Fixed MTP to work with TWRP

arch/arm64/kernel/efi-entry.S

@@ -0,0 +1,123 @@
+/*
+ * EFI entry point.
+ *
+ * Copyright (C) 2013, 2014 Red Hat, Inc.
+ * Author: Mark Salter <msalter@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+#include <asm/assembler.h>
+
+#define EFI_LOAD_ERROR 0x8000000000000001
+
+	__INIT
+
+	/*
+	 * We arrive here from the EFI boot manager with:
+	 *
+	 *    * CPU in little-endian mode
+	 *    * MMU on with identity-mapped RAM
+	 *    * Icache and Dcache on
+	 *
+	 * We will most likely be running from some place other than where
+	 * we want to be. The kernel image wants to be placed at TEXT_OFFSET
+	 * from start of RAM.
+	 */
+ENTRY(efi_stub_entry)
+	/*
+	 * Create a stack frame to save FP/LR with extra space
+	 * for image_addr variable passed to efi_entry().
+	 */
+	stp	x29, x30, [sp, #-32]!
+
+	/*
+	 * Call efi_entry to do the real work.
+	 * x0 and x1 are already set up by firmware. Current runtime
+	 * address of image is calculated and passed via *image_addr.
+	 *
+	 * unsigned long efi_entry(void *handle,
+	 *                         efi_system_table_t *sys_table,
+	 *                         unsigned long *image_addr) ;
+	 */
+	adrp	x8, _text
+	add	x8, x8, #:lo12:_text
+	add	x2, sp, 16
+	str	x8, [x2]
+	bl	efi_entry
+	cmn	x0, #1
+	b.eq	efi_load_fail
+
+	/*
+	 * efi_entry() will have copied the kernel image if necessary and we
+	 * return here with device tree address in x0 and the kernel entry
+	 * point stored at *image_addr. Save those values in registers which
+	 * are callee preserved.
+	 */
+	mov	x20, x0		// DTB address
+	ldr	x0, [sp, #16]	// relocated _text address
+	mov	x21, x0
+
+	/*
+	 * Calculate size of the kernel Image (same for original and copy).
+	 */
+	adrp	x1, _text
+	add	x1, x1, #:lo12:_text
+	adrp	x2, _edata
+	add	x2, x2, #:lo12:_edata
+	sub	x1, x2, x1
+
+	/*
+	 * Flush the copied Image to the PoC, and ensure it is not shadowed by
+	 * stale icache entries from before relocation.
+	 */
+	bl	__flush_dcache_area
+	ic	ialluis
+
+	/*
+	 * Ensure that the rest of this function (in the original Image) is
+	 * visible when the caches are disabled. The I-cache can't have stale
+	 * entries for the VA range of the current image, so no maintenance is
+	 * necessary.
+	 */
+	adr	x0, efi_stub_entry
+	adr	x1, efi_stub_entry_end
+	sub	x1, x1, x0
+	bl	__flush_dcache_area
+
+	/* Turn off Dcache and MMU */
+	mrs	x0, CurrentEL
+	cmp	x0, #CurrentEL_EL2
+	b.ne	1f
+	mrs	x0, sctlr_el2
+	bic	x0, x0, #1 << 0	// clear SCTLR.M
+	bic	x0, x0, #1 << 2	// clear SCTLR.C
+	msr	sctlr_el2, x0
+	isb
+	b	2f
+1:
+	mrs	x0, sctlr_el1
+	bic	x0, x0, #1 << 0	// clear SCTLR.M
+	bic	x0, x0, #1 << 2	// clear SCTLR.C
+	msr	sctlr_el1, x0
+	isb
+2:
+	/* Jump to kernel entry point */
+	mov	x0, x20
+	mov	x1, xzr
+	mov	x2, xzr
+	mov	x3, xzr
+	br	x21
+
+efi_load_fail:
+	mov	x0, #EFI_LOAD_ERROR
+	ldp	x29, x30, [sp], #32
+	ret
+
+efi_stub_entry_end:
+ENDPROC(efi_stub_entry)