Juni 2009 - Vax-linux

[LV] [PATCH] libgcc: Add __udivsi3 and __umodsi3 for vax-*-linux*
by Maciej W. Rozycki 12 Jun '09

12 Jun '09

Hi, The VAX processor does not support a 32-bit unsigned division operation in hardware. Which means appropriate SImode primitives have to be provided by a library. What the CPU does support is a 32-bit signed division operation and a 64-bit by 32-bit extended precision signed division operation. According to a comment in vax.md the latter tends to be painfully slow, so here's my proposed implementation, which takes the following approach: 1. If both the divisor and the dividend fit in the 31-bit positive space of signed 32-bit numbers, then the 32-bit signed division is used (as the operation does not calculate the remainder, for the modulo operation an additional multiplication and subtraction is performed). 2. Otherwise if the divisor only fits in the 31-bit positive space of signed 32-bit numbers, then the 64-bit by 32-bit extended precision signed division is used (this operation does calculate the remainder for a change). 3. Otherwise the quotient and the remainder can only have either of two values each, which is calculated by a single subtraction (and some further fiddling so that the need to take a branch does not hurt performance with more recent processor implementations). Unlike with the BSD target, for Linux I believe there is no point in putting either of the functions into the C library (with -ffreestanding to be considered too), nor in using non-standard names, either of which would make the VAX/Linux port different to all the others and thus possibly causing portability problems. Hence the implementation introduces a TARGET_BSD_DIVMOD macro to control the preference on how the two functions are handled by GCC. The default is the current arrangement. The vax-linux configuration is not capable enough for regression testing yet, but correctness of these functions has been verified by running a simple program testing boundary values of the dividend and the divisor and checking that the quotient and remainder produced was correct. The two functions are needed for further progress with the port. gcc/ 2009-06-10 Maciej W. Rozycki <macro(a)linux-mips.org> * config/vax/vax.h (TARGET_BSD_DIVMOD): New macro. Set to 1. * config/vax/linux.h (TARGET_BSD_DIVMOD): New macro. Redefine the to 0. * config/vax/vax.c (vax_init_libfuncs): Only redefine udiv_optab and umod_optab if TARGET_BSD_DIVMOD. * config/vax/lib1funcs.asm: New file. * config/vax/t-linux: New file. * config.gcc (vax-*-linux*): Set tmake_file to vax/t-linux. OK to apply? Maciej gcc-4.5.0-20090609-vax-linux-divmod.patch Index: gcc-4.5.0-20090609-vax-linux/gcc/config.gcc =================================================================== --- gcc-4.5.0-20090609-vax-linux.orig/gcc/config.gcc +++ gcc-4.5.0-20090609-vax-linux/gcc/config.gcc @@ -2414,6 +2414,7 @@ v850-*-*) ;; vax-*-linux*) tm_file="${tm_file} dbxelf.h elfos.h svr4.h linux.h vax/elf.h vax/linux.h" + tmake_file=vax/t-linux ;; vax-*-netbsdelf*) tm_file="${tm_file} elfos.h netbsd.h netbsd-elf.h vax/elf.h vax/netbsd-elf.h" Index: gcc-4.5.0-20090609-vax-linux/gcc/config/vax/lib1funcs.asm =================================================================== --- /dev/null +++ gcc-4.5.0-20090609-vax-linux/gcc/config/vax/lib1funcs.asm @@ -0,0 +1,92 @@ +/* Copyright (C) 2009 Free Software Foundation, Inc. + This file is part of GCC. + Contributed by Maciej W. Rozycki <macro(a)linux-mips.org>. + + This file is free software; you can redistribute it and/or modify it + under the terms of the GNU General Public License as published by the + Free Software Foundation; either version 3, or (at your option) any + later version. + + This file is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + Under Section 7 of