[David Mosberger <davidm@hpl.hp.com>] problem with unwind info for .init/.fini sections
H . J . Lu
hjl@lucon.org
Sat Mar 2 10:59:00 GMT 2002
On Sat, Mar 02, 2002 at 09:19:16AM -0800, David Mosberger wrote:
> >>>>> On Sat, 2 Mar 2002 20:49:31 +1030, Alan Modra <amodra@bigpond.net.au> said:
>
> Alan> On Sat, Mar 02, 2002 at 12:36:45AM -0800, H . J . Lu wrote:
> >> .init_array, .fini_array and .preinit_array are new special
> >> sections. We need to make sure their types and attributes are
> >> correct. Here is a patch.
>
> Alan> I like this, but there is a mistake in the following
>
> >> @@ -3370,18 +3371,27 @@ NAME(bfd_elf,size_dynamic_sections) (out
> >> return false; }
> >>
> >> - for (sub = info->input_bfds; sub != NULL; sub = sub->link_next)
> >> - for (o = sub->sections; o != NULL; o = o->next) - { - /* yuck,
> >> more matching by name... */
> >> -
> >> - if (strcmp (bfd_section_name (sub, o), ".preinit_array") == 0)
> >> + for (sub = info->input_bfds; sub != NULL && initfini_array !=
> >> 3; + sub = sub->link_next) + for (o = sub->sections; o != NULL &&
> >> initfini_array != 3; + o = o->next) + switch (elf_section_data
> >> (o->output_section)->this_hdr.sh_type) + { + case
> >> SHT_PREINIT_ARRAY: need_preinit_array = 1; - if (strcmp
> >> (bfd_section_name (sub, o), ".init_array") == 0) +
> >> initfini_array++;
>
> Alan> Presumably, initfini_array is trying to cut short the section
> Alan> search after finding one of each of the section types. I
> Alan> can't see anything in the ELF spec that precludes having, say,
> Alan> three SHT_PREINIT_ARRAY input sections. Best get rid of
> Alan> initfini_array entirely.
>
> The loop really only needs to determine whether any _input_ sections
> contain the preinit/init/fini arrays. You could use a bitmask and
> stop the search as soon as all three array sections have occurred at
> least once.
>
> I considered doing that but opted not to do so for clarity and because
> I wasn't sure how often preinit arrays will be used: if it turns out
> that most executables do not use preinit arrays, then the optimization
> won't be very useful.
The problem is you are searching all input files. It doesn't matter
they are used or not.
>
> Alan> The other thing is that you'll need to extend your patch a
> Alan> little to handle these section types in bfd_section_from_shdr.
>
> Also, note that elfxx-ia64.c already has code to set the section
> types. It's good if this can be moved to elf.c, but there is no point
> in keeping two copies of this code.
>
> --david
Here is a new patch. I made a few changes. I use
elf_section_data (o)->this_hdr.sh_type
since
elf_section_data (o->output_section)
is 0 when it is called. Also, those new sections should be in the
data segment. And I fixed a few typos.
BTW, should we allow both .init/.fini and the array sections. If both
exist, how should ld.so treat them?
H.J.
---
2002-03-02 H.J. Lu <hjl@gnu.org>
* elf.c (bfd_section_from_shdr): Handle special sections,
.init_array, .fini_array and .preinit_array.
(elf_fake_sections): Likewise.
* elflink.h (NAME(bfd_elf,size_dynamic_sections)): Check the
section types instead of names for .init_array, .fini_array and
.preinit_array.
* elfxx-ia64.c (elfNN_ia64_section_from_shdr): Remove
SHT_INIT_ARRAY, SHT_FINI_ARRAY and SHT_PREINIT_ARRAY.
(elfNN_ia64_fake_sections): Remove .init_array, .fini_array and
.preinit_array.
2002-03-02 H.J. Lu <hjl@gnu.org>
* config/obj-elf.c (special_section): Add .init_array,
.fini_array and .preinit_array.
* config/tc-ia64.h (ELF_TC_SPECIAL_SECTIONS): Remove
.init_array and .fini_array.
