--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_X86_SIGCONTEXT_H
+#define _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/types.h>
+
+#define FP_XSTATE_MAGIC1 0x46505853U
+#define FP_XSTATE_MAGIC2 0x46505845U
+#define FP_XSTATE_MAGIC2_SIZE sizeof(FP_XSTATE_MAGIC2)
+
+/*
+ * 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 {
+ /*
+ * If set to FP_XSTATE_MAGIC1 then this is an xstate context.
+ * 0 if a legacy frame.
+ */
+ __u32 magic1;
+
+ /*
+ * Total size of the fpstate area:
+ *
+ * - if magic1 == 0 then it's sizeof(struct _fpstate)
+ * - if magic1 == FP_XSTATE_MAGIC1 then it's sizeof(struct _xstate)
+ * plus extensions (if any)
+ */
+ __u32 extended_size;
+
+ /*
+ * Feature bit mask (including FP/SSE/extended state) that is present
+ * in the memory layout:
+ */
+ __u64 xfeatures;
+
+ /*
+ * Actual XSAVE state size, based on the xfeatures saved in the layout.
+ * 'extended_size' is greater than 'xstate_size':
+ */
+ __u32 xstate_size;
+
+ /* For future use: */
+ __u32 padding[7];
+};
+
+/*
+ * 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 {
+ __u16 significand[4];
+ __u16 exponent;
+};
+
+/* 16-byte floating point register: */
+struct _fpxreg {
+ __u16 significand[4];
+ __u16 exponent;
+ __u16 padding[3];
+};
+
+/* 16-byte XMM register: */
+struct _xmmreg {
+ __u32 element[4];
+};
+
+#define X86_FXSR_MAGIC 0x0000
+
+/*
+ * The 32-bit FPU frame:
+ */
+struct _fpstate_32 {
+ /* Legacy FPU environment: */
+ __u32 cw;
+ __u32 sw;
+ __u32 tag;
+ __u32 ipoff;
+ __u32 cssel;
+ __u32 dataoff;
+ __u32 datasel;
+ struct _fpreg _st[8];
+ __u16 status;
+ __u16 magic; /* 0xffff: regular FPU data only */
+ /* 0x0000: FXSR FPU data */
+
+ /* FXSR FPU environment */
+ __u32 _fxsr_env[6]; /* FXSR FPU env is ignored */
+ __u32 mxcsr;
+ __u32 reserved;
+ struct _fpxreg _fxsr_st[8]; /* FXSR FPU reg data is ignored */
+ struct _xmmreg _xmm[8]; /* First 8 XMM registers */
+ union {
+ __u32 padding1[44]; /* Second 8 XMM registers plus padding */
+ __u32 padding[44]; /* Alias name for old user-space */
+ };
+
+ union {
+ __u32 padding2[12];
+ struct _fpx_sw_bytes sw_reserved; /* Potential extended state is encoded here */
+ };
+};
+
+/*
+ * 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' embedds
+ * '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 {
+ __u16 cwd;
+ __u16 swd;
+ /* Note this is not the same as the 32-bit/x87/FSAVE twd: */
+ __u16 twd;
+ __u16 fop;
+ __u64 rip;
+ __u64 rdp;
+ __u32 mxcsr;
+ __u32 mxcsr_mask;
+ __u32 st_space[32]; /* 8x FP registers, 16 bytes each */
+ __u32 xmm_space[64]; /* 16x XMM registers, 16 bytes each */
+ __u32 reserved2[12];
+ union {
+ __u32 reserved3[12];
+ struct _fpx_sw_bytes sw_reserved; /* Potential extended state is encoded here */
+ };
+};
+
+#ifdef __i386__
+# define _fpstate _fpstate_32
+#else
+# define _fpstate _fpstate_64
+#endif
+
+struct _header {
+ __u64 xfeatures;
+ __u64 reserved1[2];
+ __u64 reserved2[5];
+};
+
+struct _ymmh_state {
+ /* 16x YMM registers, 16 bytes each: */
+ __u32 ymmh_space[64];
+};
+
+/*
+ * 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 {
+ struct _fpstate fpstate;
+ struct _header xstate_hdr;
+ struct _ymmh_state ymmh;
+ /* New processor state extensions go here: */
+};
+
+/*
+ * The 32-bit signal frame:
+ */
+struct sigcontext_32 {
+ __u16 gs, __gsh;
+ __u16 fs, __fsh;
+ __u16 es, __esh;
+ __u16 ds, __dsh;
+ __u32 di;
+ __u32 si;
+ __u32 bp;
+ __u32 sp;
+ __u32 bx;
+ __u32 dx;
+ __u32 cx;
+ __u32 ax;
+ __u32 trapno;
+ __u32 err;
+ __u32 ip;
+ __u16 cs, __csh;
+ __u32 flags;
+ __u32 sp_at_signal;
+ __u16 ss, __ssh;
+
+ /*
+ * fpstate is really (struct _fpstate *) or (struct _xstate *)
+ * depending on the FP_XSTATE_MAGIC1 encoded in the SW reserved
+ * bytes of (struct _fpstate) and FP_XSTATE_MAGIC2 present at the end
+ * of extended memory layout. See comments at the definition of
+ * (struct _fpx_sw_bytes)
+ */
+ __u32 fpstate; /* Zero when no FPU/extended context */
+ __u32 oldmask;
+ __u32 cr2;
+};
+
+/*
+ * The 64-bit signal frame:
+ */
+struct sigcontext_64 {
+ __u64 r8;
+ __u64 r9;
+ __u64 r10;
+ __u64 r11;
+ __u64 r12;
+ __u64 r13;
+ __u64 r14;
+ __u64 r15;
+ __u64 di;
+ __u64 si;
+ __u64 bp;
+ __u64 bx;
+ __u64 dx;
+ __u64 ax;
+ __u64 cx;
+ __u64 sp;
+ __u64 ip;
+ __u64 flags;
+ __u16 cs;
+ __u16 gs;
+ __u16 fs;
+ __u16 ss;
+ __u64 err;
+ __u64 trapno;
+ __u64 oldmask;
+ __u64 cr2;
+
+ /*
+ * fpstate is really (struct _fpstate *) or (struct _xstate *)
+ * depending on the FP_XSTATE_MAGIC1 encoded in the SW reserved
+ * bytes of (struct _fpstate) and FP_XSTATE_MAGIC2 present at the end
+ * of extended memory layout. See comments at the definition of
+ * (struct _fpx_sw_bytes)
+ */
+ __u64 fpstate; /* Zero when no FPU/extended context */
+ __u64 reserved1[8];
+};
+
+/*
+ * Create the real 'struct sigcontext' type:
+ */
+
+/*
+ * 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.
+ */
+
+#define _fpstate_ia32 _fpstate_32
+#define sigcontext_ia32 sigcontext_32
+
+
+# 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 *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 *fpstate; /* Zero when no FPU context */
+# ifdef __ILP32__
+ __u32 __fpstate_pad;
+# endif
+ __u64 reserved1[8];
+};
+# endif /* __x86_64__ */
+
+#endif /* _ASM_X86_SIGCONTEXT_H */
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