From 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 12:05:51 +0200 Subject: Adding upstream version 5.10.209. Signed-off-by: Daniel Baumann --- arch/x86/include/uapi/asm/ucontext.h | 56 ++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 arch/x86/include/uapi/asm/ucontext.h (limited to 'arch/x86/include/uapi/asm/ucontext.h') diff --git a/arch/x86/include/uapi/asm/ucontext.h b/arch/x86/include/uapi/asm/ucontext.h new file mode 100644 index 000000000..5657b7a49 --- /dev/null +++ b/arch/x86/include/uapi/asm/ucontext.h @@ -0,0 +1,56 @@ +/* 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back to 64-bit mode without killing them, + * despite the fact that the SS selector when the signal was raised is + * no longer valid.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 + +#endif /* _ASM_X86_UCONTEXT_H */ -- cgit v1.2.3