/*
 * COMPILE:  arm-none-eabi-gcc -mthumb -march=armv7-m ...
 *	... plus, provide at least a default exception vector table.
 *
 * RUN:  this is best run from SRAM.  It starts at main() then triggers
 * a fault before more than a handful of instructions have executed.
 * Run each test case in two modes:
 *
 * (1)	Faults caught on the Cortex-M3.  Default handlers are usually
 *	loop-to-self NOPs, so a debugger won't notice faults until they
 *	halt the core and examine xSPR and other registers.
 *
 *	To verify the fault triggered, issue "halt" from OpenOCD; you
 *	should be told about the fault and (some of) its details.
 *	Then it's time to run the next test.
 *
 *	NOTE however that "reset" will restart everything; verify that
 *	case by observing your reset handler doing its normal work.
 *
 * (2)	Faults intercepted by OpenOCD "vector_catch ..." commands.
 *
 *	OpenOCD should tell you about the fault, and show the same
 *	details, without your "halt" command.
 *
 * Someday, a fancy version of this code could provide a vector table and
 * fault handlers which use semihosting (when that works on Cortex-M3) to
 * report what happened, again without needing a "halt" command.
 */


/* These symbols match the OpenOCD "cortex_m3 vector_catch" bit names. */
enum vc_case {
	hard_err,
	int_err,
	bus_err,
	state_err,
	chk_err,
	nocp_err,
	mm_err,
	reset,
};

/* REVISIT come up with a way to avoid recompiling, maybe:
 *  - write it in RAM before starting
 *  - compiled-in BKPT, manual patch of r0, then resume
 *  - ...
 */

#ifndef VC_ID
#warning "no VC_ID ... using reset"
#define VC_ID reset
#endif

int main(void) __attribute__ ((externally_visible, noreturn));

/*
 * Trigger various Cortex-M3 faults to verify that OpenOCD behaves OK
 * in terms of its vector_catch handling.
 *
 * Fault handling should be left entirely up to the application code
 * UNLESS a "vector_catch" command tells OpenOCD to intercept a fault.
 *
 * See ARMv7-M architecure spec table B1-9 for the list of faults and
 * their mappings to the vector catch bits.
 */
int main(void)
{
	/* One test case for each vector catch bit.  We're not doing
	 * hardware testing; so it doesn't matter when some DEMCR bits
	 * could apply in multiple ways.
	 */
	switch (VC_ID) {

	/* "cortex_m3 vector_catch hard_err" */
	case hard_err:
		/* FORCED - Fault escalation */

		/* FIXME code this */
		break;

	/* "cortex_m3 vector_catch int_err" */
	case int_err:
		/* STKERR -- Exception stack BusFault */

		/* FIXME code this */
		break;

	/* "cortex_m3 vector_catch bus_err" */
	case bus_err:
		/* PRECISERR -- precise data bus read
		 * Here we assume a Cortex-M3 with 512 MBytes SRAM is very
		 * unlikely, so the last SRAM byte isn't a valid address.
		 */
		__asm__ volatile(
			"mov r0, #0x3fffffff\n"
			"ldrb r0, [r0]\n"
			);
		break;

	/* "cortex_m3 vector_catch state_err" */
	case state_err:
		/* UNDEFINSTR -- architectural undefined instruction */
		__asm__ volatile(".hword 0xde00");
		break;

	/* "cortex_m3 vector_catch chk_err" */
	case chk_err:
		/* UNALIGNED ldm */
		__asm__ volatile(
			"mov r0, #1\n"
			"ldm r0, {r1, r2}\n"
			);
		break;

	/* "cortex_m3 vector_catch nocp_err" */
	case nocp_err:
		/* NOCP ... Cortex-M3 has no coprocessors (like CP14 DCC),
		 * but these instructions are allowed by ARMv7-M.
		 */
		__asm__ volatile("mrc p14, 0, r0, c0, c5, 0");
		break;

	/* "cortex_m3 vector_catch mm_err" */
	case mm_err:
		/* IACCVIOL -- instruction fetch from an XN region */
		__asm__ volatile(
			"mov r0, #0xe0000000\n"
			"mov pc, r0\n"
			);
		break;

