* Re: [PATCH] kexec jump: fix code size checking
@ 2008-08-13 3:05 ` Huang Ying
0 siblings, 0 replies; 20+ messages in thread
From: Huang Ying @ 2008-08-13 3:05 UTC (permalink / raw)
To: Simon Horman
Cc: Eric W. Biederman, Pavel Machek, nigel, Rafael J. Wysocki,
Andrew Morton, Vivek Goyal, mingo, Linus Torvalds,
Kexec Mailing List, linux-kernel
On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
> On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
> > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
> > reminding.
> >
> > Signed-off-by: Huang Ying <ying.huang@intel.com>
> >
> > ---
> > include/asm-x86/kexec.h | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > --- a/include/asm-x86/kexec.h
> > +++ b/include/asm-x86/kexec.h
> > @@ -43,6 +43,9 @@
> >
> > #ifdef CONFIG_X86_32
> > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
> > +# ifndef CONFIG_KEXEC
> > +# define kexec_control_code_size 0
> > +# endif
> > #endif
> >
> > #ifndef __ASSEMBLY__
>
> Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
It is possible. I think there are several ways to do that.
1) use #ifdef in vmlinux_32.lds.S, such as:
#ifdef CONFIG_KEXEC
ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
"kexec control code size is too big")
#endif
2) #define a macro for kexec check ld script in asm/kexec.h, such as:
#define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, \
"kexec control code size is too big")
and use that in vmlinux_32.lds.S.
3) #define kexec_control_code_size 0. So that the check can be passed
always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
I think 3) is better. What do you think about?
Best Regards,
Huang Ying
^ permalink raw reply [flat|nested] 20+ messages in thread* Re: [PATCH] kexec jump: fix code size checking
2008-08-13 3:05 ` Huang Ying
@ 2008-08-13 3:40 ` Eric W. Biederman
-1 siblings, 0 replies; 20+ messages in thread
From: Eric W. Biederman @ 2008-08-13 3:40 UTC (permalink / raw)
To: Huang Ying
Cc: nigel, Kexec Mailing List, linux-kernel, Rafael J. Wysocki,
Simon Horman, Pavel Machek, Andrew Morton, Linus Torvalds, mingo,
Vivek Goyal
Huang Ying <ying.huang@intel.com> writes:
> On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
>> On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
>> > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
>> > reminding.
>> >
>> > Signed-off-by: Huang Ying <ying.huang@intel.com>
>> >
>> > ---
>> > include/asm-x86/kexec.h | 3 +++
>> > 1 file changed, 3 insertions(+)
>> >
>> > --- a/include/asm-x86/kexec.h
>> > +++ b/include/asm-x86/kexec.h
>> > @@ -43,6 +43,9 @@
>> >
>> > #ifdef CONFIG_X86_32
>> > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
>> > +# ifndef CONFIG_KEXEC
>> > +# define kexec_control_code_size 0
>> > +# endif
>> > #endif
>> >
>> > #ifndef __ASSEMBLY__
>>
>> Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
>
> It is possible. I think there are several ways to do that.
>
> 1) use #ifdef in vmlinux_32.lds.S, such as:
>
> #ifdef CONFIG_KEXEC
> ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
> "kexec control code size is too big")
> #endif
>
> 2) #define a macro for kexec check ld script in asm/kexec.h, such as:
>
> #define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <=
> KEXEC_CONTROL_CODE_MAX_SIZE, \
> "kexec control code size is too big")
>
> and use that in vmlinux_32.lds.S.
>
> 3) #define kexec_control_code_size 0. So that the check can be passed
> always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
>
>
> I think 3) is better. What do you think about?
4) Put the code is a special section .text.kexec? and have the linker
always do the size comparison and the computation of the section size.
The fewer conditionals we have the less likely something is to break.
Eric
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
@ 2008-08-13 3:40 ` Eric W. Biederman
0 siblings, 0 replies; 20+ messages in thread
From: Eric W. Biederman @ 2008-08-13 3:40 UTC (permalink / raw)
To: Huang Ying
Cc: Simon Horman, Pavel Machek, nigel, Rafael J. Wysocki,
Andrew Morton, Vivek Goyal, mingo, Linus Torvalds,
Kexec Mailing List, linux-kernel
Huang Ying <ying.huang@intel.com> writes:
> On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
>> On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
>> > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
>> > reminding.
