[PATCH 0/2] Macros for section name cleanup

[PATCH 0/2] Macros for section name cleanup

[Tim Abbott]

These are the remaining changes from my previous macros for section
name cleanup patch series that were not subsumed by Sam Ravnborg's
recent update to vmlinux.lds.h (commit
7923f90fffa8746f6457d4eea2109fd3d6414189).

I've dropped the patch reworking __read_mostly to be a generic thing
in include/linux/cache.h.  I think the consensus on that patch was
that we should first make all the architectures support
.data.read_mostly in their linker scripts and then do a single patch
removing all the architecture implementations in favor of a single one
in include/linux/cache.h.

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 */

Sam Ravnborg proposed that rather than just renaming all the sections
outright, we should start by first getting more control over the
section names used in the kernel so that we can later rename sections
without touching too many files.  This patch series provides the
architecture-independent macros needed for that cleanup.

Tim Abbott (2):
  Add new macros for page-aligned data and bss sections.
  Add new __init_task_data macro to be used in arch init_task.c files.

 include/linux/init_task.h |    3 +++
 include/linux/linkage.h   |    9 +++++++++
 2 files changed, 12 insertions(+), 0 deletions(-)

[PATCH 1/2] Add new macros for page-aligned data and bss sections.

[Tim Abbott]

This patch is preparation for replacing most uses of
".bss.page_aligned" and ".data.page_aligned" in the kernel with
macros, so that the section name can later be changed without having
to touch a lot of the kernel.

The long-term goal here is to be able to change the kernel's magic
section names to those that are compatible with -ffunction-sections
-fdata-sections.  This requires renaming all magic sections with names
of the form ".data.foo".

Signed-off-by: Tim Abbott <tabbott@ksplice.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: David Howells <dhowells@redhat.com>
---
 include/linux/linkage.h |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index fee9e59..691f591 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -22,6 +22,15 @@
 #define __page_aligned_bss	__section(.bss.page_aligned) __aligned(PAGE_SIZE)
 
 /*
+ * For assembly routines.
+ *
+ * Note when using these that you must specify the appropriate
+ * alignment directives yourself
+ */
+#define __PAGE_ALIGNED_DATA	.section ".data.page_aligned", "aw"
+#define __PAGE_ALIGNED_BSS	.section ".bss.page_aligned", "aw"
+
+/*
  * This is used by architectures to keep arguments on the stack
  * untouched by the compiler by keeping them live until the end.
  * The argument stack may be owned by the assembly-language
-- 
1.6.3.1

[PATCH 2/2] Add new __init_task_data macro to be used in arch init_task.c files.

[Tim Abbott]

This patch is preparation for replacing most ".data.init_task" in the
kernel with macros, so that the section name can later be changed
without having to touch a lot of the kernel.

The long-term goal here is to be able to change the kernel's magic
section names to those that are compatible with -ffunction-sections
-fdata-sections.  This requires renaming all magic sections with names
of the form ".data.foo".

Signed-off-by: Tim Abbott <tabbott@ksplice.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
---
 include/linux/init_task.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 5368fbd..7fc01b1 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -183,5 +183,8 @@ extern struct cred init_cred;
 	LIST_HEAD_INIT(cpu_timers[2]),					\
 }
 
+/* Attach to the init_task data structure for proper alignment */
+#define __init_task_data __attribute__((__section__(".data.init_task")))
+
 
 #endif
-- 
1.6.3.1

Re: [PATCH 0/2] Macros for section name cleanup

[Sam Ravnborg]

On Tue, Jun 23, 2009 at 07:57:30PM -0400, Tim Abbott wrote:
> These are the remaining changes from my previous macros for section
> name cleanup patch series that were not subsumed by Sam Ravnborg's
> recent update to vmlinux.lds.h (commit
> 7923f90fffa8746f6457d4eea2109fd3d6414189).
> 
> I've dropped the patch reworking __read_mostly to be a generic thing
> in include/linux/cache.h.  I think the consensus on that patch was
> that we should first make all the architectures support
> .data.read_mostly in their linker scripts and then do a single patch
> removing all the architecture implementations in favor of a single one
> in include/linux/cache.h.
> 
> 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 */
> 
> Sam Ravnborg proposed that rather than just renaming all the sections
> outright, we should start by first getting more control over the
> section names used in the kernel so that we can later rename sections
> without touching too many files.  This patch series provides the
> architecture-independent macros needed for that cleanup.
> 
> Tim Abbott (2):
>   Add new macros for page-aligned data and bss sections.
>   Add new __init_task_data macro to be used in arch init_task.c files.

Applied all thre patches from you - replacing one from Jesper Nilsson
with the one from you.

	Sam