[PATCH v3 2/8] x86: Make it so that __pa_symbol can only process kernel symbols on x86_64

Alexander Duyck
2012-11-05T19:04:21Z

I submitted an earlier patch that make __phys_addr an inline. This obviously
results in an increase in the code size. One step I can take to reduce that
is to make it so that the __pa_symbol call does a direct translation for
kernel addresses instead of covering all of virtual memory.

On my system this reduced the size for __pa_symbol from 5 instructions
totalling 30 bytes to 3 instructions totalling 16 bytes.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
---

arch/x86/include/asm/page.h | 3 ++-
arch/x86/include/asm/page_32.h | 1 +
arch/x86/include/asm/page_64_types.h | 3 +++
arch/x86/mm/physaddr.c | 15 +++++++++++++++
4 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 8ca8283..3698a6a 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -44,7 +44,8 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
* case properly. Once all supported versions of gcc understand it, we can
* remove this Voodoo magic stuff. (i.e. once gcc3.x is deprecated)
*/
-#define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x)))
+#define __pa_symbol(x) \
+ __phys_addr_symbol(__phys_reloc_hide((unsigned long)(x)))

#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))

diff --git a/arch/x86/include/asm/page_32.h b/arch/x86/include/asm/page_32.h
index da4e762..4d550d0 100644
--- a/arch/x86/include/asm/page_32.h
+++ b/arch/x86/include/asm/page_32.h
@@ -15,6 +15,7 @@ extern unsigned long __phys_addr(unsigned long);
#else
#define __phys_addr(x) __phys_addr_nodebug(x)
#endif
+#define __phys_addr_symbol(x) __phys_addr(x)
#define __phys_reloc_hide(x) RELOC_HIDE((x), 0)

#ifdef CONFIG_FLATMEM
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 1ca93d3..a130589 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -69,8 +69,11 @@ static inline unsigned long __phys_addr_nodebug(unsigned long x)
}
#ifdef CONFIG_DEBUG_VIRTUAL
extern unsigned long __phys_addr(unsigned long);
+extern unsigned long __phys_addr_symbol(unsigned long);
#else
#define __phys_addr(x) __phys_addr_nodebug(x)
+#define __phys_addr_symbol(x) \
+ ((unsigned long)(x) - __START_KERNEL_map + phys_base)
#endif
#define __phys_reloc_hide(x) (x)

diff --git a/arch/x86/mm/physaddr.c b/arch/x86/mm/physaddr.c
index fd40d75..8420708 100644
--- a/arch/x86/mm/physaddr.c
+++ b/arch/x86/mm/physaddr.c
@@ -28,6 +28,21 @@ unsigned long __phys_addr(unsigned long x)
return x;
}
EXPORT_SYMBOL(__phys_addr);
+
+unsigned long __phys_addr_symbol(unsigned long x)
+{
+ unsigned long y = x - __START_KERNEL_map;
+
+ /* use the carry flag to determine if x was < __START_KERNEL_map */
+ VIRTUAL_BUG_ON(x < y);
+
+ x = y + phys_base;
+
+ VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);
+
+ return x;
+}
+EXPORT_SYMBOL(__phys_addr_symbol);
#endif

bool __virt_addr_valid(unsigned long x)