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| author | Keno Fischer <keno@juliacomputing.com> | 2016-08-23 23:06:07 -0400 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-09-25 21:00:52 +0200 |
| commit | dd6d3d2e5fdd373d78698d2e7c5bb80f80049c03 (patch) | |
| tree | a0e2a84ceb4afb30d27891b04c0efde703fee481 | |
| parent | 2293a55f93080704fe059b87f2f6c1cdca99721e (diff) | |
| download | man-pages-dd6d3d2e5fdd373d78698d2e7c5bb80f80049c03.tar.gz | |
clone.2: Adjust syscall prototype and expand CLONE_SETTLS description
The prototype for the system call was added in kernel commit
81f10dad, but looking at the kernel's fork.c, I believe the
relevant definition is
SYSCALL_DEFINE5(clone, unsigned long, clone_flags,
unsigned long, newsp,
int __user *, parent_tidptr,
int __user *, child_tidptr,
unsigned long, tls)
so the last argument is the tls argument, not a pt_regs argument.
I stumbled upon this while trying to understand CLONE_SETTLS, so
I expanded that description a little to cover other architectures.
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| -rw-r--r-- | man2/clone.2 | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/man2/clone.2 b/man2/clone.2 index dda9b41da0..5997f43d0c 100644 --- a/man2/clone.2 +++ b/man2/clone.2 @@ -51,14 +51,14 @@ clone, __clone2 \- create a child process .BI "int clone(int (*" "fn" ")(void *), void *" child_stack , .BI " int " flags ", void *" "arg" ", ... " -.BI " /* pid_t *" ptid ", struct user_desc *" tls \ +.BI " /* pid_t *" ptid ", void *" newtls \ ", pid_t *" ctid " */ );" /* Prototype for the raw system call */ .BI "long clone(unsigned long " flags ", void *" child_stack , .BI " void *" ptid ", void *" ctid , -.BI " struct pt_regs *" regs ); +.BI " unsigned long " newtls ); .fi .SH DESCRIPTION .BR clone () @@ -544,11 +544,25 @@ then trace the child also (see .BR ptrace (2)). .TP .BR CLONE_SETTLS " (since Linux 2.5.32)" -The +The TLS (Thread Local Storage) descriptor is set to +.I newtls. + +The interpretation of +.I newtls +and the resulting effect is architecture dependent. +On x86, .I newtls -argument is the new TLS (Thread Local Storage) descriptor. +is interpreted as a +.IR "struct user_desc *" (See -.BR set_thread_area (2).) +.BR set_thread_area (2)). +On x86_64 it is the new value to be set for the %fs base register +(See the +.I ARCH_SET_FS +argument to +.BR arch_prctl (2)). +On architectures with a dedicated TLS register, it is the new value +of that register. .TP .BR CLONE_SIGHAND " (since Linux 2.0)" If @@ -813,7 +827,7 @@ The raw system call interface on x86 and many other architectures is roughly: .BI "long clone(unsigned long " flags ", void *" child_stack , .BI " void *" ptid ", void *" ctid , -.BI " struct pt_regs *" regs ); +.BI " unsigned long " newtls ); .fi .in |