| 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 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 | #ifdef CONFIG_KALLSYMS_ALL |
| 16 | |
| 17 | #include <linux/kallsyms.h> |
| 18 | #include <wrapper/kallsyms.h> |
| 19 | |
| 20 | static struct wb_domain *global_wb_domain_sym; |
| 21 | |
| 22 | static inline |
| 23 | unsigned long wrapper_global_dirty_limit(void) |
| 24 | { |
| 25 | if (!global_wb_domain_sym) |
| 26 | global_wb_domain_sym = |
| 27 | (void *) kallsyms_lookup_dataptr("global_wb_domain"); |
| 28 | if (global_wb_domain_sym) { |
| 29 | return global_wb_domain_sym->dirty_limit; |
| 30 | } else { |
| 31 | printk_once(KERN_WARNING "LTTng: global_wb_domain symbol lookup failed.\n"); |
| 32 | return 0; |
| 33 | } |
| 34 | } |
| 35 | |
| 36 | /* |
| 37 | * Canary function to check for 'global_wb_domain' at compile time. |
| 38 | * |
| 39 | * From 'include/linux/writeback.h': |
| 40 | * |
| 41 | * extern struct wb_domain global_wb_domain; |
| 42 | */ |
| 43 | static inline |
| 44 | unsigned long __canary__global_wb_domain(void) |
| 45 | { |
| 46 | return global_wb_domain.dirty_limit; |
| 47 | } |
| 48 | |
| 49 | #else /* CONFIG_KALLSYMS_ALL */ |
| 50 | |
| 51 | #include <linux/writeback.h> |
| 52 | |
| 53 | static inline |
| 54 | unsigned long wrapper_global_dirty_limit(void) |
| 55 | { |
| 56 | return global_dirty_limit; |
| 57 | } |
| 58 | |
| 59 | #endif /* CONFIG_KALLSYMS_ALL */ |
| 60 | |
| 61 | #endif /* _LTTNG_WRAPPER_WRITEBACK_H */ |