linux-toradex.git/arch/x86/include/uapi/asm/sigcontext.h, branch v5.14

x86: Fix various typos in comments

2021-03-18T14:31:53+00:00

Fix ~144 single-word typos in arch/x86/ code comments.

Doing this in a single commit should reduce the churn.

Signed-off-by: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Paolo Bonzini 
Cc: Bjorn Helgaas 
Cc: linux-kernel@vger.kernel.org

License cleanup: add SPDX license identifier to uapi header files with no license

2017-11-02T10:19:54+00:00

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2.  Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

   NOTE! This copyright does *not* cover user programs that use kernel
   services by normal system calls - this is merely considered normal use
   of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier.  The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception.  SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.  See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart 
Reviewed-by: Philippe Ombredanne 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

x86/signal/64: Re-add support for SS in the 64-bit signal context

2016-02-17T07:32:11+00:00

This is a second attempt to make the improvements from c6f2062935c8
("x86/signal/64: Fix SS handling for signals delivered to 64-bit
programs"), which was reverted by 51adbfbba5c6 ("x86/signal/64: Add
support for SS in the 64-bit signal context").

This adds two new uc_flags flags.  UC_SIGCONTEXT_SS will be set for
all 64-bit signals (including x32).  It indicates that the saved SS
field is valid and that the kernel supports the new behavior.

The goal is to fix a problems with signal handling in 64-bit tasks:
SS wasn't saved in the 64-bit signal context, making it awkward to
determine what SS was at the time of signal delivery and making it
impossible to return to a non-flat SS (as calling sigreturn clobbers
SS).

This also made it extremely difficult for 64-bit tasks to return to
fully-defined 16-bit contexts, because only the kernel can easily do
espfix64, but sigreturn was unable to set a non-flag SS:ESP.
(DOSEMU has a monstrous hack to partially work around this
limitation.)

If we could go back in time, the correct fix would be to make 64-bit
signals work just like 32-bit signals with respect to SS: save it
in signal context, reset it when delivering a signal, and restore
it in sigreturn.

Unfortunately, doing that (as I tried originally) breaks DOSEMU:
DOSEMU wouldn't reset the signal context's SS when clearing the LDT
and changing the saved CS to 64-bit mode, since it predates the SS
context field existing in the first place.

This patch is a bit more complicated, and it tries to balance a
bunch of goals.  It makes most cases of changing ucontext->ss during
signal handling work as expected.

I do this by special-casing the interesting case.  On sigreturn,
ucontext->ss will be honored by default, unless the ucontext was
created from scratch by an old program and had a 64-bit CS
(unfortunately, CRIU can do this) or was the result of changing a
32-bit signal context to 64-bit without resetting SS (as DOSEMU
does).

For the benefit of new 64-bit software that uses segmentation (new
versions of DOSEMU might), the new behavior can be detected with a
new ucontext flag UC_SIGCONTEXT_SS.

To avoid compilation issues, __pad0 is left as an alias for ss in
ucontext.

The nitty-gritty details are documented in the header file.

This patch also re-enables the sigreturn_64 and ldt_gdt_64 selftests,
as the kernel change allows both of them to pass.

Tested-by: Stas Sergeev 
Signed-off-by: Andy Lutomirski 
Acked-by: Borislav Petkov 
Cc: Al Viro 
Cc: Andy Lutomirski 
Cc: Brian Gerst 
Cc: Cyrill Gorcunov 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Pavel Emelyanov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/749149cbfc3e75cd7fcdad69a854b399d792cc6f.1455664054.git.luto@kernel.org
[ Small readability edit. ]
Signed-off-by: Ingo Molnar

x86/signal/64: Add a comment about sigcontext->fs and gs

2016-02-17T07:32:11+00:00

These fields have a strange history.  This tries to document it.

This borrows from 9a036b93a344 ("x86/signal/64: Remove 'fs' and 'gs'
from sigcontext"), which was reverted by ed596cde9425 ("Revert x86
sigcontext cleanups").

Signed-off-by: Andy Lutomirski 
Acked-by: Borislav Petkov 
Cc: Al Viro 
Cc: Andy Lutomirski 
Cc: Brian Gerst 
Cc: Cyrill Gorcunov 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Pavel Emelyanov 
Cc: Peter Zijlstra 
Cc: Stas Sergeev 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/baa78f3c84106fa5acbc319377b1850602f5deec.1455664054.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/headers: Clean up too long lines

2015-09-14T09:09:33+00:00

Signed-off-by: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Thomas Gleixner 
Cc: bp@alien8.de
Cc: brgerst@gmail.com
Cc: dvlasenk@redhat.com
Cc: luto@amacapital.net
Cc: mikko.rapeli@iki.fi
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/20150909071244.GM3644@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar

x86/headers: Convert sigcontext_ia32 uses to sigcontext_32

2015-09-08T08:03:59+00:00

Use the new name in kernel code, and move the old name to the
user-space-only legacy section of the UAPI header.

Acked-by: Mikko Rapeli 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-14-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar

x86/headers: Unify 'struct sigcontext_ia32' and 'struct sigcontext_32'

2015-09-08T08:03:58+00:00

The two structures are identical - merge them and keep the
legacy name as a define.

Acked-by: Mikko Rapeli 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-13-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar

x86/headers: Make sigcontext pointers bit independent

2015-09-08T08:03:58+00:00

Before we can eliminate the duplication between 'struct
sigcontext_32' and 'struct sigcontext_ia32', make the 'fpstate'
pointer field in 'struct sigcontext_32' bit independent.

Acked-by: Mikko Rapeli 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-12-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar

x86/headers: Move the 'struct sigcontext' definitions into the UAPI header

2015-09-08T08:03:58+00:00

Our goal is to eliminate the duplicate struct sigcontext_ia32
definition, so move the kernel's primary sigcontext type into
the UAPI header, defining these two variants:

	struct sigcontext_32
	struct sigcontext_64

... and map them to 'struct sigcontext'.

Acked-by: Mikko Rapeli 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-11-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar

x86/headers: Convert uses of _fpstate_ia32 to _fpstate_32

2015-09-08T08:03:57+00:00

Remove uses of _fpstate_ia32 from the kernel, and move the
legacy _fpstate_ia32 definition to the user-space only portion
of the header.

Acked-by: Mikko Rapeli 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-9-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar