tools/sched_ext/include/scx/user_exit_info.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Define struct user_exit_info which is shared between BPF and userspace parts
   4  * to communicate exit status and other information.
   5  *
   6  * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
   7  * Copyright (c) 2022 Tejun Heo <[email protected]>
   8  * Copyright (c) 2022 David Vernet <[email protected]>
   9  */
  10 #ifndef __USER_EXIT_INFO_H
  11 #define __USER_EXIT_INFO_H
  12
  13 enum uei_sizes {
  14         UEI_REASON_LEN          = 128,
  15         UEI_MSG_LEN             = 1024,
  16         UEI_DUMP_DFL_LEN        = 32768,
  17 };
  18
  19 struct user_exit_info {
  20         int             kind;
  21         s64             exit_code;
  22         char            reason[UEI_REASON_LEN];
  23         char            msg[UEI_MSG_LEN];
  24 };
  25
  26 #ifdef __bpf__
  27
  28 #ifdef LSP
  29 #include "../vmlinux/vmlinux.h"
  30 #else
  31 #include "vmlinux.h"
  32 #endif
  33 #include <bpf/bpf_core_read.h>
  34
  35 #define UEI_DEFINE(__name)                                                      \
  36         char RESIZABLE_ARRAY(data, __name##_dump);                              \
  37         const volatile u32 __name##_dump_len;                                   \
  38         struct user_exit_info __name SEC(".data")
  39
  40 #define UEI_RECORD(__uei_name, __ei) ({                                         \
  41         bpf_probe_read_kernel_str(__uei_name.reason,                            \
  42                                   sizeof(__uei_name.reason), (__ei)->reason);   \
  43         bpf_probe_read_kernel_str(__uei_name.msg,                               \
  44                                   sizeof(__uei_name.msg), (__ei)->msg);         \
  45         bpf_probe_read_kernel_str(__uei_name##_dump,                            \
  46                                   __uei_name##_dump_len, (__ei)->dump);         \
  47         if (bpf_core_field_exists((__ei)->exit_code))                           \
  48                 __uei_name.exit_code = (__ei)->exit_code;                       \
  49         /* use __sync to force memory barrier */                                \
  50         __sync_val_compare_and_swap(&__uei_name.kind, __uei_name.kind,          \
  51                                     (__ei)->kind);                              \
  52 })
  53
  54 #else   /* !__bpf__ */
  55
  56 #include <stdio.h>
  57 #include <stdbool.h>
  58
  59 /* no need to call the following explicitly if SCX_OPS_LOAD() is used */
  60 #define UEI_SET_SIZE(__skel, __ops_name, __uei_name) ({                                 \
  61         u32 __len = (__skel)->struct_ops.__ops_name->exit_dump_len ?: UEI_DUMP_DFL_LEN; \
  62         (__skel)->rodata->__uei_name##_dump_len = __len;                                \
  63         RESIZE_ARRAY((__skel), data, __uei_name##_dump, __len);                         \
  64 })
  65
  66 #define UEI_EXITED(__skel, __uei_name) ({                                       \
  67         /* use __sync to force memory barrier */                                \
  68         __sync_val_compare_and_swap(&(__skel)->data->__uei_name.kind, -1, -1);  \
  69 })
  70
  71 #define UEI_REPORT(__skel, __uei_name) ({                                       \
  72         struct user_exit_info *__uei = &(__skel)->data->__uei_name;             \
  73         char *__uei_dump = (__skel)->data_##__uei_name##_dump->__uei_name##_dump; \
  74         if (__uei_dump[0] != '\0') {                                            \
  75                 fputs("\nDEBUG DUMP\n", stderr);                                \
  76                 fputs("================================================================================\n\n", stderr); \
  77                 fputs(__uei_dump, stderr);                                      \
  78                 fputs("\n================================================================================\n\n", stderr); \
  79         }                                                                       \
  80         fprintf(stderr, "EXIT: %s", __uei->reason);                             \
  81         if (__uei->msg[0] != '\0')                                              \
  82                 fprintf(stderr, " (%s)", __uei->msg);                           \
  83         fputs("\n", stderr);                                                    \
  84         __uei->exit_code;                                                       \
  85 })
  86
  87 /*
  88  * We can't import vmlinux.h while compiling user C code. Let's duplicate
  89  * scx_exit_code definition.
  90  */
  91 enum scx_exit_code {
  92         /* Reasons */
  93         SCX_ECODE_RSN_HOTPLUG           = 1LLU << 32,
  94
  95         /* Actions */
  96         SCX_ECODE_ACT_RESTART           = 1LLU << 48,
  97 };
  98
  99 enum uei_ecode_mask {
 100         UEI_ECODE_USER_MASK             = ((1LLU << 32) - 1),
 101         UEI_ECODE_SYS_RSN_MASK          = ((1LLU << 16) - 1) << 32,
 102         UEI_ECODE_SYS_ACT_MASK          = ((1LLU << 16) - 1) << 48,
 103 };
 104
 105 /*
 106  * These macro interpret the ecode returned from UEI_REPORT().
 107  */
 108 #define UEI_ECODE_USER(__ecode)         ((__ecode) & UEI_ECODE_USER_MASK)
 109 #define UEI_ECODE_SYS_RSN(__ecode)      ((__ecode) & UEI_ECODE_SYS_RSN_MASK)
 110 #define UEI_ECODE_SYS_ACT(__ecode)      ((__ecode) & UEI_ECODE_SYS_ACT_MASK)
 111
 112 #define UEI_ECODE_RESTART(__ecode)      (UEI_ECODE_SYS_ACT((__ecode)) == SCX_ECODE_ACT_RESTART)
 113
 114 #endif  /* __bpf__ */
 115 #endif  /* __USER_EXIT_INFO_H */