SystemTap 笔记 （2）—— 函数probe

函数probe的语法定义：

{kernel|module("module-pattern")}.function("function-pattern")[.{call|return[.maxactive(VALUE)]|inline}]

kernel指的是kernle image文件（vmlinux），而module则指“/lib/modules/uname -r”下的模块，即ko文件。

关于call，return，maxactive(VALUE)和inline的解释：

call is used to attach entry point non-inlined function, while .inline is used to attach first instruction of inlined function;

maxactive specifies how many instances of the specified function can be probed simultaneously. You can leave off .maxactive in most cases, as the default (KRETACTIVE) should be sufficient. However, if you notice an excessive number of skipped probes, try setting .maxactive to incrementally higher values to see if the number of skipped probes decreases.

.return is used for return points of non-inlined functions;

empty suffix is treated as combination of .call and .inline suffixes.

function-pattern的定义：

function-name[@source-path[{:line-number|:first-line-last-line|+relative-line-number}]]

stap -l 'kernel.function("*")'列出当前所有kernel的function probe:

linux: # stap -l 'kernel.function("*")'
kernel.function("AUDIT_MODE@../security/apparmor/include/policy.h:401")
kernel.function("BLEND_OP@../crypto/sha256_generic.c:48")
kernel.function("C_SYSC_epoll_pwait@../fs/eventpoll.c:2051")
kernel.function("C_SYSC_fanotify_mark@../fs/notify/fanotify/fanotify_user.c:912")
kernel.function("C_SYSC_ftruncate@../fs/open.c:205")
kernel.function("C_SYSC_futex@../kernel/futex_compat.c:174")
kernel.function("C_SYSC_get_robust_list@../kernel/futex_compat.c:135")
kernel.function("C_SYSC_getitimer@../kernel/compat.c:293")
......

stap -l 'module("ahci").function("*")'列出当前所有ahci模块的function probe:

linux: # stap -l 'module("ahci").function("*")'
module("ahci").function("__ahci_port_base@../drivers/ata/ahci.h:372")
module("ahci").function("ahci_broken_online@../drivers/ata/ahci.c:1024")
module("ahci").function("ahci_broken_suspend@../drivers/ata/ahci.c:940")
module("ahci").function("ahci_broken_system_poweroff@../drivers/ata/ahci.c:905")
module("ahci").function("ahci_configure_dma_masks@../drivers/ata/ahci.c:700")
module("ahci").function("ahci_gtf_filter_workaround@../drivers/ata/ahci.c:1075")
module("ahci").function("ahci_host_activate@../drivers/ata/ahci.c:1164")
module("ahci").function("ahci_init_interrupts@../drivers/ata/ahci.c:1122")
module("ahci").function("ahci_init_one@../drivers/ata/ahci.c:1211")
module("ahci").function("ahci_nr_ports@../drivers/ata/ahci.h:386")
module("ahci").function("ahci_p5wdh_hardreset@../drivers/ata/ahci.c:604")
module("ahci").function("ahci_p5wdh_workaround@../drivers/ata/ahci.c:775")
module("ahci").function("ahci_pci_device_resume@../drivers/ata/ahci.c:677")
module("ahci").function("ahci_pci_device_suspend@../drivers/ata/ahci.c:649")