ARM: 7373/1: add support for the generic syscall.h interface

Supplying the asm-generic/syscall.h interface is a
pre-requisite for HAVE_ARCH_TRACEHOOK
Signed-off-by: NSteven Walter <stevenrwalter@gmail.com>
Signed-off-by: NWade Farnsworth <wade_farnsworth@mentor.com>
Reviewed-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/syscall.h

+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_ARM_SYSCALL_H
+#define _ASM_ARM_SYSCALL_H
+
+#include <linux/err.h>
+
+extern const unsigned long sys_call_table[];
+
+static inline int syscall_get_nr(struct task_struct *task,
+				 struct pt_regs *regs)
+{
+	return task_thread_info(task)->syscall;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->ARM_r0 = regs->ARM_ORIG_r0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	unsigned long error = regs->ARM_r0;
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->ARM_r0;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->ARM_r0 = (long) error ? error : val;
+}
+
+#define SYSCALL_MAX_ARGS 7
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
+		unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		memset(args_bad, 0, n_bad * sizeof(args[0]));
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		args[0] = regs->ARM_ORIG_r0;
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	if (i + n > SYSCALL_MAX_ARGS) {
+		pr_warning("%s called with max args %d, handling only %d\n",
+			   __func__, i + n, SYSCALL_MAX_ARGS);
+		n = SYSCALL_MAX_ARGS - i;
+	}
+
+	if (i == 0) {
+		regs->ARM_ORIG_r0 = args[0];
+		args++;
+		i++;
+		n--;
+	}
+
+	memcpy(&regs->ARM_r0 + i, args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_ARM_SYSCALL_H */