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Re: [PATCH: PR gas/11323] Add R_ARM_GOT_PREL relocation to arm assembler
Now this new patch can process the following relocation expression
.word i(GOT_PREL) + (. - (.LPIC0+4))
bfd/
2010-03-15 Wei Guozhi <carrot@google.com>
PR gas/11323
* bfd-in2.h (enum bfd_reloc_code_real): New BFD_RELOC_GOT_PREL type.
* elf32-arm.c (elf32_arm_reloc_map): BFD_RELOC_GOT_PREL to
R_ARM_GOT_PREL map.
* libbfd.h (bfd_reloc_code_real_names): BFD_RELOC_GOT_PREL name.
* reloc.c (comments): Document the new relocation.
gas/
2010-03-15 Wei Guozhi <carrot@google.com>
PR gas/11323
* config/tc-arm.c (reloc_names): New relocation names.
(md_apply_fix): New case for BFD_RELOC_ARM_GOT_PREL.
(tc_gen_reloc): New case for BFD_RELOC_ARM_GOT_PREL.
* doc/c-arm.texi (ARM-Relocations): Document the new relocation.
gas/testsuite
2010-03-15 Wei Guozhi <carrot@google.com>
PR gas/11323
* gas/arm/got_prel.s: New test case.
* gas/arm/got_prel.d: Likewise.
Index: bfd-in2.h
===================================================================
RCS file: /cvs/src/src/bfd/bfd-in2.h,v
retrieving revision 1.507
diff -u -r1.507 bfd-in2.h
--- bfd-in2.h 8 Feb 2010 20:28:43 -0000 1.507
+++ bfd-in2.h 15 Mar 2010 14:03:08 -0000
@@ -3114,6 +3114,7 @@
BFD_RELOC_ARM_RELATIVE,
BFD_RELOC_ARM_GOTOFF,
BFD_RELOC_ARM_GOTPC,
+ BFD_RELOC_ARM_GOT_PREL,
/* ARM thread-local storage relocations. */
BFD_RELOC_ARM_TLS_GD32,
Index: elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.227
diff -u -r1.227 elf32-arm.c
--- elf32-arm.c 4 Mar 2010 17:16:08 -0000 1.227
+++ elf32-arm.c 15 Mar 2010 14:03:10 -0000
@@ -1721,6 +1721,7 @@
{BFD_RELOC_ARM_RELATIVE, R_ARM_RELATIVE},
{BFD_RELOC_ARM_GOTOFF, R_ARM_GOTOFF32},
{BFD_RELOC_ARM_GOTPC, R_ARM_GOTPC},
+ {BFD_RELOC_ARM_GOT_PREL, R_ARM_GOT_PREL},
{BFD_RELOC_ARM_GOT32, R_ARM_GOT32},
{BFD_RELOC_ARM_PLT32, R_ARM_PLT32},
{BFD_RELOC_ARM_TARGET1, R_ARM_TARGET1},
Index: libbfd.h
===================================================================
RCS file: /cvs/src/src/bfd/libbfd.h,v
retrieving revision 1.227
diff -u -r1.227 libbfd.h
--- libbfd.h 8 Feb 2010 20:28:43 -0000 1.227
+++ libbfd.h 15 Mar 2010 14:03:10 -0000
@@ -1330,6 +1330,7 @@
"BFD_RELOC_ARM_RELATIVE",
"BFD_RELOC_ARM_GOTOFF",
"BFD_RELOC_ARM_GOTPC",
+ "BFD_RELOC_ARM_GOT_PREL",
"BFD_RELOC_ARM_TLS_GD32",
"BFD_RELOC_ARM_TLS_LDO32",
"BFD_RELOC_ARM_TLS_LDM32",
Index: reloc.c
===================================================================
RCS file: /cvs/src/src/bfd/reloc.c,v
retrieving revision 1.198
diff -u -r1.198 reloc.c
--- reloc.c 21 Feb 2010 22:24:03 -0000 1.198
+++ reloc.c 15 Mar 2010 14:03:11 -0000
@@ -2940,6 +2940,8 @@
BFD_RELOC_ARM_GOTOFF
ENUMX
BFD_RELOC_ARM_GOTPC
+ENUMX
+ BFD_RELOC_ARM_GOT_PREL
ENUMDOC
Relocations for setting up GOTs and PLTs for shared libraries.