2002-03-02 H.J. Lu <hjl@gnu.org>
* scripttempl/elf.sc: Fix a few typos. Put .preinit_array,
.init_array and .fini_array in the data segment.
--- binutils/bfd/elf.c.array Tue Feb 19 15:17:40 2002
+++ binutils/bfd/elf.c Sat Mar 2 09:55:43 2002
@@ -1564,6 +1564,9 @@ bfd_section_from_shdr (abfd, shindex)
case SHT_NOBITS: /* .bss section. */
case SHT_HASH: /* .hash section. */
case SHT_NOTE: /* .note section. */
+ case SHT_INIT_ARRAY: /* .init_array section. */
+ case SHT_FINI_ARRAY: /* .fini_array section. */
+ case SHT_PREINIT_ARRAY: /* .preinit_array section. */
return _bfd_elf_make_section_from_shdr (abfd, hdr, name);
case SHT_SYMTAB: /* A symbol table */
@@ -2178,6 +2181,12 @@ elf_fake_sections (abfd, asect, failedpt
this_hdr->sh_type = SHT_REL;
this_hdr->sh_entsize = bed->s->sizeof_rel;
}
+ else if (strcmp (asect->name, ".init_array") == 0)
+ this_hdr->sh_type = SHT_INIT_ARRAY;
+ else if (strcmp (asect->name, ".fini_array") == 0)
+ this_hdr->sh_type = SHT_FINI_ARRAY;
+ else if (strcmp (asect->name, ".preinit_array") == 0)
+ this_hdr->sh_type = SHT_PREINIT_ARRAY;
else if (strncmp (asect->name, ".note", 5) == 0)
this_hdr->sh_type = SHT_NOTE;
else if (strncmp (asect->name, ".stab", 5) == 0
--- binutils/bfd/elflink.h.array Fri Mar 1 23:44:22 2002
+++ binutils/bfd/elflink.h Sat Mar 2 10:48:17 2002
@@ -3199,7 +3199,11 @@ NAME(bfd_elf,size_dynamic_sections) (out
bfd_size_type soname_indx;
bfd *dynobj, *sub;
asection *o;
- int need_preinit_array = 0, need_init_array = 0, need_fini_array = 0;
+#define PREINIT_ARRAY_MASK 1
+#define INIT_ARRAY_MASK 2
+#define FINI_ARRAY_MASK 4
+#define ALL_ARRAY_MASK 7
+ int dt_array = 0;
struct elf_backend_data *bed;
struct elf_assign_sym_version_info asvinfo;
@@ -3373,39 +3377,50 @@ NAME(bfd_elf,size_dynamic_sections) (out
for (sub = info->input_bfds; sub != NULL; sub = sub->link_next)
for (o = sub->sections; o != NULL; o = o->next)
{
- /* yuck, more matching by name... */
+ int array = 0, arraysz = 0;
- if (strcmp (bfd_section_name (sub, o), ".preinit_array") == 0)
- need_preinit_array = 1;
- if (strcmp (bfd_section_name (sub, o), ".init_array") == 0)
- need_init_array = 1;
- if (strcmp (bfd_section_name (sub, o), ".fini_array") == 0)
- need_fini_array = 1;
- }
- if (need_preinit_array)
- {
- if (!elf_add_dynamic_entry (info, (bfd_vma) DT_PREINIT_ARRAY,
- (bfd_vma) 0)
- || !elf_add_dynamic_entry (info, (bfd_vma) DT_PREINIT_ARRAYSZ,
- (bfd_vma) 0))
- return false;
- }
- if (need_init_array)
- {
- if (!elf_add_dynamic_entry (info, (bfd_vma) DT_INIT_ARRAY,
- (bfd_vma) 0)
- || !elf_add_dynamic_entry (info, (bfd_vma) DT_INIT_ARRAYSZ,
- (bfd_vma) 0))
- return false;
- }
- if (need_fini_array)
