metag: ptrace

The ptrace interface for metag provides access to some core register
sets using the PTRACE_GETREGSET and PTRACE_SETREGSET operations. The
details of the internal context structures is abstracted into user API
structures to both ease use and allow flexibility to change the internal
context layouts. Copyin and copyout functions for these register sets
are exposed to allow signal handling code to use them to copy to and
from the signal context.

struct user_gp_regs (NT_PRSTATUS) provides access to the core general
purpose register context.

struct user_cb_regs (NT_METAG_CBUF) provides access to the TXCATCH*
registers which contains information abuot a memory fault, unaligned
access error or watchpoint. This can be modified to alter the way the
fault is replayed on resume ("catch replay"), or to prevent the replay
taking place.

struct user_rp_state (NT_METAG_RPIPE) provides access to the state of
the Meta read pipeline which can be used to hide memory latencies in
hand optimised data loops.

Extended DSP register state, DSP RAM, and hardware breakpoint registers
aren't yet exposed through ptrace.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

1 files changed, 380 insertions, 0 deletions

diff --git a/arch/metag/kernel/ptrace.c b/arch/metag/kernel/ptrace.c
new file mode 100644
index 000000000000..47a8828615a5
--- /dev/null
+++ b/arch/metag/kernel/ptrace.c
@@ -0,0 +1,380 @@
+/*
+ *  Copyright (C) 2005-2012 Imagination Technologies Ltd.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License.  See the file COPYING in the main directory of
+ * this archive for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <linux/user.h>
+#include <linux/regset.h>
+#include <linux/tracehook.h>
+#include <linux/elf.h>
+#include <linux/uaccess.h>
+#include <trace/syscall.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/syscalls.h>
+
+/*
+ * user_regset definitions.
+ */
+
+int metag_gp_regs_copyout(const struct pt_regs *regs,
+			  unsigned int pos, unsigned int count,
+			  void *kbuf, void __user *ubuf)
+{
+	const void *ptr;
+	unsigned long data;
+	int ret;
+
+	/* D{0-1}.{0-7} */
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  regs->ctx.DX, 0, 4*16);
+	if (ret)
+		goto out;
+	/* A{0-1}.{0-1} */
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  regs->ctx.AX, 4*16, 4*20);
+	if (ret)
+		goto out;
+	/* A{0-1}.2 */
+	if (regs->ctx.SaveMask & TBICTX_XEXT_BIT)
+		ptr = regs->ctx.Ext.Ctx.pExt;
+	else
+		ptr = &regs->ctx.Ext.AX2;
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  ptr, 4*20, 4*22);
+	if (ret)
+		goto out;
+	/* A{0-1}.3 */
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  &regs->ctx.AX3, 4*22, 4*24);
+	if (ret)
+		goto out;
+	/* PC */
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  &regs->ctx.CurrPC, 4*24, 4*25);
+	if (ret)
+		goto out;
+	/* TXSTATUS */
+	data = (unsigned long)regs->ctx.Flags;
+	if (regs->ctx.SaveMask & TBICTX_CBUF_BIT)
+		data |= USER_GP_REGS_STATUS_CATCH_BIT;
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  &data, 4*25, 4*26);
+	if (ret)
+		goto out;
+	/* TXRPT, TXBPOBITS, TXMODE */
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  &regs->ctx.CurrRPT, 4*26, 4*29);
+	if (ret)
+		goto out;
+	/* Padding */
+	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+				       4*29, 4*30);
+out:
+	return ret;
+}
+
+int metag_gp_regs_copyin(struct pt_regs *regs,
+			 unsigned int pos, unsigned int count,
+			 const void *kbuf, const void __user *ubuf)
+{
+	void *ptr;
+	unsigned long data;
+	int ret;
+
+	/* D{0-1}.{0-7} */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs->ctx.DX, 0, 4*16);
+	if (ret)
+		goto out;
