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ppc476 plt call stubs

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Fuss over bctr in call stubs.

	* elf32-ppc.c (BA): Define
	(ppc_elf_link_hash_table_create): Correct default_params.
	(write_glink_stub): Pad small plt call stub with "ba 0" rather
	than "nop" for ppc476_workaround.
	(ppc_elf_finish_dynamic_sections): Likewise for branch table
	and __glink_PLTresolve.  Ensure plt call stub at end of page
	doesn't allow fall-thru prefetch.
This commit is contained in:
Alan Modra 2014-04-14 11:48:06 +09:30
parent f871211585
commit da3a208854
2 changed files with 57 additions and 5 deletions
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10
bfd/ChangeLog
View File

@ -1,3 +1,13 @@
2014-04-14 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (BA): Define
(ppc_elf_link_hash_table_create): Correct default_params.
(write_glink_stub): Pad small plt call stub with "ba 0" rather
than "nop" for ppc476_workaround.
(ppc_elf_finish_dynamic_sections): Likewise for branch table
and __glink_PLTresolve. Ensure plt call stub at end of page
doesn't allow fall-thru prefetch.
2014-04-11 Nick Clifton <nickc@redhat.com>
PR ld/16821

52
bfd/elf32-ppc.c
View File

@ -147,6 +147,7 @@ static const bfd_vma ppc_elf_vxworks_pic_plt0_entry
#define ADD_3_12_2 0x7c6c1214
#define ADD_11_0_11 0x7d605a14
#define B 0x48000000
#define BA 0x48000002
#define BCL_20_31 0x429f0005
#define BCTR 0x4e800420
#define BEQLR 0x4d820020
@ -3249,7 +3250,7 @@ static struct bfd_link_hash_table *
ppc_elf_link_hash_table_create (bfd *abfd)
{
struct ppc_elf_link_hash_table *ret;
static struct ppc_elf_params default_params = { PLT_OLD, 0, 1, 0, 0, 4096 };
static struct ppc_elf_params default_params = { PLT_OLD, 0, 1, 0, 0, 12 };
ret = bfd_zmalloc (sizeof (struct ppc_elf_link_hash_table));
if (ret == NULL)
@ -7336,7 +7337,7 @@ write_glink_stub (struct plt_entry *ent, asection *plt_sec, unsigned char *p,
p += 4;
bfd_put_32 (output_bfd, BCTR, p);
p += 4;
bfd_put_32 (output_bfd, NOP, p);
bfd_put_32 (output_bfd, htab->params->ppc476_workaround ? BA : NOP, p);
p += 4;
}
else
@ -10115,7 +10116,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
p += htab->glink_pltresolve;
endp = htab->glink->contents;
endp += htab->glink->size - GLINK_PLTRESOLVE;
while (p < endp - 8 * 4)
while (p < endp - (htab->params->ppc476_workaround ? 0 : 8 * 4))
{
bfd_put_32 (output_bfd, B + endp - p, p);
p += 4;
@ -10130,6 +10131,39 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
+ htab->glink->output_section->vma
+ htab->glink->output_offset);
if (htab->params->ppc476_workaround)
{
/* Ensure that a call stub at the end of a page doesn't
result in prefetch over the end of the page into the
glink branch table. */
bfd_vma pagesize = (bfd_vma) 1 << htab->params->pagesize_p2;
bfd_vma page_addr;
bfd_vma glink_start = (htab->glink->output_section->vma
+ htab->glink->output_offset);
for (page_addr = res0 & -pagesize;
page_addr > glink_start;
page_addr -= pagesize)
{
/* We have a plt call stub that may need fixing. */
bfd_byte *loc;
unsigned int insn;
loc = htab->glink->contents + page_addr - 4 - glink_start;
insn = bfd_get_32 (output_bfd, loc);
if (insn == BCTR)
{
/* By alignment, we know that there must be at least
one other call stub before this one. */
insn = bfd_get_32 (output_bfd, loc - 16);
if (insn == BCTR)
bfd_put_32 (output_bfd, B | (-16 & 0x3fffffc), loc);
else
bfd_put_32 (output_bfd, B | (-20 & 0x3fffffc), loc);
}
}
}
/* Last comes the PLTresolve stub. */
if (info->shared)
{
@ -10137,7 +10171,11 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
for (i = 0; i < ARRAY_SIZE (pic_plt_resolve); i++)
{
bfd_put_32 (output_bfd, pic_plt_resolve[i], p);
unsigned int insn = pic_plt_resolve[i];
if (htab->params->ppc476_workaround && insn == NOP)
insn = BA + 0;
bfd_put_32 (output_bfd, insn, p);
p += 4;
}
p -= 4 * ARRAY_SIZE (pic_plt_resolve);
@ -10171,7 +10209,11 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
{
for (i = 0; i < ARRAY_SIZE (plt_resolve); i++)
{
bfd_put_32 (output_bfd, plt_resolve[i], p);
unsigned int insn = plt_resolve[i];
if (htab->params->ppc476_workaround && insn == NOP)
insn = BA + 0;
bfd_put_32 (output_bfd, insn, p);
p += 4;
}
p -= 4 * ARRAY_SIZE (plt_resolve);