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Re: The current linker failed to generate working Linux kernel
- From: Alan Modra <amodra at bigpond dot net dot au>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: binutils at sources dot redhat dot com
- Date: Wed, 16 Aug 2006 18:00:17 +0930
- Subject: Re: The current linker failed to generate working Linux kernel
- References: <20060816011042.GA14198@lucon.org>
On Tue, Aug 15, 2006 at 06:10:42PM -0700, H. J. Lu wrote:
> FYI, I opened a linker bug
>
> http://sources.redhat.com/bugzilla/show_bug.cgi?id=3052
>
> The current linker failed to generate working Linux 2.6 x86-64 kernel.
> There is a small testcase in the bug report.
The kernel script is invalid because it moves dot backwards. Sigh.
This patch moves the code the sets section lmas from lang_do_assignments
to lang_size_sections, which I think is a more natural place to do
this. I've also tweaked the lma code to fall back to lma == vma if dot
moves backwards, for compatibility with buggy ld scripts.
ld/
PR 3052
* ldlang.h (lang_output_section_statement_type): Replace
"processed" field with "processed_vma" and "processed_lma".
* ldlang.c (lang_do_assignments_1): Move lma setting code..
(lang_size_sections_1): ..to here.
(lang_reset_memory_regions): Adjust for
lang_output_section_statement_type change.
* ldexp.c (fold_name): Likewise.
And this is something I forgot the check in from the previous patch.
ld/testsuite/
* ld-scripts/overlay-size-map.d: Adjust.
Index: ld/ldlang.h
===================================================================
RCS file: /cvs/src/src/ld/ldlang.h,v
retrieving revision 1.65
diff -u -p -r1.65 ldlang.h
--- ld/ldlang.h 8 Aug 2006 16:08:47 -0000 1.65
+++ ld/ldlang.h 16 Aug 2006 08:03:00 -0000
@@ -150,7 +150,8 @@ typedef struct lang_output_section_state
int constraint;
flagword flags;
enum section_type sectype;
- unsigned int processed : 1;
+ unsigned int processed_vma : 1;
+ unsigned int processed_lma : 1;
unsigned int all_input_readonly : 1;
unsigned int ignored : 1;
} lang_output_section_statement_type;
Index: ld/ldlang.c
===================================================================
RCS file: /cvs/src/src/ld/ldlang.c,v
retrieving revision 1.233
diff -u -p -r1.233 ldlang.c
--- ld/ldlang.c 8 Aug 2006 16:08:47 -0000 1.233
+++ ld/ldlang.c 16 Aug 2006 08:02:59 -0000
@@ -4228,11 +4228,12 @@ lang_size_sections_1
{
bfd_vma newdot, after;
lang_output_section_statement_type *os;
+ lang_memory_region_type *r;
os = &s->output_section_statement;
if (os->addr_tree != NULL)
{
- os->processed = FALSE;
+ os->processed_vma = FALSE;
exp_fold_tree (os->addr_tree, bfd_abs_section_ptr, &dot);
if (!expld.result.valid_p
@@ -4361,24 +4362,90 @@ lang_size_sections_1
lang_size_sections_1 (os->children.head, os, &os->children.head,
os->fill, newdot, relax, check_regions);
- os->processed = TRUE;
+ os->processed_vma = TRUE;
if (bfd_is_abs_section (os->bfd_section) || os->ignored)
+ ASSERT (os->bfd_section->size == 0);
+ else
{
- ASSERT (os->bfd_section->size == 0);
- break;
+ dot = os->bfd_section->vma;
+
+ /* Put the section within the requested block size, or
+ align at the block boundary. */
+ after = ((dot
+ + TO_ADDR (os->bfd_section->size)
+ + os->block_value - 1)
+ & - (bfd_vma) os->block_value);
+
+ os->bfd_section->size = TO_SIZE (after - os->bfd_section->vma);
+ }
+
+ /* Set section lma. */
+ r = os->region;
+ if (r == NULL)
+ r = lang_memory_region_lookup (DEFAULT_MEMORY_REGION, FALSE);
