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Re: [PATCH] Fix type and alignment of ARM/Thumb EABI mapping symbols
Paul Brook wrote:
! 4.5.7 Mapping symbols
! A section of an ELF file can contain a mixture of ARM code, Thumb
code
There's no need to quote the entirety of this section in the source
file. A cross reference is fine. The correct reference should be to
v1.0 of the spec, where the section number is 4.5.5.
Might also be worth explicitly noting that this is a change from previous
behaviour.
I'll apply this version on mainline and binutils-csl-arm-2005q1-branch.
ChangeLog:
* bfd/bfd-in.h (bfd_elf32_is_arm_mapping_symbol_name): Add prototype.
* bfd/bfd-in2.h: Regenerate.
* bfd/elf32-arm.c (elf32_arm_is_target_special_symbol): Rename call to
bfd_elf32_is_arm_mapping_symbol_name.
(elf32_arm_output_symbol_hook): Likewise.
(arm_elf_find_function): Likewise, and include STT_NOTYPE in test
for mapping symbols.
(is_arm_mapping_symbol_name): Function moved from here...
* bfd/cpu-arm.c (bfd_elf32_is_arm_mapping_symbol_name): ...to here,
renamed and made global.
* gas/config/tc-arm.c (mapping_state): Change documentation in
function comment to cross-reference spec instead. Change type of
mapping symbols to BSF_NO_TYPE.
(arm_adjust_symtab): Don't change type of mapping symbols here.
* gas/testsuite/gas/arm/mapping.d: Update expected output.
* ld/testsuite/ld-arm/arm-app-abs32.d: Likewise.
* ld/testsuite/ld-arm/arm-app.d: Likewise.
* ld/testsuite/ld-arm/mixed-app.d: Likewise.
Index: bfd/bfd-in.h
===================================================================
RCS file: /cvs/src/src/bfd/bfd-in.h,v
retrieving revision 1.95
diff -c -p -r1.95 bfd-in.h
*** bfd/bfd-in.h 23 Mar 2005 04:14:42 -0000 1.95
--- bfd/bfd-in.h 30 Mar 2005 15:25:34 -0000
*************** extern bfd_boolean bfd_elf32_arm_get_bfd
*** 824,829 ****
--- 824,833 ----
extern bfd_boolean bfd_elf32_arm_add_glue_sections_to_bfd
(bfd *, struct bfd_link_info *);
+ /* ELF ARM mapping symbol support */
+ extern bfd_boolean bfd_elf32_is_arm_mapping_symbol_name
+ (const char * name);
+
/* ARM Note section processing. */
extern bfd_boolean bfd_arm_merge_machines
(bfd *, bfd *);
Index: bfd/elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.28
diff -c -p -r1.28 elf32-arm.c
*** bfd/elf32-arm.c 29 Mar 2005 16:54:19 -0000 1.28
--- bfd/elf32-arm.c 30 Mar 2005 15:25:35 -0000
*************** elf32_arm_check_relocs (bfd *abfd, struc
*** 4705,4725 ****
return TRUE;
}
- static bfd_boolean
- is_arm_mapping_symbol_name (const char * name)
- {
- return (name != NULL)
- && (name[0] == '$')
- && ((name[1] == 'a') || (name[1] == 't') || (name[1] == 'd'))
- && (name[2] == 0);
- }
-
/* Treat mapping symbols as special target symbols. */
static bfd_boolean
elf32_arm_is_target_special_symbol (bfd * abfd ATTRIBUTE_UNUSED, asymbol * sym)
{
! return is_arm_mapping_symbol_name (sym->name);
}
/* This is a copy of elf_find_function() from elf.c except that
--- 4705,4716 ----
return TRUE;
}
/* Treat mapping symbols as special target symbols. */
static bfd_boolean
elf32_arm_is_target_special_symbol (bfd * abfd ATTRIBUTE_UNUSED, asymbol * sym)
{
! return bfd_elf32_is_arm_mapping_symbol_name (sym->name);
