Add a handler for SIGILL, SIGBUS, SIGSEGV.

When an exception occurs print the program counter and the loaded UEFI binaries and reset the system if CONFIG_SANDBOX_CRASH_RESET=y or exit to the OS otherwise.

Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- v2: add a customizing switch set SA_NODEFER flag for sigaction --- arch/sandbox/Kconfig | 9 ++++++++ arch/sandbox/cpu/os.c | 40 +++++++++++++++++++++++++++++++++++ arch/sandbox/cpu/start.c | 4 ++++ arch/sandbox/lib/interrupts.c | 35 ++++++++++++++++++++++++++++++ include/os.h | 17 +++++++++++++++ 5 files changed, 105 insertions(+)

diff --git a/arch/sandbox/Kconfig b/arch/sandbox/Kconfig index 65f988e736..f83282d9d5 100644 --- a/arch/sandbox/Kconfig +++ b/arch/sandbox/Kconfig @@ -51,6 +51,15 @@ config HOST_64BIT

endchoice

+config SANDBOX_CRASH_RESET + bool "Reset on crash" + help + If an illegal instruction or an illegal memory access occurs, the + sandbox by default writes a crash dump and exits. If you set this + flag, the sandbox is reset instead. This may be useful when running + test suites like the UEFI self certification test which continue + with the next test after a crash. + config SANDBOX_BITS_PER_LONG int default 32 if HOST_32BIT diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c index 0d8efd83f6..b56fa04a34 100644 --- a/arch/sandbox/cpu/os.c +++ b/arch/sandbox/cpu/os.c @@ -3,6 +3,8 @@ * Copyright (c) 2011 The Chromium OS Authors. */

+#define _GNU_SOURCE + #include <dirent.h> #include <errno.h> #include <fcntl.h> @@ -15,11 +17,13 @@ #include <string.h> #include <termios.h> #include <time.h> +#include <ucontext.h> #include <unistd.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/time.h> #include <sys/types.h> +#include <linux/compiler_attributes.h> #include <linux/types.h>

#include <asm/getopt.h> @@ -191,6 +195,42 @@ static void os_sigint_handler(int sig) raise(SIGINT); }

+static void os_signal_handler(int sig, siginfo_t *info, void *con) +{ + ucontext_t __maybe_unused *context = con; + unsigned long pc; + +#if defined(__x86_64__) + pc = context->uc_mcontext.gregs[REG_RIP]; +#elif defined(__aarch64__) + pc = context->uc_mcontext.pc; +#elif defined(__riscv) + pc = context->uc_mcontext.__gregs[REG_PC]; +#else + const char msg[] = + "\nUnsupported architecture, cannot read program counter\n"; + + os_write(1, msg, sizeof(msg)); + pc = 0; +#endif + + os_signal_action(sig, pc); +} + +int os_setup_signal_handlers(void) +{ + struct sigaction act; + + act.sa_sigaction = os_signal_handler; + sigemptyset(&act.sa_mask); + act.sa_flags = SA_SIGINFO | SA_NODEFER; + if (sigaction(SIGILL, &act, NULL) || + sigaction(SIGBUS, &act, NULL) || + sigaction(SIGSEGV, &act, NULL)) + return -1; + return 0; +} + /* Put tty into raw mode so <tab> and <ctrl+c> work */ void os_tty_raw(int fd, bool allow_sigs) { diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c index a03e5aa0b3..f6c98545e0 100644 --- a/arch/sandbox/cpu/start.c +++ b/arch/sandbox/cpu/start.c @@ -451,6 +451,10 @@ int main(int argc, char *argv[]) if (ret) goto err;

+ ret = os_setup_signal_handlers(); + if (ret) + goto err; + #if CONFIG_VAL(SYS_MALLOC_F_LEN) gd->malloc_base = CONFIG_MALLOC_F_ADDR; #endif diff --git a/arch/sandbox/lib/interrupts.c b/arch/sandbox/lib/interrupts.c index 21f761ac3b..9c2c60b8c6 100644 --- a/arch/sandbox/lib/interrupts.c +++ b/arch/sandbox/lib/interrupts.c @@ -6,7 +6,13 @@ */

