[PATCH 04/18] tracing/x86: Add arch_get_func_args() function

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rost...@goodmis.org>

Add function to get the function arguments from pt_regs.

Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
 arch/x86/kernel/ftrace.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 01ebcb6f263e..5e845c8cf89d 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -46,6 +46,34 @@ int ftrace_arch_code_modify_post_process(void)
        return 0;
 }
 
+int arch_get_func_args(struct pt_regs *regs,
+                      int start, int end, long *args)
+{
+#ifdef CONFIG_X86_64
+# define MAX_ARGS 6
+# define INIT_REGS                             \
+       {       regs->di, regs->si, regs->dx,   \
+               regs->cx, regs->r8, regs->r9    \
+       }
+#else
+# define MAX_ARGS 3
+# define INIT_REGS                             \
+       {       regs->ax, regs->dx, regs->cx    }
+#endif
+       if (!regs)
+               return MAX_ARGS;
+
+       {
+               long pt_args[] = INIT_REGS;
+               int i;
+
+               for (i = start; i <= end && i < MAX_ARGS; i++)
+                       args[i - start] = pt_args[i];
+
+               return i - start;
+       }
+}
+
 union ftrace_code_union {
        char code[MCOUNT_INSN_SIZE];
        struct {
-- 
2.15.1