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Fix support for i386 TLS GD-to-IE optimization. 

There are two cases to support, one with an SIB-form (6-byte) LEA,
the other with a 5-byte LEA and a NOP after the call __tls_get_addr.
Gold did not yet support the second case. This patch adds that
support.

gold/
	PR gold/18106
	* i386.cc (Target_i386::Relocate::tls_gd_to_ie): Fix support for
	non-SIB form of lea, with nop after the call.
This commit is contained in:
Cary Coutant 2015-03-22 11:59:21 -07:00
parent bccffdfdf2
commit 152f702439
2 changed files with 14 additions and 19 deletions
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6
gold/ChangeLog
View File

@ -1,3 +1,9 @@
2015-03-22 Cary Coutant <cary@google.com>
PR gold/18106
* i386.cc (Target_i386::Relocate::tls_gd_to_ie): Fix support for
non-SIB form of lea, with nop after the call.
2015-03-21 Cary Coutant <cary@google.com>
PR gold/14217

27
gold/i386.cc
View File

@ -3253,6 +3253,8 @@ Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
{
// leal foo(,%ebx,1),%eax; call ___tls_get_addr
// ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
// leal foo(%ebx),%eax; call ___tls_get_addr; nop
// ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
@ -3264,10 +3266,7 @@ Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
op2 == 0x8d || op2 == 0x04);
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
int roff = 5;
// FIXME: For now, support only the first (SIB) form.
tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x04);
int roff;
if (op2 == 0x04)
{
@ -3275,28 +3274,18 @@ Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
roff = 5;
}
else
{
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 10);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
(op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
if (rel.get_r_offset() + 9 < view_size
&& view[9] == 0x90)
{
// FIXME: This is not the right instruction sequence.
// There is a trailing nop. Use the size byte subl.
memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
roff = 6;
}
else
{
// FIXME: This is not the right instruction sequence.
// Use the five byte subl.
memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
}
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[9] == 0x90);
roff = 6;
}
memcpy(view + roff - 8, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
Relocate_functions<32, false>::rel32(view + roff, value);
// The next reloc should be a PLT32 reloc against __tls_get_addr.