>> >
>> > Signed-off-by: Huang Ying <ying.huang@intel.com>
>> >
>> > ---
>> > include/asm-x86/kexec.h | 3 +++
>> > 1 file changed, 3 insertions(+)
>> >
>> > --- a/include/asm-x86/kexec.h
>> > +++ b/include/asm-x86/kexec.h
>> > @@ -43,6 +43,9 @@
>> >
>> > #ifdef CONFIG_X86_32
>> > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
>> > +# ifndef CONFIG_KEXEC
>> > +# define kexec_control_code_size 0
>> > +# endif
>> > #endif
>> >
>> > #ifndef __ASSEMBLY__
>>
>> Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
>
> It is possible. I think there are several ways to do that.
>
> 1) use #ifdef in vmlinux_32.lds.S, such as:
>
> #ifdef CONFIG_KEXEC
> ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
> "kexec control code size is too big")
> #endif
>
> 2) #define a macro for kexec check ld script in asm/kexec.h, such as:
>
> #define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <=
> KEXEC_CONTROL_CODE_MAX_SIZE, \
> "kexec control code size is too big")
>
> and use that in vmlinux_32.lds.S.
>
> 3) #define kexec_control_code_size 0. So that the check can be passed
> always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
>
>
> I think 3) is better. What do you think about?
4) Put the code is a special section .text.kexec? and have the linker
always do the size comparison and the computation of the section size.
The fewer conditionals we have the less likely something is to break.
Eric
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
2008-08-13 3:40 ` Eric W. Biederman
@ 2008-08-13 5:18 ` Huang Ying
-1 siblings, 0 replies; 20+ messages in thread
From: Huang Ying @ 2008-08-13 5:18 UTC (permalink / raw)
To: Eric W. Biederman
Cc: nigel, Kexec Mailing List, linux-kernel, Rafael J. Wysocki,
Simon Horman, Pavel Machek, Andrew Morton, Linus Torvalds, mingo,
Vivek Goyal
On Tue, 2008-08-12 at 20:40 -0700, Eric W. Biederman wrote:
[...]
> 4) Put the code is a special section .text.kexec? and have the linker
> always do the size comparison and the computation of the section size.
>
> The fewer conditionals we have the less likely something is to break.
Yes. This one is good. But I think current one is acceptable too.
Best Regards,
Huang Ying
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
@ 2008-08-13 5:18 ` Huang Ying
0 siblings, 0 replies; 20+ messages in thread
From: Huang Ying @ 2008-08-13 5:18 UTC (permalink / raw)
To: Eric W. Biederman
Cc: Simon Horman, Pavel Machek, nigel, Rafael J. Wysocki,
Andrew Morton, Vivek Goyal, mingo, Linus Torvalds,
Kexec Mailing List, linux-kernel
On Tue, 2008-08-12 at 20:40 -0700, Eric W. Biederman wrote:
[...]
> 4) Put the code is a special section .text.kexec? and have the linker
> always do the size comparison and the computation of the section size.
>
> The fewer conditionals we have the less likely something is to break.
Yes. This one is good. But I think current one is acceptable too.
Best Regards,
Huang Ying
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
2008-08-13 5:18 ` Huang Ying
@ 2008-08-13 5:51 ` Simon Horman
-1 siblings, 0 replies; 20+ messages in thread
From: Simon Horman @ 2008-08-13 5:51 UTC (permalink / raw)
To: Huang Ying
Cc: nigel, Kexec Mailing List, linux-kernel, Rafael J. Wysocki,
Eric W. Biederman, Pavel Machek, Andrew Morton, Linus Torvalds,
mingo, Vivek Goyal
On Wed, Aug 13, 2008 at 01:18:12PM +0800, Huang Ying wrote:
> On Tue, 2008-08-12 at 20:40 -0700, Eric W. Biederman wrote:
> [...]
> > 4) Put the code is a special section .text.kexec? and have the linker
> > always do the size comparison and the computation of the section size.
> >
> > The fewer conditionals we have the less likely something is to break.
>
> Yes. This one is good. But I think current one is acceptable too.
If you really think that 1) is the best way
Acked-by: Simon Horman <horms@verge.net.au>
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
@ 2008-08-13 5:51 ` Simon Horman
0 siblings, 0 replies; 20+ messages in thread
From: Simon Horman @ 2008-08-13 5:51 UTC (permalink / raw)
To: Huang Ying
Cc: Eric W. Biederman, Pavel Machek, nigel, Rafael J. Wysocki,
Andrew Morton, Vivek Goyal, mingo, Linus Torvalds,
Kexec Mailing List, linux-kernel
On Wed, Aug 13, 2008 at 01:18:12PM +0800, Huang Ying wrote:
> On Tue, 2008-08-12 at 20:40 -0700, Eric W. Biederman wrote:
> [...]
