Thread-Local Storage
To permit association of separate copies of data allocated at compile-time with individual threads of execution, thread-local storage sections can be used to specify the size and initial contents of such data.
Sections of type SHF_TLS provide uninitialized and initialized thread-local storage. The uninitialized section, .tbss, is allocated immediately following any initialized sections, .tdata and .tdata1, subject to padding for proper alignment. The combined sections together form a TLS template that is used to allocate thread-local storage whenever a new thread is created.
The initialized portion of this template is called the TLS initialization image. All relocations generated as a result of initialized thread-local variables are applied to this template, so that the relocated values can be used when a new thread requires the initial values.
A PT_TLS program entry describes a TLS template, and has the following members:
Table 7-35 ELF PT_TLS program entry|
Member |
Value |
|---|---|
|
p_offset |
File offset of the TLS initialization image |
|
p_vaddr |
Virtual memory address of the TLS initialization image |
|
p_paddr |
Reserved |
|
p_filesz |
Size of the TLS initialization image |
|
p_memsz |
Total size of the TLS template |
|
p_flags |
PF_R |
|
p_align |
Alignment of the TLS template |
- © 2010, Oracle Corporation and/or its affiliates