+
+ if (os->load_base)
+ {
+ bfd_vma lma = exp_get_abs_int (os->load_base, 0, "load base");
+ os->bfd_section->lma = lma;
+ }
+ else if (os->region != NULL
+ && os->lma_region != NULL
+ && os->lma_region != os->region)
+ {
+ bfd_vma lma = os->lma_region->current;
+
+ if (os->section_alignment != -1)
+ lma = align_power (lma, os->section_alignment);
+ os->bfd_section->lma = lma;
}
+ else if (r->last_os != NULL)
+ {
+ bfd_vma lma;
+ asection *last;
+
+ last = r->last_os->output_section_statement.bfd_section;
+ /* If dot moved backwards (which is invalid according
+ to ld docs) then leave lma equal to vma. This
+ keeps users of buggy ld scripts happy. */
+ if (dot >= last->vma)
+ {
+ /* If the current vma overlaps the previous section,
+ then set the current lma to that at the end of
+ the previous section. The previous section was
+ probably an overlay. */
+ if ((dot >= last->vma
+ && dot < last->vma + last->size)
+ || (last->vma >= dot
+ && last->vma < dot + os->bfd_section->size))
+ lma = last->lma + last->size;
- dot = os->bfd_section->vma;
+ /* Otherwise, keep the same lma to vma relationship
+ as the previous section. */
+ else
+ lma = dot + last->lma - last->vma;
+
+ if (os->section_alignment != -1)
+ lma = align_power (lma, os->section_alignment);
+ os->bfd_section->lma = lma;
+ }
+ }
+ os->processed_lma = TRUE;
- /* Put the section within the requested block size, or
- align at the block boundary. */
- after = ((dot
- + TO_ADDR (os->bfd_section->size)
- + os->block_value - 1)
- & - (bfd_vma) os->block_value);
+ if (bfd_is_abs_section (os->bfd_section) || os->ignored)
+ break;
- os->bfd_section->size = TO_SIZE (after - os->bfd_section->vma);
+ /* Keep track of normal sections using the default
+ lma region. We use this to set the lma for
+ following sections. Overlays or other linker
+ script assignment to lma might mean that the
+ default lma == vma is incorrect. */
+ if (((os->bfd_section->flags & SEC_HAS_CONTENTS) != 0
+ || (os->bfd_section->flags & SEC_THREAD_LOCAL) == 0)
+ && os->lma_region == NULL
+ && !link_info.relocatable)
+ r->last_os = s;
/* .tbss sections effectively have zero size. */
if ((os->bfd_section->flags & SEC_HAS_CONTENTS) != 0
@@ -4410,14 +4477,12 @@ lang_size_sections_1
if (os->lma_region != NULL && os->lma_region != os->region)
{
- /* Set load_base, which will be handled later. */
- os->load_base = exp_intop (os->lma_region->current);
- os->lma_region->current +=
- TO_ADDR (os->bfd_section->size);
+ os->lma_region->current
+ = os->bfd_section->lma + TO_ADDR (os->bfd_section->size);
if (check_regions)
os_region_check (os, os->lma_region, NULL,
- os->lma_region->current);
+ os->bfd_section->lma);
}
}
}
@@ -4717,62 +4782,15 @@ lang_do_assignments_1 (lang_statement_un
os = &(s->output_section_statement);
if (os->bfd_section != NULL && !os->ignored)
{
- lang_memory_region_type *r;
-
dot = os->bfd_section->vma;
- r = os->region;
- if (r == NULL)
- r = lang_memory_region_lookup (DEFAULT_MEMORY_REGION, FALSE);
-
- if (os->load_base)
- os->bfd_section->lma
- = exp_get_abs_int (os->load_base, 0, "load base");
- else if (r->last_os != NULL)
- {
- asection *last;
- bfd_vma lma;
-
- last = r->last_os->output_section_statement.bfd_section;
-
- /* If the current vma overlaps the previous section,
- then set the current lma to that at the end of
- the previous section. The previous section was
- probably an overlay. */
- if ((dot >= last->vma
- && dot < last->vma + last->size)
- || (last->vma >= dot
