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x86: single_step moved 

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 <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Roland McGrath 2008-01-30 13:30:50 +01:00 committed by Ingo Molnar
parent 7f232343e0
commit fa1e03eae2
3 changed files with 142 additions and 134 deletions
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2
arch/x86/kernel/Makefile_64
View File

@ -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 io_delay.o rtc.o
obj-y += step.o
obj-$(CONFIG_IA32_EMULATION) += tls.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += cpu/

134
arch/x86/kernel/ptrace_64.c
View File

@ -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..
*

140
arch/x86/kernel/step.c Normal file
View File

@ -0,0 +1,140 @@
/*
* x86 single-step support code, common to 32-bit and 64-bit.
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#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;
}
}