- {
- if (!elf_add_dynamic_entry (info, (bfd_vma) DT_FINI_ARRAY,
- (bfd_vma) 0)
- || !elf_add_dynamic_entry (info, (bfd_vma) DT_FINI_ARRAYSZ,
- (bfd_vma) 0))
- return false;
+ switch (elf_section_data (o)->this_hdr.sh_type)
+ {
+ case SHT_PREINIT_ARRAY:
+ if ((dt_array & PREINIT_ARRAY_MASK) == 0)
+ {
+ array = DT_PREINIT_ARRAY;
+ arraysz = DT_PREINIT_ARRAYSZ;
+ dt_array |= PREINIT_ARRAY_MASK;
+ }
+ break;
+ case SHT_INIT_ARRAY:
+ if ((dt_array & INIT_ARRAY_MASK) == 0)
+ {
+ array = DT_INIT_ARRAY;
+ arraysz = DT_INIT_ARRAYSZ;
+ dt_array |= INIT_ARRAY_MASK;
+ }
+ break;
+ case SHT_FINI_ARRAY:
+ if ((dt_array & FINI_ARRAY_MASK) == 0)
+ {
+ array = DT_FINI_ARRAY;
+ arraysz = DT_FINI_ARRAYSZ;
+ dt_array |= FINI_ARRAY_MASK;
+ }
+ break;
+ default:
+ }
+
+ if (array)
+ {
+ if (!elf_add_dynamic_entry (info, (bfd_vma) array,
+ (bfd_vma) 0)
+ || !elf_add_dynamic_entry (info, (bfd_vma) arraysz,
+ (bfd_vma) 0))
+ return false;
+ }
+
+ if ((dt_array & ALL_ARRAY_MASK) == ALL_ARRAY_MASK)
+ goto array_done;
}
+array_done:
dynstr = bfd_get_section_by_name (dynobj, ".dynstr");
/* If .dynstr is excluded from the link, we don't want any of
--- binutils/bfd/elfxx-ia64.c.array Tue Feb 19 15:18:24 2002
+++ binutils/bfd/elfxx-ia64.c Sat Mar 2 10:21:20 2002
@@ -1016,9 +1016,6 @@ elfNN_ia64_section_from_shdr (abfd, hdr,
switch (hdr->sh_type)
{
case SHT_IA_64_UNWIND:
- case SHT_INIT_ARRAY:
- case SHT_FINI_ARRAY:
- case SHT_PREINIT_ARRAY:
case SHT_IA_64_HP_OPT_ANOT:
break;
@@ -1076,12 +1073,6 @@ elfNN_ia64_fake_sections (abfd, hdr, sec
}
else if (strcmp (name, ELF_STRING_ia64_archext) == 0)
hdr->sh_type = SHT_IA_64_EXT;
- else if (strcmp (name, ".init_array") == 0)
- hdr->sh_type = SHT_INIT_ARRAY;
- else if (strcmp (name, ".fini_array") == 0)
- hdr->sh_type = SHT_FINI_ARRAY;
- else if (strcmp (name, ".preinit_array") == 0)
- hdr->sh_type = SHT_PREINIT_ARRAY;
else if (strcmp (name, ".HP.opt_annot") == 0)
hdr->sh_type = SHT_IA_64_HP_OPT_ANOT;
else if (strcmp (name, ".reloc") == 0)
--- binutils/gas/config/obj-elf.c.array Fri Mar 1 23:44:32 2002
+++ binutils/gas/config/obj-elf.c Sat Mar 2 00:10:52 2002
@@ -595,6 +595,9 @@ static struct special_section const spec
{ ".rodata", SHT_PROGBITS, SHF_ALLOC },
{ ".rodata1", SHT_PROGBITS, SHF_ALLOC },
{ ".text", SHT_PROGBITS, SHF_ALLOC + SHF_EXECINSTR },
+ { ".init_array",SHT_INIT_ARRAY, SHF_ALLOC + SHF_WRITE },
+ { ".fini_array",SHT_FINI_ARRAY, SHF_ALLOC + SHF_WRITE },
+ { ".preinit_array",SHT_PREINIT_ARRAY, SHF_ALLOC + SHF_WRITE },
#ifdef ELF_TC_SPECIAL_SECTIONS
ELF_TC_SPECIAL_SECTIONS
--- binutils/gas/config/tc-ia64.h.array Tue Jan 15 11:30:50 2002
+++ binutils/gas/config/tc-ia64.h Sat Mar 2 00:10:52 2002
