| 1 | /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1) |
| 2 | * |
| 3 | * wrapper/writeback.h |
| 4 | * |
| 5 | * wrapper around global_dirty_limit read. Using KALLSYMS with KALLSYMS_ALL |
| 6 | * to get its address when available, else we need to have a kernel that |
| 7 | * exports this variable to GPL modules. |
| 8 | * |
| 9 | * Copyright (C) 2013 Mentor Graphics Corp. |
| 10 | */ |
| 11 | |
| 12 | #ifndef _LTTNG_WRAPPER_WRITEBACK_H |
| 13 | #define _LTTNG_WRAPPER_WRITEBACK_H |
| 14 | |
| 15 | #include <lttng-kernel-version.h> |
| 16 | |
| 17 | #ifdef CONFIG_KALLSYMS_ALL |
| 18 | #include <linux/kallsyms.h> |
| 19 | #include <wrapper/kallsyms.h> |
| 20 | |
| 21 | |
| 22 | |
| 23 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,2,0) |
| 24 | |
| 25 | static struct wb_domain *global_wb_domain_sym; |
| 26 | |
| 27 | static inline |
| 28 | unsigned long wrapper_global_dirty_limit(void) |
| 29 | { |
| 30 | if (!global_wb_domain_sym) |
| 31 | global_wb_domain_sym = |
| 32 | (void *) kallsyms_lookup_dataptr("global_wb_domain"); |
| 33 | if (global_wb_domain_sym) { |
| 34 | return global_wb_domain_sym->dirty_limit; |
| 35 | } else { |
| 36 | printk_once(KERN_WARNING "LTTng: global_wb_domain symbol lookup failed.\n"); |
| 37 | return 0; |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | /* |
| 42 | * Canary function to check for 'global_wb_domain' at compile time. |
| 43 | * |
| 44 | * From 'include/linux/writeback.h': |
| 45 | * |
| 46 | * extern struct wb_domain global_wb_domain; |
| 47 | */ |
| 48 | static inline |
| 49 | unsigned long __canary__global_wb_domain(void) |
| 50 | { |
| 51 | return global_wb_domain.dirty_limit; |
| 52 | } |
| 53 | |
| 54 | #elif LINUX_VERSION_CODE >= KERNEL_VERSION(3,1,0) |
| 55 | |
| 56 | static unsigned long *global_dirty_limit_sym; |
| 57 | |
| 58 | static inline |
| 59 | unsigned long wrapper_global_dirty_limit(void) |
| 60 | { |
| 61 | if (!global_dirty_limit_sym) |
| 62 | global_dirty_limit_sym = |
| 63 | (void *) kallsyms_lookup_dataptr("global_dirty_limit"); |
| 64 | if (global_dirty_limit_sym) { |
| 65 | return *global_dirty_limit_sym; |
| 66 | } else { |
| 67 | printk_once(KERN_WARNING "LTTng: global_dirty_limit symbol lookup failed.\n"); |
| 68 | return 0; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | /* |
| 73 | * Canary function to check for 'global_dirty_limit' at compile time. |
| 74 | * |
| 75 | * From 'include/linux/writeback.h': |
| 76 | * |
| 77 | * extern unsigned long global_dirty_limit; |
| 78 | */ |
| 79 | static inline |
| 80 | unsigned long __canary__global_dirty_limit(void) |
| 81 | { |
| 82 | return global_dirty_limit; |
| 83 | } |
| 84 | |
| 85 | #endif |
| 86 | |
| 87 | #else /* CONFIG_KALLSYMS_ALL */ |
| 88 | |
| 89 | #include <linux/writeback.h> |
| 90 | |
| 91 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(3,1,0) |
| 92 | static inline |
| 93 | unsigned long wrapper_global_dirty_limit(void) |
| 94 | { |
| 95 | return global_dirty_limit; |
| 96 | } |
| 97 | #endif |
| 98 | |
| 99 | #endif |
| 100 | |
| 101 | #endif /* _LTTNG_WRAPPER_WRITEBACK_H */ |