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// SPDX-License-Identifier: GPL-2.0+
/*
* The 'exception' command can be used for testing exception handling.
*
* Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
*/
#include <command.h>
#include <linux/bitops.h>
static int do_undefined(struct cmd_tbl *cmdtp, int flag, int argc,
char *const argv[])
{
/*
* Instructions starting with the upper 16 bits all 0 are permanently
* undefined. The lower 16 bits can be used for some kind of immediate.
* --- ARMv8 ARM (ARM DDI 0487G.a C6.2.339: "UDF")
*/
asm volatile (".word 0x00001234\n");
return CMD_RET_FAILURE;
}
/*
* The ID_AA64MMFR2_EL1 register name is only know to binutils for ARMv8.2
* and later architecture revisions. However the register is valid regardless
* of binutils architecture support or the core the code is running on, so
* just use the generic encoding.
*/
#define ID_AA64MMFR2_EL1 "S3_0_C0_C7_2"
static int do_unaligned(struct cmd_tbl *cmdtp, int flag, int argc,
char *const argv[])
{
uint64_t reg;
/*
* The unaligned LDAR access below is only guaranteed to generate an
* alignment fault on cores not implementing FEAT_LSE2. To avoid false
* negatives, check this condition before we exectute LDAR.
*/
asm ("mrs %0, "ID_AA64MMFR2_EL1"\n" : "=r" (reg));
if (reg & GENMASK(35, 32)) {
printf("unaligned access check only supported on pre-v8.4 cores\n");
return CMD_RET_FAILURE;
}
/*
* The load acquire instruction requires the data source to be
* naturally aligned, and will fault even if strict alignment fault
* checking is disabled (but only without FEAT_LSE2).
* --- ARMv8 ARM (ARM DDI 0487G.a B2.5.2: "Alignment of data accesses")
*/
asm volatile (
"mov x1, sp\n\t"
"orr x1, x1, #3\n\t"
"ldar x0, [x1]\n"
::: "x0", "x1" );
return CMD_RET_FAILURE;
}
static int do_breakpoint(struct cmd_tbl *cmdtp, int flag, int argc,
char *const argv[])
{
asm volatile ("brk #123\n");
return CMD_RET_FAILURE;
}
static struct cmd_tbl cmd_sub[] = {
U_BOOT_CMD_MKENT(breakpoint, CONFIG_SYS_MAXARGS, 1, do_breakpoint,
"", ""),
U_BOOT_CMD_MKENT(unaligned, CONFIG_SYS_MAXARGS, 1, do_unaligned,
"", ""),
U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
"", ""),
};
static char exception_help_text[] =
"<ex>\n"
" The following exceptions are available:\n"
" breakpoint - breakpoint instruction exception\n"
" unaligned - unaligned LDAR data abort\n"
" undefined - undefined instruction exception\n"
;
#include <exception.h>
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