| /* 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| * no longer valid.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 */ |