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