The 'exception' command allows to test exception handling.
This implementation supports ARM, x86, RISC-V and the following exceptions: * 'breakpoint' - prefetch abort exception (ARM 32bit only) * 'unaligned' - data abort exception (ARM only) * 'undefined' - undefined instruction exception
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- Currently RISC-V 64bit gets into an endless loop when hitting the undefined instruction.
So it makes sense to have a testing capability. --- cmd/Kconfig | 6 ++ cmd/Makefile | 1 + cmd/exception.c | 161 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 168 insertions(+) create mode 100644 cmd/exception.c
diff --git a/cmd/Kconfig b/cmd/Kconfig index e2973b3c51..9d2b8199b8 100644 --- a/cmd/Kconfig +++ b/cmd/Kconfig @@ -1388,6 +1388,12 @@ config CMD_DISPLAY displayed on a simple board-specific display. Implement display_putc() to use it.
+config CMD_EXCEPTION + bool "exception - raise exception" + depends on ARM || RISCV || X86 + help + Enable the 'exception' command which allows to raise an exception. + config CMD_LED bool "led" default y if LED diff --git a/cmd/Makefile b/cmd/Makefile index 0534ddc679..cd67a79170 100644 --- a/cmd/Makefile +++ b/cmd/Makefile @@ -46,6 +46,7 @@ endif obj-$(CONFIG_CMD_DISPLAY) += display.o obj-$(CONFIG_CMD_DTIMG) += dtimg.o obj-$(CONFIG_CMD_ECHO) += echo.o +obj-$(CONFIG_CMD_EXCEPTION) += exception.o obj-$(CONFIG_ENV_IS_IN_EEPROM) += eeprom.o obj-$(CONFIG_CMD_EEPROM) += eeprom.o obj-$(CONFIG_EFI_STUB) += efi.o diff --git a/cmd/exception.c b/cmd/exception.c new file mode 100644 index 0000000000..fb6a15573e --- /dev/null +++ b/cmd/exception.c @@ -0,0 +1,161 @@ +// 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 <common.h> +#include <command.h> + +enum exception { + UNDEFINED_INSTRUCTION = 1, + DATA_ABORT, + BREAKPOINT, +}; + +struct exception_str { + enum exception id; + char *text; + void (*func)(void); +}; + +#if defined(CONFIG_ARM) +static void data_abort(void) +{ +#if defined(CONFIG_ARM64) + /* + * The LDR instruction requires the data source to be eight byte + * aligned. + */ + asm volatile ( + "MOV x1, sp\n" + "ADD x1, x1, 1\n" + "LDR x3, [x1]\n"); +#else + /* + * The LDRD instruction requires the data source to be four byte aligned + * even if strict alignment fault checking is disabled in the system + * control register. + */ + asm volatile ( + "MOV r5, sp\n" + "ADD r5, #1\n" + "LDRD r6, r7, [r5]\n"); +#endif +} + +#if !defined(CONFIG_ARM64) +static void breakpoint(void) +{ + asm volatile ("BKPT #123\n"); +} +#endif +#endif + +static void undefined_instruction(void) +{ +#if defined(CONFIG_ARM) + /* + * 0xe7f...f. is undefined in ARM mode + * 0xde.. is undefined in Thumb mode + */ + asm volatile (".word 0xe7f7defb\n"); +#elif defined(CONFIG_RISCV) + asm volatile (".word 0xffffffff\n"); +#elif defined(CONFIG_X86) + asm volatile (".word 0xffff\n"); +#endif +} + +struct exception_str exceptions[] = { +#if defined(CONFIG_ARM) +#if !defined(CONFIG_ARM64) + { BREAKPOINT, "breakpoint", breakpoint }, +#endif + { DATA_ABORT, "unaligned", data_abort }, +#endif + { UNDEFINED_INSTRUCTION, "undefined", undefined_instruction }, + { 0, NULL, NULL }, +}; + +static int do_exception(cmd_tbl_t *cmdtp, int flag, int argc, + char * const argv[]) +{ + struct exception_str *ex; + enum exception id = 0; + + if (argc != 2) + return CMD_RET_USAGE; + + for (ex = exceptions; ex->func ; ++ex) { + if (!strcmp(argv[1], ex->text)) { + id = ex->id; + break; + } + } + switch (id) { +#if defined(CONFIG_ARM) +#if !defined(CONFIG_ARM64) + case BREAKPOINT: + breakpoint(); + break; +#endif + case DATA_ABORT: + data_abort(); + break; +#endif + case UNDEFINED_INSTRUCTION: + undefined_instruction(); + break; + default: + return CMD_RET_USAGE; + } + + return CMD_RET_FAILURE; +} + +static int exception_complete(int argc, char * const argv[], char last_char, + int maxv, char *cmdv[]) +{ + int len = 0; + struct exception_str *ex; + int i = 0; + + switch (argc) { + case 1: + break; + case 2: + len = strlen(argv[1]); + break; + default: + return 0; + } + for (ex = exceptions; ex->func ; ++ex) { + if (i >= maxv - 1) + return i; + if (!strncmp(argv[1], ex->text, len)) + cmdv[i++] = ex->text; + } + cmdv[i] = NULL; + return i; +} + +#ifdef CONFIG_SYS_LONGHELP +static char exception_help_text[] = + "<ex>\n" + " The following exceptions are available:\n" +#if defined(CONFIG_ARM) +#if !defined(CONFIG_ARM64) + " breakpoint - prefetch abort\n" +#endif + " unaligned - data abort\n" +#endif +#endif + " undefined - undefined instruction\n" + ; + +U_BOOT_CMD_COMPLETE( + exception, 2, 0, do_exception, + "Forces an exception to occur", + exception_help_text, exception_complete +);