static int __poke_user()

in kernel/ptrace.c [329:423]

• 51 lines of code
• 20 McCabe index (conditional complexity)

static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
{
	struct user *dummy = NULL;
	addr_t offset;


	if (addr < (addr_t) &dummy->regs.acrs) {
		struct pt_regs *regs = task_pt_regs(child);
		/*
		 * psw and gprs are stored on the stack
		 */
		if (addr == (addr_t) &dummy->regs.psw.mask) {
			unsigned long mask = PSW_MASK_USER;

			mask |= is_ri_task(child) ? PSW_MASK_RI : 0;
			if ((data ^ PSW_USER_BITS) & ~mask)
				/* Invalid psw mask. */
				return -EINVAL;
			if ((data & PSW_MASK_ASC) == PSW_ASC_HOME)
				/* Invalid address-space-control bits */
				return -EINVAL;
			if ((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))
				/* Invalid addressing mode bits */
				return -EINVAL;
		}

		if (test_pt_regs_flag(regs, PIF_SYSCALL) &&
			addr == offsetof(struct user, regs.gprs[2])) {
			struct pt_regs *regs = task_pt_regs(child);

			regs->int_code = 0x20000 | (data & 0xffff);
		}
		*(addr_t *)((addr_t) &regs->psw + addr) = data;
	} else if (addr < (addr_t) (&dummy->regs.orig_gpr2)) {
		/*
		 * access registers are stored in the thread structure
		 */
		offset = addr - (addr_t) &dummy->regs.acrs;
		/*
		 * Very special case: old & broken 64 bit gdb writing
		 * to acrs[15] with a 64 bit value. Ignore the lower
		 * half of the value and write the upper 32 bit to
		 * acrs[15]. Sick...
		 */
		if (addr == (addr_t) &dummy->regs.acrs[15])
			child->thread.acrs[15] = (unsigned int) (data >> 32);
		else
			*(addr_t *)((addr_t) &child->thread.acrs + offset) = data;

	} else if (addr == (addr_t) &dummy->regs.orig_gpr2) {
		/*
		 * orig_gpr2 is stored on the kernel stack
		 */
		task_pt_regs(child)->orig_gpr2 = data;

	} else if (addr < (addr_t) &dummy->regs.fp_regs) {
		/*
		 * prevent writes of padding hole between
		 * orig_gpr2 and fp_regs on s390.
		 */
		return 0;

	} else if (addr == (addr_t) &dummy->regs.fp_regs.fpc) {
		/*
		 * floating point control reg. is in the thread structure
		 */
		if ((unsigned int) data != 0 ||
		    test_fp_ctl(data >> (BITS_PER_LONG - 32)))
			return -EINVAL;
		child->thread.fpu.fpc = data >> (BITS_PER_LONG - 32);

	} else if (addr < (addr_t) (&dummy->regs.fp_regs + 1)) {
		/*
		 * floating point regs. are either in child->thread.fpu
		 * or the child->thread.fpu.vxrs array
		 */
		offset = addr - (addr_t) &dummy->regs.fp_regs.fprs;
		if (MACHINE_HAS_VX)
			*(addr_t *)((addr_t)
				child->thread.fpu.vxrs + 2*offset) = data;
		else
			*(addr_t *)((addr_t)
				child->thread.fpu.fprs + offset) = data;

	} else if (addr < (addr_t) (&dummy->regs.per_info + 1)) {
		/*
		 * Handle access to the per_info structure.
		 */
		addr -= (addr_t) &dummy->regs.per_info;
		__poke_user_per(child, addr, data);

	}

	return 0;
}