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Commit 912000e7 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Paul Mackerras
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[POWERPC] Allow ptrace write to pt_regs trap and orig_r3 



This patch allows a ptracer to write to the "trap" and "orig_r3" words
of the pt_regs.

This, along with a subsequent patch to the signal restart code, should
enable gdb to properly handle syscall restarting after executing a separate
function (at least when there's no restart block).

This patch also removes ptrace32.c code toying directly with the registers
and makes it use the ptrace_get/put_reg() accessors for everything so that
the logic for checking what is permitted is in only one place.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 1b6610d6

arch/powerpc/kernel/ptrace.c

+6 −3
Original line number Diff line number Diff line
@@ -75,10 +75,15 @@ int ptrace_put_reg(struct task_struct *task, int regno, unsigned long data) 
	if (task->thread.regs == NULL)

		return -EIO;



	if (regno <= PT_MAX_PUT_REG) {

	if (regno <= PT_MAX_PUT_REG || regno == PT_TRAP) {

		if (regno == PT_MSR)

			data = (data & MSR_DEBUGCHANGE)

				| (task->thread.regs->msr & ~MSR_DEBUGCHANGE);

		/* We prevent mucking around with the reserved area of trap

		 * which are used internally by the kernel

		 */

		if (regno == PT_TRAP)

			data &= 0xfff0;

		((unsigned long *)task->thread.regs)[regno] = data;

		return 0;

	}
@@ -409,8 +414,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data) 
			break;



		CHECK_FULL_REGS(child->thread.regs);

		if (index == PT_ORIG_R3)

			break;

		if (index < PT_FPR0) {

			ret = ptrace_put_reg(child, index, data);

		} else {

arch/powerpc/kernel/ptrace32.c

+14 −13
Original line number Diff line number Diff line
@@ -206,7 +206,9 @@ long compat_sys_ptrace(int request, int pid, unsigned long addr, 
		else

			part = 0;  /* want the 1st half of the register (left-most). */



		/* Validate the input - check to see if address is on the wrong boundary or beyond the end of the user area */

		/* Validate the input - check to see if address is on the wrong boundary

		 * or beyond the end of the user area

		 */

		if ((addr & 3) || numReg > PT_FPSCR)

			break;
@@ -270,8 +272,6 @@ long compat_sys_ptrace(int request, int pid, unsigned long addr, 
		if ((addr & 3) || (index > PT_FPSCR32))

			break;



		if (index == PT_ORIG_R3)

			break;

		if (index < PT_FPR0) {

			ret = ptrace_put_reg(child, index, data);

		} else {
@@ -302,24 +302,25 @@ long compat_sys_ptrace(int request, int pid, unsigned long addr, 
		/* Determine which register the user wants */

		index = (u64)addr >> 2;

		numReg = index / 2;



		/*

		 * Validate the input - check to see if address is on the

		 * wrong boundary or beyond the end of the user area

		 */

		if ((addr & 3) || (numReg > PT_FPSCR))

			break;

		/* Insure it is a register we let them change */

		if ((numReg == PT_ORIG_R3)

				|| ((numReg > PT_CCR) && (numReg < PT_FPR0)))

			break;

		if (numReg >= PT_FPR0) {

		if (numReg < PT_FPR0) {

			unsigned long freg = ptrace_get_reg(child, numReg);

			if (index % 2)

				freg = (freg & ~0xfffffffful) | (data & 0xfffffffful);

			else

				freg = (freg & 0xfffffffful) | (data << 32);

			ret = ptrace_put_reg(child, numReg, freg);

		} else {

			flush_fp_to_thread(child);

		}

		if (numReg == PT_MSR)

			data = (data & MSR_DEBUGCHANGE)

				| (child->thread.regs->msr & ~MSR_DEBUGCHANGE);

		((u32*)child->thread.regs)[index] = data;

			((unsigned int *)child->thread.regs)[index] = data;

			ret = 0;

		}

		break;

	}