m68knommu: implement minimal regset support

Add code support to the m68k architecture for regsets.

Currently the only thing that will need to use regsets for m68k will be
coredump support of the elf_fdpic loader. So the changes are conditional
on that. The added support is the minimum definitions required to support
just that.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

arch/m68k/kernel/ptrace.c

@@ -19,6 +19,8 @@
 #include <linux/ptrace.h>
 #include <linux/user.h>
 #include <linux/signal.h>
+#include <linux/regset.h>
+#include <linux/elf.h>
 
 #include <linux/uaccess.h>
 #include <asm/page.h>
@@ -291,3 +293,59 @@ asmlinkage void syscall_trace_leave(void)
 		ptrace_report_syscall_exit(task_pt_regs(current), 0);
 }
 #endif /* CONFIG_COLDFIRE */
+
+#if defined(CONFIG_BINFMT_ELF_FDPIC) && defined(CONFIG_ELF_CORE)
+/*
+ * Currently the only thing that needs to use regsets for m68k is the
+ * coredump support of the elf_fdpic loader. Implement the minimum
+ * definitions required for that.
+ */
+static int m68k_regset_get(struct task_struct *target,
+			   const struct user_regset *regset,
+			   struct membuf to)
+{
+	struct pt_regs *ptregs = task_pt_regs(target);
+	u32 uregs[ELF_NGREG];
+
+	ELF_CORE_COPY_REGS(uregs, ptregs);
+	return membuf_write(&to, uregs, sizeof(uregs));
+}
+
+enum m68k_regset {
+	REGSET_GPR,
+#ifdef CONFIG_FPU
+	REGSET_FPU,
+#endif
+};
+
+static const struct user_regset m68k_user_regsets[] = {
+	[REGSET_GPR] = {
+		.core_note_type = NT_PRSTATUS,
+		.n = ELF_NGREG,
+		.size = sizeof(u32),
+		.align = sizeof(u16),
+		.regset_get = m68k_regset_get,
+	},
+#ifdef CONFIG_FPU
+	[REGSET_FPU] = {
+		.core_note_type = NT_PRFPREG,
+		.n = sizeof(struct user_m68kfp_struct) / sizeof(u32),
+		.size = sizeof(u32),
+		.align = sizeof(u32),
+	}
+#endif /* CONFIG_FPU */
+};
+
+static const struct user_regset_view user_m68k_view = {
+	.name = "m68k",
+	.e_machine = EM_68K,
+	.ei_osabi = ELF_OSABI,
+	.regsets = m68k_user_regsets,
+	.n = ARRAY_SIZE(m68k_user_regsets)
+};
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+	return &user_m68k_view;
+}
+#endif /* CONFIG_BINFMT_ELF_FDPIC && CONFIG_ELF_CORE */