This patch provides the interfaces necessary to read the dump contents, treating it as a high memory device. Signed off by Hariprasad Nellitheertha --- linux-2.6.8.1-hari/arch/i386/mm/highmem.c | 18 ++++++++++ linux-2.6.8.1-hari/drivers/char/mem.c | 44 ++++++++++++++++++++++++++ linux-2.6.8.1-hari/include/asm-i386/highmem.h | 1 linux-2.6.8.1-hari/include/linux/highmem.h | 1 4 files changed, 64 insertions(+) diff -puN arch/i386/mm/highmem.c~kd-copy-268 arch/i386/mm/highmem.c --- linux-2.6.8.1/arch/i386/mm/highmem.c~kd-copy-268 2004-08-17 17:06:21.000000000 +0530 +++ linux-2.6.8.1-hari/arch/i386/mm/highmem.c 2004-08-17 17:06:27.000000000 +0530 @@ -74,6 +74,24 @@ void kunmap_atomic(void *kvaddr, enum km preempt_check_resched(); } +/* This is the same as kmap_atomic but takes in a pfn instead of a + * struct page. + */ +void *kmap_atomic_pfn(unsigned long pfn, enum km_type type) +{ + enum fixed_addresses idx; + unsigned long vaddr; + + inc_preempt_count(); + + idx = type + KM_TYPE_NR*smp_processor_id(); + vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot)); + __flush_tlb_one(vaddr); + + return (void*) vaddr; +} + struct page *kmap_atomic_to_page(void *ptr) { unsigned long idx, vaddr = (unsigned long)ptr; diff -puN drivers/char/mem.c~kd-copy-268 drivers/char/mem.c --- linux-2.6.8.1/drivers/char/mem.c~kd-copy-268 2004-08-17 17:06:21.000000000 +0530 +++ linux-2.6.8.1-hari/drivers/char/mem.c 2004-08-17 17:06:27.000000000 +0530 @@ -23,9 +23,13 @@ #include #include #include +#include #include #include +#include +#include +#include #ifdef CONFIG_IA64 # include @@ -38,6 +42,8 @@ extern void fbmem_init(void); extern void tapechar_init(void); #endif +ssize_t copy_hmem_page(unsigned long, char *, size_t, int); + /* * Architectures vary in how they handle caching for addresses * outside of main memory. @@ -219,6 +225,44 @@ static int mmap_mem(struct file * file, return 0; } +/* + * Copy a page from "highmem". For this page, there is no pte mapped + * in the current kernel. We stitch up a pte, similar to kmap_atomic. + */ +ssize_t copy_hmem_page(unsigned long pfn, char *buf, size_t csize, int userbuf) +{ + void *page, *vaddr; + + if (!csize) + return 0; + + if (pfn == -1) { + /* Give them a zeroed page */ + if (userbuf) { + if (clear_user(buf, csize)) + return -EFAULT; + } else + memset(buf, 0, csize); + } else { + page = kmalloc(PAGE_SIZE, GFP_KERNEL); + + vaddr = kmap_atomic_pfn(pfn, KM_PTE0); + copy_page(page, vaddr); + kunmap_atomic(vaddr, KM_PTE0); + + if (userbuf) { + if (copy_to_user(buf, page, csize)) { + kfree(page); + return -EFAULT; + } + } else + memcpy(buf, page, csize); + kfree(page); + } + + return 0; +} + extern long vread(char *buf, char *addr, unsigned long count); extern long vwrite(char *buf, char *addr, unsigned long count); diff -puN include/asm-i386/highmem.h~kd-copy-268 include/asm-i386/highmem.h --- linux-2.6.8.1/include/asm-i386/highmem.h~kd-copy-268 2004-08-17 17:06:21.000000000 +0530 +++ linux-2.6.8.1-hari/include/asm-i386/highmem.h 2004-08-17 17:06:27.000000000 +0530 @@ -61,6 +61,7 @@ void *kmap(struct page *page); void kunmap(struct page *page); void *kmap_atomic(struct page *page, enum km_type type); void kunmap_atomic(void *kvaddr, enum km_type type); +void *kmap_atomic_pfn(unsigned long pfn, enum km_type type); struct page *kmap_atomic_to_page(void *ptr); #define flush_cache_kmaps() do { } while (0) diff -puN include/linux/highmem.h~kd-copy-268 include/linux/highmem.h --- linux-2.6.8.1/include/linux/highmem.h~kd-copy-268 2004-08-17 17:06:21.000000000 +0530 +++ linux-2.6.8.1-hari/include/linux/highmem.h 2004-08-17 17:06:27.000000000 +0530 @@ -30,6 +30,7 @@ static inline void *kmap(struct page *pa #define kmap_atomic(page, idx) page_address(page) #define kunmap_atomic(addr, idx) do { } while (0) +#define kmap_atomic_pfn(pfn, idx) page_address(pfn_to_page(pfn)) #define kmap_atomic_to_page(ptr) virt_to_page(ptr) #endif /* CONFIG_HIGHMEM */ _