fix(esp32): Fix access to MALLOC_CAP_IRAM_8BIT byte array in loop

The Xtensa load/store handler did not properly handle 8/16-bit
memory access to IRAM regions configured with MALLOC_CAP_IRAM_8BIT
(and CONFIG_ESP32_IRAM_AS_8BIT_ACCESSIBLE_MEMORY=y) from a loop
(LBEG/LEND/LCOUNT) context. This caused the loop to exit after
the first access, instead of continuing to iterate as intended.

Closes https://github.com/espressif/esp-idf/issues/14127

components/xtensa/include/xtensa/xtensa_zol_macros.h

@@ -0,0 +1,53 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+ /*
+ * Zero-overhead loop adjustment helpers for Xtensa assembly code.
+ *
+ * Used by exception handlers to emulate loop hardware when an exception
+ * occurs at LEND so execution resumes at LBEG with LCOUNT decremented.
+ */
+
+#ifndef XTENSA_ZOL_MACROS_H
+#define XTENSA_ZOL_MACROS_H
+
+#if __XTENSA__
+#include "xtensa/config/core-isa.h"
+#include "xtensa/config/xt_specreg.h"
+
+/**
+ * Adjust loop counter and return address for exceptions at LEND.
+ *
+ * When an exception occurs on instruction at LEND address of a zero-overhead loop,
+ * we must decrement LCOUNT and set EPC back to LBEG so the loop continues
+ * iterating after the exception is handled. Otherwise, the loop exits prematurely.
+ *
+ * if (EPC == LEND && LCOUNT != 0) {
+ *     LCOUNT--;
+ *     EPC = LBEG;
+ * }
+ *
+ * param[in/out] epc_reg - register containing EPC, updated to LBEG if needed
+ * param[in/out] tmp_reg - temporary register for intermediate values
+ *
+ * Return: Use epc_reg to set corrected EPC value.
+ */
+.macro XT_ZOL_EPC_LCOUNT_RESTORE epc_reg tmp_reg
+    #if XCHAL_HAVE_LOOPS
+    rsr     \tmp_reg, XT_REG_LEND
+    bne     \epc_reg, \tmp_reg, 1f
+    rsr     \tmp_reg, XT_REG_LCOUNT
+    beqz    \tmp_reg, 1f
+    addi    \tmp_reg, \tmp_reg, -1
+    wsr     \tmp_reg, XT_REG_LCOUNT
+    rsr     \epc_reg, XT_REG_LBEG
+1:
+    #endif
+.endm
+
+#endif /* __XTENSA__ */
+
+#endif /* XTENSA_ZOL_MACROS_H */