[ARM] 3648/1: Update struct ucontext layout for coprocessor registers

Patch from Daniel Jacobowitz

In order for userspace to find saved coprocessor registers, move them from
struct rt_sigframe into struct ucontext.  Also allow space for glibc's
sigset_t, so that userspace and kernelspace can use the same ucontext
layout.  Define the magic numbers for iWMMXt in the header file for easier
reference.  Include the size of the coprocessor data in the magic numbers.

Also define magic numbers and layout for VFP, not yet saved.

Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 78 insertions, 1 deletions

diff --git a/include/asm-arm/ucontext.h b/include/asm-arm/ucontext.h
index f853130137cc..9e6f7ca9f5ae 100644
--- a/include/asm-arm/ucontext.h
+++ b/include/asm-arm/ucontext.h
@@ -1,12 +1,89 @@
 #ifndef _ASMARM_UCONTEXT_H
 #define _ASMARM_UCONTEXT_H
 
+#include <asm/fpstate.h>
+
+/*
+ * struct sigcontext only has room for the basic registers, but struct
+ * ucontext now has room for all registers which need to be saved and
+ * restored.  Coprocessor registers are stored in uc_regspace.  Each
+ * coprocessor's saved state should start with a documented 32-bit magic
+ * number, followed by a 32-bit word giving the coproccesor's saved size.
+ * uc_regspace may be expanded if necessary, although this takes some
+ * coordination with glibc.
+ */
+
 struct ucontext {
         unsigned long     uc_flags;
         struct ucontext  *uc_link;
         stack_t           uc_stack;
         struct sigcontext uc_mcontext;
-        sigset_t          uc_sigmask;   /* mask last for extensibility */
+        sigset_t          uc_sigmask;
+        /* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+        int               __unused[32 - (sizeof (sigset_t) / sizeof (int))];
+        /* Last for extensibility.  Eight byte aligned because some
+           coprocessors require eight byte alignment.  */
+        unsigned long     uc_regspace[128] __attribute__((__aligned__(8)));
 };
 
+#ifdef __KERNEL__
+
+/*
+ * Coprocessor save state.  The magic values and specific
+ * coprocessor's layouts are part of the userspace ABI.  Each one of
+ * these should be a multiple of eight bytes and aligned to eight
+ * bytes, to prevent unpredictable padding in the signal frame.
+ */
+
+#ifdef CONFIG_IWMMXT
+/* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
+#define IWMMXT_MAGIC            0x12ef842a
+#define IWMMXT_STORAGE_SIZE     (IWMMXT_SIZE + 8)
+
+struct iwmmxt_sigframe {
+        unsigned long   magic;
+        unsigned long   size;
+        struct iwmmxt_struct storage;
+} __attribute__((__aligned__(8)));
+#endif /* CONFIG_IWMMXT */
+
+#ifdef CONFIG_VFP
+#if __LINUX_ARM_ARCH__ < 6
+/* For ARM pre-v6, we use fstmiax and fldmiax.  This adds one extra
+ * word after the registers, and a word of padding at the end for
+ * alignment.  */
+#define VFP_MAGIC               0x56465001
+#define VFP_STORAGE_SIZE        152
+#else
+#define VFP_MAGIC               0x56465002
+#define VFP_STORAGE_SIZE        144
+#endif
+
+struct vfp_sigframe
+{
+        unsigned long           magic;
+        unsigned long           size;
+        union vfp_state         storage;
+};
+#endif /* CONFIG_VFP */
+
+/*
+ * Auxiliary signal frame.  This saves stuff like FP state.
+ * The layout of this structure is not part of the user ABI,
+ * because the config options aren't.  uc_regspace is really
+ * one of these.
+ */
+struct aux_sigframe {
+#ifdef CONFIG_IWMMXT
+        struct iwmmxt_sigframe  iwmmxt;
+#endif
+#if 0 && defined CONFIG_VFP /* Not yet saved.  */
+        struct vfp_sigframe     vfp;
+#endif
+        /* Something that isn't a valid magic number for any coprocessor.  */
+        unsigned long           end_magic;
+} __attribute__((__aligned__(8)));
+
+#endif
+
 #endif /* !_ASMARM_UCONTEXT_H */