wrapper/vmalloc.h

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * wrapper/vmalloc.h
   4  *
   5  * wrapper around vmalloc_sync_all. Using KALLSYMS to get its address when
   6  * available, else we need to have a kernel that exports this function to GPL
   7  * modules.
   8  *
   9  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  */
  11
  12 #ifndef _LTTNG_WRAPPER_VMALLOC_H
  13 #define _LTTNG_WRAPPER_VMALLOC_H
  14
  15 #include <linux/version.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/mm.h>
  18
  19 #ifdef CONFIG_KALLSYMS
  20
  21 #include <linux/kallsyms.h>
  22 #include <wrapper/kallsyms.h>
  23 #include <lttng-kernel-version.h>
  24
  25 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,8,0))
  26
  27 /*
  28  * wrapper_vmalloc_sync_mappings was removed in v5.8, the vmalloc mappings
  29  * are now synchronized when they are created or torn down.
  30  */
  31 static inline
  32 void wrapper_vmalloc_sync_mappings(void)
  33 {}
  34
  35 #elif (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0) \
  36   || LTTNG_KERNEL_RANGE(5,5,12, 5,6,0)            \
  37   || LTTNG_KERNEL_RANGE(5,4,28, 5,5,0)            \
  38   || LTTNG_KERNEL_RANGE(5,2,37, 5,3,0)            \
  39   || LTTNG_KERNEL_RANGE(4,19,113, 4,20,0)         \
  40   || LTTNG_KERNEL_RANGE(4,14,175, 4,15,0)         \
  41   || LTTNG_KERNEL_RANGE(4,9,218, 4,10,0)          \
  42   || LTTNG_KERNEL_RANGE(4,4,218, 4,5,0))          \
  43   || LTTNG_UBUNTU_KERNEL_RANGE(4,15,18,97, 4,16,0,0) \
  44   || LTTNG_UBUNTU_KERNEL_RANGE(5,0,21,48, 5,1,0,0)   \
  45   || LTTNG_UBUNTU_KERNEL_RANGE(5,3,18,52, 5,4,0,0)
  46
  47 static inline
  48 void wrapper_vmalloc_sync_mappings(void)
  49 {
  50         void (*vmalloc_sync_mappings_sym)(void);
  51
  52         vmalloc_sync_mappings_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_mappings");
  53         if (vmalloc_sync_mappings_sym) {
  54                 vmalloc_sync_mappings_sym();
  55         } else {
  56 #ifdef CONFIG_X86
  57                 /*
  58                  * Only x86 needs vmalloc_sync_mappings to make sure LTTng does not
  59                  * trigger recursive page faults.
  60                  */
  61                 printk_once(KERN_WARNING "LTTng: vmalloc_sync_mappings symbol lookup failed.\n");
  62                 printk_once(KERN_WARNING "Page fault handler and NMI tracing might trigger faults.\n");
  63 #endif
  64         }
  65 }
  66
  67 /*
  68  * Canary function to check for 'vmalloc_sync_mappings()' at compile time.
  69  *
  70  * From 'include/linux/vmalloc.h':
  71  *
  72  *   void vmalloc_sync_mappings(void);
  73  */
  74 static inline
  75 void __canary__vmalloc_sync_mappings(void)
  76 {
  77         vmalloc_sync_mappings();
  78 }
  79
  80 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
  81
  82 /*
  83  * Map vmalloc_sync_mappings to vmalloc_sync_all() on kernels before 5.6.
  84  */
  85 static inline
  86 void wrapper_vmalloc_sync_mappings(void)
  87 {
  88         void (*vmalloc_sync_all_sym)(void);
  89
  90         vmalloc_sync_all_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_all");
  91         if (vmalloc_sync_all_sym) {
  92                 vmalloc_sync_all_sym();
  93         } else {
  94 #ifdef CONFIG_X86
  95                 /*
  96                  * Only x86 needs vmalloc_sync_all to make sure LTTng does not
  97                  * trigger recursive page faults.