GPL version 3, you are granted additional + permissions described in the GCC Runtime Library Exception, version + 3.1, as published by the Free Software Foundation. + + You should have received a copy of the GNU General Public License and + a copy of the GCC Runtime Library Exception along with this program; + see the files COPYING3 and COPYING.RUNTIME respectively. If not, see + <http://www.gnu.org/licenses/>. */ + +#ifdef L_udivsi3 + .text + .globl __udivsi3 + .type __udivsi3, @function +__udivsi3: + .word 0 + movl 8(%ap), %r1 + blss 0f /* Check bit #31 of divisor. */ + movl 4(%ap), %r2 + blss 1f /* Check bit #31 of dividend. */ + + /* Both zero, do a standard division. */ + + divl3 %r1, %r2, %r0 + ret + + /* MSB of divisor set, only 1 or 0 may result. */ +0: + decl %r1 + clrl %r0 + cmpl %r1, 4(%ap) + adwc $0, %r0 + ret + + /* MSB of dividend set, do an extended division. */ +1: + clrl %r3 + ediv %r1, %r2, %r0, %r3 + ret + .size __udivsi3, . - __udivsi3 + .previous +#endif + +#ifdef L_umodsi3 + .text + .globl __umodsi3 + .type __umodsi3, @function +__umodsi3: + .word 0 + movl 8(%ap), %r1 + blss 0f /* Check bit #31 of divisor. */ + movl 4(%ap), %r2 + blss 1f /* Check bit #31 of dividend. */ + + /* Both zero, do a standard division. */ + + divl3 %r1, %r2, %r0 + mull2 %r0, %r1 + subl3 %r1, %r2, %r0 + ret + + /* MSB of divisor set, subtract the divisor at most once. */ +0: + movl 4(%ap), %r2 + clrl %r0 + cmpl %r2, %r1 + sbwc $0, %r0 + bicl2 %r0, %r1 + subl3 %r1, %r2, %r0 + ret + + /* MSB of dividend set, do an extended division. */ +1: + clrl %r3 + ediv %r1, %r2, %r3, %r0 + ret + .size __umodsi3, . - __umodsi3 + .previous +#endif Index: gcc-4.5.0-20090609-vax-linux/gcc/config/vax/linux.h =================================================================== --- gcc-4.5.0-20090609-vax-linux.orig/gcc/config/vax/linux.h +++ gcc-4.5.0-20090609-vax-linux/gcc/config/vax/linux.h @@ -37,6 +37,10 @@ along with GCC; see the file COPYING3. #undef TARGET_DEFAULT #define TARGET_DEFAULT (MASK_QMATH | MASK_G_FLOAT) +/* Use standard names for udiv and umod libgcc calls. */ +#undef TARGET_BSD_DIVMOD +#define TARGET_BSD_DIVMOD 0 + #undef CPP_SPEC #define CPP_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}" Index: gcc-4.5.0-20090609-vax-linux/gcc/config/vax/t-linux =================================================================== --- /dev/null +++ gcc-4.5.0-20090609-vax-linux/gcc/config/vax/t-linux @@ -0,0 +1,2 @@ +LIB1ASMSRC = vax/lib1funcs.asm +LIB1ASMFUNCS = _udivsi3 _umodsi3 Index: gcc-4.5.0-20090609-vax-linux/gcc/config/vax/vax.c =================================================================== --- gcc-4.5.0-20090609-vax-linux.orig/gcc/config/vax/vax.c +++ gcc-4.5.0-20090609-vax-linux/gcc/config/vax/vax.c @@ -172,8 +172,11 @@ vax_file_start (void) static void vax_init_libfuncs (void) { - set_optab_libfunc (udiv_optab, SImode, TARGET_ELF ? "*__udiv" : "*udiv"); - set_optab_libfunc (umod_optab, SImode, TARGET_ELF ? "*__urem" : "*urem"); + if (TARGET_BSD_DIVMOD) + { + set_optab_libfunc (udiv_optab, SImode, TARGET_ELF ? "*__udiv" : "*udiv"); + set_optab_libfunc (umod_optab, SImode, TARGET_ELF ? "*__urem" : "*urem"); + } } /* This is like nonimmediate_operand with a restriction on the type of MEM. */ Index: gcc-4.5.0-20090609-vax-linux/gcc/config/vax/vax.h =================================================================== --- gcc-4.5.0-20090609-vax-linux.orig/gcc/config/vax/vax.h +++ gcc-4.5.0-20090609-vax-linux/gcc/config/vax/vax.h @@ -63,6 +63,9 @@ along with GCC; see the file COPYING3. /* Nonzero if ELF. Redefined by vax/elf.h. */ #define TARGET_ELF 0 +/* Use BSD names for udiv and umod libgcc calls. */ +#define TARGET_BSD_DIVMOD 1 + /* Default target_flags if no switches specified. */ #ifndef TARGET_DEFAULT _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

