SMP_ON_UP fixups lead to vmlinux link errors if those sections are
discarded at link-time. In particular this may happen for built-in
__exit stuff.
This patch modifies the vmlinux linker script to reduce the amount
of discarded sections, and tries to make sure that __exit sections
are kept in.
This is a hack and probably wrong! Further discussion is needed.
Signed-off-by: Dave Martin <dave.martin@xxxxxxxxxx>
---
On Wed, Jan 26, 2011 at 12:44:52PM +0000, Russell King - ARM Linux wrote:
> On Wed, Jan 26, 2011 at 11:11:31AM +0000, Dave Martin wrote:
> > Do we need to consider any other discarded sections? In vmlinux.lds, I have:
> >
> > /* Default discards */
> > /DISCARD/ : { *(.exit.text) *(.cpuexit.text) *(.memexit.text)
> > *(.exit.data) *(.cpuexit.data) *(.cpuexit.rodata) *(.memexit.data)
> > *(.memexit.rodata) *(.exitcall.exit) *(.discard) *(.discard.*) }
>
> We need to keep all the text exit stuff, and that could well want
> data exit stuff, so I think we need ot keep most of that. Maybe not
> the .discard* stuff though.
>
> > If we put every fixup in its own _section_ we might be able to
> > collapse those out of the list at link time too. However, that seems
> > hard to achieve, since in order to do the correct link-time filtering
> > we would need the fixup's section name to be based on the referenced
> > section's name ... due to preprocessor limitations I don't think we
> > can do that automatically (and manual maintenance would be a bad
> > plan).
>
> I suspect if it was sanely possible to do, then x86 would already be
> doing it as they've had this problem for a lot longer than we have.
> It might be worth talking to toolchain people to see if it can be made
> to work somehow - but we really don't want to get rid of all discarded
> section warnings.
>
> IOW, if we have a text segment which is included in the image and it
> references discarded .exit text, we really do want it to fail at link
> time.
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 45b5651..473e30e 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -85,6 +85,7 @@ SECTIONS
* unwind exit sections must be discarded before the rest of the
* unwind sections get included.
*/
+#ifndef CONFIG_SMP_ON_UP
/DISCARD/ : {
*(.ARM.exidx.exit.text)
*(.ARM.extab.exit.text)
@@ -99,6 +100,7 @@ SECTIONS
*(__ex_table)
#endif
}
+#endif
.text : { /* Real text segment */
_text = .; /* Text and read-only data */
@@ -107,6 +109,12 @@ SECTIONS
__exception_text_end = .;
IRQENTRY_TEXT
TEXT_TEXT
+#ifdef CONFIG_SMP_ON_UP
+ *(.exit.text)
+ CPU_KEEP(exit.text)
+ DEV_KEEP(exit.text)
+ MEM_KEEP(exit.text)
+#endif
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
@@ -116,6 +124,11 @@ SECTIONS
*(.gnu.warning)
*(.rodata)
*(.rodata.*)
+#ifdef CONFIG_SMP_ON_UP
+ CPU_KEEP(exit.rodata)
+ DEV_KEEP(exit.rodata)
+ MEM_KEEP(exit.rodata)
+#endif
*(.glue_7)
*(.glue_7t)
. = ALIGN(4);
@@ -188,6 +201,11 @@ SECTIONS
* and the usual data section
*/
DATA_DATA
+#ifdef CONFIG_SMP_ON_UP
+ DEV_KEEP(exit.data)
+ CPU_KEEP(exit.data)
+ MEM_KEEP(exit.data)
+#endif
CONSTRUCTORS
_edata = .;
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
