uboot/arch/arm/lib/cmd_boot.c
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   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * (C) Copyright 2008-2011
   4 * Graeme Russ, <graeme.russ@gmail.com>
   5 *
   6 * (C) Copyright 2002
   7 * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
   8 *
   9 * (C) Copyright 2002
  10 * Wolfgang Denk, DENX Software Engineering, <wd@denx.de>
  11 *
  12 * (C) Copyright 2002
  13 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  14 * Marius Groeger <mgroeger@sysgo.de>
  15 *
  16 * Copyright 2015 ATS Advanced Telematics Systems GmbH
  17 * Copyright 2015 Konsulko Group, Matt Porter <mporter@konsulko.com>
  18 */
  19
  20#include <common.h>
  21#include <command.h>
  22
  23/*
  24 * ARMv7M does not support ARM instruction mode. However, the
  25 * interworking BLX and BX instructions do encode the ARM/Thumb
  26 * field in bit 0. This means that when executing any Branch
  27 * and eXchange instruction we must set bit 0 to one to guarantee
  28 * that we keep the processor in Thumb instruction mode. From The
  29 * ARMv7-M Instruction Set A4.1.1:
  30 *   "ARMv7-M only supports the Thumb instruction execution state,
  31 *    therefore the value of address bit [0] must be 1 in interworking
  32 *    instructions, otherwise a fault occurs."
  33 */
  34unsigned long do_go_exec(ulong (*entry)(int, char * const []),
  35                         int argc, char * const argv[])
  36{
  37        ulong addr = (ulong)entry | 1;
  38        entry = (void *)addr;
  39
  40        return entry(argc, argv);
  41}
  42