2 1

[LV] [PATCH] libgcc: Support vax-*-linux*
by Maciej W. Rozycki 10 Jun '09

10 Jun '09

Hi, The subject says it all -- vax-*-linux* has to be added to libgcc/config.host for the platform to be supported by libgcc; otherwise: *** Configuration vax-dec-linux-gnu not supported is reported and the build stops at configure-target-libgcc. libgcc/ 2009-06-10 Maciej W. Rozycki <macro(a)linux-mips.org> * config.host (vax-*-linux*): New. Tested by building for --target=vax-linux with the C language enabled; the configuration is not capable enough for regression testing yet. OK to apply? Maciej gcc-4.5.0-20090609-vax-linux-libgcc.patch Index: gcc-4.5.0-20090609-vax-linux/libgcc/config.host =================================================================== --- gcc-4.5.0-20090609-vax-linux.orig/libgcc/config.host +++ gcc-4.5.0-20090609-vax-linux/libgcc/config.host @@ -528,6 +528,8 @@ v850e-*-*) ;; v850-*-*) ;; +vax-*-linux*) + ;; vax-*-netbsdelf*) ;; vax-*-netbsd*) _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0

[LV] [PATCH] VAX/ELF: Correctly handle R_VAX_PC32 relocs in executables
by Maciej W. Rozycki 05 Jun '09

05 Jun '09

Hello, Non-PIC executables still need to create PLT entries if the static link determines the function called comes from a shared library. In this case the associated R_VAX_PC32 relocation has to be treated as if it was a R_VAX_PLT32 one. This is similar to how other platforms handle the scenario. Regression-tested successfully with the vax-linux target; running dynamically-linked `bash' on the target system (about the best native testing possible atm) revealed no problems either. bfd/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * elf32-vax.c (elf_vax_relocate_section): For symbol references from an executable to a shared library treat R_VAX_PC32 relocations as R_VAX_PLT32 ones. OK to apply? Maciej binutils-2.19.51-20090531-vax-pcplt.patch diff -up --recursive --new-file binutils-2.19.51-20090531.macro/bfd/elf32-vax.c binutils-2.19.51-20090531/bfd/elf32-vax.c --- binutils-2.19.51-20090531.macro/bfd/elf32-vax.c 2009-06-01 23:23:15.000000000 +0000 +++ binutils-2.19.51-20090531/bfd/elf32-vax.c 2009-06-01 23:29:01.000000000 +0000 @@ -1534,6 +1534,14 @@ elf_vax_relocate_section (bfd *output_bf } break; + case R_VAX_PC32: + /* If we are creating an executable and the function this + reloc refers to is in a shared lib, then we made a PLT + entry for this symbol and need to handle the reloc like + a PLT reloc. */ + if (info->shared) + goto r_vax_pc32_shared; + /* Fall through. */ case R_VAX_PLT32: /* Relocation is to the entry for this symbol in the procedure linkage table. */ @@ -1595,7 +1603,7 @@ elf_vax_relocate_section (bfd *output_bf case R_VAX_PC8: case R_VAX_PC16: - case R_VAX_PC32: + r_vax_pc32_shared: if (h == NULL || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT || h->forced_local) _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0

[LV] [PATCH] VAX/ELF: Do not allocate GOT space for local symbols
by Maciej W. Rozycki 05 Jun '09

