1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * The 'exception' command can be used for testing exception handling.
4 *
5 * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
6 */
7
8 #include <common.h>
9 #include <command.h>
10 #include <linux/bitops.h>
11
do_undefined(struct cmd_tbl * cmdtp,int flag,int argc,char * const argv[])12 static int do_undefined(struct cmd_tbl *cmdtp, int flag, int argc,
13 char *const argv[])
14 {
15 /*
16 * Instructions starting with the upper 16 bits all 0 are permanently
17 * undefined. The lower 16 bits can be used for some kind of immediate.
18 * --- ARMv8 ARM (ARM DDI 0487G.a C6.2.339: "UDF")
19 */
20 asm volatile (".word 0x00001234\n");
21
22 return CMD_RET_FAILURE;
23 }
24
25 /*
26 * The ID_AA64MMFR2_EL1 register name is only know to binutils for ARMv8.2
27 * and later architecture revisions. However the register is valid regardless
28 * of binutils architecture support or the core the code is running on, so
29 * just use the generic encoding.
30 */
31 #define ID_AA64MMFR2_EL1 "S3_0_C0_C7_2"
32
do_unaligned(struct cmd_tbl * cmdtp,int flag,int argc,char * const argv[])33 static int do_unaligned(struct cmd_tbl *cmdtp, int flag, int argc,
34 char *const argv[])
35 {
36 uint64_t reg;
37
38 /*
39 * The unaligned LDAR access below is only guaranteed to generate an
40 * alignment fault on cores not implementing FEAT_LSE2. To avoid false
41 * negatives, check this condition before we exectute LDAR.
42 */
43 asm ("mrs %0, "ID_AA64MMFR2_EL1"\n" : "=r" (reg));
44 if (reg & GENMASK(35, 32)) {
45 printf("unaligned access check only supported on pre-v8.4 cores\n");
46 return CMD_RET_FAILURE;
47 }
48
49 /*
50 * The load acquire instruction requires the data source to be
51 * naturally aligned, and will fault even if strict alignment fault
52 * checking is disabled (but only without FEAT_LSE2).
53 * --- ARMv8 ARM (ARM DDI 0487G.a B2.5.2: "Alignment of data accesses")
54 */
55 asm volatile (
56 "mov x1, sp\n\t"
57 "orr x1, x1, #3\n\t"
58 "ldar x0, [x1]\n"
59 ::: "x0", "x1" );
60
61 return CMD_RET_FAILURE;
62 }
63
do_breakpoint(struct cmd_tbl * cmdtp,int flag,int argc,char * const argv[])64 static int do_breakpoint(struct cmd_tbl *cmdtp, int flag, int argc,
65 char *const argv[])
66 {
67 asm volatile ("brk #123\n");
68
69 return CMD_RET_FAILURE;
70 }
71
72 static struct cmd_tbl cmd_sub[] = {
73 U_BOOT_CMD_MKENT(breakpoint, CONFIG_SYS_MAXARGS, 1, do_breakpoint,
74 "", ""),
75 U_BOOT_CMD_MKENT(unaligned, CONFIG_SYS_MAXARGS, 1, do_unaligned,
76 "", ""),
77 U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
78 "", ""),
79 };
80
81 static char exception_help_text[] =
82 "<ex>\n"
83 " The following exceptions are available:\n"
84 " breakpoint - breakpoint instruction exception\n"
85 " unaligned - unaligned LDAR data abort\n"
86 " undefined - undefined instruction exception\n"
87 ;
88
89 #include <exception.h>
90