Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 517e0e1..93dffed 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -1,12 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
/*
* linux/arch/arm/boot/compressed/head.S
*
* Copyright (C) 1996-2002 Russell King
* Copyright (C) 2004 Hyok S. Choi (MPU support)
- *
- * 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 <asm/assembler.h>
@@ -114,6 +111,35 @@
#endif
.endm
+ /*
+ * Debug kernel copy by printing the memory addresses involved
+ */
+ .macro dbgkc, begin, end, cbegin, cend
+#ifdef DEBUG
+ kputc #'\n'
+ kputc #'C'
+ kputc #':'
+ kputc #'0'
+ kputc #'x'
+ kphex \begin, 8 /* Start of compressed kernel */
+ kputc #'-'
+ kputc #'0'
+ kputc #'x'
+ kphex \end, 8 /* End of compressed kernel */
+ kputc #'-'
+ kputc #'>'
+ kputc #'0'
+ kputc #'x'
+ kphex \cbegin, 8 /* Start of kernel copy */
+ kputc #'-'
+ kputc #'0'
+ kputc #'x'
+ kphex \cend, 8 /* End of kernel copy */
+ kputc #'\n'
+ kputc #'\r'
+#endif
+ .endm
+
.section ".start", #alloc, #execinstr
/*
* sort out different calling conventions
@@ -127,11 +153,23 @@
AR_CLASS( .arm )
start:
.type start,#function
+ /*
+ * These 7 nops along with the 1 nop immediately below for
+ * !THUMB2 form 8 nops that make the compressed kernel bootable
+ * on legacy ARM systems that were assuming the kernel in a.out
+ * binary format. The boot loaders on these systems would
+ * jump 32 bytes into the image to skip the a.out header.
+ * with these 8 nops filling exactly 32 bytes, things still
+ * work as expected on these legacy systems. Thumb2 mode keeps
+ * 7 of the nops as it turns out that some boot loaders
+ * were patching the initial instructions of the kernel, i.e
+ * had started to exploit this "patch area".
+ */
.rept 7
__nop
.endr
#ifndef CONFIG_THUMB2_KERNEL
- mov r0, r0
+ __nop
#else
AR_CLASS( sub pc, pc, #3 ) @ A/R: switch to Thumb2 mode
M_CLASS( nop.w ) @ M: already in Thumb2 mode
@@ -450,6 +488,20 @@
add r6, r9, r5
add r9, r9, r10
+#ifdef DEBUG
+ sub r10, r6, r5
+ sub r10, r9, r10
+ /*
+ * We are about to copy the kernel to a new memory area.
+ * The boundaries of the new memory area can be found in
+ * r10 and r9, whilst r5 and r6 contain the boundaries
+ * of the memory we are going to copy.
+ * Calling dbgkc will help with the printing of this
+ * information.
+ */
+ dbgkc r5, r6, r10, r9
+#endif
+
1: ldmdb r6!, {r0 - r3, r10 - r12, lr}
cmp r6, r5
stmdb r9!, {r0 - r3, r10 - r12, lr}
@@ -1395,7 +1447,21 @@
@ Preserve return value of efi_entry() in r4
mov r4, r0
- bl cache_clean_flush
+
+ @ our cache maintenance code relies on CP15 barrier instructions
+ @ but since we arrived here with the MMU and caches configured
+ @ by UEFI, we must check that the CP15BEN bit is set in SCTLR.
+ @ Note that this bit is RAO/WI on v6 and earlier, so the ISB in
+ @ the enable path will be executed on v7+ only.
+ mrc p15, 0, r1, c1, c0, 0 @ read SCTLR
+ tst r1, #(1 << 5) @ CP15BEN bit set?
+ bne 0f
+ orr r1, r1, #(1 << 5) @ CP15 barrier instructions
+ mcr p15, 0, r1, c1, c0, 0 @ write SCTLR
+ ARM( .inst 0xf57ff06f @ v7+ isb )
+ THUMB( isb )
+
+0: bl cache_clean_flush
bl cache_off
@ Set parameters for booting zImage according to boot protocol