x86/headers: Clean up uapi/asm/sigcontext32.h

Clean up sigcontext32.h a bit:

 - use consistent and readable vertical spacing
 - fix, harmonize and extend comments

No field name has been changed, user-space might be relying on
them.

Acked-by: Mikko Rapeli <mikko.rapeli@iki.fi>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1441438363-9999-3-git-send-email-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/uapi/asm/sigcontext32.h b/arch/x86/include/uapi/asm/sigcontext32.h
index ff7826c41a1c4b59e2e084294e9320df6ffce739..6ff4fbab650ed7c0a7a01fe4b04e813db1aed57c 100644 (file)
--- a/arch/x86/include/uapi/asm/sigcontext32.h
+++ b/arch/x86/include/uapi/asm/sigcontext32.h
@@ -1,79 +1,85 @@
 #ifndef _ASM_X86_SIGCONTEXT32_H
 #define _ASM_X86_SIGCONTEXT32_H
 
+/* Signal context definitions for compat 32-bit programs: */
+
 #include <linux/types.h>
 
 #include <asm/sigcontext.h>
 
-/* signal context for 32bit programs. */
-
-#define X86_FXSR_MAGIC         0x0000
-
+/* 10-byte legacy floating point register: */
 struct _fpreg {
-       unsigned short significand[4];
-       unsigned short exponent;
+       unsigned short                  significand[4];
+       unsigned short                  exponent;
 };
 
+/* 16-byte floating point register: */
 struct _fpxreg {
-       unsigned short significand[4];
-       unsigned short exponent;
-       unsigned short padding[3];
+       unsigned short                  significand[4];
+       unsigned short                  exponent;
+       unsigned short                  padding[3];
 };
 
+/* 16-byte XMM vector register: */
 struct _xmmreg {
        __u32   element[4];
 };
 
-/* FSAVE frame with extensions */
+#define X86_FXSR_MAGIC                 0x0000
+
+/* FXSAVE frame: FSAVE frame with extensions */
 struct _fpstate_ia32 {
-       /* Regular FPU environment */
-       __u32   cw;
-       __u32   sw;
-       __u32   tag;    /* not compatible to 64bit twd */
-       __u32   ipoff;
-       __u32   cssel;
-       __u32   dataoff;
-       __u32   datasel;
-       struct _fpreg   _st[8];
-       unsigned short  status;
-       unsigned short  magic;          /* 0xffff = regular FPU data only */
+       /* Regular FPU environment: */
+       __u32                           cw;
+       __u32                           sw;
+       __u32                           tag;            /* Not compatible with the 64-bit frame */
+       __u32                           ipoff;
+       __u32                           cssel;
+       __u32                           dataoff;
+       __u32                           datasel;
+       struct _fpreg                   _st[8];
+       unsigned short                  status;
+       unsigned short                  magic;          /* 0xffff: regular FPU data only */
+                                                       /* 0x0000: FXSR data */
 
-       /* FXSR FPU environment */
-       __u32   _fxsr_env[6];
-       __u32   mxcsr;
-       __u32   reserved;
-       struct _fpxreg  _fxsr_st[8];
-       struct _xmmreg  _xmm[8];        /* It's actually 16 */
-       __u32   padding[44];
+       /* Extended FXSR FPU environment: */
+       __u32                           _fxsr_env[6];
+       __u32                           mxcsr;
+       __u32                           reserved;
+       struct _fpxreg                  _fxsr_st[8];
+       struct _xmmreg                  _xmm[8];        /* The first  8 XMM registers */
+       __u32                           padding[44];    /* The second 8 XMM registers plus padding */
        union {
-               __u32 padding2[12];
-               struct _fpx_sw_bytes sw_reserved;
+               __u32                   padding2[12];
+               /* Might encode xstate extensions, see asm/sigcontext.h: */
+               struct _fpx_sw_bytes    sw_reserved;
        };
 };
 
+/* 32-bit compat sigcontext: */
 struct sigcontext_ia32 {
-       unsigned short gs, __gsh;
-       unsigned short fs, __fsh;
-       unsigned short es, __esh;
-       unsigned short ds, __dsh;
-       unsigned int di;
-       unsigned int si;
-       unsigned int bp;
-       unsigned int sp;
-       unsigned int bx;
-       unsigned int dx;
-       unsigned int cx;
-       unsigned int ax;
-       unsigned int trapno;
-       unsigned int err;
-       unsigned int ip;
-       unsigned short cs, __csh;
-       unsigned int flags;
-       unsigned int sp_at_signal;
-       unsigned short ss, __ssh;
-       unsigned int fpstate;           /* really (struct _fpstate_ia32 *) */
-       unsigned int oldmask;
-       unsigned int cr2;
+       unsigned short                  gs, __gsh;
+       unsigned short                  fs, __fsh;
+       unsigned short                  es, __esh;
+       unsigned short                  ds, __dsh;
+       unsigned int                    di;
+       unsigned int                    si;
+       unsigned int                    bp;
+       unsigned int                    sp;
+       unsigned int                    bx;
+       unsigned int                    dx;
+       unsigned int                    cx;
+       unsigned int                    ax;
+       unsigned int                    trapno;
+       unsigned int                    err;
+       unsigned int                    ip;
+       unsigned short                  cs, __csh;
+       unsigned int                    flags;
+       unsigned int                    sp_at_signal;
+       unsigned short                  ss, __ssh;
+       unsigned int                    fpstate;        /* Pointer to 'struct _fpstate_ia32' */
+       unsigned int                    oldmask;
+       unsigned int                    cr2;
 };
 
 #endif /* _ASM_X86_SIGCONTEXT32_H */