  98                  */
  99                 printk_once(KERN_WARNING "LTTng: vmalloc_sync_all symbol lookup failed.\n");
 100                 printk_once(KERN_WARNING "Page fault handler and NMI tracing might trigger faults.\n");
 101 #endif
 102         }
 103 }
 104
 105 /*
 106  * Canary function to check for 'vmalloc_sync_all()' at compile time.
 107  *
 108  * From 'include/linux/vmalloc.h':
 109  *
 110  *   void vmalloc_sync_all(void);
 111  */
 112 static inline
 113 void __canary__vmalloc_sync_all(void)
 114 {
 115         vmalloc_sync_all();
 116 }
 117
 118 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
 119
 120 #else
 121
 122 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0) \
 123   || LTTNG_KERNEL_RANGE(5,5,12, 5,6,0)            \
 124   || LTTNG_KERNEL_RANGE(5,4,28, 5,5,0)            \
 125   || LTTNG_KERNEL_RANGE(5,2,37, 5,3,0)            \
 126   || LTTNG_KERNEL_RANGE(4,19,113, 4,20,0)         \
 127   || LTTNG_KERNEL_RANGE(4,14,175, 4,15,0)         \
 128   || LTTNG_KERNEL_RANGE(4,9,218, 4,10,0)          \
 129   || LTTNG_KERNEL_RANGE(4,4,218, 4,5,0))          \
 130   || LTTNG_UBUNTU_KERNEL_RANGE(4,15,18,97, 4,18,0,0) \
 131   || LTTNG_UBUNTU_KERNEL_RANGE(5,0,21,48, 5,1,0,0)   \
 132   || LTTNG_UBUNTU_KERNEL_RANGE(5,3,18,52, 5,4,0,0)
 133
 134 static inline
 135 void wrapper_vmalloc_sync_mappings(void)
 136 {
 137         return vmalloc_sync_mappings();
 138 }
 139
 140 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
 141
 142 static inline
 143 void wrapper_vmalloc_sync_mappings(void)
 144 {
 145         return vmalloc_sync_all();
 146 }
 147
 148 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
 149
 150 #endif
 151
 152 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
 153 static inline
 154 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
 155 {
 156         void *ret;
 157
 158         ret = kvmalloc_node(size, flags, node);
 159         if (is_vmalloc_addr(ret)) {
 160                 /*
 161                  * Make sure we don't trigger recursive page faults in the
 162                  * tracing fast path.
 163                  */
 164                 wrapper_vmalloc_sync_mappings();
 165         }
 166         return ret;
 167 }
 168
 169 static inline
 170 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
 171 {
 172         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
 173 }
 174
 175 static inline
 176 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
 177 {
 178         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
 179 }
 180
 181 static inline
 182 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
 183 {
 184         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
 185 }
 186
 187 static inline
 188 void lttng_kvfree(const void *addr)
 189 {
 190         kvfree(addr);
 191 }
 192
 193 #else
 194
 195 #include <linux/slab.h>
 196
 197 static inline
 198 void print_vmalloc_node_range_warning(void)
 199 {
 200         printk_once(KERN_WARNING "LTTng: __vmalloc_node_range symbol lookup failed.\n");
 201         printk_once(KERN_WARNING "Tracer performance will be degraded on NUMA systems.\n");
 202         printk_once(KERN_WARNING "Please rebuild your kernel with CONFIG_KALLSYMS enabled.\n");
 203 }
 204
 205 /*
 206  * kallsyms wrapper of __vmalloc_node with a fallback to kmalloc_node.
 207  */
 208 static inline
 209 void *__lttng_vmalloc_node_range(unsigned long size, unsigned long align,
 210                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 211                         pgprot_t prot, unsigned long vm_flags, int node,
 212                         const void *caller)
 213 {
 214 #ifdef CONFIG_KALLSYMS
 215         /*
 216          * If we have KALLSYMS, get * __vmalloc_node_range which is not exported.
