[PATCH 0/6] section name cleanup for mn10300

[PATCH 0/6] section name cleanup for mn10300

[Tim Abbott]

This patch series cleans up the section names on the mn10300
architecture.  It requires the architecture-independent macro
definitions from this patch series:

<http://www.spinics.net/lists/mips/msg33499.html>

The long-term goal here is to add support for building the kernel with
-ffunction-sections -fdata-sections.  This requires renaming all the
magic section names in the kernel of the form .text.foo, .data.foo,
.bss.foo, and .rodata.foo to not have collisions with sections
generated for code like:

static int nosave = 0; /* -fdata-sections places in .data.nosave */
static void head(); /* -ffunction-sections places in .text.head */

Note that these patches have not been boot-tested (aside from testing
the analogous changes on x86), since I don't have access to the
appropriate hardware.

	-Tim Abbott


Tim Abbott (6):
  mn10300: Use macros for .bss.page_aligned section.
  mn10300: Drop unused .data.idt section.
  mn10300: use NOSAVE_DATA macro for .data.nosave section.
  mn10300: use new macro for .data.cacheline_aligned section.
  mn10300: use new macros for .data.init_task.
  mn10300: use new macro for .data.read_mostly section.

 arch/mn10300/kernel/init_task.c   |    3 +--
 arch/mn10300/kernel/vmlinux.lds.S |   29 ++++++-----------------------
 2 files changed, 7 insertions(+), 25 deletions(-)

[PATCH 1/6] mn10300: Use macros for .bss.page_aligned section.

[Tim Abbott]

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Acked-by: David Howells <dhowells@redhat.com>
---
 arch/mn10300/kernel/vmlinux.lds.S |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 24de6b9..6ad0fa8 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -131,7 +131,7 @@ SECTIONS
 
   __bss_start = .;		/* BSS */
   .bss : {
-	*(.bss.page_aligned)
+	PAGE_ALIGNED_BSS
 	*(.bss)
   }
   . = ALIGN(4);
-- 
1.6.2.1

[PATCH 2/6] mn10300: Drop unused .data.idt section.

[Tim Abbott]

Since nothing gets put into .data.idt on this architecture, eliminate
it from the linker script.

This change was apparently proposed previously:
<http://lkml.indiana.edu/hypermail/linux/kernel/0802.2/2538.html>

CCing the author and people who acked that patch in case there was a
reason it wasn't applied.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
---
 arch/mn10300/kernel/vmlinux.lds.S |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 6ad0fa8..364250f 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -59,9 +59,6 @@ SECTIONS
   . = ALIGN(PAGE_SIZE);
   __nosave_end = .;
 
-  . = ALIGN(PAGE_SIZE);
-  .data.page_aligned : { *(.data.idt) }
-
   . = ALIGN(32);
   .data.cacheline_aligned : { *(.data.cacheline_aligned) }
 
-- 
1.6.2.1

[PATCH 3/6] mn10300: use NOSAVE_DATA macro for .data.nosave section.

[Tim Abbott]

.data.nosave should not need a separate output section; this change
moves it into the .data output section.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Cc: David Howells <dhowells@redhat.com>
---
 arch/mn10300/kernel/vmlinux.lds.S |    7 +------
 1 files changed, 1 insertions(+), 6 deletions(-)

diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 364250f..5e825e8 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -49,16 +49,11 @@ SECTIONS
 
   /* writeable */
   .data : {			/* Data */
+	NOSAVE_DATA
 	DATA_DATA
 	CONSTRUCTORS
 	}
 
-  . = ALIGN(PAGE_SIZE);
-  __nosave_begin = .;
-  .data_nosave : { *(.data.nosave) }
-  . = ALIGN(PAGE_SIZE);
-  __nosave_end = .;
-
   . = ALIGN(32);
   .data.cacheline_aligned : { *(.data.cacheline_aligned) }
 
-- 
1.6.2.1

[PATCH 4/6] mn10300: use new macro for .data.cacheline_aligned section.