05 Jun '09

Hello, Here is a fix to exclude local symbols from GOT space calculation. These GOT entries would never be used anyway, because the VAX supports unlimited PC-relative addressing for all kinds of memory references. Regression-tested successfully with the vax-linux target; running dynamically-linked `bash' on the target system (about the best native testing possible atm) revealed no problems either. bfd/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * elf32-vax.c (elf_vax_instantiate_got_entries): Skip local symbols in GOT space calculation. (elf_vax_relocate_section): Adjust accordingly. OK to apply? Maciej binutils-2.19.51-20090531-vax-got-rel.patch diff -up --recursive --new-file binutils-2.19.51-20090531.macro/bfd/elf32-vax.c binutils-2.19.51-20090531/bfd/elf32-vax.c --- binutils-2.19.51-20090531.macro/bfd/elf32-vax.c 2009-04-02 04:25:18.000000000 +0000 +++ binutils-2.19.51-20090531/bfd/elf32-vax.c 2009-06-03 02:19:19.000000000 +0000 @@ -1322,6 +1322,8 @@ elf_vax_instantiate_got_entries (struct } else if (h->got.refcount > 0) { + bfd_boolean dyn; + /* Make sure this symbol is output as a dynamic symbol. */ if (h->dynindx == -1) { @@ -1329,9 +1331,15 @@ elf_vax_instantiate_got_entries (struct return FALSE; } + dyn = elf_hash_table (info)->dynamic_sections_created; /* Allocate space in the .got and .rela.got sections. */ - sgot->size += 4; - srelgot->size += sizeof (Elf32_External_Rela); + if (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT + && (info->shared + || WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, 0, h))) + { + sgot->size += 4; + srelgot->size += sizeof (Elf32_External_Rela); + } } return TRUE; @@ -1472,6 +1480,7 @@ elf_vax_relocate_section (bfd *output_bf the global offset table. */ { + bfd_boolean dyn; bfd_vma off; if (sgot == NULL) @@ -1485,9 +1494,10 @@ elf_vax_relocate_section (bfd *output_bf BFD_ASSERT (off != (bfd_vma) -1); BFD_ASSERT (off < sgot->size); - if (info->shared - && h->dynindx == -1 - && h->def_regular) + dyn = elf_hash_table (info)->dynamic_sections_created; + if (! WILL_CALL_FINISH_DYNAMIC_SYMBOL (dyn, info->shared, h) + || (info->shared + && SYMBOL_REFERENCES_LOCAL (info, h))) { /* The symbol was forced to be local because of a version file.. We must initialize _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0

