/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ #ifndef _UAPI_ASM_X86_SIGCONTEXT_H #define _UAPI_ASM_X86_SIGCONTEXT_H /* * Linux signal context definitions. The sigcontext includes a complex * hierarchy of CPU and FPU state, available to user-space (on the stack) when * a signal handler is executed. * * As over the years this ABI grew from its very simple roots towards * supporting more and more CPU state organically, some of the details (which * were rather clever hacks back in the days) became a bit quirky by today. * * The current ABI includes flexible provisions for future extensions, so we * won't have to grow new quirks for quite some time. Promise! */ #include <linux/compiler.h> #include <linux/types.h> #define FP_XSTATE_MAGIC1 … #define FP_XSTATE_MAGIC2 … #define FP_XSTATE_MAGIC2_SIZE … /* * Bytes 464..511 in the current 512-byte layout of the FXSAVE/FXRSTOR frame * are reserved for SW usage. On CPUs supporting XSAVE/XRSTOR, these bytes are * used to extend the fpstate pointer in the sigcontext, which now includes the * extended state information along with fpstate information. * * If sw_reserved.magic1 == FP_XSTATE_MAGIC1 then there's a * sw_reserved.extended_size bytes large extended context area present. (The * last 32-bit word of this extended area (at the * fpstate+extended_size-FP_XSTATE_MAGIC2_SIZE address) is set to * FP_XSTATE_MAGIC2 so that you can sanity check your size calculations.) * * This extended area typically grows with newer CPUs that have larger and * larger XSAVE areas. */ struct _fpx_sw_bytes { … }; /* * As documented in the iBCS2 standard: * * The first part of "struct _fpstate" is just the normal i387 hardware setup, * the extra "status" word is used to save the coprocessor status word before * entering the handler. * * The FPU state data structure has had to grow to accommodate the extended FPU * state required by the Streaming SIMD Extensions. There is no documented * standard to accomplish this at the moment. */ /* 10-byte legacy floating point register: */ struct _fpreg { … }; /* 16-byte floating point register: */ struct _fpxreg { … }; /* 16-byte XMM register: */ struct _xmmreg { … }; #define X86_FXSR_MAGIC … /* * The 32-bit FPU frame: */ struct _fpstate_32 { … }; /* * The 64-bit FPU frame. (FXSAVE format and later) * * Note1: If sw_reserved.magic1 == FP_XSTATE_MAGIC1 then the structure is * larger: 'struct _xstate'. Note that 'struct _xstate' embeds * 'struct _fpstate' so that you can always assume the _fpstate portion * exists so that you can check the magic value. * * Note2: Reserved fields may someday contain valuable data. Always * save/restore them when you change signal frames. */ struct _fpstate_64 { … }; #ifdef __i386__ #define _fpstate … #else #define _fpstate … #endif struct _header { … }; struct _ymmh_state { … }; /* * Extended state pointed to by sigcontext::fpstate. * * In addition to the fpstate, information encoded in _xstate::xstate_hdr * indicates the presence of other extended state information supported * by the CPU and kernel: */ struct _xstate { … }; /* * The 32-bit signal frame: */ struct sigcontext_32 { … }; /* * The 64-bit signal frame: */ struct sigcontext_64 { … }; /* * Create the real 'struct sigcontext' type: */ #ifdef __KERNEL__ # ifdef __i386__ #define sigcontext … # else #define sigcontext … # endif #endif /* * The old user-space sigcontext definition, just in case user-space still * relies on it. The kernel definition (in asm/sigcontext.h) has unified * field names but otherwise the same layout. */ #ifndef __KERNEL__ #define _fpstate_ia32 … #define sigcontext_ia32 … # ifdef __i386__ struct sigcontext { __u16 gs, __gsh; __u16 fs, __fsh; __u16 es, __esh; __u16 ds, __dsh; __u32 edi; __u32 esi; __u32 ebp; __u32 esp; __u32 ebx; __u32 edx; __u32 ecx; __u32 eax; __u32 trapno; __u32 err; __u32 eip; __u16 cs, __csh; __u32 eflags; __u32 esp_at_signal; __u16 ss, __ssh; struct _fpstate __user *fpstate; __u32 oldmask; __u32 cr2; }; # else /* __x86_64__: */ struct sigcontext { __u64 r8; __u64 r9; __u64 r10; __u64 r11; __u64 r12; __u64 r13; __u64 r14; __u64 r15; __u64 rdi; __u64 rsi; __u64 rbp; __u64 rbx; __u64 rdx; __u64 rax; __u64 rcx; __u64 rsp; __u64 rip; __u64 eflags; /* RFLAGS */ __u16 cs; /* * Prior to 2.5.64 ("[PATCH] x86-64 updates for 2.5.64-bk3"), * Linux saved and restored fs and gs in these slots. This * was counterproductive, as fsbase and gsbase were never * saved, so arch_prctl was presumably unreliable. * * These slots should never be reused without extreme caution: * * - Some DOSEMU versions stash fs and gs in these slots manually, * thus overwriting anything the kernel expects to be preserved * in these slots. * * - If these slots are ever needed for any other purpose, * there is some risk that very old 64-bit binaries could get * confused. I doubt that many such binaries still work, * though, since the same patch in 2.5.64 also removed the * 64-bit set_thread_area syscall, so it appears that there * is no TLS API beyond modify_ldt that works in both pre- * and post-2.5.64 kernels. * * If the kernel ever adds explicit fs, gs, fsbase, and gsbase * save/restore, it will most likely need to be opt-in and use * different context slots. */ __u16 gs; __u16 fs; union { __u16 ss; /* If UC_SIGCONTEXT_SS */ __u16 __pad0; /* Alias name for old (!UC_SIGCONTEXT_SS) user-space */ }; __u64 err; __u64 trapno; __u64 oldmask; __u64 cr2; struct _fpstate __user *fpstate; /* Zero when no FPU context */ # ifdef __ILP32__ __u32 __fpstate_pad; # endif __u64 reserved1[8]; }; # endif /* __x86_64__ */ #endif /* !__KERNEL__ */ #endif /* _UAPI_ASM_X86_SIGCONTEXT_H */
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