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Subject[PATCH 16/17] arm: asm/syscall.h (unfinished)
Date
This provides the user_stack_pointer() macro in asm/ptrace.h,
which some new arch-independent code wants to be able to use.

It also adds the asm/syscall.h header to let arch-independent
code interpret the registers as system call arguments or return.

The syscall_get_nr() function here is not really right. I don't
know enough about ARM to finish it correctly. It needs to figure
out if the blocked user task is really in the kernel for a system
call and return -1 if not. I also did not try to handle all the
different ABI variants, which I don't really understand.

Until this is fixed, /proc/pid/syscall can show bogus results
for a process that is blocked inside a fault or something else
that's not a system call. (It's probably all wrong for !AEABI too.)

Signed-off-by: Roland McGrath <roland@redhat.com>
---
arch/arm/include/asm/ptrace.h | 4 +-
arch/arm/include/asm/syscall.h | 65 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 67 insertions(+), 2 deletions(-)
create mode 100644 arch/arm/include/asm/syscall.h

diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 236a06b..34075dc 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -140,7 +140,8 @@ static inline int valid_user_regs(struct pt_regs *regs)
return 0;
}

-#define instruction_pointer(regs) (regs)->ARM_pc
+#define instruction_pointer(regs) ((regs)->ARM_pc)
+#define user_stack_pointer(regs) ((regs)->ARM_sp)

#ifdef CONFIG_SMP
extern unsigned long profile_pc(struct pt_regs *regs);
@@ -156,4 +157,3 @@ extern unsigned long profile_pc(struct pt_regs *regs);
#endif /* __ASSEMBLY__ */

#endif
-
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
new file mode 100644
index 0000000..56aefe6
--- /dev/null
+++ b/arch/arm/include/asm/syscall.h
@@ -0,0 +1,65 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_SYSCALL_H
+#define _ASM_SYSCALL_H 1
+
+#include <linux/sched.h>
+#include <linux/err.h>
+
+static inline long syscall_get_nr(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ /* XXX how to figure out if blocked in a syscall or not?? */
+
+ return regs->ARM_r7; /* XXX apparently */
+ return task_thread_info(task)->syscall; /* XXX if changed via ptrace */
+}
+
+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)
+{
+ return IS_ERR_VALUE(regs->ARM_r0) ? regs->ARM_r0 : 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 ?: val;
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ unsigned long *args)
+{
+ BUG_ON(i + n > 6);
+ memcpy(args, &regs->uregs[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)
+{
+ BUG_ON(i + n > 6);
+ memcpy(&regs->uregs[i], args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_SYSCALL_H */

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