nommu: ptrace support

The patch below adds ARM ptrace functions to get the process load address.
This is required for useful userspace debugging on mmuless systems.  These
values are obtained by reading magic offsets with PTRACE_PEEKUSR, as on other
nommu targets. I picked arbitrary large values for the offsets.

Signed-off-by: Paul Brook <paul@codesourcery.com>

2 files changed, 15 insertions, 1 deletions

diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 67b833c9b6b9..bbecccda76d0 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -82,6 +82,14 @@
 #define PSR_ENDSTATE    0
 #endif
 
+/* 
+ * These are 'magic' values for PTRACE_PEEKUSR that return info about where a
+ * process is located in memory.
+ */
+#define PT_TEXT_ADDR            0x10000
+#define PT_DATA_ADDR            0x10004
+#define PT_TEXT_END_ADDR        0x10008
+
 #ifndef __ASSEMBLY__
 
 /*
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 89882a1d0187..a2ea3854cb3c 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -521,7 +521,13 @@ static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
                 return -EIO;
 
         tmp = 0;
-        if (off < sizeof(struct pt_regs))
+        if (off == PT_TEXT_ADDR)
+                tmp = tsk->mm->start_code;
+        else if (off == PT_DATA_ADDR)
+                tmp = tsk->mm->start_data;
+        else if (off == PT_TEXT_END_ADDR)
+                tmp = tsk->mm->end_code;
+        else if (off < sizeof(struct pt_regs))
                 tmp = get_user_reg(tsk, off >> 2);
 
         return put_user(tmp, ret);