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| author |   Oleg Nesterov <oleg@redhat.com> | 2011-07-10 18:44:24 +0200 |
|---|---|---|
| committer |   H. Peter Anvin <hpa@linux.intel.com> | 2011-07-14 21:46:20 -0700 |
| commit | 73d382deccac186d103496bf10388bc2432a8384 (patch) | |
| tree | e842c530bad8ebbf856a7326b7b8987e176f5093 /arch/x86/kernel/signal.c | |
| parent | x86, do_signal: Simplify the TS_RESTORE_SIGMASK logic (diff) | |
| download | linux-dev-73d382deccac186d103496bf10388bc2432a8384.tar.xz linux-dev-73d382deccac186d103496bf10388bc2432a8384.zip | |
x86: Kill handle_signal()->set_fs()
handle_signal()->set_fs() has a nice comment which explains what
set_fs() is, but it doesn't explain why it is needed and why it
depends on CONFIG_X86_64.
Afaics, the history of this confusion is:
1. I guess today nobody can explain why it was needed
in arch/i386/kernel/signal.c, perhaps it was always
wrong. This predates 2.4.0 kernel.
2. then it was copy-and-past'ed to the new x86_64 arch.
3. then it was removed from i386 (but not from x86_64)
by b93b6ca3 "i386: remove unnecessary code".
4. then it was reintroduced under CONFIG_X86_64 when x86
unified i386 and x86_64, because the patch above didn't
touch x86_64.
Remove it. ->addr_limit should be correct. Even if it was possible
that it is wrong, it is too late to fix it after setup_rt_frame().
Linus commented in:
http://lkml.kernel.org/r/alpine.LFD.0.999.0707170902570.19166@woody.linux-foundation.org
... about the equivalent bit from i386:
Heh. I think it's entirely historical.
Please realize that the whole reason that function is called "set_fs()" is
that it literally used to set the %fs segment register, not
"->addr_limit".
So I think the "set_fs(USER_DS)" is there _only_ to match the other
regs->xds = __USER_DS;
regs->xes = __USER_DS;
regs->xss = __USER_DS;
regs->xcs = __USER_CS;
things, and never mattered. And now it matters even less, and has been
copied to all other architectures where it is just totally insane.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20110710164424.GA20261@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/signal.c')
| -rw-r--r-- | arch/x86/kernel/signal.c | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 8c55f97728cd..54ddaeb221c1 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -720,15 +720,6 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, if (ret) return ret; -#ifdef CONFIG_X86_64 - /* - * This has nothing to do with segment registers, - * despite the name. This magic affects uaccess.h - * macros' behavior. Reset it to the normal setting. - */ - set_fs(USER_DS); -#endif - /* * Clear the direction flag as per the ABI for function entry. */ |