	/* "cortex_m3 vector_catch reset" */
	case reset:
		__asm__ volatile(
			/* r1 = SYSRESETREQ */
			"mov r1, #0x0004\n"
			/* r1 |= VECTKEY */
			"movt r1, #0x05fa\n"
			/* r0 = &AIRCR */
			"mov r0, #0xed00\n"
			"add r0, #0xc\n"
			"movt r0, #0xe000\n"
			/* AIRCR = ... */
			"str r1, [r0, #0]\n"
			);
		break;
	}

	/* don't return */
	while (1)
		continue;
}
a id='n12' href='#n12'>12</a>
<a id='n13' href='#n13'>13</a>
<a id='n14' href='#n14'>14</a>
<a id='n15' href='#n15'>15</a>
<a id='n16' href='#n16'>16</a>
<a id='n17' href='#n17'>17</a>
<a id='n18' href='#n18'>18</a>
<a id='n19' href='#n19'>19</a>
<a id='n20' href='#n20'>20</a>
<a id='n21' href='#n21'>21</a>
<a id='n22' href='#n22'>22</a>
<a id='n23' href='#n23'>23</a>
<a id='n24' href='#n24'>24</a>
<a id='n25' href='#n25'>25</a>
<a id='n26' href='#n26'>26</a>
<a id='n27' href='#n27'>27</a>
<a id='n28' href='#n28'>28</a>
<a id='n29' href='#n29'>29</a>
<a id='n30' href='#n30'>30</a>
<a id='n31' href='#n31'>31</a>
<a id='n32' href='#n32'>32</a>
<a id='n33' href='#n33'>33</a>
<a id='n34' href='#n34'>34</a>
<a id='n35' href='#n35'>35</a>
<a id='n36' href='#n36'>36</a>
<a id='n37' href='#n37'>37</a>
<a id='n38' href='#n38'>38</a>
<a id='n39' href='#n39'>39</a>
<a id='n40' href='#n40'>40</a>
<a id='n41' href='#n41'>41</a>
<a id='n42' href='#n42'>42</a>
<a id='n43' href='#n43'>43</a>
<a id='n44' href='#n44'>44</a>
<a id='n45' href='#n45'>45</a>
<a id='n46' href='#n46'>46</a>
<a id='n47' href='#n47'>47</a>
<a id='n48' href='#n48'>48</a>
<a id='n49' href='#n49'>49</a>
<a id='n50' href='#n50'>50</a>
<a id='n51' href='#n51'>51</a>
<a id='n52' href='#n52'>52</a>
<a id='n53' href='#n53'>53</a>
<a id='n54' href='#n54'>54</a>
<a id='n55' href='#n55'>55</a>
<a id='n56' href='#n56'>56</a>
<a id='n57' href='#n57'>57</a>
<a id='n58' href='#n58'>58</a>
<a id='n59' href='#n59'>59</a>
<a id='n60' href='#n60'>60</a>
<a id='n61' href='#n61'>61</a>
<a id='n62' href='#n62'>62</a>
<a id='n63' href='#n63'>63</a>
<a id='n64' href='#n64'>64</a>
<a id='n65' href='#n65'>65</a>
<a id='n66' href='#n66'>66</a>
<a id='n67' href='#n67'>67</a>
<a id='n68' href='#n68'>68</a>
<a id='n69' href='#n69'>69</a>
<a id='n70' href='#n70'>70</a>
<a id='n71' href='#n71'>71</a>
<a id='n72' href='#n72'>72</a>
<a id='n73' href='#n73'>73</a>
<a id='n74' href='#n74'>74</a>
<a id='n75' href='#n75'>75</a>
<a id='n76' href='#n76'>76</a>
<a id='n77' href='#n77'>77</a>
<a id='n78' href='#n78'>78</a>
<a id='n79' href='#n79'>79</a>
<a id='n80' href='#n80'>80</a>
<a id='n81' href='#n81'>81</a>
<a id='n82' href='#n82'>82</a>
<a id='n83' href='#n83'>83</a>
<a id='n84' href='#n84'>84</a>
<a id='n85' href='#n85'>85</a>
<a id='n86' href='#n86'>86</a>
<a id='n87' href='#n87'>87</a>
<a id='n88' href='#n88'>88</a>
<a id='n89' href='#n89'>89</a>
<a id='n90' href='#n90'>90</a>
<a id='n91' href='#n91'>91</a>
<a id='n92' href='#n92'>92</a>
<a id='n93' href='#n93'>93</a>
<a id='n94' href='#n94'>94</a>
<a id='n95' href='#n95'>95</a>
