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Commit 7122ec81 authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

x86: single_step: share code 



This removes the single-step code from ptrace_32.c and uses the step.c code
shared with the 64-bit kernel.  The two versions of the code were nearly
identical already, so the shared code has only a couple of simple #ifdef's.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5f76cb1f

arch/x86/kernel/Makefile_32

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ obj-y := process_32.o signal_32.o entry_32.o traps_32.o irq_32.o \ 
		quirks.o i8237.o topology.o alternative.o i8253.o tsc_32.o io_delay.o rtc.o



obj-y				+= tls.o

obj-y				+= step.o

obj-$(CONFIG_STACKTRACE)	+= stacktrace.o

obj-y				+= cpu/

obj-y				+= acpi/

arch/x86/kernel/ptrace_32.c

+0 −125
Original line number Diff line number Diff line
@@ -137,131 +137,6 @@ static unsigned long getreg(struct task_struct *child, 
	return retval;

}



#define LDT_SEGMENT 4



static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_regs *regs)

{

	unsigned long addr, seg;



	addr = regs->eip;

	seg = regs->xcs & 0xffff;

	if (regs->eflags & VM_MASK) {

		addr = (addr & 0xffff) + (seg << 4);

		return addr;

	}



	/*

	 * 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 inline int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)

{

	int i, copied;

	unsigned char opcode[15];

	unsigned long addr = convert_eip_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;

		/* 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 0xf0: case 0xf2: case 0xf3:

			continue;



		/*

		 * 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 = get_child_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 = get_child_regs(child);

		regs->eflags &= ~X86_EFLAGS_TF;

		child->ptrace &= ~PT_DTRACE;

	}

}



/*

 * Called by kernel/ptrace.c when detaching..

 *

arch/x86/kernel/step.c

+14 −0
Original line number Diff line number Diff line
@@ -5,12 +5,24 @@ 
#include <linux/mm.h>

#include <linux/ptrace.h>



#ifdef CONFIG_X86_32

static

#endif

unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs)

{

	unsigned long addr, seg;



#ifdef CONFIG_X86_64

	addr = regs->rip;

	seg = regs->cs & 0xffff;

#else

	addr = regs->eip;

	seg = regs->xcs & 0xffff;

	if (regs->eflags & X86_EFLAGS_VM) {

		addr = (addr & 0xffff) + (seg << 4);

		return addr;

	}

#endif



	/*

	 * We'll assume that the code segments in the GDT
@@ -69,12 +81,14 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs) 
		case 0xf0: case 0xf2: case 0xf3:

			continue;



#ifdef CONFIG_X86_64

		case 0x40 ... 0x4f:

			if (regs->cs != __USER_CS)

				/* 32-bit mode: register increment */

				return 0;

			/* 64-bit mode: REX prefix */

			continue;

#endif



			/* CHECKME: f2, f3 */