}
/* This is a copy of elf_find_function() from elf.c except that
*************** arm_elf_find_function (bfd * abf
*** 4754,4765 ****
break;
case STT_FUNC:
case STT_ARM_TFUNC:
/* Skip $a and $t symbols. */
if ((q->symbol.flags & BSF_LOCAL)
! && is_arm_mapping_symbol_name (q->symbol.name))
continue;
/* Fall through. */
- case STT_NOTYPE:
if (bfd_get_section (&q->symbol) == section
&& q->symbol.value >= low_func
&& q->symbol.value <= offset)
--- 4745,4756 ----
break;
case STT_FUNC:
case STT_ARM_TFUNC:
+ case STT_NOTYPE:
/* Skip $a and $t symbols. */
if ((q->symbol.flags & BSF_LOCAL)
! && bfd_elf32_is_arm_mapping_symbol_name (q->symbol.name))
continue;
/* Fall through. */
if (bfd_get_section (&q->symbol) == section
&& q->symbol.value >= low_func
&& q->symbol.value <= offset)
*************** elf32_arm_output_symbol_hook (struct bfd
*** 6086,6092 ****
return TRUE;
/* We only want mapping symbols. */
! if (! is_arm_mapping_symbol_name (name))
return TRUE;
mapcount = ++(elf32_arm_section_data (input_sec)->mapcount);
--- 6077,6083 ----
return TRUE;
/* We only want mapping symbols. */
! if (! bfd_elf32_is_arm_mapping_symbol_name (name))
return TRUE;
mapcount = ++(elf32_arm_section_data (input_sec)->mapcount);
Index: bfd/cpu-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/cpu-arm.c,v
retrieving revision 1.15
diff -c -p -r1.15 cpu-arm.c
*** bfd/cpu-arm.c 20 Feb 2005 14:59:06 -0000 1.15
--- bfd/cpu-arm.c 30 Mar 2005 15:25:35 -0000
*************** bfd_arm_get_mach_from_notes (bfd *abfd,
*** 400,402 ****
--- 400,412 ----
free (buffer);
return bfd_mach_arm_unknown;
}
+
+ bfd_boolean
+ bfd_elf32_is_arm_mapping_symbol_name (const char * name)
+ {
+ return (name != NULL)
+ && (name[0] == '$')
+ && ((name[1] == 'a') || (name[1] == 't') || (name[1] == 'd'))
+ && (name[2] == 0);
+ }
+
Index: gas/config/tc-arm.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-arm.c,v
retrieving revision 1.199
diff -c -p -r1.199 tc-arm.c
*** gas/config/tc-arm.c 29 Mar 2005 16:54:21 -0000 1.199
--- gas/config/tc-arm.c 30 Mar 2005 15:25:35 -0000
*************** validate_offset_imm (unsigned int val, i
*** 1243,1320 ****
#ifdef OBJ_ELF
/* This code is to handle mapping symbols as defined in the ARM ELF spec.
! (This text is taken from version B-02 of the spec):
!
! 4.4.7 Mapping and tagging symbols
!
! A section of an ARM ELF file can contain a mixture of ARM code,
! Thumb code, and data. There are inline transitions between code
! and data at literal pool boundaries. There can also be inline
! transitions between ARM code and Thumb code, for example in
! ARM-Thumb inter-working veneers. Linkers, machine-level
! debuggers, profiling tools, and disassembly tools need to map
! images accurately. For example, setting an ARM breakpoint on a
! Thumb location, or in a literal pool, can crash the program
! being debugged, ruining the debugging session.
!
! ARM ELF entities are mapped (see section 4.4.7.1 below) and
! tagged (see section 4.4.7.2 below) using local symbols (with
! binding STB_LOCAL). To assist consumers, mapping and tagging
! symbols should be collated first in the symbol table, before
! other symbols with binding STB_LOCAL.
