[PATCH] x86-64: add unwind annotations to early_idt_handler

[PATCH] x86-64: add unwind annotations to early_idt_handler

[Jan Beulich]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>

---
 arch/x86/kernel/head_64.S |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- linux-2.6.29-rc7/arch/x86/kernel/head_64.S	2009-03-11 17:52:10.000000000 +0100
+++ 2.6.29-rc7-x86_64-unwind-early_idt_handler/arch/x86/kernel/head_64.S	2009-02-18 13:38:09.000000000 +0100
@@ -280,6 +280,8 @@ early_idt_handlers:
 
 ENTRY(early_idt_handler)
 #ifdef CONFIG_EARLY_PRINTK
+#include <asm/calling.h>
+#include <asm/dwarf2.h>
 	cmpl $2,early_recursion_flag(%rip)
 	jz  1f
 	incl early_recursion_flag(%rip)
@@ -295,6 +297,16 @@ ENTRY(early_idt_handler)
 	testl $0x27d00,%eax
 	je 0f
 	popq %r8		# get error code
+
+	CFI_STARTPROC	simple
+	CFI_SIGNAL_FRAME
+	CFI_DEF_CFA	rsp, SS+8-RIP
+#	CFI_REL_OFFSET	ss, SS-RIP
+	CFI_REL_OFFSET	rsp, RSP-RIP
+#	CFI_REL_OFFSET	rflags, EFLAGS-RIP
+#	CFI_REL_OFFSET	cs, CS-RIP
+	CFI_REL_OFFSET	rip, RIP-RIP
+
 0:	movq 0(%rsp),%rcx	# get ip
 	movq 8(%rsp),%rdx	# get cs
 	xorl %eax,%eax
@@ -308,6 +320,7 @@ ENTRY(early_idt_handler)
 	movq 0(%rsp),%rsi	# get rip again
 	call __print_symbol
 #endif
+	CFI_ENDPROC
 #endif /* EARLY_PRINTK */
 1:	hlt
 	jmp 1b

Re: [PATCH] x86-64: add unwind annotations to early_idt_handler

[Ingo Molnar]

* Jan Beulich <jbeulich@novell.com> wrote:

> Signed-off-by: Jan Beulich <jbeulich@novell.com>
> Cc: Andi Kleen <andi@firstfloor.org>
> 
> ---
>  arch/x86/kernel/head_64.S |   13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> --- linux-2.6.29-rc7/arch/x86/kernel/head_64.S	2009-03-11 17:52:10.000000000 +0100
> +++ 2.6.29-rc7-x86_64-unwind-early_idt_handler/arch/x86/kernel/head_64.S	2009-02-18 13:38:09.000000000 +0100
> @@ -280,6 +280,8 @@ early_idt_handlers:
>  
>  ENTRY(early_idt_handler)
>  #ifdef CONFIG_EARLY_PRINTK
> +#include <asm/calling.h>
> +#include <asm/dwarf2.h>
>  	cmpl $2,early_recursion_flag(%rip)
>  	jz  1f
>  	incl early_recursion_flag(%rip)
> @@ -295,6 +297,16 @@ ENTRY(early_idt_handler)
>  	testl $0x27d00,%eax
>  	je 0f
>  	popq %r8		# get error code
> +
> +	CFI_STARTPROC	simple
> +	CFI_SIGNAL_FRAME
> +	CFI_DEF_CFA	rsp, SS+8-RIP
> +#	CFI_REL_OFFSET	ss, SS-RIP
> +	CFI_REL_OFFSET	rsp, RSP-RIP
> +#	CFI_REL_OFFSET	rflags, EFLAGS-RIP
> +#	CFI_REL_OFFSET	cs, CS-RIP
> +	CFI_REL_OFFSET	rip, RIP-RIP
> +

This too is too ugly - there should be a structured macro that 
expresses this - instead of open-coded CFI details. This is a 
regular x86 entry layout with a lot of commonalities with other 
entry points.

	Ingo

Re: [PATCH] x86-64: add unwind annotations to early_idt_handler

[Jan Beulich]

>>> Ingo Molnar <mingo@elte.hu> 12.03.09 11:53 >>>
>* Jan Beulich <jbeulich@novell.com> wrote:
>> @@ -295,6 +297,16 @@ ENTRY(early_idt_handler)
>>  	testl $0x27d00,%eax
>>  	je 0f
>>  	popq %r8		# get error code
>> +
>> +	CFI_STARTPROC	simple
>> +	CFI_SIGNAL_FRAME
>> +	CFI_DEF_CFA	rsp, SS+8-RIP
>> +#	CFI_REL_OFFSET	ss, SS-RIP
>> +	CFI_REL_OFFSET	rsp, RSP-RIP
>> +#	CFI_REL_OFFSET	rflags, EFLAGS-RIP
>> +#	CFI_REL_OFFSET	cs, CS-RIP
>> +	CFI_REL_OFFSET	rip, RIP-RIP
>> +
>
>This too is too ugly - there should be a structured macro that 
>expresses this - instead of open-coded CFI details. This is a 
>regular x86 entry layout with a lot of commonalities with other 
>entry points.

I can certainly do that, but it'll introduce yet another patch
dependency (with the patch fixing the entry_64.S annotations), as it
would mean moving out some of the macros from entry_64.S to one
of the headers. That means I'll first have to get clarification on where
you want to go with these annotations altogether.

Jan