84 lines
2.6 KiB
Diff
84 lines
2.6 KiB
Diff
From: Aurelien Jarno <aurelien@aurel32.net>
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Date: Wed, 11 May 2016 00:37:42 +0200
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Subject: MIPS: Octeon: detect and fix byte swapped initramfs
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Origin: https://patchwork.linux-mips.org/patch/13219/
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Octeon machines support running in little endian mode. U-Boot usually
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runs in big endian-mode. Therefore the initramfs is loaded in big endian
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mode, and the kernel later tries to access it in little endian mode.
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This patch fixes that by detecting byte swapped initramfs using either the
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CPIO header or the header from standard compression methods, and
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byte swaps it if needed. It first checks that the header doesn't match
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in the native endianness to avoid false detections. It uses the kernel
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decompress library so that we don't have to maintain the list of magics
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if some decompression methods are added to the kernel.
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Cc: Ralf Baechle <ralf@linux-mips.org>
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Acked-by: David Daney <david.daney@cavium.com>
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Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
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---
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arch/mips/kernel/setup.c | 32 ++++++++++++++++++++++++++++++++
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1 file changed, 32 insertions(+)
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diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
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index 4f60734..8841d7982 100644
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--- a/arch/mips/kernel/setup.c
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+++ b/arch/mips/kernel/setup.c
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@@ -26,6 +26,7 @@
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#include <linux/sizes.h>
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#include <linux/device.h>
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#include <linux/dma-contiguous.h>
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+#include <linux/decompress/generic.h>
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#include <asm/addrspace.h>
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#include <asm/bootinfo.h>
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@@ -250,6 +251,35 @@ disable:
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return 0;
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}
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+/* In some conditions (e.g. big endian bootloader with a little endian
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+ kernel), the initrd might appear byte swapped. Try to detect this and
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+ byte swap it if needed. */
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+static void __init maybe_bswap_initrd(void)
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+{
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+#if defined(CONFIG_CPU_CAVIUM_OCTEON)
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+ u64 buf;
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+
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+ /* Check for CPIO signature */
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+ if (!memcmp((void *)initrd_start, "070701", 6))
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+ return;
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+
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+ /* Check for compressed initrd */
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+ if (decompress_method((unsigned char *)initrd_start, 8, NULL))
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+ return;
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+
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+ /* Try again with a byte swapped header */
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+ buf = swab64p((u64 *)initrd_start);
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+ if (!memcmp(&buf, "070701", 6) ||
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+ decompress_method((unsigned char *)(&buf), 8, NULL)) {
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+ unsigned long i;
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+
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+ pr_info("Byteswapped initrd detected\n");
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+ for (i = initrd_start; i < ALIGN(initrd_end, 8); i += 8)
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+ swab64s((u64 *)i);
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+ }
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+#endif
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+}
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+
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static void __init finalize_initrd(void)
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{
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unsigned long size = initrd_end - initrd_start;
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@@ -263,6 +293,8 @@ static void __init finalize_initrd(void)
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goto disable;
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}
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+ maybe_bswap_initrd();
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+
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reserve_bootmem(__pa(initrd_start), size, BOOTMEM_DEFAULT);
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initrd_below_start_ok = 1;
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--
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2.8.1
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