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/usr/src/linux-headers-5.15.0-181/arch/x86/include/uapi/asm/

/usr/src/linux-headers-5.15.0-181/arch/x86/include/uapi/asm

Name	Size	Mode	Actions
a.out.h	756	0644	edit dl rm
auxvec.h	546	0644	edit dl rm
bitsperlong.h	321	0644	edit dl rm
boot.h	338	0644	edit dl rm
bootparam.h	8233	0644	edit dl rm
byteorder.h	200	0644	edit dl rm
debugreg.h	3344	0644	edit dl rm
e820.h	2620	0644	edit dl rm
hwcap2.h	324	0644	edit dl rm
hw_breakpoint.h	69	0644	edit dl rm
ist.h	869	0644	edit dl rm
Kbuild	117	0644	edit dl rm
kvm.h	10858	0644	edit dl rm
kvm_para.h	4315	0644	edit dl rm
kvm_perf.h	388	0644	edit dl rm
ldt.h	1306	0644	edit dl rm
mce.h	1745	0644	edit dl rm
mman.h	1002	0644	edit dl rm
msgbuf.h	1079	0644	edit dl rm
msr.h	361	0644	edit dl rm
mtrr.h	4240	0644	edit dl rm
perf_regs.h	1403	0644	edit dl rm
posix_types.h	250	0644	edit dl rm
posix_types_32.h	765	0644	edit dl rm
posix_types_64.h	609	0644	edit dl rm
posix_types_x32.h	581	0644	edit dl rm
prctl.h	524	0644	edit dl rm
processor-flags.h	6638	0644	edit dl rm
ptrace-abi.h	2037	0644	edit dl rm
ptrace.h	1630	0644	edit dl rm
sembuf.h	1070	0644	edit dl rm
setup.h	6	0644	edit dl rm
sgx.h	5935	0644	edit dl rm
shmbuf.h	1258	0644	edit dl rm
sigcontext.h	9950	0644	edit dl rm
sigcontext32.h	271	0644	edit dl rm
siginfo.h	422	0644	edit dl rm
signal.h	2200	0644	edit dl rm
stat.h	3131	0644	edit dl rm
statfs.h	416	0644	edit dl rm
svm.h	8917	0644	edit dl rm
swab.h	769	0644	edit dl rm
ucontext.h	2117	0644	edit dl rm
unistd.h	664	0644	edit dl rm
vm86.h	3201	0644	edit dl rm
vmx.h	7383	0644	edit dl rm
vsyscall.h	278	0644	edit dl rm

Edit: /usr/src/linux-headers-5.15.0-181/arch/x86/include/uapi/asm/ucontext.h (2117B)

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _ASM_X86_UCONTEXT_H
#define _ASM_X86_UCONTEXT_H

/*
 * Indicates the presence of extended state information in the memory
 * layout pointed by the fpstate pointer in the ucontext's sigcontext
 * struct (uc_mcontext).
 */
#define UC_FP_XSTATE	0x1

#ifdef __x86_64__
/*
 * UC_SIGCONTEXT_SS will be set when delivering 64-bit or x32 signals on
 * kernels that save SS in the sigcontext.  All kernels that set
 * UC_SIGCONTEXT_SS will correctly restore at least the low 32 bits of esp
 * regardless of SS (i.e. they implement espfix).
 *
 * Kernels that set UC_SIGCONTEXT_SS will also set UC_STRICT_RESTORE_SS
 * when delivering a signal that came from 64-bit code.
 *
 * Sigreturn restores SS as follows:
 *
 * if (saved SS is valid || UC_STRICT_RESTORE_SS is set ||
 *     saved CS is not 64-bit)
 *         new SS = saved SS  (will fail IRET and signal if invalid)
 * else
 *         new SS = a flat 32-bit data segment
 *
 * This behavior serves three purposes:
 *
 * - Legacy programs that construct a 64-bit sigcontext from scratch
 *   with zero or garbage in the SS slot (e.g. old CRIU) and call
 *   sigreturn will still work.
 *
 * - Old DOSEMU versions sometimes catch a signal from a segmented
 *   context, delete the old SS segment (with modify_ldt), and change
 *   the saved CS to a 64-bit segment.  These DOSEMU versions expect
 *   sigreturn to send them back to 64-bit mode without killing them,
 *   despite the fact that the SS selector when the signal was raised is
 *   no longer valid.  UC_STRICT_RESTORE_SS will be clear, so the kernel
 *   will fix up SS for these DOSEMU versions.
 *
 * - Old and new programs that catch a signal and return without
 *   modifying the saved context will end up in exactly the state they
 *   started in, even if they were running in a segmented context when
 *   the signal was raised..  Old kernels would lose track of the
 *   previous SS value.
 */
#define UC_SIGCONTEXT_SS	0x2
#define UC_STRICT_RESTORE_SS	0x4
#endif

#include <asm-generic/ucontext.h>

#endif /* _ASM_X86_UCONTEXT_H */

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