When the dwarf2 unwinder does its thing, sometimes it ends up in
kernel startup code in head.S. Changing arch_unw_user_mode() to
treat that case as if it were user mode is the easy fix.
Signed-off-by: Chuck Ebbert <[email protected]>
---
I copied people who posted traces where this happened. Can anyone
test if this fixes the problem?
--- 2.6.18-rc3-d4.orig/include/asm-i386/unwind.h
+++ 2.6.18-rc3-d4/include/asm-i386/unwind.h
@@ -71,13 +71,14 @@ extern asmlinkage int arch_unwind_init_r
void *arg),
void *arg);
+extern void stext(void); /* real start of kernel text */
static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
{
#if 0 /* This can only work when selector register and EFLAGS saves/restores
are properly annotated (and tracked in UNW_REGISTER_INFO). */
return user_mode_vm(&info->regs);
#else
- return info->regs.eip < PAGE_OFFSET
+ return info->regs.eip < (unsigned long)stext
|| (info->regs.eip >= __fix_to_virt(FIX_VDSO)
&& info->regs.eip < __fix_to_virt(FIX_VDSO) + PAGE_SIZE)
|| info->regs.esp < PAGE_OFFSET;
--
Chuck
> --- 2.6.18-rc3-d4.orig/include/asm-i386/unwind.h
> +++ 2.6.18-rc3-d4/include/asm-i386/unwind.h
> @@ -71,13 +71,14 @@ extern asmlinkage int arch_unwind_init_r
> void *arg),
> void *arg);
>
> +extern void stext(void); /* real start of kernel text */
Can't you use _stext[] from asm/sections.h?
-Andi
In-Reply-To: <[email protected]>
On Sun, 6 Aug 2006 04:30:06 +0200, Andi Kleen wrote:
>
> > +extern void stext(void); /* real start of kernel text */
>
> Can't you use _stext[] from asm/sections.h?
OK.
[patch] i386: fix one case of stuck dwarf2 unwinder
When the dwarf2 unwinder does its thing, sometimes it ends up in
kernel startup code in head.S. Changing arch_unw_user_mode() to
treat that case as if it were user mode is the easy fix.
Signed-off-by: Chuck Ebbert <[email protected]>
--- 2.6.18-rc3-32.orig/include/asm-i386/unwind.h
+++ 2.6.18-rc3-32/include/asm-i386/unwind.h
@@ -13,6 +13,7 @@
#include <asm/fixmap.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>
+#include <asm/sections.h>
struct unwind_frame_info
{
@@ -71,13 +72,14 @@ extern asmlinkage int arch_unwind_init_r
void *arg),
void *arg);
+/* check if unwind has reached either user mode or kernel startup code */
static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
{
#if 0 /* This can only work when selector register and EFLAGS saves/restores
are properly annotated (and tracked in UNW_REGISTER_INFO). */
return user_mode_vm(&info->regs);
#else
- return info->regs.eip < PAGE_OFFSET
+ return info->regs.eip < (unsigned long)_stext
|| (info->regs.eip >= __fix_to_virt(FIX_VDSO)
&& info->regs.eip < __fix_to_virt(FIX_VDSO) + PAGE_SIZE)
|| info->regs.esp < PAGE_OFFSET;
--
Chuck
On Sunday 06 August 2006 07:00, Chuck Ebbert wrote:
> In-Reply-To: <[email protected]>
>
> On Sun, 6 Aug 2006 04:30:06 +0200, Andi Kleen wrote:
> >
> > > +extern void stext(void); /* real start of kernel text */
> >
> > Can't you use _stext[] from asm/sections.h?
>
> OK.
Applied thanks. I did a similar x86-64 change.
-Andi
On Sunday 06 August 2006 07:00, Chuck Ebbert wrote:
> In-Reply-To: <[email protected]>
>
> On Sun, 6 Aug 2006 04:30:06 +0200, Andi Kleen wrote:
> >
> > > +extern void stext(void); /* real start of kernel text */
> >
> > Can't you use _stext[] from asm/sections.h?
>
> OK.
Hmm, actually I applied it but then I had doubts it actually
works -- I think you don't need _stext but the code before
the first call in head. Since head.S doesn't do a call
that's probably start_kernel
Can you please resubmit a patch that does this properly?
-Andi