From 82497fa02d60757c2cfa645cf89a79abb1435273 Mon Sep 17 00:00:00 2001
From: Jean Delvare <jdelvare@suse.de>
Date: Fri, 16 Nov 2018 11:18:25 +0100
Subject: [PATCH 02/18] dmidecode: Don't use memcpy on /dev/mem on arm64

On arm64, calling memcpy on /dev/mem will cause a bus error if the
start and the end of the buffer are not aligned on a 64-bit boundary.
Using option --no-sysfs triggers this.

Use a slow manual byte-by-byte copy in that case, to prevent the bus
error. This is only a fallback path (at least on Linux) and not
performance-critical anyway, as it is a one-time operation and DMI
tables are usually not too large.

This fixes bug #55026:
https://savannah.nongnu.org/bugs/index.php?55026

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
 config.h |  5 +++++
 util.c   | 14 +++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/config.h b/config.h
index e39091f..4237355 100644
--- a/config.h
+++ b/config.h
@@ -26,4 +26,9 @@
 #define ALIGNMENT_WORKAROUND
 #endif
 
+/* Avoid unaligned memcpy on /dev/mem */
+#ifdef __aarch64__
+#define USE_SLOW_MEMCPY
+#endif
+
 #endif
diff --git a/util.c b/util.c
index eeffdae..04aaadd 100644
--- a/util.c
+++ b/util.c
@@ -155,6 +155,18 @@ void *read_file(off_t base, size_t *max_len, const char *filename)
 	return p;
 }
 
+static void safe_memcpy(void *dest, const void *src, size_t n)
+{
+#ifdef USE_SLOW_MEMCPY
+	size_t i;
+
+	for (i = 0; i < n; i++)
+		*((u8 *)dest + i) = *((const u8 *)src + i);
+#else
+	memcpy(dest, src, n);
+#endif
+}
+
 /*
  * Copy a physical memory chunk into a memory buffer.
  * This function allocates memory.
@@ -214,7 +226,7 @@ void *mem_chunk(off_t base, size_t len, const char *devmem)
 	if (mmp == MAP_FAILED)
 		goto try_read;
 
-	memcpy(p, (u8 *)mmp + mmoffset, len);
+	safe_memcpy(p, (u8 *)mmp + mmoffset, len);
 
 	if (munmap(mmp, mmoffset + len) == -1)
 	{
-- 
2.24.0