+	/* A{0-1}.{0-1} */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs->ctx.AX, 4*16, 4*20);
+	if (ret)
+		goto out;
+	/* A{0-1}.2 */
+	if (regs->ctx.SaveMask & TBICTX_XEXT_BIT)
+		ptr = regs->ctx.Ext.Ctx.pExt;
+	else
+		ptr = &regs->ctx.Ext.AX2;
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 ptr, 4*20, 4*22);
+	if (ret)
+		goto out;
+	/* A{0-1}.3 */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &regs->ctx.AX3, 4*22, 4*24);
+	if (ret)
+		goto out;
+	/* PC */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &regs->ctx.CurrPC, 4*24, 4*25);
+	if (ret)
+		goto out;
+	/* TXSTATUS */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &data, 4*25, 4*26);
+	if (ret)
+		goto out;
+	regs->ctx.Flags = data & 0xffff;
+	if (data & USER_GP_REGS_STATUS_CATCH_BIT)
+		regs->ctx.SaveMask |= TBICTX_XCBF_BIT | TBICTX_CBUF_BIT;
+	else
+		regs->ctx.SaveMask &= ~TBICTX_CBUF_BIT;
+	/* TXRPT, TXBPOBITS, TXMODE */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &regs->ctx.CurrRPT, 4*26, 4*29);
+out:
+	return ret;
+}
+
+static int metag_gp_regs_get(struct task_struct *target,
+			     const struct user_regset *regset,
+			     unsigned int pos, unsigned int count,
+			     void *kbuf, void __user *ubuf)
+{
+	const struct pt_regs *regs = task_pt_regs(target);
+	return metag_gp_regs_copyout(regs, pos, count, kbuf, ubuf);
+}
+
+static int metag_gp_regs_set(struct task_struct *target,
+			     const struct user_regset *regset,
+			     unsigned int pos, unsigned int count,
+			     const void *kbuf, const void __user *ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	return metag_gp_regs_copyin(regs, pos, count, kbuf, ubuf);
+}
+
+int metag_cb_regs_copyout(const struct pt_regs *regs,
+			  unsigned int pos, unsigned int count,
+			  void *kbuf, void __user *ubuf)
+{
+	int ret;
+
+	/* TXCATCH{0-3} */
+	if (regs->ctx.SaveMask & TBICTX_XCBF_BIT)
+		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+					  regs->extcb0, 0, 4*4);
+	else
+		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+					       0, 4*4);
+	return ret;
+}
+
+int metag_cb_regs_copyin(struct pt_regs *regs,
+			 unsigned int pos, unsigned int count,
+			 const void *kbuf, const void __user *ubuf)
+{
+	int ret;
+
+	/* TXCATCH{0-3} */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 regs->extcb0, 0, 4*4);
+	return ret;
+}
+
+static int metag_cb_regs_get(struct task_struct *target,
+			     const struct user_regset *regset,
+			     unsigned int pos, unsigned int count,
+			     void *kbuf, void __user *ubuf)
+{
+	const struct pt_regs *regs = task_pt_regs(target);
+	return metag_cb_regs_copyout(regs, pos, count, kbuf, ubuf);
+}
+
+static int metag_cb_regs_set(struct task_struct *target,
+			     const struct user_regset *regset,
+			     unsigned int pos, unsigned int count,
+			     const void *kbuf, const void __user *ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	return metag_cb_regs_copyin(regs, pos, count, kbuf, ubuf);
+}
+
+int metag_rp_state_copyout(const struct pt_regs *regs,
+			   unsigned int pos, unsigned int count,
+			   void *kbuf, void __user *ubuf)
+{
+	unsigned long mask;
+	u64 *ptr;
+	int ret, i;
+
+	/* Empty read pipeline */
+	if (!(regs->ctx.SaveMask & TBICTX_CBRP_BIT)) {
+		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+					       0, 4*13);
+		goto out;
+	}
+
+	mask = (regs->ctx.CurrDIVTIME & TXDIVTIME_RPMASK_BITS) >>
+		TXDIVTIME_RPMASK_S;
+
+	/* Read pipeline entries */
+	ptr = (void *)&regs->extcb0[1];
+	for (i = 0; i < 6; ++i, ++ptr) {
+		if (mask & (1 << i))
+			ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+						  ptr, 8*i, 8*(i + 1));
+		else
+			ret = user_regset_copyout_zero(&pos, &count, &kbuf,
+						       &ubuf, 8*i, 8*(i + 1));
+		if (ret)
+			goto out;
