cregit-Linux how code gets into the kernel

Release 4.18 tools/testing/selftests/vm/virtual_address_range.c

/*
 * Copyright 2017, Anshuman Khandual, IBM Corp.
 * Licensed under GPLv2.
 *
 * Works on architectures which support 128TB virtual
 * address range and beyond.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/time.h>

/*
 * Maximum address range mapped with a single mmap()
 * call is little bit more than 16GB. Hence 16GB is
 * chosen as the single chunk size for address space
 * mapping.
 */

#define MAP_CHUNK_SIZE   17179869184UL 
/* 16GB */

/*
 * Address space till 128TB is mapped without any hint
 * and is enabled by default. Address space beyond 128TB
 * till 512TB is obtained by passing hint address as the
 * first argument into mmap() system call.
 *
 * The process heap address space is divided into two
 * different areas one below 128TB and one above 128TB
 * till it reaches 512TB. One with size 128TB and the
 * other being 384TB.
 *
 * On Arm64 the address space is 256TB and no high mappings
 * are supported so far.
 */


#define NR_CHUNKS_128TB   8192UL 
/* Number of 16GB chunks for 128TB */

#define NR_CHUNKS_256TB   (NR_CHUNKS_128TB * 2UL)

#define NR_CHUNKS_384TB   (NR_CHUNKS_128TB * 3UL)


#define ADDR_MARK_128TB  (1UL << 47) 
/* First address beyond 128TB */

#define ADDR_MARK_256TB  (1UL << 48) 
/* First address beyond 256TB */

#ifdef __aarch64__

#define HIGH_ADDR_MARK  ADDR_MARK_256TB

#define HIGH_ADDR_SHIFT 49

#define NR_CHUNKS_LOW   NR_CHUNKS_256TB

#define NR_CHUNKS_HIGH  0
#else

#define HIGH_ADDR_MARK  ADDR_MARK_128TB

#define HIGH_ADDR_SHIFT 48

#define NR_CHUNKS_LOW   NR_CHUNKS_128TB

#define NR_CHUNKS_HIGH  NR_CHUNKS_384TB
#endif


static char *hind_addr(void) { int bits = HIGH_ADDR_SHIFT + rand() % (63 - HIGH_ADDR_SHIFT); return (char *) (1UL << bits); }

Contributors

PersonTokensPropCommitsCommitProp
Anshuman Khandual2882.35%150.00%
Michal Suchanek617.65%150.00%
Total34100.00%2100.00%


static int validate_addr(char *ptr, int high_addr) { unsigned long addr = (unsigned long) ptr; if (high_addr) { if (addr < HIGH_ADDR_MARK) { printf("Bad address %lx\n", addr); return 1; } return 0; } if (addr > HIGH_ADDR_MARK) { printf("Bad address %lx\n", addr); return 1; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Anshuman Khandual6997.18%150.00%
Michal Suchanek22.82%150.00%
Total71100.00%2100.00%


static int validate_lower_address_hint(void) { char *ptr; ptr = mmap((void *) (1UL << 45), MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (ptr == MAP_FAILED) return 0; return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Anshuman Khandual54100.00%1100.00%
Total54100.00%1100.00%


int main(int argc, char *argv[]) { char *ptr[NR_CHUNKS_LOW]; char *hptr[NR_CHUNKS_HIGH]; char *hint; unsigned long i, lchunks, hchunks; for (i = 0; i < NR_CHUNKS_LOW; i++) { ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (ptr[i] == MAP_FAILED) { if (validate_lower_address_hint()) return 1; break; } if (validate_addr(ptr[i], 0)) return 1; } lchunks = i; for (i = 0; i < NR_CHUNKS_HIGH; i++) { hint = hind_addr(); hptr[i] = mmap(hint, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (hptr[i] == MAP_FAILED) break; if (validate_addr(hptr[i], 1)) return 1; } hchunks = i; for (i = 0; i < lchunks; i++) munmap(ptr[i], MAP_CHUNK_SIZE); for (i = 0; i < hchunks; i++) munmap(hptr[i], MAP_CHUNK_SIZE); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Anshuman Khandual23798.34%150.00%
Michal Suchanek41.66%150.00%
Total241100.00%2100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Anshuman Khandual42887.17%150.00%
Michal Suchanek6312.83%150.00%
Total491100.00%2100.00%
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