Release 4.14 arch/x86/include/uapi/asm/sigcontext.h
/* 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 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:
*/
#ifdef __KERNEL__
# ifdef __i386__
# define sigcontext sigcontext_32
# else
# define sigcontext sigcontext_64
# 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 _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 __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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| Person | Tokens | Prop | Commits | CommitProp |
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