* Re: Don't use STT_ARM_TFUNC for final links
2004-11-18 20:03 Richard Earnshaw
@ 2004-11-19 15:49 ` Paul Brook
0 siblings, 0 replies; 3+ messages in thread
From: Paul Brook @ 2004-11-19 15:49 UTC (permalink / raw)
To: binutils; +Cc: Richard Earnshaw, Daniel Jacobowitz
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On Thursday 18 November 2004 20:03, Richard Earnshaw wrote:
> > I made this change only for final links because it's less of
> > a compatibility
> > issue than for relocatable output. For EABI objects,
> > presumably we should
> > do the same. For non-EABI objects, I'm not sure if it should
> > be changed or
> > left alone; I have no idea what other tools are affected.
> > However, since
> > dynamic objects containing Thumb symbols did not work
> > properly before my
> > last change, I see no reason to conditionalize it.
>
> It needs to be done for objects too. Without it, other toolchains can't
> consume GAS assembled objects that claim to conform to the EABI.
>
> There's no reason why the tricks shouldn't work on objects, so I think
> it should be done there too.
>
> As to the issue of backward compatibility, there shouldn't be a problem
> in binutils, they will just do the appropriate transformation when
> reading in object files. As for other tools, then I think they are just
> going to have to get used to the new form. It is better that functions
> really are tagged with STT_FUNC rather than a machine-dependent value,
> and Thumb-ness really isn't that special.
The attached patch does this. I pushed the transformation down into
bfd_swap_symbol_{in,out} so that objcopy works. I had to make this change
unconditionally because objcopy does not set the EABI version in e_flags
until after the symbol table has been written out.
This means and ABI change for thumb objects. New binutils/BFD will
transparently handle both new and old format symbol tables.
Tested with cross to arm-none-eabi, and light testing on arm-linux.
Ok?
Paul
2004-11-19 Paul Brook <paul@codesourcery.com>
bfd/
* elf32-arm.c (elf32_arm_swap_symbol_in): New function.
(elf32_arm_swap_symbol_out): New function.
(elf32_arm_size_info): Add.
(elf_backend_size_info): Define.
ld/
* testsuite/ld-arm/mixed-lib.sym: Update for THUMB_FUNC change.
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Index: bfd/elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.10
diff -u -p -r1.10 elf32-arm.c
--- bfd/elf32-arm.c 19 Nov 2004 11:58:02 -0000 1.10
+++ bfd/elf32-arm.c 19 Nov 2004 14:34:15 -0000
@@ -5662,6 +5662,82 @@ elf32_arm_symbol_processing (bfd *abfd A
elfsym->symbol.flags |= BSF_FUNCTION;
}
+
+/* Mangle thumb function symbols as we read them in. */
+
+static void
+elf32_arm_swap_symbol_in (bfd * abfd,
+ const void *psrc,
+ const void *pshn,
+ Elf_Internal_Sym *dst)
+{
+ bfd_elf32_swap_symbol_in (abfd, psrc, pshn, dst);
+
+ /* New EABI objects mark thumb function symbols by setting the low bit of
+ the address. Turn these into STT_ARM_TFUNC. */
+ if (ELF_ST_TYPE (dst->st_info) == STT_FUNC
+ && (dst->st_value & 1))
+ {
+ dst->st_info = ELF_ST_INFO (ELF_ST_BIND (dst->st_info), STT_ARM_TFUNC);
+ dst->st_value &= ~(bfd_vma) 1;
+ }
+}
+
+
+/* Mangle thumb function symbols as we write them out. */
+
+static void
+elf32_arm_swap_symbol_out (bfd *abfd,
+ const Elf_Internal_Sym *src,
+ void *cdst,
+ void *shndx)
+{
+ Elf_Internal_Sym newsym;
+
+ /* We convert STT_ARM_TFUNC symbols into STT_FUNC with the low bit
+ of the address set, as per the new EABI. We do this unconditionally
+ because objcopy does not set the elf header flags until after
+ it writes out the symbol table. */
+ if (ELF_ST_TYPE (src->st_info) == STT_ARM_TFUNC)
+ {
+ newsym = *src;
+ newsym.st_info = ELF_ST_INFO (ELF_ST_BIND (src->st_info), STT_FUNC);
+ newsym.st_value |= 1;
+
+ src = &newsym;
+ }
+ bfd_elf32_swap_symbol_out (abfd, src, cdst, shndx);
+}
+
+/* We use this to override swap_symbol_in and swap_symbol_out. */
+const struct elf_size_info elf32_arm_size_info = {
+ sizeof (Elf32_External_Ehdr),
+ sizeof (Elf32_External_Phdr),
+ sizeof (Elf32_External_Shdr),
+ sizeof (Elf32_External_Rel),
+ sizeof (Elf32_External_Rela),
+ sizeof (Elf32_External_Sym),
+ sizeof (Elf32_External_Dyn),
+ sizeof (Elf_External_Note),
+ 4,
+ 1,
+ 32, 2,
+ ELFCLASS32, EV_CURRENT,
+ bfd_elf32_write_out_phdrs,
+ bfd_elf32_write_shdrs_and_ehdr,
+ bfd_elf32_write_relocs,
+ elf32_arm_swap_symbol_in,
+ elf32_arm_swap_symbol_out,
+ bfd_elf32_slurp_reloc_table,
+ bfd_elf32_slurp_symbol_table,
+ bfd_elf32_swap_dyn_in,
+ bfd_elf32_swap_dyn_out,
+ bfd_elf32_swap_reloc_in,
+ bfd_elf32_swap_reloc_out,
+ bfd_elf32_swap_reloca_in,
+ bfd_elf32_swap_reloca_out
+};
+
#define ELF_ARCH bfd_arch_arm
#define ELF_MACHINE_CODE EM_ARM
#ifdef __QNXTARGET__
@@ -5701,6 +5777,7 @@ elf32_arm_symbol_processing (bfd *abfd A
#define elf_backend_final_write_processing elf32_arm_final_write_processing
#define elf_backend_copy_indirect_symbol elf32_arm_copy_indirect_symbol
#define elf_backend_symbol_processing elf32_arm_symbol_processing
+#define elf_backend_size_info elf32_arm_size_info
#define elf_backend_can_refcount 1
#define elf_backend_can_gc_sections 1
Index: ld/testsuite/ld-arm/mixed-lib.sym
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-arm/mixed-lib.sym,v
retrieving revision 1.1
diff -u -p -r1.1 mixed-lib.sym
--- ld/testsuite/ld-arm/mixed-lib.sym 17 Nov 2004 17:50:27 -0000 1.1
+++ ld/testsuite/ld-arm/mixed-lib.sym 19 Nov 2004 14:34:16 -0000
@@ -3,7 +3,7 @@ Symbol table for image:
Num Buc: Value Size Type Bind Vis Ndx Name
.. ..: ........ 0 NOTYPE GLOBAL DEFAULT ABS _edata
.. ..: .......0 20 FUNC GLOBAL DEFAULT 6 lib_func1
- .. ..: .......0 2 THUMB_FUNC GLOBAL DEFAULT 6 lib_func2
+ .. ..: .......1 2 FUNC GLOBAL DEFAULT 6 lib_func2
.. ..: ........ 0 NOTYPE GLOBAL DEFAULT ABS _bss_end__
.. ..: ........ 0 OBJECT GLOBAL DEFAULT ABS _DYNAMIC
.. ..: ........ 0 NOTYPE GLOBAL DEFAULT ABS __bss_end__
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