include/wrapper/vmalloc.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   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
  24 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0))
  25
  26 static inline
  27 void wrapper_vmalloc_sync_mappings(void)
  28 {
  29         void (*vmalloc_sync_mappings_sym)(void);
  30
  31         vmalloc_sync_mappings_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_mappings");
  32         if (vmalloc_sync_mappings_sym) {
  33                 vmalloc_sync_mappings_sym();
  34         } else {
  35 #ifdef CONFIG_X86
  36                 /*
  37                  * Only x86 needs vmalloc_sync_mappings to make sure LTTng does not
  38                  * trigger recursive page faults.
  39                  */
  40                 printk_once(KERN_WARNING "LTTng: vmalloc_sync_mappings symbol lookup failed.\n");
  41                 printk_once(KERN_WARNING "Page fault handler and NMI tracing might trigger faults.\n");
  42 #endif
  43         }
  44 }
  45
  46 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
  47
  48 /*
  49  * Map vmalloc_sync_mappings to vmalloc_sync_all() on kernels before 5.7.
  50  */
  51 static inline
  52 void wrapper_vmalloc_sync_mappings(void)
  53 {
  54         void (*vmalloc_sync_all_sym)(void);
  55
  56         vmalloc_sync_all_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_all");
  57         if (vmalloc_sync_all_sym) {
  58                 vmalloc_sync_all_sym();
  59         } else {
  60 #ifdef CONFIG_X86
  61                 /*
  62                  * Only x86 needs vmalloc_sync_all to make sure LTTng does not
  63                  * trigger recursive page faults.
  64                  */
  65                 printk_once(KERN_WARNING "LTTng: vmalloc_sync_all symbol lookup failed.\n");
  66                 printk_once(KERN_WARNING "Page fault handler and NMI tracing might trigger faults.\n");
  67 #endif
  68         }
  69 }
  70
  71 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
  72
  73 #else
  74
  75 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0))
  76
  77 static inline
  78 void wrapper_vmalloc_sync_mappings(void)
  79 {
  80         return vmalloc_sync_mappings();
  81 }
  82
  83 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
  84
  85 static inline
  86 void wrapper_vmalloc_sync_mappings(void)
  87 {
  88         return vmalloc_sync_all();
  89 }
  90
  91 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,6,0)) */
  92
  93 #endif
  94
  95 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
  96 static inline
  97 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
  98 {
  99         void *ret;
 100
 101         ret = kvmalloc_node(size, flags, node);
 102         if (is_vmalloc_addr(ret)) {
 103                 /*
 104                  * Make sure we don't trigger recursive page faults in the
 105                  * tracing fast path.
 106                  */
 107                 wrapper_vmalloc_sync_mappings();
 108         }
 109         return ret;
 110 }
 111
 112 static inline
 113 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
 114 {
 115         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
 116 }
 117
 118 static inline
 119 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
 120 {
 121         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
 122 }
 123
 124 static inline
 125 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
 126 {
 127         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
 128 }
 129
 130 static inline
 131 void lttng_kvfree(const void *addr)
 132 {
 133         kvfree(addr);
 134 }
 135
 136 #else
 137
 138 #include <linux/slab.h>
 139
 140 static inline
 141 void print_vmalloc_node_range_warning(void)
 142 {
 143         printk_once(KERN_WARNING "LTTng: __vmalloc_node_range symbol lookup failed.\n");
 144         printk_once(KERN_WARNING "Tracer performance will be degraded on NUMA systems.\n");
 145         printk_once(KERN_WARNING "Please rebuild your kernel with CONFIG_KALLSYMS enabled.\n");
 146 }
 147
 148 /*
 149  * kallsyms wrapper of __vmalloc_node with a fallback to kmalloc_node.