+	}
+	/* Mask of entries */
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  &mask, 4*12, 4*13);
+out:
+	return ret;
+}
+
+int metag_rp_state_copyin(struct pt_regs *regs,
+			  unsigned int pos, unsigned int count,
+			  const void *kbuf, const void __user *ubuf)
+{
+	struct user_rp_state rp;
+	unsigned long long *ptr;
+	int ret, i;
+
+	/* Read the entire pipeline before making any changes */
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &rp, 0, 4*13);
+	if (ret)
+		goto out;
+
+	/* Write pipeline entries */
+	ptr = (void *)&regs->extcb0[1];
+	for (i = 0; i < 6; ++i, ++ptr)
+		if (rp.mask & (1 << i))
+			*ptr = rp.entries[i];
+
+	/* Update RPMask in TXDIVTIME */
+	regs->ctx.CurrDIVTIME &= ~TXDIVTIME_RPMASK_BITS;
+	regs->ctx.CurrDIVTIME |= (rp.mask << TXDIVTIME_RPMASK_S)
+				 & TXDIVTIME_RPMASK_BITS;
+
+	/* Set/clear flags to indicate catch/read pipeline state */
+	if (rp.mask)
+		regs->ctx.SaveMask |= TBICTX_XCBF_BIT | TBICTX_CBRP_BIT;
+	else
+		regs->ctx.SaveMask &= ~TBICTX_CBRP_BIT;
+out:
+	return ret;
+}
+
+static int metag_rp_state_get(struct task_struct *target,
+			      const struct user_regset *regset,
+			      unsigned int pos, unsigned int count,
+			      void *kbuf, void __user *ubuf)
+{
+	const struct pt_regs *regs = task_pt_regs(target);
+	return metag_rp_state_copyout(regs, pos, count, kbuf, ubuf);
+}
+
+static int metag_rp_state_set(struct task_struct *target,
+			      const struct user_regset *regset,
+			      unsigned int pos, unsigned int count,
+			      const void *kbuf, const void __user *ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	return metag_rp_state_copyin(regs, pos, count, kbuf, ubuf);
+}
+
+enum metag_regset {
+	REGSET_GENERAL,
+	REGSET_CBUF,
+	REGSET_READPIPE,
+};
+
+static const struct user_regset metag_regsets[] = {
+	[REGSET_GENERAL] = {
+		.core_note_type = NT_PRSTATUS,
+		.n = ELF_NGREG,
+		.size = sizeof(long),
+		.align = sizeof(long long),
+		.get = metag_gp_regs_get,
+		.set = metag_gp_regs_set,
+	},
+	[REGSET_CBUF] = {
+		.core_note_type = NT_METAG_CBUF,
+		.n = sizeof(struct user_cb_regs) / sizeof(long),
+		.size = sizeof(long),
+		.align = sizeof(long long),
+		.get = metag_cb_regs_get,
+		.set = metag_cb_regs_set,
+	},
+	[REGSET_READPIPE] = {
+		.core_note_type = NT_METAG_RPIPE,
+		.n = sizeof(struct user_rp_state) / sizeof(long),
+		.size = sizeof(long),
+		.align = sizeof(long long),
+		.get = metag_rp_state_get,
+		.set = metag_rp_state_set,
+	},
+};
+
+static const struct user_regset_view user_metag_view = {
+	.name = "metag",
+	.e_machine = EM_METAG,
+	.regsets = metag_regsets,
+	.n = ARRAY_SIZE(metag_regsets)
+};
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+	return &user_metag_view;
+}
+
+/*
+ * Called by kernel/ptrace.c when detaching..
+ *
+ * Make sure single step bits etc are not set.
+ */
+void ptrace_disable(struct task_struct *child)
+{
+	/* nothing to do.. */
+}
+
+long arch_ptrace(struct task_struct *child, long request, unsigned long addr,
+		 unsigned long data)
+{
+	int ret;
+
+	switch (request) {
+	default:
+		ret = ptrace_request(child, request, addr, data);
+		break;
+	}
+
+	return ret;
+}
+
+int syscall_trace_enter(struct pt_regs *regs)
+{
+	int ret = 0;
+
+	if (test_thread_flag(TIF_SYSCALL_TRACE))
+		ret = tracehook_report_syscall_entry(regs);
+
+	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+		trace_sys_enter(regs, regs->ctx.DX[0].U1);
+
+	return ret ? -1 : regs->ctx.DX[0].U1;
+}
+
+void syscall_trace_leave(struct pt_regs *regs)
+{
+	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+		trace_sys_exit(regs, regs->ctx.DX[0].U1);
+
+	if (test_thread_flag(TIF_SYSCALL_TRACE))
+		tracehook_report_syscall_exit(regs, 0);
+}