wrapper/vmalloc.h

   1 #ifndef _LTTNG_WRAPPER_VMALLOC_H
   2 #define _LTTNG_WRAPPER_VMALLOC_H
   3
   4 /*
   5  * wrapper/vmalloc.h
   6  *
   7  * wrapper around vmalloc_sync_all. Using KALLSYMS to get its address when
   8  * available, else we need to have a kernel that exports this function to GPL
   9  * modules.
  10  *
  11  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  12  *
  13  * This library is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU Lesser General Public
  15  * License as published by the Free Software Foundation; only
  16  * version 2.1 of the License.
  17  *
  18  * This library is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  21  * Lesser General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public
  24  * License along with this library; if not, write to the Free Software
  25  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  26  */
  27
  28 #include <linux/version.h>
  29 #include <linux/vmalloc.h>
  30 #include <linux/mm.h>
  31
  32 #ifdef CONFIG_KALLSYMS
  33
  34 #include <linux/kallsyms.h>
  35 #include <wrapper/kallsyms.h>
  36
  37 static inline
  38 void wrapper_vmalloc_sync_all(void)
  39 {
  40         void (*vmalloc_sync_all_sym)(void);
  41
  42         vmalloc_sync_all_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_all");
  43         if (vmalloc_sync_all_sym) {
  44                 vmalloc_sync_all_sym();
  45         } else {
  46 #ifdef CONFIG_X86
  47                 /*
  48                  * Only x86 needs vmalloc_sync_all to make sure LTTng does not
  49                  * trigger recursive page faults.
  50                  */
  51                 printk_once(KERN_WARNING "LTTng: vmalloc_sync_all symbol lookup failed.\n");
  52                 printk_once(KERN_WARNING "Page fault handler and NMI tracing might trigger faults.\n");
  53 #endif
  54         }
  55 }
  56 #else
  57
  58 static inline
  59 void wrapper_vmalloc_sync_all(void)
  60 {
  61         return vmalloc_sync_all();
  62 }
  63 #endif
  64
  65 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
  66 static inline
  67 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
  68 {
  69         void *ret;
  70
  71         ret = kvmalloc_node(size, flags, node);
  72         if (is_vmalloc_addr(ret)) {
  73                 /*
  74                  * Make sure we don't trigger recursive page faults in the
  75                  * tracing fast path.
  76                  */
  77                 wrapper_vmalloc_sync_all();
  78         }
  79         return ret;
  80 }
  81
  82 static inline
  83 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
  84 {
  85         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
  86 }
  87
  88 static inline
  89 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
  90 {
  91         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
  92 }
  93
  94 static inline
  95 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
  96 {
  97         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
  98 }
  99
 100 static inline
 101 void lttng_kvfree(const void *addr)
 102 {
 103         kvfree(addr);
 104 }
 105
 106 #else
 107
 108 #include <linux/slab.h>
 109
 110 /*
 111  * kallsyms wrapper of __vmalloc_node with a fallback to kmalloc_node.
 112  */
 113 static inline
 114 void *__lttng_vmalloc_node_fallback(unsigned long size, unsigned long align,
 115                          gfp_t gfp_mask, pgprot_t prot, int node, void *caller)
 116 {
 117         void *ret;
 118
 119 #ifdef CONFIG_KALLSYMS
 120         /*
 121          * If we have KALLSYMS, get * __vmalloc_node which is not exported.
 122          */
 123         void *(*lttng__vmalloc_node)(unsigned long size, unsigned long align,
 124                         gfp_t gfp_mask, pgprot_t prot, int node, void *caller);
 125
 126         lttng__vmalloc_node = (void *) kallsyms_lookup_funcptr("__vmalloc_node");
 127         ret = lttng__vmalloc_node(size, align, gfp_mask, prot, node, caller);
 128 #else
 129         /*
 130          * If we don't have KALLSYMS, fallback to kmalloc_node.
 131          */
 132         ret = kmalloc_node(size, flags, node);
 133 #endif
 134
 135         return ret;
 136 }
 137
 138 /**
 139  * lttng_kvmalloc_node - attempt to allocate physically contiguous memory, but upon
 140  * failure, fall back to non-contiguous (vmalloc) allocation.
 141  * @size: size of the request.
 142  * @flags: gfp mask for the allocation - must be compatible with GFP_KERNEL.
 143  *
 144  * Uses kmalloc to get the memory but if the allocation fails then falls back
 145  * to the vmalloc allocator. Use lttng_kvfree to free the memory.
 146  *
 147  * Reclaim modifiers - __GFP_NORETRY, __GFP_REPEAT and __GFP_NOFAIL are not supported
 148  */
 149 static inline
 150 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
 151 {
 152         void *ret;
 153
 154         /*
 155          * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
 156          * so the given set of flags has to be compatible.
 157          */
 158         WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
 159
 160         /*
 161          * If the allocation fits in a single page, do not fallback.
 162          */
 163         if (size <= PAGE_SIZE) {
 164                 return kmalloc_node(size, flags, node);
 165         }
 166
 167         /*
 168          * Make sure that larger requests are not too disruptive - no OOM
 169          * killer and no allocation failure warnings as we have a fallback
 170          */
 171         ret = kmalloc_node(size, flags | __GFP_NOWARN | __GFP_NORETRY, node);
 172         if (!ret) {
 173                 if (node == NUMA_NO_NODE) {
 174                         /*
 175                          * If no node was specified, use __vmalloc which is
 176                          * always exported.
 177                          */
 178                         ret = __vmalloc(size, flags | __GFP_HIGHMEM, PAGE_KERNEL);
 179                 } else {
 180                         /*
 181                          * Otherwise, we need to select a node but __vmalloc_node
 182                          * is not exported, use this fallback wrapper which uses
 183                          * kallsyms if available or falls back to kmalloc_node.
 184                          */
 185                         ret = __lttng_vmalloc_node_fallback(size, 1,
 186                                         flags | __GFP_HIGHMEM, PAGE_KERNEL, node,
 187                                         __builtin_return_address(0));
 188                 }
 189
 190                 /*
 191                  * Make sure we don't trigger recursive page faults in the
 192                  * tracing fast path.
 193                  */
 194                 wrapper_vmalloc_sync_all();
 195         }
 196         return ret;
 197 }
 198
 199 static inline
 200 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
 201 {
 202         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
 203 }
 204
 205 static inline
 206 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
 207 {
 208         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
 209 }
 210
 211 static inline
 212 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
 213 {
 214         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
 215 }
 216
 217 static inline
 218 void lttng_kvfree(const void *addr)
 219 {
 220         if (is_vmalloc_addr(addr)) {
 221                 vfree(addr);
 222         } else {
 223                 kfree(addr);
 224         }
 225 }
 226 #endif
 227
 228 #endif /* _LTTNG_WRAPPER_VMALLOC_H */