 217          */
 218         void *(*lttng__vmalloc_node_range)(unsigned long size, unsigned long align,
 219                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 220                         pgprot_t prot, unsigned long vm_flags, int node,
 221                         const void *caller);
 222
 223         lttng__vmalloc_node_range = (void *) kallsyms_lookup_funcptr("__vmalloc_node_range");
 224         if (lttng__vmalloc_node_range)
 225                 return lttng__vmalloc_node_range(size, align, start, end, gfp_mask, prot,
 226                                 vm_flags, node, caller);
 227 #endif
 228         if (node != NUMA_NO_NODE)
 229                 print_vmalloc_node_range_warning();
 230         return __vmalloc(size, gfp_mask, prot);
 231 }
 232
 233 /*
 234  * Canary function to check for '__vmalloc_node_range()' at compile time.
 235  *
 236  * From 'include/linux/vmalloc.h':
 237  *
 238  *   extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
 239  *                           unsigned long start, unsigned long end, gfp_t gfp_mask,
 240  *                           pgprot_t prot, unsigned long vm_flags, int node,
 241  *                           const void *caller);
 242  */
 243 static inline
 244 void *__canary____lttng_vmalloc_node_range(unsigned long size, unsigned long align,
 245                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 246                         pgprot_t prot, unsigned long vm_flags, int node,
 247                         const void *caller)
 248 {
 249         return __vmalloc_node_range(size, align, start, end, gfp_mask, prot,
 250                         vm_flags, node, caller);
 251 }
 252
 253 /**
 254  * lttng_kvmalloc_node - attempt to allocate physically contiguous memory, but upon
 255  * failure, fall back to non-contiguous (vmalloc) allocation.
 256  * @size: size of the request.
 257  * @flags: gfp mask for the allocation - must be compatible with GFP_KERNEL.
 258  *
 259  * Uses kmalloc to get the memory but if the allocation fails then falls back
 260  * to the vmalloc allocator. Use lttng_kvfree to free the memory.
 261  *
 262  * Reclaim modifiers - __GFP_NORETRY, __GFP_REPEAT and __GFP_NOFAIL are not supported
 263  */
 264 static inline
 265 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
 266 {
 267         void *ret;
 268
 269         /*
 270          * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
 271          * so the given set of flags has to be compatible.
 272          */
 273         WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
 274
 275         /*
 276          * If the allocation fits in a single page, do not fallback.
 277          */
 278         if (size <= PAGE_SIZE) {
 279                 return kmalloc_node(size, flags, node);
 280         }
 281
 282         /*
 283          * Make sure that larger requests are not too disruptive - no OOM
 284          * killer and no allocation failure warnings as we have a fallback
 285          */
 286         ret = kmalloc_node(size, flags | __GFP_NOWARN | __GFP_NORETRY, node);
 287         if (!ret) {
 288                 ret = __lttng_vmalloc_node_range(size, 1,
 289                                 VMALLOC_START, VMALLOC_END,
 290                                 flags | __GFP_HIGHMEM, PAGE_KERNEL, 0,
 291                                 node, __builtin_return_address(0));
 292                 /*
 293                  * Make sure we don't trigger recursive page faults in the
 294                  * tracing fast path.
 295                  */
 296                 wrapper_vmalloc_sync_mappings();
 297         }
 298         return ret;
 299 }
 300
 301 static inline
 302 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
 303 {
 304         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
 305 }
 306
 307 static inline
 308 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
 309 {
 310         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
 311 }
 312
 313 static inline
 314 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
 315 {
 316         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
 317 }
 318
 319 static inline
 320 void lttng_kvfree(const void *addr)
 321 {
 322         if (is_vmalloc_addr(addr)) {
 323                 vfree(addr);
 324         } else {
 325                 kfree(addr);
 326         }
 327 }
 328 #endif
 329
 330 #endif /* _LTTNG_WRAPPER_VMALLOC_H */