- && last->vma < dot + os->bfd_section->size))
- lma = last->lma + last->size;
-
- /* Otherwise, keep the same lma to vma relationship
- as the previous section. */
- else
- lma = dot + last->lma - last->vma;
-
- if (os->section_alignment != -1)
- lma = align_power (lma, os->section_alignment);
- os->bfd_section->lma = lma;
- }
- lang_do_assignments_1 (os->children.head,
- os, os->fill, dot);
+ lang_do_assignments_1 (os->children.head, os, os->fill, dot);
/* .tbss sections effectively have zero size. */
if ((os->bfd_section->flags & SEC_HAS_CONTENTS) != 0
|| (os->bfd_section->flags & SEC_THREAD_LOCAL) == 0
|| link_info.relocatable)
- {
- dot += TO_ADDR (os->bfd_section->size);
-
- /* Keep track of normal sections using the default
- lma region. We use this to set the lma for
- following sections. Overlays or other linker
- script assignment to lma might mean that the
- default lma == vma is incorrect. */
- if (!link_info.relocatable
- && os->lma_region == NULL)
- r->last_os = s;
- }
+ dot += TO_ADDR (os->bfd_section->size);
}
}
break;
@@ -5451,7 +5469,10 @@ lang_reset_memory_regions (void)
for (os = &lang_output_section_statement.head->output_section_statement;
os != NULL;
os = os->next)
- os->processed = FALSE;
+ {
+ os->processed_vma = FALSE;
+ os->processed_lma = FALSE;
+ }
for (o = output_bfd->sections; o != NULL; o = o->next)
{
Index: ld/ldexp.c
===================================================================
RCS file: /cvs/src/src/ld/ldexp.c,v
retrieving revision 1.61
diff -u -p -r1.61 ldexp.c
--- ld/ldexp.c 26 Jul 2006 05:05:52 -0000 1.61
+++ ld/ldexp.c 16 Aug 2006 08:02:56 -0000
@@ -563,7 +563,7 @@ fold_name (etree_type *tree)
lang_output_section_statement_type *os;
os = lang_output_section_find (tree->name.name);
- if (os != NULL && os->processed)
+ if (os != NULL && os->processed_vma)
new_rel (0, NULL, os->bfd_section);
}
break;
@@ -574,7 +574,7 @@ fold_name (etree_type *tree)
lang_output_section_statement_type *os;
os = lang_output_section_find (tree->name.name);
- if (os != NULL && os->processed)
+ if (os != NULL && os->processed_lma)
{
if (os->load_base == NULL)
new_rel (os->bfd_section->lma - os->bfd_section->vma,
@@ -594,7 +594,7 @@ fold_name (etree_type *tree)
os = lang_output_section_find (tree->name.name);
if (os == NULL)
new_abs (0);
- else if (os->processed)
+ else if (os->processed_vma)
new_abs (os->bfd_section->size / opb);
}
break;
Index: ld/testsuite/ld-scripts/overlay-size-map.d
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-scripts/overlay-size-map.d,v
retrieving revision 1.2
diff -u -p -r1.2 overlay-size-map.d
--- ld/testsuite/ld-scripts/overlay-size-map.d 26 Jul 2006 05:10:05 -0000 1.2
+++ ld/testsuite/ld-scripts/overlay-size-map.d 16 Aug 2006 08:03:02 -0000
@@ -5,19 +5,19 @@
#...
\.bss3 *0x0*20000 *0x20
#...
-\.mtext *0x0*10000 *0x20 load address 0x0*30000
+\.mtext *0x0*10000 *0x20
#...
\.mbss *0x0*20030 *0x230 load address 0x0*20060
#...
-\.text1 *0x0*10020 *0x80 load address 0x0*30020
+\.text1 *0x0*10020 *0x80
#...
-\.text2 *0x0*10020 *0x40 load address 0x0*300a0
+\.text2 *0x0*10020 *0x40
#...
-\.text3 *0x0*10020 *0x20 load address 0x0*300e0
+\.text3 *0x0*10020 *0x20
#...
-\.data1 *0x0*20260 *0x30 load address 0x0*30100
+\.data1 *0x0*20260 *0x30
#...
-\.data2 *0x0*20260 *0x40 load address 0x0*30130
+\.data2 *0x0*20260 *0x40
#...
-\.data3 *0x0*20260 *0x50 load address 0x0*30170
+\.data3 *0x0*20260 *0x50
#pass
--
Alan Modra
IBM OzLabs - Linux Technology Centre