m68k: runtime patching infrastructure

Add the basic infrastructure to allow runtime patching of kernel and modules
to optimize a few functions with parameters, which are only calculated once
during bootup and are otherwise constant.  Use this for the conversion between
virtual and physical addresses.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 58 insertions, 4 deletions

diff --git a/include/asm-m68k/module.h b/include/asm-m68k/module.h
index c6d75af2d8d3..71a1f76ac891 100644
--- a/include/asm-m68k/module.h
+++ b/include/asm-m68k/module.h
@@ -1,7 +1,38 @@
 #ifndef _ASM_M68K_MODULE_H
 #define _ASM_M68K_MODULE_H
-struct mod_arch_specific { };
+
+struct mod_arch_specific {
+        struct m68k_fixup_info *fixup_start, *fixup_end;
+};
+
+#define MODULE_ARCH_INIT {                              \
+        .fixup_start            = __start_fixup,        \
+        .fixup_end              = __stop_fixup,         \
+}
+
 #define Elf_Shdr Elf32_Shdr
 #define Elf_Sym Elf32_Sym
 #define Elf_Ehdr Elf32_Ehdr
+
+
+enum m68k_fixup_type {
+        m68k_fixup_memoffset,
+};
+
+struct m68k_fixup_info {
+        enum m68k_fixup_type type;
+        void *addr;
+};
+
+#define m68k_fixup(type, addr)                  \
+        "       .section \".m68k_fixup\",\"aw\"\n"      \
+        "       .long " #type "," #addr "\n"    \
+        "       .previous\n"
+
+extern struct m68k_fixup_info __start_fixup[], __stop_fixup[];
+
+struct module;
+extern void module_fixup(struct module *mod, struct m68k_fixup_info *start,
+                         struct m68k_fixup_info *end);
+
 #endif /* _ASM_M68K_MODULE_H */
diff --git a/include/asm-m68k/page.h b/include/asm-m68k/page.h
index fcc165ddd09e..7650b99dcae6 100644
--- a/include/asm-m68k/page.h
+++ b/include/asm-m68k/page.h
@@ -27,6 +27,8 @@
 
 #ifndef __ASSEMBLY__
 
+#include <asm/module.h>
+
 #define get_user_page(vaddr)            __get_free_page(GFP_KERNEL)
 #define free_user_page(page, addr)      free_page(addr)
 
@@ -114,14 +116,35 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 
 #ifndef __ASSEMBLY__
 
+extern unsigned long m68k_memoffset;
+
 #ifndef CONFIG_SUN3
 
 #define WANT_PAGE_VIRTUAL
 #ifdef CONFIG_SINGLE_MEMORY_CHUNK
-extern unsigned long m68k_memoffset;
 
-#define __pa(vaddr)             ((unsigned long)(vaddr)+m68k_memoffset)
-#define __va(paddr)             ((void *)((unsigned long)(paddr)-m68k_memoffset))
+static inline unsigned long ___pa(void *vaddr)
+{
+        unsigned long paddr;
+        asm (
+                "1:     addl #0,%0\n"
+                m68k_fixup(%c2, 1b+2)
+                : "=r" (paddr)
+                : "0" (vaddr), "i" (m68k_fixup_memoffset));
+        return paddr;
+}
+#define __pa(vaddr)    ___pa((void *)(vaddr))
+static inline void *__va(unsigned long paddr)
+{
+        void *vaddr;
+        asm (
+                "1:     subl #0,%0\n"
+                m68k_fixup(%c2, 1b+2)
+                : "=r" (vaddr)
+                : "0" (paddr), "i" (m68k_fixup_memoffset));
+        return vaddr;
+}
+
 #else
 #define __pa(vaddr)             virt_to_phys((void *)(vaddr))
 #define __va(paddr)             phys_to_virt((unsigned long)(paddr))