Introduce CONFIG_STACKLEAK_METRICS providing STACKLEAK information about tasks via the /proc file system. In particular, /proc/<pid>/stack_depth shows the maximum kernel stack consumption for the current and previous syscalls. Although this information is not precise, it can be useful for estimating the STACKLEAK performance impact for your workloads.
Unified · Split
| @@ -2891,6 +2891,21 @@ static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns, · 2890 unmodified lines | |||
| 2891 | } | 2891 | } |
| 2892 | #endif /* CONFIG_LIVEPATCH */ | 2892 | #endif /* CONFIG_LIVEPATCH */ |
| 2893 | 2893 | ||
| 2894 | #ifdef CONFIG_STACKLEAK_METRICS | ||
| 2895 | static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns, | ||
| 2896 | struct pid *pid, struct task_struct *task) | ||
| 2897 | { | ||
| 2898 | unsigned long prev_depth = THREAD_SIZE - | ||
| 2899 | (task->prev_lowest_stack & (THREAD_SIZE - 1)); | ||
| 2900 | unsigned long depth = THREAD_SIZE - | ||
| 2901 | (task->lowest_stack & (THREAD_SIZE - 1)); | ||
| 2902 | |||
| 2903 | seq_printf(m, "previous stack depth: %lu\nstack depth: %lu\n", | ||
| 2904 | prev_depth, depth); | ||
| 2905 | return 0; | ||
| 2906 | } | ||
| 2907 | #endif /* CONFIG_STACKLEAK_METRICS */ | ||
| 2908 | |||
| 2894 | /* | 2909 | /* |
| 2895 | * Thread groups | 2910 | * Thread groups |
| 2896 | */ | 2911 | */ |
| @@ -2992,6 +3007,9 @@ static const struct pid_entry tgid_base_stuff[] = { · 95 unmodified lines | |||
| 2992 | #ifdef CONFIG_LIVEPATCH | 3007 | #ifdef CONFIG_LIVEPATCH |
| 2993 | ONE("patch_state", S_IRUSR, proc_pid_patch_state), | 3008 | ONE("patch_state", S_IRUSR, proc_pid_patch_state), |
| 2994 | #endif | 3009 | #endif |
| 3010 | #ifdef CONFIG_STACKLEAK_METRICS | ||
| 3011 | ONE("stack_depth", S_IRUGO, proc_stack_depth), | ||
| 3012 | #endif | ||
| 2995 | }; | 3013 | }; |
| 2996 | 3014 | ||
| 2997 | static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx) | 3015 | static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx) |
| @@ -1194,6 +1194,7 @@ struct task_struct { · 1193 unmodified lines | |||
| 1194 | 1194 | ||
| 1195 | #ifdef CONFIG_GCC_PLUGIN_STACKLEAK | 1195 | #ifdef CONFIG_GCC_PLUGIN_STACKLEAK |
| 1196 | unsigned long lowest_stack; | 1196 | unsigned long lowest_stack; |
| 1197 | unsigned long prev_lowest_stack; | ||
| 1197 | #endif | 1198 | #endif |
| 1198 | 1199 | ||
| 1199 | /* | 1200 | /* |
| @@ -18,6 +18,9 @@ · 17 unmodified lines | |||
| 18 | static inline void stackleak_task_init(struct task_struct *t) | 18 | static inline void stackleak_task_init(struct task_struct *t) |
| 19 | { | 19 | { |
| 20 | t->lowest_stack = (unsigned long)end_of_stack(t) + sizeof(unsigned long); | 20 | t->lowest_stack = (unsigned long)end_of_stack(t) + sizeof(unsigned long); |
| 21 | # ifdef CONFIG_STACKLEAK_METRICS | ||
| 22 | t->prev_lowest_stack = t->lowest_stack; | ||
| 23 | # endif | ||
| 21 | } | 24 | } |
| 22 | #else /* !CONFIG_GCC_PLUGIN_STACKLEAK */ | 25 | #else /* !CONFIG_GCC_PLUGIN_STACKLEAK */ |
| 23 | static inline void stackleak_task_init(struct task_struct *t) { } | 26 | static inline void stackleak_task_init(struct task_struct *t) { } |
| @@ -41,6 +41,10 @@ asmlinkage void stackleak_erase(void) · 40 unmodified lines | |||
| 41 | if (kstack_ptr == boundary) | 41 | if (kstack_ptr == boundary) |
| 42 | kstack_ptr += sizeof(unsigned long); | 42 | kstack_ptr += sizeof(unsigned long); |
| 43 | 43 | ||
| 44 | #ifdef CONFIG_STACKLEAK_METRICS | ||
| 45 | current->prev_lowest_stack = kstack_ptr; | ||
| 46 | #endif | ||
| 47 | |||
| 44 | /* | 48 | /* |
| 45 | * Now write the poison value to the kernel stack. Start from | 49 | * Now write the poison value to the kernel stack. Start from |
| 46 | * 'kstack_ptr' and move up till the new 'boundary'. We assume that | 50 | * 'kstack_ptr' and move up till the new 'boundary'. We assume that |
| @@ -170,4 +170,16 @@ config STACKLEAK_TRACK_MIN_SIZE · 169 unmodified lines | |||
| 170 | a stack frame size greater than or equal to this parameter. | 170 | a stack frame size greater than or equal to this parameter. |
| 171 | If unsure, leave the default value 100. | 171 | If unsure, leave the default value 100. |
| 172 | 172 | ||
| 173 | config STACKLEAK_METRICS | ||
| 174 | bool "Show STACKLEAK metrics in the /proc file system" | ||
| 175 | depends on GCC_PLUGIN_STACKLEAK | ||
| 176 | depends on PROC_FS | ||
| 177 | help | ||
| 178 | If this is set, STACKLEAK metrics for every task are available in | ||
| 179 | the /proc file system. In particular, /proc/<pid>/stack_depth | ||
| 180 | shows the maximum kernel stack consumption for the current and | ||
| 181 | previous syscalls. Although this information is not precise, it | ||
| 182 | can be useful for estimating the STACKLEAK performance impact for | ||
| 183 | your workloads. | ||
| 184 | |||
| 173 | endif | 185 | endif |