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109 lines
2.4 KiB
109 lines
2.4 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Example of using hugepage memory in a user application using the mmap |
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* system call with MAP_HUGETLB flag. Before running this program make |
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* sure the administrator has allocated enough default sized huge pages |
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* to cover the 256 MB allocation. |
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* |
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* For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. |
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* That means the addresses starting with 0x800000... will need to be |
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* specified. Specifying a fixed address is not required on ppc64, i386 |
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* or x86_64. |
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*/ |
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#include <stdlib.h> |
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#include <stdio.h> |
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#include <unistd.h> |
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#include <sys/mman.h> |
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#include <fcntl.h> |
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#define LENGTH (256UL*1024*1024) |
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#define PROTECTION (PROT_READ | PROT_WRITE) |
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#ifndef MAP_HUGETLB |
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#define MAP_HUGETLB 0x40000 /* arch specific */ |
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#endif |
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#ifndef MAP_HUGE_SHIFT |
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#define MAP_HUGE_SHIFT 26 |
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#endif |
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#ifndef MAP_HUGE_MASK |
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#define MAP_HUGE_MASK 0x3f |
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#endif |
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/* Only ia64 requires this */ |
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#ifdef __ia64__ |
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#define ADDR (void *)(0x8000000000000000UL) |
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#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) |
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#else |
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#define ADDR (void *)(0x0UL) |
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#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) |
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#endif |
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static void check_bytes(char *addr) |
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{ |
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printf("First hex is %x\n", *((unsigned int *)addr)); |
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} |
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static void write_bytes(char *addr, size_t length) |
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{ |
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unsigned long i; |
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for (i = 0; i < length; i++) |
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*(addr + i) = (char)i; |
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} |
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static int read_bytes(char *addr, size_t length) |
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{ |
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unsigned long i; |
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check_bytes(addr); |
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for (i = 0; i < length; i++) |
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if (*(addr + i) != (char)i) { |
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printf("Mismatch at %lu\n", i); |
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return 1; |
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} |
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return 0; |
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} |
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int main(int argc, char **argv) |
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{ |
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void *addr; |
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int ret; |
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size_t length = LENGTH; |
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int flags = FLAGS; |
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int shift = 0; |
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if (argc > 1) |
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length = atol(argv[1]) << 20; |
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if (argc > 2) { |
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shift = atoi(argv[2]); |
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if (shift) |
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flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT; |
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} |
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if (shift) |
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printf("%u kB hugepages\n", 1 << (shift - 10)); |
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else |
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printf("Default size hugepages\n"); |
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printf("Mapping %lu Mbytes\n", (unsigned long)length >> 20); |
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addr = mmap(ADDR, length, PROTECTION, flags, -1, 0); |
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if (addr == MAP_FAILED) { |
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perror("mmap"); |
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exit(1); |
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} |
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printf("Returned address is %p\n", addr); |
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check_bytes(addr); |
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write_bytes(addr, length); |
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ret = read_bytes(addr, length); |
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/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ |
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if (munmap(addr, length)) { |
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perror("munmap"); |
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exit(1); |
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} |
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return ret; |
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}
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