#include <common.h> +#include <efi_loader.h> #include <irq_func.h> +#include <os.h> +#include <asm-generic/signal.h> +#include <asm/u-boot-sandbox.h> + +DECLARE_GLOBAL_DATA_PTR;

int interrupt_init(void) { @@ -21,3 +27,32 @@ int disable_interrupts(void) { return 0; } + +void os_signal_action(int sig, unsigned long pc) +{ + efi_restore_gd(); + + switch (sig) { + case SIGILL: + printf("\nIllegal instruction\n"); + break; + case SIGBUS: + printf("\nBus error\n"); + break; + case SIGSEGV: + printf("\nSegmentation violation\n"); + break; + default: + break; + } + printf("pc = 0x%lx, ", pc); + printf("pc_reloc = 0x%lx\n\n", pc - gd->reloc_off); + efi_print_image_infos((void *)pc); + + if (IS_ENABLED(CONFIG_SANDBOX_CRASH_RESET)) { + printf("resetting ...\n\n"); + sandbox_reset(); + } else { + sandbox_exit(); + } +} diff --git a/include/os.h b/include/os.h index 1fe44f3510..0913b47b3a 100644 --- a/include/os.h +++ b/include/os.h @@ -407,4 +407,21 @@ void *os_find_text_base(void); */ void os_relaunch(char *argv[]);

+/** + * os_setup_signal_handlers() - setup signal handlers + * + * Install signal handlers for SIGBUS and SIGSEGV. + * + * Return: 0 for success + */ +int os_setup_signal_handlers(void); + +/** + * os_signal_action() - handle a signal + * + * @sig: signal + * @pc: program counter + */ +void os_signal_action(int sig, unsigned long pc); + #endif -- 2.28.0

Implement the commands

* exception undefined - execute an illegal instruction * exception sigsegv - cause a segment violation

Here is a possible output:

=> exception undefined Illegal instruction pc = 0x55eb8d0a7575, pc_reloc = 0x57575 Resetting ...

Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de Reviewed-by: Simon Glass sjg@chromium.org --- v2: no change --- cmd/Kconfig | 2 +- cmd/Makefile | 1 + cmd/sandbox/Makefile | 3 +++ cmd/sandbox/exception.c | 41 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 46 insertions(+), 1 deletion(-) create mode 100644 cmd/sandbox/Makefile create mode 100644 cmd/sandbox/exception.c

diff --git a/cmd/Kconfig b/cmd/Kconfig index 1595de999b..f9b72449c5 100644 --- a/cmd/Kconfig +++ b/cmd/Kconfig @@ -1682,7 +1682,7 @@ config CMD_EFIDEBUG

config CMD_EXCEPTION bool "exception - raise exception" - depends on ARM || RISCV || X86 + depends on ARM || RISCV || SANDBOX || X86 help Enable the 'exception' command which allows to raise an exception.

diff --git a/cmd/Makefile b/cmd/Makefile index dd86675bf2..5b3400a840 100644 --- a/cmd/Makefile +++ b/cmd/Makefile @@ -193,6 +193,7 @@ obj-$(CONFIG_CMD_AVB) += avb.o

obj-$(CONFIG_ARM) += arm/ obj-$(CONFIG_RISCV) += riscv/ +obj-$(CONFIG_SANDBOX) += sandbox/ obj-$(CONFIG_X86) += x86/

obj-$(CONFIG_ARCH_MVEBU) += mvebu/ diff --git a/cmd/sandbox/Makefile b/cmd/sandbox/Makefile new file mode 100644 index 0000000000..24df023ece --- /dev/null +++ b/cmd/sandbox/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0+ + +obj-$(CONFIG_CMD_EXCEPTION) += exception.o diff --git a/cmd/sandbox/exception.c b/cmd/sandbox/exception.c new file mode 100644 index 0000000000..1aa1d673ae --- /dev/null +++ b/cmd/sandbox/exception.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * The 'exception' command can be used for testing exception handling. + * + * Copyright (c) 2020, Heinrich Schuchardt xypron.glpk@gmx.de + */ + +#include <common.h> +#include <command.h> + +static int do_sigsegv(struct cmd_tbl *cmdtp, int flag, int argc, + char *const argv[]) +{ + u8 *ptr = NULL; + + *ptr = 0; + return CMD_RET_FAILURE; +} + +static int do_undefined(struct cmd_tbl *cmdtp, int flag, int argc, + char *const argv[]) +{ + asm volatile (".word 0xffff\n"); + return CMD_RET_FAILURE; +} + +static struct cmd_tbl cmd_sub[] = { + U_BOOT_CMD_MKENT(sigsegv, CONFIG_SYS_MAXARGS, 1, do_sigsegv, + "", ""), + U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined, + "", ""), +}; + +static char exception_help_text[] = + "<ex>\n" + " The following exceptions are available:\n" + " undefined - undefined instruction\n" + " sigsegv - illegal memory access\n" + ; + +#include <exception.h> -- 2.28.0

