linux-kernel - [PATCH] update v2 fix X86_64 procfs provide stack information for threads

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Date:	Tue, 03 Nov 2009 10:22:40 +0100
From:	Stefani Seibold <stefani@...bold.net>
To:	linux-kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Americo Wang <xiyou.wangcong@...il.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	ThomasGleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH] update v2 fix X86_64 procfs provide stack information for
 threads

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.

Please apply this patch!

Greetings,
Stefani

Signed-off-by: Stefani Seibold <stefani@...bold.net>
---
 arch/x86/include/asm/processor.h |    2 +-
 arch/x86/kernel/process_64.c     |    6 ++++++
 fs/compat.c                      |    2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)

--- x/linux-2.6.32-rc5/fs/compat.c	2009-10-16 02:41:50.000000000 +0200
+++ linux-2.6.32-rc5/fs/compat.c	2009-11-03 08:38:48.975196941 +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;
--- x/linux-2.6.32-rc5/arch/x86/include/asm/processor.h	2009-10-16 02:41:50.000000000 +0200
+++ linux-2.6.32-rc5/arch/x86/include/asm/processor.h	2009-11-03 10:15:12.094769885 +0100
@@ -1000,7 +1000,7 @@
 #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. */
+extern unsigned long KSTK_ESP(struct task_struct *task);
 #endif /* CONFIG_X86_64 */
 
 extern void start_thread(struct pt_regs *regs, unsigned long new_ip,
--- x/linux-2.6.32-rc5/arch/x86/kernel/process_64.c	2009-10-16 02:41:50.000000000 +0200
+++ linux-2.6.32-rc5/arch/x86/kernel/process_64.c	2009-11-03 10:11:11.202957393 +0100
@@ -664,3 +664,9 @@
 	return do_arch_prctl(current, code, addr);
 }
 
+unsigned long KSTK_ESP(struct task_struct *task)
+{
+	return (test_tsk_thread_flag(task, TIF_IA32)) ? \
+			(task_pt_regs(task)->sp) : \
+			((task)->thread.usersp);
+}


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