!
! To allow properly collated mapping and tagging symbols to be
! skipped by consumers that have no interest in them, the first
! such symbol should have the name $m and its st_value field equal
! to the total number of mapping and tagging symbols (including
! the $m) in the symbol table.
!
! 4.4.7.1 Mapping symbols
!
! $a Labels the first byte of a sequence of ARM instructions.
! Its type is STT_FUNC.
!
! $d Labels the first byte of a sequence of data items.
! Its type is STT_OBJECT.
!
! $t Labels the first byte of a sequence of Thumb instructions.
! Its type is STT_FUNC.
!
! This list of mapping symbols may be extended in the future.
!
! Section-relative mapping symbols
!
! Mapping symbols defined in a section define a sequence of
! half-open address intervals that cover the address range of the
! section. Each interval starts at the address defined by a
! mapping symbol, and continues up to, but not including, the
! address defined by the next (in address order) mapping symbol or
! the end of the section. A corollary is that there must be a
! mapping symbol defined at the beginning of each section.
! Consumers can ignore the size of a section-relative mapping
! symbol. Producers can set it to 0.
!
! Absolute mapping symbols
!
! Because of the need to crystallize a Thumb address with the
! Thumb-bit set, absolute symbol of type STT_FUNC (symbols of type
! STT_FUNC defined in section SHN_ABS) need to be mapped with $a
! or $t.
!
! The extent of a mapping symbol defined in SHN_ABS is [st_value,
! st_value + st_size), or [st_value, st_value + 1) if st_size = 0,
! where [x, y) denotes the half-open address range from x,
! inclusive, to y, exclusive.
!
! In the absence of a mapping symbol, a consumer can interpret a
! function symbol with an odd value as the Thumb code address
! obtained by clearing the least significant bit of the
! value. This interpretation is deprecated, and it may not work in
! the future.
!
! Note - the Tagging symbols ($b, $f, $p $m) have been dropped from
! the EABI (which is still under development), so they are not
! implemented here. */
static enum mstate mapstate = MAP_UNDEFINED;
--- 1243,1251 ----
#ifdef OBJ_ELF
/* This code is to handle mapping symbols as defined in the ARM ELF spec.
! (See "Mapping symbols", section 4.5.5, ARM AAELF version 1.0).
! Note that previously, $a and $t has type STT_FUNC (BSF_OBJECT flag),
! and $d has type STT_OBJECT (BSF_OBJECT flag). Now all three are untyped. */
static enum mstate mapstate = MAP_UNDEFINED;
*************** mapping_state (enum mstate state)
*** 1336,1350 ****
{
case MAP_DATA:
symname = "$d";
! type = BSF_OBJECT;
break;
case MAP_ARM:
symname = "$a";
! type = BSF_FUNCTION;
break;
case MAP_THUMB:
symname = "$t";
! type = BSF_FUNCTION;
break;
case MAP_UNDEFINED:
return;
--- 1267,1281 ----
{
case MAP_DATA:
symname = "$d";
! type = BSF_NO_FLAGS;
break;
case MAP_ARM:
symname = "$a";
! type = BSF_NO_FLAGS;
break;
case MAP_THUMB:
symname = "$t";
