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 static inline
 111 void print_vmalloc_node_range_warning(void)
 112 {
 113         printk_once(KERN_WARNING "LTTng: __vmalloc_node_range symbol lookup failed.\n");
 114         printk_once(KERN_WARNING "Tracer performance will be degraded on NUMA systems.\n");
 115         printk_once(KERN_WARNING "Please rebuild your kernel with CONFIG_KALLSYMS enabled.\n");
 116 }
 117
 118 /*
 119  * kallsyms wrapper of __vmalloc_node with a fallback to kmalloc_node.
 120  */
 121 static inline
 122 void *__lttng_vmalloc_node_range(unsigned long size, unsigned long align,
 123                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 124                         pgprot_t prot, unsigned long vm_flags, int node,
 125                         const void *caller)
 126 {
 127 #ifdef CONFIG_KALLSYMS
 128         /*
 129          * If we have KALLSYMS, get * __vmalloc_node_range which is not exported.
 130          */
 131         void *(*lttng__vmalloc_node_range)(unsigned long size, unsigned long align,
 132                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 133                         pgprot_t prot, unsigned long vm_flags, int node,
 134                         const void *caller);
 135
 136         lttng__vmalloc_node_range = (void *) kallsyms_lookup_funcptr("__vmalloc_node_range");
 137         if (lttng__vmalloc_node_range)
 138                 return lttng__vmalloc_node_range(size, align, start, end, gfp_mask, prot,
 139                                 vm_flags, node, caller);
 140 #endif
 141         if (node != NUMA_NO_NODE)
 142                 print_vmalloc_node_range_warning();
 143         return __vmalloc(size, gfp_mask, prot);
 144 }
 145
 146 /**
 147  * lttng_kvmalloc_node - attempt to allocate physically contiguous memory, but upon
 148  * failure, fall back to non-contiguous (vmalloc) allocation.
 149  * @size: size of the request.
 150  * @flags: gfp mask for the allocation - must be compatible with GFP_KERNEL.
 151  *
 152  * Uses kmalloc to get the memory but if the allocation fails then falls back
 153  * to the vmalloc allocator. Use lttng_kvfree to free the memory.
 154  *
 155  * Reclaim modifiers - __GFP_NORETRY, __GFP_REPEAT and __GFP_NOFAIL are not supported
 156  */
 157 static inline
 158 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
 159 {
 160         void *ret;
 161
 162         /*
 163          * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
 164          * so the given set of flags has to be compatible.
 165          */
 166         WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
 167
 168         /*
 169          * If the allocation fits in a single page, do not fallback.
 170          */
 171         if (size <= PAGE_SIZE) {
 172                 return kmalloc_node(size, flags, node);
 173         }
 174
 175         /*
 176          * Make sure that larger requests are not too disruptive - no OOM
 177          * killer and no allocation failure warnings as we have a fallback
 178          */
 179         ret = kmalloc_node(size, flags | __GFP_NOWARN | __GFP_NORETRY, node);
 180         if (!ret) {
 181                 ret = __lttng_vmalloc_node_range(size, 1,
 182                                 VMALLOC_START, VMALLOC_END,
 183                                 flags | __GFP_HIGHMEM, PAGE_KERNEL, 0,
 184                                 node, __builtin_return_address(0));
 185                 /*
 186                  * Make sure we don't trigger recursive page faults in the
 187                  * tracing fast path.
 188                  */
 189                 wrapper_vmalloc_sync_all();
 190         }
 191         return ret;
 192 }
 193
 194 static inline
 195 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
 196 {
 197         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
 198 }
 199
 200 static inline
 201 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
 202 {
 203         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
 204 }
 205
 206 static inline
 207 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
 208 {
 209         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
 210 }
 211
 212 static inline
 213 void lttng_kvfree(const void *addr)
 214 {
 215         if (is_vmalloc_addr(addr)) {
 216                 vfree(addr);
 217         } else {
 218                 kfree(addr);
 219         }
 220 }
 221 #endif
 222
 223 #endif /* _LTTNG_WRAPPER_VMALLOC_H */