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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-09-11 04:34:46 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-09-11 04:34:46 -0300
commit863981e96738983919de841ec669e157e6bdaeb0 (patch)
treed6d89a12e7eb8017837c057935a2271290907f76 /arch/x86/boot/compressed/string.c
parent8dec7c70575785729a6a9e6719a955e9c545bcab (diff)
Linux-libre 4.7.1-gnupck-4.7.1-gnu
Diffstat (limited to 'arch/x86/boot/compressed/string.c')
-rw-r--r--arch/x86/boot/compressed/string.c37
1 files changed, 35 insertions, 2 deletions
diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
index 00e788be1..cea140ce6 100644
--- a/arch/x86/boot/compressed/string.c
+++ b/arch/x86/boot/compressed/string.c
@@ -1,7 +1,16 @@
+/*
+ * This provides an optimized implementation of memcpy, and a simplified
+ * implementation of memset and memmove. These are used here because the
+ * standard kernel runtime versions are not yet available and we don't
+ * trust the gcc built-in implementations as they may do unexpected things
+ * (e.g. FPU ops) in the minimal decompression stub execution environment.
+ */
+#include "error.h"
+
#include "../string.c"
#ifdef CONFIG_X86_32
-void *memcpy(void *dest, const void *src, size_t n)
+static void *__memcpy(void *dest, const void *src, size_t n)
{
int d0, d1, d2;
asm volatile(
@@ -15,7 +24,7 @@ void *memcpy(void *dest, const void *src, size_t n)
return dest;
}
#else
-void *memcpy(void *dest, const void *src, size_t n)
+static void *__memcpy(void *dest, const void *src, size_t n)
{
long d0, d1, d2;
asm volatile(
@@ -39,3 +48,27 @@ void *memset(void *s, int c, size_t n)
ss[i] = c;
return s;
}
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+ unsigned char *d = dest;
+ const unsigned char *s = src;
+
+ if (d <= s || d - s >= n)
+ return __memcpy(dest, src, n);
+
+ while (n-- > 0)
+ d[n] = s[n];
+
+ return dest;
+}
+
+/* Detect and warn about potential overlaps, but handle them with memmove. */
+void *memcpy(void *dest, const void *src, size_t n)
+{
+ if (dest > src && dest - src < n) {
+ warn("Avoiding potentially unsafe overlapping memcpy()!");
+ return memmove(dest, src, n);
+ }
+ return __memcpy(dest, src, n);
+}