Commit fa1e03ea authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

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: 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 7f232343

arch/x86/kernel/Makefile_64

+2 −0
Original line number Diff line number Diff line
@@ -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/

arch/x86/kernel/ptrace_64.c

+0 −134
Original line number Diff line number Diff line
@@ -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..

 *

arch/x86/kernel/step.c

0 → 100644
+140 −0
Original line number Diff line number Diff line 
/*

 * 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;

	}

}

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