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6f52b16c5b
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 <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
56 lines
2.1 KiB
C
56 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _ASM_X86_UCONTEXT_H
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#define _ASM_X86_UCONTEXT_H
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/*
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* Indicates the presence of extended state information in the memory
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* layout pointed by the fpstate pointer in the ucontext's sigcontext
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* struct (uc_mcontext).
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*/
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#define UC_FP_XSTATE 0x1
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#ifdef __x86_64__
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/*
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* UC_SIGCONTEXT_SS will be set when delivering 64-bit or x32 signals on
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* kernels that save SS in the sigcontext. All kernels that set
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* UC_SIGCONTEXT_SS will correctly restore at least the low 32 bits of esp
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* regardless of SS (i.e. they implement espfix).
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*
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* Kernels that set UC_SIGCONTEXT_SS will also set UC_STRICT_RESTORE_SS
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* when delivering a signal that came from 64-bit code.
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*
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* Sigreturn restores SS as follows:
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*
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* if (saved SS is valid || UC_STRICT_RESTORE_SS is set ||
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* saved CS is not 64-bit)
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* new SS = saved SS (will fail IRET and signal if invalid)
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* else
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* new SS = a flat 32-bit data segment
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*
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* This behavior serves three purposes:
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*
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* - Legacy programs that construct a 64-bit sigcontext from scratch
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* with zero or garbage in the SS slot (e.g. old CRIU) and call
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* sigreturn will still work.
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*
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* - Old DOSEMU versions sometimes catch a signal from a segmented
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* context, delete the old SS segment (with modify_ldt), and change
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* the saved CS to a 64-bit segment. These DOSEMU versions expect
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* sigreturn to send them back to 64-bit mode without killing them,
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* despite the fact that the SS selector when the signal was raised is
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* no longer valid. UC_STRICT_RESTORE_SS will be clear, so the kernel
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* will fix up SS for these DOSEMU versions.
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*
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* - Old and new programs that catch a signal and return without
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* modifying the saved context will end up in exactly the state they
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* started in, even if they were running in a segmented context when
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* the signal was raised.. Old kernels would lose track of the
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* previous SS value.
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*/
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#define UC_SIGCONTEXT_SS 0x2
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#define UC_STRICT_RESTORE_SS 0x4
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#endif
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#include <asm-generic/ucontext.h>
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#endif /* _ASM_X86_UCONTEXT_H */
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