esp32s3: improve exception handlers, add procPin/procUnpin, and linker wrap flags

Rewrite kernel and double exception handlers to save EXCCAUSE/EPC1 to
RTC STORE registers before triggering a software reset, replacing the
LED-blink diagnostic with post-mortem debug info that survives reset.

Add user exception dispatch in the level-1 handler with a weak
espradio_user_exception symbol so programs without espradio still link.

Implement procPin/procUnpin for Xtensa using RSIL/WSR PS to properly
disable interrupts during atomic operations. Fix abort() to use a
waiti loop instead of bare spin.

Add --wrap ldflags for malloc/calloc/free/realloc/ppCheckTxConnTrafficIdle
to support espradio WiFi blob integration.

Signed-off-by: deadprogram <ron@hybridgroup.com>

src/runtime/arch_xtensa.go

@@ -2,6 +2,8 @@
 
 package runtime
 
+import "device"
+
 const GOARCH = "arm" // xtensa pretends to be arm
 
 // The bitness of the CPU (e.g. 8, 32, 64).
@@ -19,3 +21,21 @@ func align(ptr uintptr) uintptr {
 func getCurrentStackPointer() uintptr {
 	return uintptr(stacksave())
 }
+
+// Disable interrupts for procPin/procUnpin using the Xtensa RSIL/WSR PS
+// instructions.  A global variable is safe here because accesses happen
+// with interrupts disabled.
+var procPinnedMask uintptr
+
+//go:linkname procPin sync/atomic.runtime_procPin
+func procPin() {
+	// rsil sets PS.INTLEVEL=15 (mask all) and returns the old PS.
+	procPinnedMask = uintptr(device.AsmFull("rsil {}, 15", nil))
+}
+
+//go:linkname procUnpin sync/atomic.runtime_procUnpin
+func procUnpin() {
+	device.AsmFull("wsr {state}, PS", map[string]interface{}{
+		"state": procPinnedMask,
+	})
+}

src/runtime/runtime_esp32s3.go

@@ -96,8 +96,11 @@ func init() {
 }
 
 func abort() {
-	// lock up forever
 	print("abort called\n")
+	// lock up forever
+	for {
+		device.Asm("waiti 0")
+	}
 }
 
 // interruptInit installs the Xtensa vector table by writing its address