[LV] [PATCH] VAX/ELF: PLT disassembly support
by Maciej W. Rozycki 05 Jun '09

05 Jun '09

Hello, The VAX/ELF backend lacks a platform-specific PLT disassembly helper. The result is the table is messed up in the dump. Here's an example: $ vax-linux-objdump -d -j .plt ld.so.1 ld.so.1: file format elf32-vax Disassembly of section .plt: 000005c8 <.plt>: 5c8: dd ef 7e 42 pushl 1484c <_GLOBAL_OFFSET_TABLE_+0x4> 5cc: 01 00 5ce: 17 ff 7c 42 jmp *14850 <_GLOBAL_OFFSET_TABLE_+0x8> 5d2: 01 00 5d4: fc xfc 5d5: 0f 16 ef ec remque $0x16,5c8 <GLIBC_2.0+0x5c8> 5d9: ff ff ff 5dc: 00 halt 5dd: 00 halt 5de: 00 halt 5df: 00 halt 5e0: fc xfc 5e1: 0f 16 ef e0 remque $0x16,5c8 <GLIBC_2.0+0x5c8> 5e5: ff ff ff 5e8: 0c 00 00 00 prober $0x0,$0x0,$0x0 5ec: fc xfc 5ed: 0f 16 ef d4 remque $0x16,5c8 <GLIBC_2.0+0x5c8> 5f1: ff ff ff 5f4: 18 00 bgeq 5f6 <GLIBC_2.0+0x5f6> 5f6: 00 halt 5f7: 00 halt 5f8: fc xfc 5f9: 0f 16 ef c8 remque $0x16,5c8 <GLIBC_2.0+0x5c8> 5fd: ff ff ff 600: 24 00 00 00 cvtpt $0x0,$0x0,$0x0,*0xbcef160f(ap),*31060d <_end+0x2fb511> 604: fc 0f 16 ef 608: bc ff ff ff 60c: 30 00 ... The patch below implements the helper needed. There is a small issue with weak symbols which do not have the BSF_FUNCTION flag set and therefore do not match the usual logic to trigger entry mask decoding. To solve this problem, I have made use of an observation that the BSF_SYNTHETIC flag is only set for PLT symbols for the VAX target. If this ever changes in the future code will have to be adjusted accordingly. Here's a dump of the same PLT as above obtained with the patch applied: $ vax-linux-objdump -d -j .plt ld.so.1 ld.so.1: file format elf32-vax Disassembly of section .plt: 000005c8 <__libc_memalign@plt-0xc>: 5c8: dd ef 7e 42 pushl 1484c <_GLOBAL_OFFSET_TABLE_+0x4> 5cc: 01 00 5ce: 17 ff 7c 42 jmp *14850 <_GLOBAL_OFFSET_TABLE_+0x8> 5d2: 01 00 000005d4 <__libc_memalign@plt>: 5d4: fc 0f .word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > 5d6: 16 ef ec ff jsb 5c8 <GLIBC_2.0+0x5c8> 5da: ff ff 5dc: 00 00 00 00 .long 0x00000000 000005e0 <malloc@plt>: 5e0: fc 0f .word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > 5e2: 16 ef e0 ff jsb 5c8 <GLIBC_2.0+0x5c8> 5e6: ff ff 5e8: 0c 00 00 00 .long 0x0000000c 000005ec <calloc@plt>: 5ec: fc 0f .word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > 5ee: 16 ef d4 ff jsb 5c8 <GLIBC_2.0+0x5c8> 5f2: ff ff 5f4: 18 00 00 00 .long 0x00000018 000005f8 <realloc@plt>: 5f8: fc 0f .word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > 5fa: 16 ef c8 ff jsb 5c8 <GLIBC_2.0+0x5c8> 5fe: ff ff 600: 24 00 00 00 .long 0x00000024 00000604 <free@plt>: 604: fc 0f .word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > 606: 16 ef bc ff jsb 5c8 <GLIBC_2.0+0x5c8> 60a: ff ff 60c: 30 00 00 00 .long 0x00000030 bfd/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * elf32-vax.c (elf_vax_plt_sym_val): New function. (elf_backend_plt_sym_val): Define. opcodes/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * vax-dis.c (is_function_entry): Return success for synthetic symbols too. (is_plt_tail): New function. (print_insn_vax): Decode PLT entry offset longword. OK to apply? Maciej binutils-2.19.1-vax-plt-sym.patch diff -up --recursive --new-file binutils-2.19.1.macro/bfd/elf32-vax.c binutils-2.19.1/bfd/elf32-vax.c --- binutils-2.19.1.macro/bfd/elf32-vax.c 2008-01-11 09:07:03.000000000 +0000 +++ binutils-2.19.1/bfd/elf32-vax.c 2009-05-15 22:46:54.000000000 +0000 @@ -47,6 +47,8 @@ static bfd_boolean elf_vax_finish_dynami Elf_Internal_Sym *); static bfd_boolean elf_vax_finish_dynamic_sections (bfd *, struct bfd_link_info *); +static bfd_vma elf_vax_plt_sym_val (bfd_vma, const asection *, + const arelent *); static