Subject: DWARF2 EH-frame based stack unwinding
From: jbeulich@novell.com
Patch-mainline: no

This includes reverting f1883f86dea84fe47a71a39fc1afccc005915ed8.

Update Jan 17 2009 jeffm:
- Something in 2.6.29-rc1 tweaked the frame pointer code somehow, so I fixed
  that up.
Update Jul 02 2010 jbeulich:
- fix after upstream commit 9e565292270a2d55524be38835104c564ac8f795

Automatically created from "patches.suse/stack-unwind" by xen-port-patches.py

--- head-2011-02-17.orig/arch/x86/include/mach-xen/asm/system.h	2011-03-03 16:11:05.000000000 +0100
+++ head-2011-02-17/arch/x86/include/mach-xen/asm/system.h	2011-03-03 16:13:47.000000000 +0100
@@ -124,12 +124,22 @@ do {									\
 #define __switch_canary_iparam
 #endif	/* CC_STACKPROTECTOR */
 
+/* The stack unwind code needs this but it pollutes traces otherwise */
+#ifdef CONFIG_UNWIND_INFO
+#define THREAD_RETURN_SYM \
+	".globl thread_return\n" \
+	"thread_return:\n\t"
+#else
+#define THREAD_RETURN_SYM
+#endif
+
 /* Save restore flags to clear handle leaking NT */
 #define switch_to(prev, next, last) \
 	asm volatile(SAVE_CONTEXT					  \
 	     "movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */	  \
 	     "movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */	  \
 	     "call __switch_to\n\t"					  \
+	     THREAD_RETURN_SYM						  \
 	     "movq "__percpu_arg([current_task])",%%rsi\n\t"		  \
 	     __switch_canary						  \
 	     "movq %P[thread_info](%%rsi),%%r8\n\t"			  \
--- head-2011-02-17.orig/arch/x86/kernel/entry_32-xen.S	2011-02-01 15:41:35.000000000 +0100
+++ head-2011-02-17/arch/x86/kernel/entry_32-xen.S	2011-02-02 15:07:22.000000000 +0100
@@ -1225,6 +1225,41 @@ END(spurious_interrupt_bug)
  */
 	.popsection
 
+#ifdef CONFIG_STACK_UNWIND
+ENTRY(arch_unwind_init_running)
+	CFI_STARTPROC
+	movl	4(%esp), %edx
+	movl	(%esp), %ecx
+	leal	4(%esp), %eax
+	movl	%ebx, PT_EBX(%edx)
+	xorl	%ebx, %ebx
+	movl	%ebx, PT_ECX(%edx)
+	movl	%ebx, PT_EDX(%edx)
+	movl	%esi, PT_ESI(%edx)
+	movl	%edi, PT_EDI(%edx)
+	movl	%ebp, PT_EBP(%edx)
+	movl	%ebx, PT_EAX(%edx)
+	movl	$__USER_DS, PT_DS(%edx)
+	movl	$__USER_DS, PT_ES(%edx)
+	movl	$__KERNEL_PERCPU, PT_FS(%edx)
+	movl	$__KERNEL_STACK_CANARY, PT_GS(%edx)
+	movl	%eax, PT_OLDESP(%edx)
+	movl	16(%esp), %eax
+	movl	%ebx, PT_ORIG_EAX(%edx)
+	movl	%ecx, PT_EIP(%edx)
+	movl	12(%esp), %ecx
+	movl	$__KERNEL_CS, PT_CS(%edx)
+	movl	%eax, 12(%esp)
+	movl	8(%esp), %eax
+	movl	%ecx, 8(%esp)
+	movl	%ebx, PT_EFLAGS(%edx)
+	movl	PT_EBX(%edx), %ebx
+	movl	$__KERNEL_DS, PT_OLDSS(%edx)
+	jmpl	*%eax
+	CFI_ENDPROC
+ENDPROC(arch_unwind_init_running)
+#endif
+
 ENTRY(kernel_thread_helper)
 	pushl $0		# fake return address for unwinder
 	CFI_STARTPROC
--- head-2011-02-17.orig/arch/x86/kernel/entry_64-xen.S	2011-02-01 15:41:35.000000000 +0100
+++ head-2011-02-17/arch/x86/kernel/entry_64-xen.S	2011-02-02 15:07:22.000000000 +0100
@@ -1135,6 +1135,40 @@ ENTRY(call_softirq)
 	CFI_ENDPROC
 END(call_softirq)
 
+#ifdef CONFIG_STACK_UNWIND
+ENTRY(arch_unwind_init_running)
+	CFI_STARTPROC
+	movq	%r15, R15(%rdi)
+	movq	%r14, R14(%rdi)
+	xchgq	%rsi, %rdx
+	movq	%r13, R13(%rdi)
+	movq	%r12, R12(%rdi)
+	xorl	%eax, %eax
+	movq	%rbp, RBP(%rdi)
+	movq	%rbx, RBX(%rdi)
+	movq	(%rsp), %r9
+	xchgq	%rdx, %rcx
+	movq	%rax, R11(%rdi)
+	movq	%rax, R10(%rdi)
+	movq	%rax, R9(%rdi)
+	movq	%rax, R8(%rdi)
+	movq	%rax, RAX(%rdi)
+	movq	%rax, RCX(%rdi)
+	movq	%rax, RDX(%rdi)
+	movq	%rax, RSI(%rdi)
+	movq	%rax, RDI(%rdi)
+	movq	%rax, ORIG_RAX(%rdi)
+	movq	%r9, RIP(%rdi)
+	leaq	8(%rsp), %r9
+	movq	$__KERNEL_CS, CS(%rdi)
+	movq	%rax, EFLAGS(%rdi)
+	movq	%r9, RSP(%rdi)
+	movq	$__KERNEL_DS, SS(%rdi)
+	jmpq	*%rcx
+	CFI_ENDPROC
+END(arch_unwind_init_running)
+#endif
+
 /*
  * Some functions should be protected against kprobes
  */