Provide a unit test that causes an illegal instruction to occur.

The test can be run with the following commands:

=> setenv efi_selftest exception => bootefi selftest

This might be the output:

Executing 'exception' EFI application triggers exception. Illegal instruction pc = 0x1444d016, pc_reloc = 0xffffaa078e8dd016 UEFI image [0x0000000000000000:0xffffffffffffffff] '/\selftest' UEFI image [0x000000001444b000:0x0000000014451fff] pc=0x2016 '/bug.efi' Resetting ...

It would tell us that the exception was triggered by an instruction 0x2016 bytes after the load address of the binary with filename /bug.efi.

Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- v2: no change --- lib/efi_selftest/efi_selftest_miniapp_exception.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/lib/efi_selftest/efi_selftest_miniapp_exception.c b/lib/efi_selftest/efi_selftest_miniapp_exception.c index 63c63d75f1..59b7e5100a 100644 --- a/lib/efi_selftest/efi_selftest_miniapp_exception.c +++ b/lib/efi_selftest/efi_selftest_miniapp_exception.c @@ -33,6 +33,8 @@ efi_status_t EFIAPI efi_main(efi_handle_t handle, asm volatile (".word 0xe7f7defb\n"); #elif defined(CONFIG_RISCV) asm volatile (".word 0xffffffff\n"); +#elif defined(CONFIG_SANDBOX) + asm volatile (".word 0xffffffff\n"); #elif defined(CONFIG_X86) asm volatile (".word 0xffff\n"); #endif -- 2.28.0

Test that an exception SIGILL is answered by a reset on the sandbox if CONFIG_SANDBOX_CRASH_RESET=y or by exiting to the OS otherwise.

Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- v2: new patch --- arch/Kconfig | 1 + test/py/tests/test_sandbox_exit.py | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig index 3aa99e08fc..b936d2dffc 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -112,6 +112,7 @@ config SANDBOX imply BITREVERSE select BLOBLIST imply CMD_DM + imply CMD_EXCEPTION imply CMD_GETTIME imply CMD_HASH imply CMD_IO diff --git a/test/py/tests/test_sandbox_exit.py b/test/py/tests/test_sandbox_exit.py index 2d242ae0f6..706f5fa359 100644 --- a/test/py/tests/test_sandbox_exit.py +++ b/test/py/tests/test_sandbox_exit.py @@ -19,3 +19,27 @@ def test_ctrl_c(u_boot_console):

u_boot_console.kill(signal.SIGINT) assert(u_boot_console.validate_exited()) + +@pytest.mark.boardspec('sandbox') +@pytest.mark.buildconfigspec('cmd_exception') +@pytest.mark.buildconfigspec('sandbox_crash_reset') +def test_exception_reset(u_boot_console): + """Test that SIGILL causes a reset.""" + + u_boot_console.run_command('exception undefined', wait_for_prompt=False) + m = u_boot_console.p.expect(['resetting ...', 'U-Boot']) + if m != 0: + raise Exception('SIGILL did not lead to reset') + m = u_boot_console.p.expect(['U-Boot', '=>']) + if m != 0: + raise Exception('SIGILL did not lead to reset') + u_boot_console.restart_uboot() + +@pytest.mark.boardspec('sandbox') +@pytest.mark.buildconfigspec('cmd_exception') +@pytest.mark.notbuildconfigspec('sandbox_crash_reset') +def test_exception_exit(u_boot_console): + """Test that SIGILL causes a reset.""" + + u_boot_console.run_command('exception undefined', wait_for_prompt=False) + assert(u_boot_console.validate_exited()) -- 2.28.0