[PATCH] fix X86_64 procfs provide stack information for threads

[Stefani Seibold <stefani@seibold.net>]

This patch fix two issues in the procfs stack information on X86_64
linux. 

The 32 bit loader compat_do_execve did not store stack start (this was
figured out by alexey).

The stack information on a X64_64 kernel always show 0 kbyte stack
usage, because of a miss implemented KSTK_ESP macro which always return
-1. The new implementation returns now the right value. 

The patch is against 2.6.32-rc5-git5.

Andrew would you so kind to apply this patch?

Greetings,
Stefani

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 arch/x86/include/asm/processor.h |    9 ++++++++-
 arch/x86/kernel/process_64.c     |    8 ++++++++
 fs/compat.c                      |    2 ++
 3 files changed, 18 insertions(+), 1 deletion(-)

--- linux-2.6.32-rc5/fs/compat.c	2009-10-16 02:41:50.000000000 +0200
+++ linux-2.6.32-rc5.new/fs/compat.c	2009-11-02 09:00:52.871909633 +0100
@@ -1532,6 +1532,8 @@
 	if (retval < 0)
 		goto out;
 
+	current->stack_start = current->mm->start_stack;
+
 	/* execve succeeded */
 	current->fs->in_exec = 0;
 	current->in_execve = 0;
--- linux-2.6.32-rc5/arch/x86/include/asm/processor.h	2009-10-16 02:41:50.000000000 +0200
+++ linux-2.6.32-rc5.new/arch/x86/include/asm/processor.h	2009-11-02 10:39:47.177909657 +0100
@@ -29,6 +29,7 @@
 #include <linux/threads.h>
 #include <linux/math64.h>
 #include <linux/init.h>
+//#include <linux/sched.h>
 
 /*
  * Default implementation of macro that returns current
@@ -1000,7 +1001,13 @@
 #define thread_saved_pc(t)	(*(unsigned long *)((t)->thread.sp - 8))
 
 #define task_pt_regs(tsk)	((struct pt_regs *)(tsk)->thread.sp0 - 1)
-#define KSTK_ESP(tsk)		-1 /* sorry. doesn't work for syscall. */
+
+#ifdef CONFIG_IA32_EMULATION
+extern unsigned long KSTK_ESP(struct task_struct *task);
+#else
+#define KSTK_ESP(task)		((task)->thread.usersp)
+#endif
+
 #endif /* CONFIG_X86_64 */
 
 extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
--- linux-2.6.32-rc5/arch/x86/kernel/process_64.c	2009-10-16 02:41:50.000000000 +0200
+++ linux-2.6.32-rc5.new/arch/x86/kernel/process_64.c	2009-11-02 10:48:23.614936810 +0100
@@ -664,3 +669,11 @@
 	return do_arch_prctl(current, code, addr);
 }
 
+#ifdef CONFIG_IA32_EMULATION
+unsigned long KSTK_ESP(struct task_struct *task)
+{
+	return (test_tsk_thread_flag(task, TIF_IA32)) ? \
+			(task_pt_regs(task)->sp) : \
+			((task)->thread.usersp);
+}
+#endif