ARM: avoid unwanted GCC memset()/memcpy() optimisations for IO variants

We don't want GCC optimising our memset_io(), memcpy_fromio() or
memcpy_toio() variants, so we must not call one of the standard
functions.  Provide a separate name for our assembly memcpy() and
memset() functions, and use that instead, thereby bypassing GCC's
ability to optimise these operations.

GCCs optimisation may introduce unaligned accesses which are invalid
for device mappings.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index a5ed237c87d9a2d9f1688b29e0a7c38dbead835a..485982084fe96aef7218aeb134527b41f90beb1e 100644 (file)
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -316,21 +316,24 @@ extern void _memset_io(volatile void __iomem *, int, size_t);
 static inline void memset_io(volatile void __iomem *dst, unsigned c,
        size_t count)
 {
-       memset((void __force *)dst, c, count);
+       extern void mmioset(void *, unsigned int, size_t);
+       mmioset((void __force *)dst, c, count);
 }
 #define memset_io(dst,c,count) memset_io(dst,c,count)
 
 static inline void memcpy_fromio(void *to, const volatile void __iomem *from,
        size_t count)
 {
-       memcpy(to, (const void __force *)from, count);
+       extern void mmiocpy(void *, const void *, size_t);
+       mmiocpy(to, (const void __force *)from, count);
 }
 #define memcpy_fromio(to,from,count) memcpy_fromio(to,from,count)
 
 static inline void memcpy_toio(volatile void __iomem *to, const void *from,
        size_t count)
 {
-       memcpy((void __force *)to, from, count);
+       extern void mmiocpy(void *, const void *, size_t);
+       mmiocpy((void __force *)to, from, count);
 }
 #define memcpy_toio(to,from,count) memcpy_toio(to,from,count)
 

diff --git a/arch/arm/kernel/armksyms.c b/arch/arm/kernel/armksyms.c
index a88671cfe1ffb1e1ee43b06a7c8c6fd704f38580..5e5a51a99e68ec77b38b8101611bc853eb8496af 100644 (file)
--- a/arch/arm/kernel/armksyms.c
+++ b/arch/arm/kernel/armksyms.c
@@ -50,6 +50,9 @@ extern void __aeabi_ulcmp(void);
 
 extern void fpundefinstr(void);
 
+void mmioset(void *, unsigned int, size_t);
+void mmiocpy(void *, const void *, size_t);
+
        /* platform dependent support */
 EXPORT_SYMBOL(arm_delay_ops);
 
@@ -88,6 +91,9 @@ EXPORT_SYMBOL(memmove);
 EXPORT_SYMBOL(memchr);
 EXPORT_SYMBOL(__memzero);
 
+EXPORT_SYMBOL(mmioset);
+EXPORT_SYMBOL(mmiocpy);
+
 #ifdef CONFIG_MMU
 EXPORT_SYMBOL(copy_page);
 

diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
index 7797e81e40e00f72a85ba90dc5abcc1227504b44..64111bd4440b1aa3702c469ce349b303a0244ebd 100644 (file)
--- a/arch/arm/lib/memcpy.S
+++ b/arch/arm/lib/memcpy.S
@@ -61,8 +61,10 @@
 
 /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
 
+ENTRY(mmiocpy)
 ENTRY(memcpy)
 
 #include "copy_template.S"
 
 ENDPROC(memcpy)
+ENDPROC(mmiocpy)

diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S
index a4ee97b5a2bfcfd3099353b44e8678c4df5bff6b..3c65e3bd790fe1f7aec59d9568cb4c0799be0e9a 100644 (file)
--- a/arch/arm/lib/memset.S
+++ b/arch/arm/lib/memset.S
@@ -16,6 +16,7 @@
        .text
        .align  5
 
+ENTRY(mmioset)
 ENTRY(memset)
 UNWIND( .fnstart         )
        ands    r3, r0, #3              @ 1 unaligned?
@@ -133,3 +134,4 @@ UNWIND( .fnstart            )
        b       1b
 UNWIND( .fnend   )
 ENDPROC(memset)
+ENDPROC(mmioset)