Index: config/tc-arm.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-arm.c,v
retrieving revision 1.437
diff -u -r1.437 tc-arm.c
--- config/tc-arm.c 5 Mar 2010 10:41:04 -0000 1.437
+++ config/tc-arm.c 15 Mar 2010 14:09:16 -0000
@@ -16191,7 +16191,8 @@
{ "tlsldm", BFD_RELOC_ARM_TLS_LDM32}, { "TLSLDM", BFD_RELOC_ARM_TLS_LDM32},
{ "tlsldo", BFD_RELOC_ARM_TLS_LDO32}, { "TLSLDO", BFD_RELOC_ARM_TLS_LDO32},
{ "gottpoff",BFD_RELOC_ARM_TLS_IE32}, { "GOTTPOFF",BFD_RELOC_ARM_TLS_IE32},
- { "tpoff", BFD_RELOC_ARM_TLS_LE32}, { "TPOFF", BFD_RELOC_ARM_TLS_LE32}
+ { "tpoff", BFD_RELOC_ARM_TLS_LE32}, { "TPOFF", BFD_RELOC_ARM_TLS_LE32},
+ { "got_prel", BFD_RELOC_ARM_GOT_PREL},{ "GOT_PREL", BFD_RELOC_ARM_GOT_PREL}
};
#endif
@@ -20477,7 +20478,12 @@
if (fixP->fx_done || !seg->use_rela_p)
md_number_to_chars (buf, 0, 4);
break;
-
+
+ case BFD_RELOC_ARM_GOT_PREL:
+ if (fixP->fx_done || !seg->use_rela_p)
+ md_number_to_chars (buf, value, 4);
+ break;
+
case BFD_RELOC_ARM_TARGET2:
/* TARGET2 is not partial-inplace, so we need to write the
addend here for REL targets, because it won't be written out
@@ -21062,6 +21068,7 @@
#ifdef OBJ_ELF
case BFD_RELOC_ARM_GOT32:
case BFD_RELOC_ARM_GOTOFF:
+ case BFD_RELOC_ARM_GOT_PREL:
case BFD_RELOC_ARM_PLT32:
case BFD_RELOC_ARM_TARGET1:
case BFD_RELOC_ARM_ROSEGREL32:
Index: doc/c-arm.texi
===================================================================
RCS file: /cvs/src/src/gas/doc/c-arm.texi,v
retrieving revision 1.68
diff -u -r1.68 c-arm.texi
--- doc/c-arm.texi 18 Feb 2010 10:56:27 -0000 1.68
+++ doc/c-arm.texi 15 Mar 2010 14:09:16 -0000
@@ -452,7 +452,8 @@
@code{TLSGD},
@code{TLSLDM},
@code{TLSLDO},
-@code{GOTTPOFF}
+@code{GOTTPOFF},
+@code{GOT_PREL}
and
@code{TPOFF}.
gas/testsuite/gas/arm/got_prel.s
=============================================================
.code 16
.text
.Ltext0:
.section .text.foo,"ax",%progbits
.align 2
.global foo
.code 16
.thumb_func
.type foo, %function
foo:
.fnstart
ldr r3, .L3
.LPIC0:
add r3, pc
ldr r3, [r3]
ldr r2, [r3]
str r0, [r3]
mov r0, r2
bx lr
.align 2
.L3:
.word i(GOT_PREL) + (. - (.LPIC0+4))
.fnend
gas/testsuite/gas/arm/got_prel.d
=============================================================
# name: R_ARM_GOT_PREL relocation
# source: got_prel.s
# as: -march=armv5te -meabi=5
# readelf: -x 4 -r
Relocation section '.rel.text.foo' at offset 0x3f0 contains 1 entries:
Offset Info Type Sym.Value Sym. Name
00000010 00000c60 R_ARM_GOT_PREL 00000000 i
Relocation section '.rel.ARM.exidx.text.foo' at offset 0x3f8 contains 2 entries:
Offset Info Type Sym.Value Sym. Name
00000000 0000042a R_ARM_PREL31 00000000 .text.foo
00000000 00000d00 R_ARM_NONE 00000000 __aeabi_unwind_cpp_pr0
Hex dump of section '.text.foo':
NOTE: This section has relocations against it, but these have NOT
been applied to this dump.
0x00000000 034b7b44 1b681a68 1860101c 7047c046 .K{D.h.h.`..pG.F
0x00000010 0a000000 ....
On Mon, Mar 15, 2010 at 4:51 PM, Richard Earnshaw <rearnsha@arm.com> wrote:
>
> On Mon, 2010-03-15 at 16:37 +0800, Carrot Wei wrote:
>> Hi
>>
>> ? As described in http://sourceware.org/bugzilla/show_bug.cgi?id=11323, this
>> patch processes following expression
>>
>> ? ? ? .word ? var(GOTABS)-(.LPIC0+4)
>>
>> And produces a relocation of type R_ARM_GOT_PREL.
>>
>> This patch has been tested by "make check-gas".
>>
>
> I understand why you've done it this way, but I don't like the fact that
> the (GOTABS) annotation leads to a GOT_PREL relocation. ?I think the
> correct way of expressing this is to have a GOT_PREL annotation itself,
> and then to factor compensation for the addend into the remainder of the
> expression:
>
> So, mathematically
> ? ? ? ?var(GOT_PREL) = &GOT_SLOT(var) - .
>
> and the expression that should then be used in the assembly should
> compensate for this:
>
> ? ? ? ?.word var(GOT_PREL) - (.LPIC0+4 - .)
>
> The advantage of this way of expressing things is that we've now got two
> parts to the expression: a var (with relocation type) and and addend
> (that's constant). ?Further, if the addend is zero, then the expression
> collapses naturally to '.word var(GOT_PREL)' and we still get exactly
> the right output.
>