@@ -124,8 +124,6 @@ extern void ia64_after_parse_args PARAMS
#define WORKING_DOT_WORD /* don't do broken word processing for now */
#define ELF_TC_SPECIAL_SECTIONS \
-{ ".init_array",SHT_INIT_ARRAY, SHF_ALLOC + SHF_WRITE }, \
-{ ".fini_array",SHT_FINI_ARRAY, SHF_ALLOC + SHF_WRITE }, \
{ ".sbss", SHT_NOBITS, SHF_ALLOC + SHF_WRITE + SHF_IA_64_SHORT }, \
{ ".sdata", SHT_PROGBITS, SHF_ALLOC + SHF_WRITE + SHF_IA_64_SHORT },
--- binutils/ld/scripttempl/elf.sc.array Fri Mar 1 23:45:33 2002
+++ binutils/ld/scripttempl/elf.sc Sat Mar 2 10:43:32 2002
@@ -246,23 +246,6 @@ cat <<EOF
${RELOCATING+${INIT_END}}
} =${NOP-0}
- /* Ensure the __preinit_array_start label is properly aligned. We
- could instead move the label definition inside the section, but
- the linker would then create the section even if it turns out to
- be empty, which isn't pretty. */
- ${RELOCATING+. = ALIGN(${ALIGNMENT})}
- ${RELOCATING+${CREATE_SHLIB-PROVIDE (__preinit_array_start = .);}}
- .preinit_array ${RELOCATING-0} : { *(.preinit_array) }
- ${RELOCATING+${CREATE_SHLIB-PROVIDE (__preinit_array_end = .);}}
-
- ${RELOCATING+${CREATE_SHLIB-PROVIDE (__init_array_start = .)}};
- .init_array ${RELOCATING-0} : { *(.init_array) }
- ${RELOCATING+${CREATE_SHLIB-PROVIDE (__init_array_end = .);}}
-
- ${RELOCATING+${CREATE_SHLIB-PROVIDE (__fini_array_start = .);}}
- .fini_array ${RELOCATING-0} : { *(.fini_array) }
- ${RELOCATING+${CREATE_SHLIB-PROVIDE (__fini_array_end = .);}}
-
${DATA_PLT-${BSS_PLT-${PLT}}}
.text ${RELOCATING-0} :
{
@@ -293,6 +276,23 @@ cat <<EOF
${CREATE_SHLIB-${RELOCATING+. = ${DATA_ADDR-${DATA_SEGMENT_ALIGN}};}}
${CREATE_SHLIB+${RELOCATING+. = ${SHLIB_DATA_ADDR-${DATA_SEGMENT_ALIGN}};}}
+ /* Ensure the __preinit_array_start label is properly aligned. We
+ could instead move the label definition inside the section, but
+ the linker would then create the section even if it turns out to
+ be empty, which isn't pretty. */
+ ${RELOCATING+. = ALIGN(${ALIGNMENT});}
+ ${RELOCATING+${CREATE_SHLIB-PROVIDE (__preinit_array_start = .);}}
+ .preinit_array ${RELOCATING-0} : { *(.preinit_array) }
+ ${RELOCATING+${CREATE_SHLIB-PROVIDE (__preinit_array_end = .);}}
+
+ ${RELOCATING+${CREATE_SHLIB-PROVIDE (__init_array_start = .);}}
+ .init_array ${RELOCATING-0} : { *(.init_array) }
+ ${RELOCATING+${CREATE_SHLIB-PROVIDE (__init_array_end = .);}}
+
+ ${RELOCATING+${CREATE_SHLIB-PROVIDE (__fini_array_start = .);}}
+ .fini_array ${RELOCATING-0} : { *(.fini_array) }
+ ${RELOCATING+${CREATE_SHLIB-PROVIDE (__fini_array_end = .);}}
+
.data ${RELOCATING-0} :
{
${RELOCATING+${DATA_START_SYMBOLS}}
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