[Tim Abbott]

.data.cacheline_aligned should not need a separate output section;
this change moves it into the .data section.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Cc: David Howells <dhowells@redhat.com>
---
 arch/mn10300/kernel/vmlinux.lds.S |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 5e825e8..cb43406 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -50,13 +50,11 @@ SECTIONS
   /* writeable */
   .data : {			/* Data */
 	NOSAVE_DATA
+	CACHELINE_ALIGNED_DATA(32)
 	DATA_DATA
 	CONSTRUCTORS
 	}
 
-  . = ALIGN(32);
-  .data.cacheline_aligned : { *(.data.cacheline_aligned) }
-
   /* rarely changed data like cpu maps */
   . = ALIGN(32);
   .data.read_mostly : AT(ADDR(.data.read_mostly)) {
-- 
1.6.2.1

[PATCH 5/6] mn10300: use new macros for .data.init_task.

[Tim Abbott]

.data.init_task should not need a separate output section; this change
moves it into the .data section.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Cc: David Howells <dhowells@redhat.com>
---
 arch/mn10300/kernel/init_task.c   |    3 +--
 arch/mn10300/kernel/vmlinux.lds.S |    4 +---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/mn10300/kernel/init_task.c b/arch/mn10300/kernel/init_task.c
index 5ac3566..7a89fc3 100644
--- a/arch/mn10300/kernel/init_task.c
+++ b/arch/mn10300/kernel/init_task.c
@@ -30,8 +30,7 @@ EXPORT_SYMBOL(init_mm);
  * way process stacks are handled. This is done by having a special
  * "init_task" linker map entry..
  */
-union thread_union init_thread_union
-	__attribute__((__section__(".data.init_task"))) =
+union thread_union init_thread_union __init_task_data =
 		{ INIT_THREAD_INFO(init_task) };
 
 /*
diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index cb43406..4dc63e6 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -49,6 +49,7 @@ SECTIONS
 
   /* writeable */
   .data : {			/* Data */
+	INIT_TASK_DATA(THREAD_SIZE)
 	NOSAVE_DATA
 	CACHELINE_ALIGNED_DATA(32)
 	DATA_DATA
@@ -62,9 +63,6 @@ SECTIONS
 	_edata = .;		/* End of data section */
   }
 
-  . = ALIGN(THREAD_SIZE);	/* init_task */
-  .data.init_task : { *(.data.init_task) }
-
   /* might get freed after init */
   . = ALIGN(PAGE_SIZE);
   .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
-- 
1.6.2.1

[PATCH 6/6] mn10300: use new macro for .data.read_mostly section.

[Tim Abbott]

.data.read_mostly should not need a separate output section; this
change moves it into the .data section.

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Cc: David Howells <dhowells@redhat.com>
---
 arch/mn10300/kernel/vmlinux.lds.S |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 4dc63e6..3da48d5 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -52,16 +52,11 @@ SECTIONS
 	INIT_TASK_DATA(THREAD_SIZE)
 	NOSAVE_DATA
 	CACHELINE_ALIGNED_DATA(32)
+	READ_MOSTLY_DATA(32)
 	DATA_DATA
 	CONSTRUCTORS
-	}
-
-  /* rarely changed data like cpu maps */
-  . = ALIGN(32);
-  .data.read_mostly : AT(ADDR(.data.read_mostly)) {
-	*(.data.read_mostly)
 	_edata = .;		/* End of data section */
-  }
+	}
 
   /* might get freed after init */
   . = ALIGN(PAGE_SIZE);
-- 
1.6.2.1

Re: [PATCH 5/6] mn10300: use new macros for .data.init_task.

[David Howells]

Tim Abbott <tabbott@MIT.EDU> wrote:

> .data.init_task should not need a separate output section; this change
> moves it into the .data section.