! type = BSF_NO_FLAGS;
break;
case MAP_UNDEFINED:
return;
*************** arm_adjust_symtab (void)
*** 13738,13751 ****
elf_sym = elf_symbol (symbol_get_bfdsym (sym));
bind = ELF_ST_BIND (elf_sym->internal_elf_sym.st_info);
! /* If it's a .thumb_func, declare it as so,
! otherwise tag label as .code 16. */
! if (THUMB_IS_FUNC (sym))
! elf_sym->internal_elf_sym.st_info =
! ELF_ST_INFO (bind, STT_ARM_TFUNC);
! else
! elf_sym->internal_elf_sym.st_info =
! ELF_ST_INFO (bind, STT_ARM_16BIT);
}
}
#endif
--- 13669,13685 ----
elf_sym = elf_symbol (symbol_get_bfdsym (sym));
bind = ELF_ST_BIND (elf_sym->internal_elf_sym.st_info);
! if (! bfd_elf32_is_arm_mapping_symbol_name (elf_sym->symbol.name))
! {
! /* If it's a .thumb_func, declare it as so,
! otherwise tag label as .code 16. */
! if (THUMB_IS_FUNC (sym))
! elf_sym->internal_elf_sym.st_info =
! ELF_ST_INFO (bind, STT_ARM_TFUNC);
! else
! elf_sym->internal_elf_sym.st_info =
! ELF_ST_INFO (bind, STT_ARM_16BIT);
! }
}
}
#endif
Index: gas/testsuite/gas/arm/mapping.d
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/arm/mapping.d,v
retrieving revision 1.4
diff -c -p -r1.4 mapping.d
*** gas/testsuite/gas/arm/mapping.d 11 Dec 2004 04:32:36 -0000 1.4
--- gas/testsuite/gas/arm/mapping.d 30 Mar 2005 15:25:35 -0000
*************** SYMBOL TABLE:
*** 9,18 ****
0+00 l d .text 0+0 (|.text)
0+00 l d .data 0+0 (|.data)
0+00 l d .bss 0+0 (|.bss)
! 0+00 l F .text 0+0 \$a
! 0+08 l F .text 0+0 \$t
! 0+00 l O .data 0+0 \$d
0+00 l d foo 0+0 (|foo)
! 0+00 l F foo 0+0 \$t
0+00 g .text 0+0 mapping
0+08 g F .text 0+0 thumb_mapping
--- 9,18 ----
0+00 l d .text 0+0 (|.text)
0+00 l d .data 0+0 (|.data)
0+00 l d .bss 0+0 (|.bss)
! 0+00 l .text 0+0 \$a
! 0+08 l .text 0+0 \$t
! 0+00 l .data 0+0 \$d
0+00 l d foo 0+0 (|foo)
! 0+00 l foo 0+0 \$t
0+00 g .text 0+0 mapping
0+08 g F .text 0+0 thumb_mapping
Index: ld/testsuite/ld-arm/arm-app-abs32.d
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-arm/arm-app-abs32.d,v
retrieving revision 1.2
diff -c -p -r1.2 arm-app-abs32.d
*** ld/testsuite/ld-arm/arm-app-abs32.d 17 Nov 2004 17:50:27 -0000 1.2
--- ld/testsuite/ld-arm/arm-app-abs32.d 30 Mar 2005 15:25:35 -0000
*************** Disassembly of section .plt:
*** 8,14 ****
.* <.plt>:
.*: e52de004 str lr, \[sp, #-4\]!
! .*: e59fe004 ldr lr, \[pc, #4\] ; .* <.plt\+0x10>
.*: e08fe00e add lr, pc, lr
.*: e5bef008 ldr pc, \[lr, #8\]!
.*: .* .*
--- 8,14 ----
.* <.plt>:
.*: e52de004 str lr, \[sp, #-4\]!
! .*: e59fe004 ldr lr, \[pc, #4\] ; .* <_start-0x10>
.*: e08fe00e add lr, pc, lr
.*: e5bef008 ldr pc, \[lr, #8\]!
.*: .* .*
Index: ld/testsuite/ld-arm/arm-app.d
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-arm/arm-app.d,v
retrieving revision 1.2
diff -c -p -r1.2 arm-app.d
*** ld/testsuite/ld-arm/arm-app.d 17 Nov 2004 17:50:27 -0000 1.2
--- ld/testsuite/ld-arm/arm-app.d 30 Mar 2005 15:25:35 -0000
*************** Disassembly of section .plt:
*** 8,14 ****
.* <.plt>:
.*: e52de004 str lr, \[sp, #-4\]!
