Edit: sigcontext.h
/* 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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