tools: hvmloader: attempt to SHUTDOWN_crash on BUG

Executing UD2 (invalid opcode) triggers a triple fault which signals
reboot to the toolstack, rather than crash.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Keir Fraser <keir@xen.org>
xen-unstable changeset:   23245:3539ef956a37
xen-unstable date:        Mon Apr 18 18:34:45 2011 +0100

tools/firmware/hvmloader/hvmloader.c

@@ -704,6 +704,9 @@ int main(void)
     uint32_t etherboot_phys_addr, option_rom_phys_addr, bios32_addr;
     struct bios_info *bios_info;
 
+    /* Initialise hypercall stubs with RET, rendering them no-ops. */
+    memset((void *)HYPERCALL_PHYSICAL_ADDRESS, 0xc3 /* RET */, PAGE_SIZE);
+
     printf("HVM Loader\n");
 
     init_hypercalls();

tools/firmware/hvmloader/util.c

@@ -25,6 +25,7 @@
 #include <stdint.h>
 #include <xen/xen.h>
 #include <xen/memory.h>
+#include <xen/sched.h>
 
 void wrmsr(uint32_t idx, uint64_t v)
 {
@@ -538,19 +539,27 @@ int vprintf(const char *fmt, va_list ap)
     return 0;
 }
 
+static void __attribute__((noreturn)) crash(void)
+{
+    struct sched_shutdown shutdown = { .reason = SHUTDOWN_crash };
+    printf("*** HVMLoader crashed.\n");
+    hypercall_sched_op(SCHEDOP_shutdown, &shutdown);
+    printf("*** Failed to crash. Halting.\n");
+    for ( ; ; )
+        asm volatile ( "hlt" );
+}
+
 void __assert_failed(char *assertion, char *file, int line)
 {
-    printf("HVMLoader assertion '%s' failed at %s:%d\n",
+    printf("*** HVMLoader assertion '%s' failed at %s:%d\n",
            assertion, file, line);
-    for ( ; ; )
-        asm volatile ( "ud2" );
+    crash();
 }
 
 void __bug(char *file, int line)
 {
-    printf("HVMLoader bug at %s:%d\n", file, line);
-    for ( ; ; )
-        asm volatile ( "ud2" );
+    printf("*** HVMLoader bug at %s:%d\n", file, line);
+    crash();
 }
 
 static void validate_hvm_info(struct hvm_info_table *t)