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Diffstat (limited to 'Documentation/kprobes.txt')
| -rw-r--r-- | Documentation/kprobes.txt | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 2f9115c0ae62..61c291cddf18 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt | |||
| @@ -165,8 +165,8 @@ the user entry_handler invocation is also skipped. | |||
| 165 | 165 | ||
| 166 | 1.4 How Does Jump Optimization Work? | 166 | 1.4 How Does Jump Optimization Work? |
| 167 | 167 | ||
| 168 | If you configured your kernel with CONFIG_OPTPROBES=y (currently | 168 | If your kernel is built with CONFIG_OPTPROBES=y (currently this flag |
| 169 | this option is supported on x86/x86-64, non-preemptive kernel) and | 169 | is automatically set 'y' on x86/x86-64, non-preemptive kernel) and |
| 170 | the "debug.kprobes_optimization" kernel parameter is set to 1 (see | 170 | the "debug.kprobes_optimization" kernel parameter is set to 1 (see |
| 171 | sysctl(8)), Kprobes tries to reduce probe-hit overhead by using a jump | 171 | sysctl(8)), Kprobes tries to reduce probe-hit overhead by using a jump |
| 172 | instruction instead of a breakpoint instruction at each probepoint. | 172 | instruction instead of a breakpoint instruction at each probepoint. |
| @@ -271,8 +271,6 @@ tweak the kernel's execution path, you need to suppress optimization, | |||
| 271 | using one of the following techniques: | 271 | using one of the following techniques: |
| 272 | - Specify an empty function for the kprobe's post_handler or break_handler. | 272 | - Specify an empty function for the kprobe's post_handler or break_handler. |
| 273 | or | 273 | or |
| 274 | - Config CONFIG_OPTPROBES=n. | ||
| 275 | or | ||
| 276 | - Execute 'sysctl -w debug.kprobes_optimization=n' | 274 | - Execute 'sysctl -w debug.kprobes_optimization=n' |
| 277 | 275 | ||
| 278 | 2. Architectures Supported | 276 | 2. Architectures Supported |
| @@ -307,10 +305,6 @@ it useful to "Compile the kernel with debug info" (CONFIG_DEBUG_INFO), | |||
| 307 | so you can use "objdump -d -l vmlinux" to see the source-to-object | 305 | so you can use "objdump -d -l vmlinux" to see the source-to-object |
| 308 | code mapping. | 306 | code mapping. |
| 309 | 307 | ||
| 310 | If you want to reduce probing overhead, set "Kprobes jump optimization | ||
| 311 | support" (CONFIG_OPTPROBES) to "y". You can find this option under the | ||
| 312 | "Kprobes" line. | ||
| 313 | |||
| 314 | 4. API Reference | 308 | 4. API Reference |
| 315 | 309 | ||
| 316 | The Kprobes API includes a "register" function and an "unregister" | 310 | The Kprobes API includes a "register" function and an "unregister" |
