From b5666f70395016a55cc9d57826508b8a346398d0 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Mon, 5 Dec 2005 10:24:33 -0600 Subject: [PATCH] powerpc: Separate usage of KERNELBASE and PAGE_OFFSET This patch separates usage of KERNELBASE and PAGE_OFFSET. I haven't looked at any of the PPC32 code, if we ever want to support Kdump on PPC we'll have to do another audit, ditto for iSeries. This patch makes PAGE_OFFSET the constant, it'll always be 0xC * 1 gazillion for 64-bit. To get a physical address from a virtual one you subtract PAGE_OFFSET, _not_ KERNELBASE. KERNELBASE is the virtual address of the start of the kernel, it's often the same as PAGE_OFFSET, but _might not be_. If you want to know something's offset from the start of the kernel you should subtract KERNELBASE. Signed-off-by: Michael Ellerman Signed-off-by: Paul Mackerras --- include/asm-powerpc/page.h | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) (limited to 'include/asm-powerpc/page.h') diff --git a/include/asm-powerpc/page.h b/include/asm-powerpc/page.h index 94905ba2cf41..4696bdbcc085 100644 --- a/include/asm-powerpc/page.h +++ b/include/asm-powerpc/page.h @@ -37,6 +37,20 @@ */ #define PAGE_MASK (~((1 << PAGE_SHIFT) - 1)) +/* + * KERNELBASE is the virtual address of the start of the kernel, it's often + * the same as PAGE_OFFSET, but _might not be_. + * + * The kdump dump kernel is one example where KERNELBASE != PAGE_OFFSET. + * + * To get a physical address from a virtual one you subtract PAGE_OFFSET, + * _not_ KERNELBASE. + * + * If you want to know something's offset from the start of the kernel you + * should subtract KERNELBASE. + * + * If you want to test if something's a kernel address, use is_kernel_addr(). + */ #define PAGE_OFFSET ASM_CONST(CONFIG_KERNEL_START) #define KERNELBASE PAGE_OFFSET @@ -56,7 +70,7 @@ #define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT) #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) -#define __va(x) ((void *)((unsigned long)(x) + KERNELBASE)) +#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET)) #define __pa(x) ((unsigned long)(x) - PAGE_OFFSET) /* -- cgit v1.2.3