; } -#define LDT_SEGMENT 4 - -unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs) -{ - unsigned long addr, seg; - - addr = regs->rip; - seg = regs->cs & 0xffff; - - /* - * We'll assume that the code segments in the GDT - * are all zero-based. That is largely true: the - * TLS segments are used for data, and the PNPBIOS - * and APM bios ones we just ignore here. - */ - if (seg & LDT_SEGMENT) { - u32 *desc; - unsigned long base; - - seg &= ~7UL; - - mutex_lock(&child->mm->context.lock); - if (unlikely((seg >> 3) >= child->mm->context.size)) - addr = -1L; /* bogus selector, access would fault */ - else { - desc = child->mm->context.ldt + seg; - base = ((desc[0] >> 16) | - ((desc[1] & 0xff) << 16) | - (desc[1] & 0xff000000)); - - /* 16-bit code segment? */ - if (!((desc[1] >> 22) & 1)) - addr &= 0xffff; - addr += base; - } - mutex_unlock(&child->mm->context.lock); - } - - return addr; -} - -static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs) -{ - int i, copied; - unsigned char opcode[15]; - unsigned long addr = convert_rip_to_linear(child, regs); - - copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); - for (i = 0; i < copied; i++) { - switch (opcode[i]) { - /* popf and iret */ - case 0x9d: case 0xcf: - return 1; - - /* CHECKME: 64 65 */ - - /* opcode and address size prefixes */ - case 0x66: case 0x67: - continue; - /* irrelevant prefixes (segment overrides and repeats) */ - case 0x26: case 0x2e: - case 0x36: case 0x3e: - case 0x64: case 0x65: - case 0xf2: case 0xf3: - continue; - - case 0x40 ... 0x4f: - if (regs->cs != __USER_CS) - /* 32-bit mode: register increment */ - return 0; - /* 64-bit mode: REX prefix */ - continue; - - /* CHECKME: f2, f3 */ - - /* - * pushf: NOTE! We should probably not let - * the user see the TF bit being set. But - * it's more pain than it's worth to avoid - * it, and a debugger could emulate this - * all in user space if it _really_ cares. - */ - case 0x9c: - default: - return 0; - } - } - return 0; -} - -void user_enable_single_step(struct task_struct *child) -{ - struct pt_regs *regs = task_pt_regs(child); - - /* - * Always set TIF_SINGLESTEP - this guarantees that - * we single-step system calls etc.. This will also - * cause us to set TF when returning to user mode. - */ - set_tsk_thread_flag(child, TIF_SINGLESTEP); - - /* - * If TF was already set, don't do anything else - */ - if (regs->eflags & X86_EFLAGS_TF) - return; - - /* Set TF on the kernel stack.. */ - regs->eflags |= X86_EFLAGS_TF; - - /* - * ..but if TF is changed by the instruction we will trace, - * don't mark it as being "us" that set it, so that we - * won't clear it by hand later. - */ - if (is_setting_trap_flag(child, regs)) - return; - - child->ptrace |= PT_DTRACE; -} - -void user_disable_single_step(struct task_struct *child) -{ - /* Always clear TIF_SINGLESTEP... */ - clear_tsk_thread_flag(child, TIF_SINGLESTEP); - - /* But touch TF only if it was set by us.. */ - if (child->ptrace & PT_DTRACE) { - struct pt_regs *regs = task_pt_regs(child); - regs->eflags &= ~X86_EFLAGS_TF; - child->ptrace &= ~PT_DTRACE; - } -} - /* * Called by kernel/ptrace.c when detaching.. * diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c new file mode 100644 index 0000000..cb3c8bc --- /dev/null +++ b/arch/x86/kernel/step.c @@ -0,0 +1,140 @@ +/* + * x86 single-step support code, common to 32-bit and 64-bit. + */ +#include +#include +#include + +#define LDT_SEGMENT 4 + +unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs) +{ + unsigned long addr, seg; + + addr = regs->rip; + seg = regs->cs & 0xffff; + + /* + * We'll assume that the code segments in the GDT + * are all zero-based. That is largely true: the + * TLS segments are used for data, and the PNPBIOS + * and APM bios ones we just ignore here. + */ + if (seg & LDT_SEGMENT) { + u32 *desc; + unsigned long base; + + seg &= ~7UL; + + mutex_lock(&child->mm->context.lock); + if (unlikely((seg >> 3) >= child->mm->context.size)) + addr = -1L; /* bogus selector, access would fault */ + else { + desc = child->mm->context.ldt + seg; + base = ((desc[0] >> 16) | + ((desc[1] & 0xff) << 16) | + (desc[1] & 0xff000000)); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + } + mutex_unlock(&child->mm->context.lock); + } + + return addr; +} + +static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs) +{ + int i, copied; + unsigned char opcode[15]; + unsigned long addr = convert_rip_to_linear(child, regs); + + copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); + for (i = 0; i < copied; i++) { + switch (opcode[i]) { + /* popf and iret */ + case 0x9d: case 0xcf: + return 1; + + /* CHECKME: 64 65 */ + + /* opcode and address size prefixes */ + case 0x66: case 0x67: + continue; + /* irrelevant prefixes (segment overrides and repeats) */ + case 0x26: case 0x2e: + case 0x36: case 0x3e: + case 0x64: case 0x65: + case 0xf2: case 0xf3: + continue; + + case 0x40 ... 0x4f: + if (regs->cs != __USER_CS) + /* 32-bit mode: register increment */ + return 0; + /* 64-bit mode: REX prefix */ + continue; + + /* CHECKME: f2, f3 */ + + /* + * pushf: NOTE! We should probably not let + * the user see the TF bit being set. But + * it's more pain than it's worth to avoid + * it, and a debugger could emulate this + * all in user space if it _really_ cares. + */ + case 0x9c: + default: + return 0; + } + } + return 0; +} + +void user_enable_single_step(struct task_struct *child) +{ + struct pt_regs *regs = task_pt_regs(child); + + /* + * Always set TIF_SINGLESTEP - this guarantees that + * we single-step system calls etc.. This will also + * cause us to set TF when returning to user mode. + */ + set_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* + * If TF was already set, don't do anything else + */ + if (regs->eflags & X86_EFLAGS_TF) + return; + + /* Set TF on the kernel stack.. */ + regs->eflags |= X86_EFLAGS_TF; + + /* + * ..but if TF is changed by the instruction we will trace, + * don't mark it as being "us" that set it, so that we + * won't clear it by hand later. + */ + if (is_setting_trap_flag(child, regs)) + return; + + child->ptrace |= PT_DTRACE; +} + +void user_disable_single_step(struct task_struct *child) +{ + /* Always clear TIF_SINGLESTEP... */ + clear_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* But touch TF only if it was set by us.. */ + if (child->ptrace & PT_DTRACE) { + struct pt_regs *regs = task_pt_regs(child); + regs->eflags &= ~X86_EFLAGS_TF; + child->ptrace &= ~PT_DTRACE; + } +} - 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/