! .*: e59fe004 ldr lr, \[pc, #4\] ; .* <.plt\+0x10>
.*: e08fe00e add lr, pc, lr
.*: e5bef008 ldr pc, \[lr, #8\]!
.*: .*
--- 8,14 ----
.* <.plt>:
.*: e52de004 str lr, \[sp, #-4\]!
! .*: e59fe004 ldr lr, \[pc, #4\] ; .* <_start-0x10>
.*: e08fe00e add lr, pc, lr
.*: e5bef008 ldr pc, \[lr, #8\]!
.*: .*
*************** Disassembly of section .text:
*** 27,33 ****
.* <app_func>:
.*: e1a0c00d mov ip, sp
.*: e92dd800 stmdb sp!, {fp, ip, lr, pc}
! .*: ebfffff4 bl .* <.text-0xc>
.*: e89d6800 ldmia sp, {fp, sp, lr}
.*: e12fff1e bx lr
--- 27,33 ----
.* <app_func>:
.*: e1a0c00d mov ip, sp
.*: e92dd800 stmdb sp!, {fp, ip, lr, pc}
! .*: ebfffff4 bl .* <_start-0xc>
.*: e89d6800 ldmia sp, {fp, sp, lr}
.*: e12fff1e bx lr
Index: ld/testsuite/ld-arm/mixed-app.d
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-arm/mixed-app.d,v
retrieving revision 1.1
diff -c -p -r1.1 mixed-app.d
*** ld/testsuite/ld-arm/mixed-app.d 17 Nov 2004 17:50:27 -0000 1.1
--- ld/testsuite/ld-arm/mixed-app.d 30 Mar 2005 15:25:35 -0000
*************** Disassembly of section .plt:
*** 8,14 ****
.* <.plt>:
.*: e52de004 str lr, \[sp, #-4\]!
! .*: e59fe004 ldr lr, \[pc, #4\] ; .* <.plt\+0x10>
.*: e08fe00e add lr, pc, lr
.*: e5bef008 ldr pc, \[lr, #8\]!
.*: .*
--- 8,14 ----
.* <.plt>:
.*: e52de004 str lr, \[sp, #-4\]!
! .*: e59fe004 ldr lr, \[pc, #4\] ; .* <_start-0x2c>
.*: e08fe00e add lr, pc, lr
.*: e5bef008 ldr pc, \[lr, #8\]!
.*: .*
*************** Disassembly of section .text:
*** 34,40 ****
.* <app_func>:
.*: e1a0c00d mov ip, sp
.*: e92dd800 stmdb sp!, {fp, ip, lr, pc}
! .*: ebffffe. bl .* <.text-0x..>
.*: e89d6800 ldmia sp, {fp, sp, lr}
.*: e12fff1e bx lr
.*: e1a00000 nop \(mov r0,r0\)
--- 34,40 ----
.* <app_func>:
.*: e1a0c00d mov ip, sp
.*: e92dd800 stmdb sp!, {fp, ip, lr, pc}
! .*: ebffffe. bl .* <_start-0x..>
.*: e89d6800 ldmia sp, {fp, sp, lr}
.*: e12fff1e bx lr
.*: e1a00000 nop \(mov r0,r0\)
*************** Disassembly of section .text:
*** 49,55 ****
.* <app_tfunc>:
.*: b500 push {lr}
! .*: (ffc.f7ff|f7ffffc.) bl .* <.text-0x..>
.*: bd00 pop {pc}
.*: 4770 bx lr
.*: 46c0 nop \(mov r8, r8\)
--- 49,55 ----
.* <app_tfunc>:
.*: b500 push {lr}
! .*: (ffc.f7ff|f7ffffc.) bl .* <_start-0x..>
.*: bd00 pop {pc}
.*: 4770 bx lr
.*: 46c0 nop \(mov r8, r8\)