[MIPS] Fix optimization for size build.

It took a while longer than on other architectures but gcc has finally
started to strike us as well ...
    
This also fixes the damage by 6edfba1b33c701108717f4e036320fc39abe1912.
    
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -83,6 +83,8 @@ cflags-y			+= -msoft-float
 LDFLAGS_vmlinux			+= -G 0 -static -n -nostdlib
 MODFLAGS			+= -mlong-calls
 
+cflags-y += -ffreestanding
+
 #
 # We explicitly add the endianness specifier if needed, this allows
 # to compile kernels with a toolchain for the other endianness. We

arch/mips/lib/Makefile

@@ -7,4 +7,7 @@ lib-y	+= csum_partial_copy.o memcpy.o promlib.o strlen_user.o strncpy_user.o \
 
 obj-y	+= iomap.o
 
+# libgcc-style stuff needed in the kernel
+lib-y += ashldi3.o ashrdi3.o lshrdi3.o
+
 EXTRA_AFLAGS := $(CFLAGS)

arch/mips/lib/ashldi3.c

@@ -0,0 +1,29 @@
+#include <linux/module.h>
+
+#include "libgcc.h"
+
+long long __ashldi3(long long u, word_type b)
+{
+	DWunion uu, w;
+	word_type bm;
+
+	if (b == 0)
+		return u;
+
+	uu.ll = u;
+	bm = 32 - b;
+
+	if (bm <= 0) {
+		w.s.low = 0;
+		w.s.high = (unsigned int) uu.s.low << -bm;
+	} else {
+		const unsigned int carries = (unsigned int) uu.s.low >> bm;
+
+		w.s.low = (unsigned int) uu.s.low << b;
+		w.s.high = ((unsigned int) uu.s.high << b) | carries;
+	}
+
+	return w.ll;
+}
+
+EXPORT_SYMBOL(__ashldi3);

arch/mips/lib/ashrdi3.c

@@ -0,0 +1,31 @@
+#include <linux/module.h>
+
+#include "libgcc.h"
+
+long long __ashrdi3(long long u, word_type b)
+{
+	DWunion uu, w;
+	word_type bm;
+
+	if (b == 0)
+		return u;
+
+	uu.ll = u;
+	bm = 32 - b;
+
+	if (bm <= 0) {
+		/* w.s.high = 1..1 or 0..0 */
+		w.s.high =
+		    uu.s.high >> 31;
+		w.s.low = uu.s.high >> -bm;
+	} else {
+		const unsigned int carries = (unsigned int) uu.s.high << bm;
+
+		w.s.high = uu.s.high >> b;
+		w.s.low = ((unsigned int) uu.s.low >> b) | carries;
+	}
+
+	return w.ll;
+}
+
+EXPORT_SYMBOL(__ashrdi3);

arch/mips/lib/libgcc.h

@@ -0,0 +1,26 @@
+#ifndef __ASM_LIBGCC_H
+#define __ASM_LIBGCC_H
+
+#include <asm/byteorder.h>
+
+typedef int word_type __attribute__ ((mode (__word__)));
+
+#ifdef __BIG_ENDIAN
+struct DWstruct {
+	int high, low;
+};
+#elif defined(__LITTLE_ENDIAN)
+struct DWstruct {
+	int low, high;
+};
+#else
+#error I feel sick.
+#endif
+
+typedef union
+{
+	struct DWstruct s;
+	long long ll;
+} DWunion;
+
+#endif /* __ASM_LIBGCC_H */

arch/mips/lib/lshrdi3.c

@@ -0,0 +1,29 @@
+#include <linux/module.h>
+
+#include "libgcc.h"
+
+long long __lshrdi3(long long u, word_type b)
+{
+	DWunion uu, w;
+	word_type bm;
+
+	if (b == 0)
+		return u;
+
+	uu.ll = u;
+	bm = 32 - b;
+
+	if (bm <= 0) {
+		w.s.high = 0;
+		w.s.low = (unsigned int) uu.s.high >> -bm;
+	} else {
+		const unsigned int carries = (unsigned int) uu.s.high << bm;
+
+		w.s.high = (unsigned int) uu.s.high >> b;
+		w.s.low = ((unsigned int) uu.s.low >> b) | carries;
+	}
+
+	return w.ll;
+}
+
+EXPORT_SYMBOL(__lshrdi3);