<a id='n96' href='#n96'>96</a>
<a id='n97' href='#n97'>97</a>
<a id='n98' href='#n98'>98</a>
<a id='n99' href='#n99'>99</a>
<a id='n100' href='#n100'>100</a>
<a id='n101' href='#n101'>101</a>
<a id='n102' href='#n102'>102</a>
<a id='n103' href='#n103'>103</a>
<a id='n104' href='#n104'>104</a>
<a id='n105' href='#n105'>105</a>
<a id='n106' href='#n106'>106</a>
<a id='n107' href='#n107'>107</a>
<a id='n108' href='#n108'>108</a>
<a id='n109' href='#n109'>109</a>
<a id='n110' href='#n110'>110</a>
<a id='n111' href='#n111'>111</a>
<a id='n112' href='#n112'>112</a>
<a id='n113' href='#n113'>113</a>
<a id='n114' href='#n114'>114</a>
<a id='n115' href='#n115'>115</a>
<a id='n116' href='#n116'>116</a>
<a id='n117' href='#n117'>117</a>
<a id='n118' href='#n118'>118</a>
<a id='n119' href='#n119'>119</a>
<a id='n120' href='#n120'>120</a>
<a id='n121' href='#n121'>121</a>
<a id='n122' href='#n122'>122</a>
<a id='n123' href='#n123'>123</a>
<a id='n124' href='#n124'>124</a>
<a id='n125' href='#n125'>125</a>
<a id='n126' href='#n126'>126</a>
<a id='n127' href='#n127'>127</a>
<a id='n128' href='#n128'>128</a>
<a id='n129' href='#n129'>129</a>
<a id='n130' href='#n130'>130</a>
<a id='n131' href='#n131'>131</a>
<a id='n132' href='#n132'>132</a>
<a id='n133' href='#n133'>133</a>
<a id='n134' href='#n134'>134</a>
<a id='n135' href='#n135'>135</a>
<a id='n136' href='#n136'>136</a>
<a id='n137' href='#n137'>137</a>
<a id='n138' href='#n138'>138</a>
<a id='n139' href='#n139'>139</a>
<a id='n140' href='#n140'>140</a>
<a id='n141' href='#n141'>141</a>
<a id='n142' href='#n142'>142</a>
<a id='n143' href='#n143'>143</a>
<a id='n144' href='#n144'>144</a>
<a id='n145' href='#n145'>145</a>
<a id='n146' href='#n146'>146</a>
<a id='n147' href='#n147'>147</a>
<a id='n148' href='#n148'>148</a>
<a id='n149' href='#n149'>149</a>
<a id='n150' href='#n150'>150</a>
<a id='n151' href='#n151'>151</a>
<a id='n152' href='#n152'>152</a>
<a id='n153' href='#n153'>153</a>
<a id='n154' href='#n154'>154</a>
<a id='n155' href='#n155'>155</a>
<a id='n156' href='#n156'>156</a>
<a id='n157' href='#n157'>157</a>
<a id='n158' href='#n158'>158</a>
<a id='n159' href='#n159'>159</a>
<a id='n160' href='#n160'>160</a>
<a id='n161' href='#n161'>161</a>
<a id='n162' href='#n162'>162</a>
<a id='n163' href='#n163'>163</a>
<a id='n164' href='#n164'>164</a>
<a id='n165' href='#n165'>165</a>
<a id='n166' href='#n166'>166</a>
<a id='n167' href='#n167'>167</a>
<a id='n168' href='#n168'>168</a>
<a id='n169' href='#n169'>169</a>
<a id='n170' href='#n170'>170</a>
<a id='n171' href='#n171'>171</a>
<a id='n172' href='#n172'>172</a>
<a id='n173' href='#n173'>173</a>
<a id='n174' href='#n174'>174</a>
<a id='n175' href='#n175'>175</a>
<a id='n176' href='#n176'>176</a>
<a id='n177' href='#n177'>177</a>
<a id='n178' href='#n178'>178</a>
<a id='n179' href='#n179'>179</a>
<a id='n180' href='#n180'>180</a>
<a id='n181' href='#n181'>181</a>
<a id='n182' href='#n182'>182</a>
</pre></td>
<td class='lines'><pre><code>