 150  */
 151 static inline
 152 void *__lttng_vmalloc_node_range(unsigned long size, unsigned long align,
 153                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 154                         pgprot_t prot, unsigned long vm_flags, int node,
 155                         const void *caller)
 156 {
 157 #ifdef CONFIG_KALLSYMS
 158         /*
 159          * If we have KALLSYMS, get * __vmalloc_node_range which is not exported.
 160          */
 161         void *(*lttng__vmalloc_node_range)(unsigned long size, unsigned long align,
 162                         unsigned long start, unsigned long end, gfp_t gfp_mask,
 163                         pgprot_t prot, unsigned long vm_flags, int node,
 164                         const void *caller);
 165
 166         lttng__vmalloc_node_range = (void *) kallsyms_lookup_funcptr("__vmalloc_node_range");
 167         if (lttng__vmalloc_node_range)
 168                 return lttng__vmalloc_node_range(size, align, start, end, gfp_mask, prot,
 169                                 vm_flags, node, caller);
 170 #endif
 171         if (node != NUMA_NO_NODE)
 172                 print_vmalloc_node_range_warning();
 173         return __vmalloc(size, gfp_mask, prot);
 174 }
 175
 176 /**
 177  * lttng_kvmalloc_node - attempt to allocate physically contiguous memory, but upon
 178  * failure, fall back to non-contiguous (vmalloc) allocation.
 179  * @size: size of the request.
 180  * @flags: gfp mask for the allocation - must be compatible with GFP_KERNEL.
 181  *
 182  * Uses kmalloc to get the memory but if the allocation fails then falls back
 183  * to the vmalloc allocator. Use lttng_kvfree to free the memory.
 184  *
 185  * Reclaim modifiers - __GFP_NORETRY, __GFP_REPEAT and __GFP_NOFAIL are not supported
 186  */
 187 static inline
 188 void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
 189 {
 190         void *ret;
 191
 192         /*
 193          * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
 194          * so the given set of flags has to be compatible.
 195          */
 196         WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL);
 197
 198         /*
 199          * If the allocation fits in a single page, do not fallback.
 200          */
 201         if (size <= PAGE_SIZE) {
 202                 return kmalloc_node(size, flags, node);
 203         }
 204
 205         /*
 206          * Make sure that larger requests are not too disruptive - no OOM
 207          * killer and no allocation failure warnings as we have a fallback
 208          */
 209         ret = kmalloc_node(size, flags | __GFP_NOWARN | __GFP_NORETRY, node);
 210         if (!ret) {
 211                 ret = __lttng_vmalloc_node_range(size, 1,
 212                                 VMALLOC_START, VMALLOC_END,
 213                                 flags | __GFP_HIGHMEM, PAGE_KERNEL, 0,
 214                                 node, __builtin_return_address(0));
 215                 /*
 216                  * Make sure we don't trigger recursive page faults in the
 217                  * tracing fast path.
 218                  */
 219                 wrapper_vmalloc_sync_mappings();
 220         }
 221         return ret;
 222 }
 223
 224 static inline
 225 void *lttng_kvzalloc_node(unsigned long size, gfp_t flags, int node)
 226 {
 227         return lttng_kvmalloc_node(size, flags | __GFP_ZERO, node);
 228 }
 229
 230 static inline
 231 void *lttng_kvmalloc(unsigned long size, gfp_t flags)
 232 {
 233         return lttng_kvmalloc_node(size, flags, NUMA_NO_NODE);
 234 }
 235
 236 static inline
 237 void *lttng_kvzalloc(unsigned long size, gfp_t flags)
 238 {
 239         return lttng_kvzalloc_node(size, flags, NUMA_NO_NODE);
 240 }
 241
 242 static inline
 243 void lttng_kvfree(const void *addr)
 244 {
 245         if (is_vmalloc_addr(addr)) {
 246                 vfree(addr);
 247         } else {
 248                 kfree(addr);
 249         }
 250 }
 251 #endif
 252
 253 #endif /* _LTTNG_WRAPPER_VMALLOC_H */