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| * no longer valid.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