Hmmm...  This causes the kernel I'm building to make an extra page of RAM into
dead space.

David

Re: [PATCH 5/6] mn10300: use new macros for .data.init_task.

[Tim Abbott]

On Fri, 1 May 2009, David Howells wrote:

> Tim Abbott <tabbott@MIT.EDU> wrote:
> 
> > .data.init_task should not need a separate output section; this change
> > moves it into the .data section.
> 
> Hmmm...  This causes the kernel I'm building to make an extra page of RAM into
> dead space.

I would try reversing the order of the things inside the .data output 
section, since the stuff after .data at the end of this patch series is 
page-aligned, while the stuff before .data isn't.

	-Tim Abbott

Re: [PATCH 5/6] mn10300: use new macros for .data.init_task.

[Sam Ravnborg]

On Fri, May 01, 2009 at 11:00:12AM -0400, Tim Abbott wrote:
> On Fri, 1 May 2009, David Howells wrote:
> 
> > Tim Abbott <tabbott@MIT.EDU> wrote:
> > 
> > > .data.init_task should not need a separate output section; this change
> > > moves it into the .data section.
> > 
> > Hmmm...  This causes the kernel I'm building to make an extra page of RAM into
> > dead space.
> 
> I would try reversing the order of the things inside the .data output 
> section, since the stuff after .data at the end of this patch series is 
> page-aligned, while the stuff before .data isn't.

I'm looking into creating a WRDATA macro like we have RODATA today.
If that flys then we will hide a lot in that section,
including the correct order.

But it will take a few hours before I'm ready.

	Sam

Re: [PATCH 0/6] section name cleanup for mn10300

[David Howells]

Tim Abbott <tabbott@MIT.EDU> wrote:

> This patch series cleans up the section names on the mn10300
> architecture.  It requires the architecture-independent macro
> definitions from this patch series:

Interesting...  Whilst it compiles and links with no problems, this cleanup
has the following detrimental effects:

None of these patches applied

	   text    data     bss     dec     hex filename
	1879329   82980  321772 2284081  22da31 vmlinux

All of these patches applied:

	   text    data     bss     dec     hex filename
	1879329   87076  321772 2288177  22ea31 vmlinux

Somewhere it eats an extra page.

David

Re: [PATCH 0/6] section name cleanup for mn10300

[Sam Ravnborg]

On Fri, May 01, 2009 at 03:35:19PM +0100, David Howells wrote:
> Tim Abbott <tabbott@MIT.EDU> wrote:
> 
> > This patch series cleans up the section names on the mn10300
> > architecture.  It requires the architecture-independent macro
> > definitions from this patch series:
> 
> Interesting...  Whilst it compiles and links with no problems, this cleanup
> has the following detrimental effects:
> 
> None of these patches applied
> 
> 	   text    data     bss     dec     hex filename
> 	1879329   82980  321772 2284081  22da31 vmlinux
> 
> All of these patches applied:
> 
> 	   text    data     bss     dec     hex filename
> 	1879329   87076  321772 2288177  22ea31 vmlinux
> 
> Somewhere it eats an extra page.

This is likely due to moving around the sections and
we have got them in less perfect order.

I also thing 5/6 is wrong as it moves
init_task befoe _edata.

Could you try to back out them one by one
to see which one causes the extra memory waste.

	Sam

Re: [PATCH 0/6] section name cleanup for mn10300

[David Howells]

Sam Ravnborg <sam@ravnborg.org> wrote:

> I also thing 5/6 is wrong as it moves
> init_task befoe _edata.
> 
> Could you try to back out them one by one
> to see which one causes the extra memory waste.

Moving init_task around is the culprit.

I guess the extra page has a 50% chance of being leaked anyway, as it depends
on the alignment of the previous section.

I can probably make the kernel reclaim it by sticking a label either side of
the alignment and if they're more than a page apart, reclaim the page that
ends at the second label.

David