bfd_boolean elf32_vax_set_private_flags (bfd *, flagword); static bfd_boolean elf32_vax_merge_private_bfd_data (bfd *, bfd *); @@ -2068,6 +2070,13 @@ elf_vax_finish_dynamic_sections (bfd *ou return TRUE; } +static bfd_vma +elf_vax_plt_sym_val (bfd_vma i, const asection *plt, + const arelent *rel ATTRIBUTE_UNUSED) +{ + return plt->vma + (i + 1) * PLT_ENTRY_SIZE; +} + #define TARGET_LITTLE_SYM bfd_elf32_vax_vec #define TARGET_LITTLE_NAME "elf32-vax" #define ELF_MACHINE_CODE EM_VAX @@ -2092,6 +2101,7 @@ elf_vax_finish_dynamic_sections (bfd *ou elf_vax_finish_dynamic_sections #define elf_backend_gc_mark_hook elf_vax_gc_mark_hook #define elf_backend_gc_sweep_hook elf_vax_gc_sweep_hook +#define elf_backend_plt_sym_val elf_vax_plt_sym_val #define bfd_elf32_bfd_merge_private_bfd_data \ elf32_vax_merge_private_bfd_data #define bfd_elf32_bfd_set_private_flags \ diff -up --recursive --new-file binutils-2.19.1.macro/opcodes/vax-dis.c binutils-2.19.1/opcodes/vax-dis.c --- binutils-2.19.1.macro/opcodes/vax-dis.c 2007-07-05 09:49:02.000000000 +0000 +++ binutils-2.19.1/opcodes/vax-dis.c 2009-05-15 23:52:10.000000000 +0000 @@ -171,21 +171,24 @@ free_entry_array (void) } } #endif -/* Check if the given address is a known function entry. Either there must - be a symbol of function type at this address, or the address must be - a forced entry point. The later helps in disassembling ROM images, because - there's no symbol table at all. Forced entry points can be given by - supplying several -M options to objdump: -M entry:0xffbb7730. */ +/* Check if the given address is a known function entry point. This is + the case if there is a symbol of the function type at this address. + We also check for synthetic symbols as these are used for PLT entries + (weak undefined symbols may not have the function type set). Finally + the address may have been forced to be treated as an entry point. The + latter helps in disassembling ROM images, because there's no symbol + table at all. Forced entry points can be given by supplying several + -M options to objdump: -M entry:0xffbb7730. */ static bfd_boolean is_function_entry (struct disassemble_info *info, bfd_vma addr) { unsigned int i; - /* Check if there's a BSF_FUNCTION symbol at our address. */ + /* Check if there's a function or PLT symbol at our address. */ if (info->symbols && info->symbols[0] - && (info->symbols[0]->flags & BSF_FUNCTION) + && (info->symbols[0]->flags & (BSF_FUNCTION | BSF_SYNTHETIC)) && addr == bfd_asymbol_value (info->symbols[0])) return TRUE; @@ -197,6 +200,22 @@ is_function_entry (struct disassemble_in return FALSE; } +/* Check if the given address is the last longword of a PLT entry. + This longword is data and depending on the value it may interfere + with disassembly of further PLT entries. We make use of the fact + PLT symbols are marked BSF_SYNTHETIC. */ +static bfd_boolean +is_plt_tail (struct disassemble_info *info, bfd_vma addr) +{ + if (info->symbols + && info->symbols[0] + && (info->symbols[0]->flags & BSF_SYNTHETIC) + && addr == bfd_asymbol_value (info->symbols[0]) + 8) + return TRUE; + + return FALSE; +} + static int print_insn_mode (const char *d, int size, @@ -412,6 +431,18 @@ print_insn_vax (bfd_vma memaddr, disasse return 2; } + /* Decode PLT entry offset longword. */ + if (is_plt_tail (info, memaddr)) + { + int offset; + + FETCH_DATA (info, buffer + 4); + offset = buffer[3] << 24 | buffer[2] << 16 | buffer[1] << 8 | buffer[0]; + (*info->fprintf_func) (info->stream, ".long 0x%08x", offset); + + return 4; + } + for (votp = &votstrs[0]; votp->name[0]; votp++) { vax_opcodeT opcode = votp->detail.code; _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0

