[PATCH v2 1/4] sandbox: add handler for exceptions

[Heinrich Schuchardt]

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 at 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