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From:   Greg Ungerer <gerg@linux-m68k.org>
To:     linux-m68k@vger.kernel.org
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org, dalias@libc.org,
        Greg Ungerer <gerg@linux-m68k.org>
Subject: [PATCH 2/4] m68knommu: implement minimal regset support
Date:   Thu, 28 Apr 2022 13:33:17 +1000
Message-Id: <20220428033319.239341-3-gerg@linux-m68k.org>
In-Reply-To: <20220428033319.239341-1-gerg@linux-m68k.org>
References: <20220428033319.239341-1-gerg@linux-m68k.org>
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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 | 58 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/arch/m68k/kernel/ptrace.c b/arch/m68k/kernel/ptrace.c
index 6342ff4d2073..4349b9c4dd68 100644
--- a/arch/m68k/kernel/ptrace.c
+++ b/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 */
-- 
2.25.1