Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP BEGINNERS GUIDE Información técnica descargar pdf (Pagina 102)

88 System Analysis and Tuning Guide

6.1 Supported Architectures

Kernel probes are fully implemented on the following architectures:

• i386

• x86_64 (AMD-64, EM64T)

• ppc64

• arm

• ppc

Kernel probes are partially implemented on the following architectures:

• ia64 (does not support probes on instruction slot1)

• sparc64 (return probes not yet implemented)

6.2 Types of Kernel Probes

There are three types of kernel probes: kprobes, jprobes, and kretprobes. Kret-

probes are sometimes referred to as return probes. You can find vivid source code

examples of all three type of kernel probes in the /usr/src/linux/sam

ples/kprobes/ directory (package kernel-source).

6.2.1 Kprobe

Kprobe can be attached to any instruction in the Linux kernel. When it is registered,

it inserts a break-point at the first bytes of the probed instruction. When the processor

hits this break-point, the processor registers are saved, and the processing passes to

kprobes. First, a pre-handler is executed, then the probed instruction is stepped, and,

finally a post-handler is executed. The control is then passed to the instruction follow-

ing the probe point.

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Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP BEGINNERS GUIDE Información técnica Pagina 102