hw/xtensa/xtfpga: rewrite mini bootloader

Don't load jump target into the CPU config, instead put it and initial
a2 as literals into the mini bootloader and use l32r to load them
natively. With these changes it should be possible to do warm reboot of
the guest.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

diff --git a/hw/xtensa/xtfpga.c b/hw/xtensa/xtfpga.c
index 1971ecf..ba68168 100644 (file)
--- a/hw/xtensa/xtfpga.c
+++ b/hw/xtensa/xtfpga.c
@@ -372,15 +372,33 @@ static void lx_init(const LxBoardDesc *board, MachineState *machine)
             }
         }
         if (entry_point != env->pc) {
-            static const uint8_t jx_a0[] = {
+            uint8_t boot[] = {
 #ifdef TARGET_WORDS_BIGENDIAN
-                0x0a, 0, 0,
+                0x60, 0x00, 0x08,       /* j    1f */
+                0x00,                   /* .literal_position */
+                0x00, 0x00, 0x00, 0x00, /* .literal entry_pc */
+                0x00, 0x00, 0x00, 0x00, /* .literal entry_a2 */
+                                        /* 1: */
+                0x10, 0xff, 0xfe,       /* l32r a0, entry_pc */
+                0x12, 0xff, 0xfe,       /* l32r a2, entry_a2 */
+                0x0a, 0x00, 0x00,       /* jx   a0 */
 #else
-                0xa0, 0, 0,
+                0x06, 0x02, 0x00,       /* j    1f */
+                0x00,                   /* .literal_position */
+                0x00, 0x00, 0x00, 0x00, /* .literal entry_pc */
+                0x00, 0x00, 0x00, 0x00, /* .literal entry_a2 */
+                                        /* 1: */
+                0x01, 0xfe, 0xff,       /* l32r a0, entry_pc */
+                0x21, 0xfe, 0xff,       /* l32r a2, entry_a2 */
+                0xa0, 0x00, 0x00,       /* jx   a0 */
 #endif
             };
-            env->regs[0] = entry_point;
-            cpu_physical_memory_write(env->pc, jx_a0, sizeof(jx_a0));
+            uint32_t entry_pc = tswap32(entry_point);
+            uint32_t entry_a2 = tswap32(tagptr);
+
+            memcpy(boot + 4, &entry_pc, sizeof(entry_pc));
+            memcpy(boot + 8, &entry_a2, sizeof(entry_a2));
+            cpu_physical_memory_write(env->pc, boot, sizeof(boot));
         }
     } else {
         if (flash) {