diff options
Diffstat (limited to 'man2/set_thread_area.2')
| -rw-r--r-- | man2/set_thread_area.2 | 60 |
1 files changed, 30 insertions, 30 deletions
diff --git a/man2/set_thread_area.2 b/man2/set_thread_area.2 index b982112..389d65b 100644 --- a/man2/set_thread_area.2 +++ b/man2/set_thread_area.2 @@ -4,7 +4,7 @@ .\" .\" SPDX-License-Identifier: GPL-1.0-or-later .\" -.TH set_thread_area 2 2023-03-30 "Linux man-pages 6.05.01" +.TH set_thread_area 2 2023-10-31 "Linux man-pages 6.7" .SH NAME get_thread_area, set_thread_area \- manipulate thread-local storage information .SH LIBRARY @@ -14,25 +14,25 @@ Standard C library .nf .BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */" .B #include <unistd.h> -.PP +.P .B #if defined __i386__ || defined __x86_64__ .BR "# include <asm/ldt.h>" " /* Definition of " "struct user_desc" " */" -.PP +.P .BI "int syscall(SYS_get_thread_area, struct user_desc *" u_info ); .BI "int syscall(SYS_set_thread_area, struct user_desc *" u_info ); -.PP +.P .B #elif defined __m68k__ -.PP +.P .B "int syscall(SYS_get_thread_area);" .BI "int syscall(SYS_set_thread_area, unsigned long " tp ); -.PP -.B #elif defined __mips__ -.PP +.P +.B #elif defined __mips__ || defined __csky__ +.P .BI "int syscall(SYS_set_thread_area, unsigned long " addr ); -.PP +.P .B #endif .fi -.PP +.P .IR Note : glibc provides no wrappers for these system calls, necessitating the use of @@ -42,31 +42,31 @@ These calls provide architecture-specific support for a thread-local storage implementation. At the moment, .BR set_thread_area () -is available on m68k, MIPS, and x86 (both 32-bit and 64-bit variants); +is available on m68k, MIPS, C-SKY, and x86 (both 32-bit and 64-bit variants); .BR get_thread_area () is available on m68k and x86. -.PP -On m68k and MIPS, +.P +On m68k, MIPS and C-SKY, .BR set_thread_area () allows storing an arbitrary pointer (provided in the .B tp argument on m68k and in the .B addr -argument on MIPS) +argument on MIPS and C-SKY) in the kernel data structure associated with the calling thread; this pointer can later be retrieved using .BR get_thread_area () (see also NOTES for information regarding obtaining the thread pointer on MIPS). -.PP +.P On x86, Linux dedicates three global descriptor table (GDT) entries for thread-local storage. For more information about the GDT, see the Intel Software Developer's Manual or the AMD Architecture Programming Manual. -.PP +.P Both of these system calls take an argument that is a pointer to a structure of the following type: -.PP +.P .in +4n .EX struct user_desc { @@ -85,16 +85,16 @@ struct user_desc { }; .EE .in -.PP +.P .BR get_thread_area () reads the GDT entry indicated by .I u_info\->entry_number and fills in the rest of the fields in .IR u_info . -.PP +.P .BR set_thread_area () sets a TLS entry in the GDT. -.PP +.P The TLS array entry set by .BR set_thread_area () corresponds to the value of @@ -105,7 +105,7 @@ If this value is in bounds, writes the TLS descriptor pointed to by .I u_info into the thread's TLS array. -.PP +.P When .BR set_thread_area () is passed an @@ -116,7 +116,7 @@ If finds a free TLS entry, the value of .I u_info\->entry_number is set upon return to show which entry was changed. -.PP +.P A .I user_desc is considered "empty" if @@ -128,7 +128,7 @@ If an "empty" descriptor is passed to .BR set_thread_area (), the corresponding TLS entry will be cleared. See BUGS for additional details. -.PP +.P Since Linux 3.19, .BR set_thread_area () cannot be used to write non-present segments, 16-bit segments, or code @@ -138,8 +138,8 @@ On x86, these system calls return 0 on success, and \-1 on failure, with .I errno set to indicate the error. -.PP -On MIPS and m68k, +.P +On C-SKY, MIPS and m68k, .BR set_thread_area () always returns 0. On m68k, @@ -175,7 +175,7 @@ Linux 2.5.29. Linux 2.5.32. .SH NOTES These system calls are generally intended for use only by threading libraries. -.PP +.P .BR arch_prctl (2) can interfere with .BR set_thread_area () @@ -186,16 +186,16 @@ for more details. This is not normally a problem, as .BR arch_prctl (2) is normally used only by 64-bit programs. -.PP +.P On MIPS, the current value of the thread area pointer can be obtained using the instruction: -.PP +.P .in +4n .EX rdhwr dest, $29 .EE .in -.PP +.P This instruction traps and is handled by kernel. .SH BUGS On 64-bit kernels before Linux 3.19, @@ -219,7 +219,7 @@ consisting entirely of zeros except for .I entry_number will also be interpreted as a request to clear a TLS entry, but this behaved differently on older kernels. -.PP +.P Prior to Linux 3.19, the DS and ES segment registers must not reference TLS entries. .SH SEE ALSO |