> > 4) Put the code is a special section .text.kexec? and have the linker
> > always do the size comparison and the computation of the section size.
> >
> > The fewer conditionals we have the less likely something is to break.
>
> Yes. This one is good. But I think current one is acceptable too.
If you really think that 1) is the best way
Acked-by: Simon Horman <horms@verge.net.au>
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
2008-08-13 3:05 ` Huang Ying
@ 2008-08-13 3:48 ` Simon Horman
-1 siblings, 0 replies; 20+ messages in thread
From: Simon Horman @ 2008-08-13 3:48 UTC (permalink / raw)
To: Huang Ying
Cc: nigel, Kexec Mailing List, linux-kernel, Rafael J. Wysocki,
Eric W. Biederman, Pavel Machek, Andrew Morton, Linus Torvalds,
mingo, Vivek Goyal
On Wed, Aug 13, 2008 at 11:05:15AM +0800, Huang Ying wrote:
> On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
> > On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
> > > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
> > > reminding.
> > >
> > > Signed-off-by: Huang Ying <ying.huang@intel.com>
> > >
> > > ---
> > > include/asm-x86/kexec.h | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > --- a/include/asm-x86/kexec.h
> > > +++ b/include/asm-x86/kexec.h
> > > @@ -43,6 +43,9 @@
> > >
> > > #ifdef CONFIG_X86_32
> > > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
> > > +# ifndef CONFIG_KEXEC
> > > +# define kexec_control_code_size 0
> > > +# endif
> > > #endif
> > >
> > > #ifndef __ASSEMBLY__
> >
> > Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
>
> It is possible. I think there are several ways to do that.
>
> 1) use #ifdef in vmlinux_32.lds.S, such as:
>
> #ifdef CONFIG_KEXEC
> ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
> "kexec control code size is too big")
> #endif
>
> 2) #define a macro for kexec check ld script in asm/kexec.h, such as:
>
> #define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, \
> "kexec control code size is too big")
>
> and use that in vmlinux_32.lds.S.
>
> 3) #define kexec_control_code_size 0. So that the check can be passed
> always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
>
>
> I think 3) is better. What do you think about?
Hi Huang,
I think that 1) with possibly the slight variation of moving
#include <asm/kexec.h> inside #ifdef CONFIG_KEXEC is better
because it avoids introducing kexec_control_code_size,
which is currently only used in arch/x86/kernel/relocate_kernel_32.S
and arch/x86/kernel/vmlinux_32.lds.S, into kexec.h.
/* Link time checks */
#ifdef CONFIG_KEXEC
#include <asm/kexec.h>
ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
"kexec control code size is too big")
#endif
My second preference would be 3) as it seems simpler than 2).
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 20+ messages in thread* Re: [PATCH] kexec jump: fix code size checking
@ 2008-08-13 3:48 ` Simon Horman
0 siblings, 0 replies; 20+ messages in thread
From: Simon Horman @ 2008-08-13 3:48 UTC (permalink / raw)
To: Huang Ying
Cc: nigel, Kexec Mailing List, linux-kernel, Rafael J. Wysocki,
Eric W. Biederman, Pavel Machek, Andrew Morton, Linus Torvalds,
mingo, Vivek Goyal
On Wed, Aug 13, 2008 at 11:05:15AM +0800, Huang Ying wrote:
> On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
> > On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
> > > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
> > > reminding.
> > >
> > > Signed-off-by: Huang Ying <ying.huang@intel.com>
> > >
> > > ---
> > > include/asm-x86/kexec.h | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > --- a/include/asm-x86/kexec.h
> > > +++ b/include/asm-x86/kexec.h
> > > @@ -43,6 +43,9 @@
> > >
> > > #ifdef CONFIG_X86_32
> > > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
> > > +# ifndef CONFIG_KEXEC
> > > +# define kexec_control_code_size 0
> > > +# endif
> > > #endif
> > >
> > > #ifndef __ASSEMBLY__
> >
> > Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
>
> It is possible. I think there are several ways to do that.
>
> 1) use #ifdef in vmlinux_32.lds.S, such as:
>
> #ifdef CONFIG_KEXEC
> ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
> "kexec control code size is too big")
> #endif
>
> 2) #define a macro for kexec check ld script in asm/kexec.h, such as:
>
> #define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, \
> "kexec control code size is too big")
>
> and use that in vmlinux_32.lds.S.
>
> 3) #define kexec_control_code_size 0. So that the check can be passed
> always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
>
>
> I think 3) is better. What do you think about?
