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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/arm64/kernel/efi-entry.S
Initial import
Diffstat (limited to 'arch/arm64/kernel/efi-entry.S')
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diff --git a/arch/arm64/kernel/efi-entry.S b/arch/arm64/kernel/efi-entry.S
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+/*
+ * 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
+ ldr x21, =stext_offset
+ add x21, x0, x21
+
+ /*
+ * 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)