[LV] [PATCH] VAX/ELF: Provide correct relocation classes
by Maciej W. Rozycki 05 Jun '09

05 Jun '09

Hello, Class annotation for VAX relocations is missing. Here's an obvious fix. Regression-tested successfully with the vax-linux target. 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * elf32-vax.c (elf_vax_reloc_type_class): New function. (elf_backend_reloc_type_class): Define. OK to apply? Maciej binutils-2.19.1-vax-reloc-class.patch diff -up --recursive --new-file binutils-2.19.1.macro/bfd/elf32-vax.c binutils-2.19.1/bfd/elf32-vax.c --- binutils-2.19.1.macro/bfd/elf32-vax.c 2008-01-11 09:07:03.000000000 +0000 +++ binutils-2.19.1/bfd/elf32-vax.c 2009-05-05 05:35:06.000000000 +0000 @@ -2068,6 +2068,22 @@ elf_vax_finish_dynamic_sections (bfd *ou return TRUE; } +static enum elf_reloc_type_class +elf_vax_reloc_type_class (const Elf_Internal_Rela *rela) +{ + switch ((int) ELF32_R_TYPE (rela->r_info)) + { + case R_VAX_RELATIVE: + return reloc_class_relative; + case R_VAX_JMP_SLOT: + return reloc_class_plt; + case R_VAX_COPY: + return reloc_class_copy; + default: + return reloc_class_normal; + } +} + #define TARGET_LITTLE_SYM bfd_elf32_vax_vec #define TARGET_LITTLE_NAME "elf32-vax" #define ELF_MACHINE_CODE EM_VAX @@ -2090,6 +2106,7 @@ elf_vax_finish_dynamic_sections (bfd *ou elf_vax_finish_dynamic_symbol #define elf_backend_finish_dynamic_sections \ elf_vax_finish_dynamic_sections +#define elf_backend_reloc_type_class elf_vax_reloc_type_class #define elf_backend_gc_mark_hook elf_vax_gc_mark_hook #define elf_backend_gc_sweep_hook elf_vax_gc_sweep_hook #define bfd_elf32_bfd_merge_private_bfd_data \ _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0

[LV] [PATCH] VAX/ELF: Store all call-saved registers upon PLT stub entry
by Maciej W. Rozycki 05 Jun '09

05 Jun '09

Hello, For the VAX processor the list of registers to be preserved across procedure calls is specified by the 16-bit word at the entry point, called the entry mask. That word is interpreted by the procedure call instruction and the registers requested are stored on the stack together with a copy of the entry mask before control is transferred. Later on, this data is used by the return instruction to restore the registers previously saved. This poses a problem with PLT stubs used for lazy run-time resolving. The stubs are called as if they were actual procedures, so they have to provide information about which registers to store. That information is not available at the static link time as PLT entries are normally only created for global symbol references to shared objects and such symbols, even if available from the same binary, are subject to preemption. Therefore this information has to be orchestrated somehow. I could see two possible solutions: 1. Either to create a fake mask to include the call-saved registers the lazy resolver actually clobbers. This approach has a potential advantage of not requiring unnecessary stack transfers. Unfortunately the advantage is quickly flushed down the drain as the piece of code called by the PLT stub has to recreate the stack frame manually by retrieving the mask from the address to be called once it has been resolved, determining which registers have to be saved, copying part of the stack frame already created down the stack, inserting the extra registers and updating the mask stored on the stack. 2. Always save all the call-saved registers. This has a potential performance disadvantage, but I believe it to be negligible as the area near the stack pointer is typically hot in the cache and the lazy resolver is only called at most once per function per program execution. The advantage is simplicity. All the stores are done by the call instruction, which has been designed (and undoubtedly optimised) for this kind of operation. There is no need to do fragile fiddling with the stack in the lazy resolver and on average the actual performance may not be worse at all. The difference is going to be lost in the lazy resolver's overhead anyway. The current approach in BFD seems to be #1 above and I would like to get it changed to the #2. Given the issues with the VAX/ELF backend I'm not sure if the PLT stubs have already been used in actual software, raising binary compatibility concerns. If so, I would limit this change to Linux (regrettably creating an incompatible ELF flavour), otherwise I suggest it to be applied universally. While the standard VAX ABI only defines <R11:R6> as call-saved, the mask I chose includes <R5:R2> too due to the -fcall-saved-REG GCC option -- the information about which registers are consider call-saved is not carried along binaries. OTOH, <R1:R0> are skipped as they are result registers and must never be saved across calls. bfd/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * elf32-vax.c (elf_vax_plt_entry): Set the entry mask to include <R11:R2>. Comments? Maciej binutils-2.19.1-vax-plt-mask.patch diff -up --recursive --new-file binutils-2.19.1.macro/bfd/elf32-vax.c binutils-2.19.1/bfd/elf32-vax.c --- binutils-2.19.1.macro/bfd/elf32-vax.c 2008-01-11 09:07:03.000000000 +0000 +++ binutils-2.19.1/bfd/elf32-vax.c 2009-04-20 20:11:20.000000000 +0000 @@ -368,7 +368,7 @@ static const bfd_byte elf_vax_plt0_entry static const bfd_byte elf_vax_plt_entry[PLT_ENTRY_SIZE] = { - 0x40, 0x00, /* .word ^M<r6> */ + 0xfc, 0x0f, /* .word ^M<r11:r2> */ 0x16, 0xef, /* jsb L^(pc) */ 0, 0, 0, 0, /* replaced with offset to start of .plt */ 0, 0, 0, 0, /* index into .rela.plt */ _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0