Hi Huang,
I think that 1) with possibly the slight variation of moving
#include <asm/kexec.h> inside #ifdef CONFIG_KEXEC is better
because it avoids introducing kexec_control_code_size,
which is currently only used in arch/x86/kernel/relocate_kernel_32.S
and arch/x86/kernel/vmlinux_32.lds.S, into kexec.h.
/* Link time checks */
#ifdef CONFIG_KEXEC
#include <asm/kexec.h>
ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
"kexec control code size is too big")
#endif
My second preference would be 3) as it seems simpler than 2).
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
2008-08-13 3:05 ` Huang Ying
@ 2008-08-13 13:21 ` Vivek Goyal
-1 siblings, 0 replies; 20+ messages in thread
From: Vivek Goyal @ 2008-08-13 13:21 UTC (permalink / raw)
To: Huang Ying
Cc: nigel, Kexec Mailing List, linux-kernel, Rafael J. Wysocki,
Simon Horman, Eric W. Biederman, Pavel Machek, Andrew Morton,
Linus Torvalds, mingo
On Wed, Aug 13, 2008 at 11:05:15AM +0800, Huang Ying wrote:
> On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
> > On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
> > > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
> > > reminding.
> > >
> > > Signed-off-by: Huang Ying <ying.huang@intel.com>
> > >
> > > ---
> > > include/asm-x86/kexec.h | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > --- a/include/asm-x86/kexec.h
> > > +++ b/include/asm-x86/kexec.h
> > > @@ -43,6 +43,9 @@
> > >
> > > #ifdef CONFIG_X86_32
> > > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
> > > +# ifndef CONFIG_KEXEC
> > > +# define kexec_control_code_size 0
> > > +# endif
> > > #endif
> > >
> > > #ifndef __ASSEMBLY__
> >
> > Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
>
> It is possible. I think there are several ways to do that.
>
> 1) use #ifdef in vmlinux_32.lds.S, such as:
>
> #ifdef CONFIG_KEXEC
> ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
> "kexec control code size is too big")
> #endif
>
> 2) #define a macro for kexec check ld script in asm/kexec.h, such as:
>
> #define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, \
> "kexec control code size is too big")
>
> and use that in vmlinux_32.lds.S.
>
> 3) #define kexec_control_code_size 0. So that the check can be passed
> always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
>
>
> I think 3) is better. What do you think about?
>
I think 1) is good enough.
Thanks
Vivek
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] kexec jump: fix code size checking
@ 2008-08-13 13:21 ` Vivek Goyal
0 siblings, 0 replies; 20+ messages in thread
From: Vivek Goyal @ 2008-08-13 13:21 UTC (permalink / raw)
To: Huang Ying
Cc: Simon Horman, Eric W. Biederman, Pavel Machek, nigel,
Rafael J. Wysocki, Andrew Morton, mingo, Linus Torvalds,
Kexec Mailing List, linux-kernel
On Wed, Aug 13, 2008 at 11:05:15AM +0800, Huang Ying wrote:
> On Wed, 2008-08-13 at 12:47 +1000, Simon Horman wrote:
> > On Wed, Aug 13, 2008 at 09:04:35AM +0800, Huang Ying wrote:
> > > Fix building issue when CONFIG_KEXEC=n. Thanks to Vivek Goyal for his
> > > reminding.
> > >
> > > Signed-off-by: Huang Ying <ying.huang@intel.com>
> > >
> > > ---
> > > include/asm-x86/kexec.h | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > --- a/include/asm-x86/kexec.h
> > > +++ b/include/asm-x86/kexec.h
> > > @@ -43,6 +43,9 @@
> > >
> > > #ifdef CONFIG_X86_32
> > > # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
> > > +# ifndef CONFIG_KEXEC
> > > +# define kexec_control_code_size 0
> > > +# endif
> > > #endif
> > >
> > > #ifndef __ASSEMBLY__
> >
> > Is it impossible to skip the linker check in the !CONFIG_KEXEC case?
>
> It is possible. I think there are several ways to do that.
>
> 1) use #ifdef in vmlinux_32.lds.S, such as:
>
> #ifdef CONFIG_KEXEC
> ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,
> "kexec control code size is too big")
> #endif
>
> 2) #define a macro for kexec check ld script in asm/kexec.h, such as:
>
> #define LD_CHECK_KEXEC() ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE, \
> "kexec control code size is too big")
>
> and use that in vmlinux_32.lds.S.
>
> 3) #define kexec_control_code_size 0. So that the check can be passed
> always. And, code size = 0 is reasonable for no code (CONFIG_KEXEC=n).
>
>
> I think 3) is better. What do you think about?
>
I think 1) is good enough.
Thanks
Vivek
^ permalink raw reply [flat|nested] 20+ messages in thread