diff options
| -rw-r--r-- | arch/powerpc/include/asm/page.h | 85 | ||||
| -rw-r--r-- | arch/powerpc/mm/init_32.c | 7 |
2 files changed, 89 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h index f149967ee6b..f072e974f8a 100644 --- a/arch/powerpc/include/asm/page.h +++ b/arch/powerpc/include/asm/page.h @@ -97,12 +97,26 @@ extern unsigned int HPAGE_SHIFT; extern phys_addr_t memstart_addr; extern phys_addr_t kernstart_addr; + +#ifdef CONFIG_RELOCATABLE_PPC32 +extern long long virt_phys_offset; #endif + +#endif /* __ASSEMBLY__ */ #define PHYSICAL_START kernstart_addr -#else + +#else /* !CONFIG_NONSTATIC_KERNEL */ #define PHYSICAL_START ASM_CONST(CONFIG_PHYSICAL_START) #endif +/* See Description below for VIRT_PHYS_OFFSET */ +#ifdef CONFIG_RELOCATABLE_PPC32 +#define VIRT_PHYS_OFFSET virt_phys_offset +#else +#define VIRT_PHYS_OFFSET (KERNELBASE - PHYSICAL_START) +#endif + + #ifdef CONFIG_PPC64 #define MEMORY_START 0UL #elif defined(CONFIG_NONSTATIC_KERNEL) @@ -125,12 +139,77 @@ extern phys_addr_t kernstart_addr; * determine MEMORY_START until then. However we can determine PHYSICAL_START * from information at hand (program counter, TLB lookup). * + * On BookE with RELOCATABLE (RELOCATABLE_PPC32) + * + * With RELOCATABLE_PPC32, we support loading the kernel at any physical + * address without any restriction on the page alignment. + * + * We find the runtime address of _stext and relocate ourselves based on + * the following calculation: + * + * virtual_base = ALIGN_DOWN(KERNELBASE,256M) + + * MODULO(_stext.run,256M) + * and create the following mapping: + * + * ALIGN_DOWN(_stext.run,256M) => ALIGN_DOWN(KERNELBASE,256M) + * + * When we process relocations, we cannot depend on the + * existing equation for the __va()/__pa() translations: + * + * __va(x) = (x) - PHYSICAL_START + KERNELBASE + * + * Where: + * PHYSICAL_START = kernstart_addr = Physical address of _stext + * KERNELBASE = Compiled virtual address of _stext. + * + * This formula holds true iff, kernel load address is TLB page aligned. + * + * In our case, we need to also account for the shift in the kernel Virtual + * address. + * + * E.g., + * + * Let the kernel be loaded at 64MB and KERNELBASE be 0xc0000000 (same as PAGE_OFFSET). + * In this case, we would be mapping 0 to 0xc0000000, and kernstart_addr = 64M + * + * Now __va(1MB) = (0x100000) - (0x4000000) + 0xc0000000 + * = 0xbc100000 , which is wrong. + * + * Rather, it should be : 0xc0000000 + 0x100000 = 0xc0100000 + * according to our mapping. + * + * Hence we use the following formula to get the translations right: + * + * __va(x) = (x) - [ PHYSICAL_START - Effective KERNELBASE ] + * + * Where : + * PHYSICAL_START = dynamic load address.(kernstart_addr variable) + * Effective KERNELBASE = virtual_base = + * = ALIGN_DOWN(KERNELBASE,256M) + + * MODULO(PHYSICAL_START,256M) + * + * To make the cost of __va() / __pa() more light weight, we introduce + * a new variable virt_phys_offset, which will hold : + * + * virt_phys_offset = Effective KERNELBASE - PHYSICAL_START + * = ALIGN_DOWN(KERNELBASE,256M) - + * ALIGN_DOWN(PHYSICALSTART,256M) + * + * Hence : + * + * __va(x) = x - PHYSICAL_START + Effective KERNELBASE + * = x + virt_phys_offset + * + * and + * __pa(x) = x + PHYSICAL_START - Effective KERNELBASE + * = x - virt_phys_offset + * * On non-Book-E PPC64 PAGE_OFFSET and MEMORY_START are constants so use * the other definitions for __va & __pa. */ #ifdef CONFIG_BOOKE -#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) - PHYSICAL_START + KERNELBASE)) -#define __pa(x) ((unsigned long)(x) + PHYSICAL_START - KERNELBASE) +#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + VIRT_PHYS_OFFSET)) +#define __pa(x) ((unsigned long)(x) - VIRT_PHYS_OFFSET) #else #define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + PAGE_OFFSET - MEMORY_START)) #define __pa(x) ((unsigned long)(x) - PAGE_OFFSET + MEMORY_START) diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c index 161cefde5c1..60a4e4e84e8 100644 --- a/arch/powerpc/mm/init_32.c +++ b/arch/powerpc/mm/init_32.c @@ -65,6 +65,13 @@ phys_addr_t memstart_addr = (phys_addr_t)~0ull; EXPORT_SYMBOL(memstart_addr); phys_addr_t kernstart_addr; EXPORT_SYMBOL(kernstart_addr); + +#ifdef CONFIG_RELOCATABLE_PPC32 +/* Used in __va()/__pa() */ +long long virt_phys_offset; +EXPORT_SYMBOL(virt_phys_offset); +#endif + phys_addr_t lowmem_end_addr; int boot_mapsize; |