[LV] [PATCH] VAX/ELF: Symbol visibility support
by Maciej W. Rozycki 05 Jun '09

05 Jun '09

Hello, This is a patch to add symbol visibility support to the VAX/ELF backend. Changes include attribute recognition in BFD so that GOT or PLT entries are not created as expected (unlimited PC-relative addressing is supported by VAX for all kinds of memory references, so there is no need for run-time relocation of local symbols) as well as a fix to GAS so as to permit indirect symbol references which inevitably will be generated for some hidden symbols by GCC. Any errors resulting from the inability to route indirect references via the GOT -- which may happen for handcoded assembly only -- are already reported by the linker as they should be. Regression-tested successfully with the vax-linux target; running dynamically-linked `bash' on the target system (about the best native testing possible atm) revealed no problems either. bfd/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * elf32-vax.c (elf_vax_check_relocs): Handle the visibility attribute. (elf_vax_relocate_section): Likewise. gas/ 2009-06-04 Maciej W. Rozycki <macro(a)linux-mips.org> * config/tc-vax.c (md_estimate_size_before_relax): Accept indirect symbol references in the PIC mode and emit a PC-relative relocation instead of a GOT/PLT one. Likewise for symbols known to be hidden at this point. OK to apply? Maciej binutils-2.19.51-20090531-vax-elf-visibility.patch diff -up --recursive --new-file binutils-2.19.51-20090531.macro/bfd/elf32-vax.c binutils-2.19.51-20090531/bfd/elf32-vax.c --- binutils-2.19.51-20090531.macro/bfd/elf32-vax.c 2009-04-02 04:25:18.000000000 +0000 +++ binutils-2.19.51-20090531/bfd/elf32-vax.c 2009-06-01 23:23:15.000000000 +0000 @@ -605,6 +605,11 @@ elf_vax_check_relocs (bfd *abfd, struct || h == elf_hash_table (info)->hplt) break; + /* If this is a local symbol, we resolve it directly without + creating a global offset table entry. */ + if (h == NULL || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT) + break; + /* This symbol requires a global offset table entry. */ if (dynobj == NULL) @@ -677,7 +682,7 @@ elf_vax_check_relocs (bfd *abfd, struct /* If this is a local symbol, we resolve it directly without creating a procedure linkage table entry. */ BFD_ASSERT (h != NULL); - if (h->forced_local) + if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT || h->forced_local) break; h->needs_plt = 1; @@ -706,7 +711,9 @@ elf_vax_check_relocs (bfd *abfd, struct && (!info->symbolic || !h->def_regular))) { - if (h != NULL && !h->forced_local) + if (h != NULL + && ELF_ST_VISIBILITY (h->other) == STV_DEFAULT + && !h->forced_local) { /* Make sure a plt entry is created for this symbol if it turns out to be a function defined by a dynamic @@ -718,14 +725,17 @@ elf_vax_check_relocs (bfd *abfd, struct } break; } - if (h != NULL && h->forced_local) + /* If this is a local symbol, we can resolve it directly. */ + if (h != NULL + && (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT + || h->forced_local)) break; /* Fall through. */ case R_VAX_8: case R_VAX_16: case R_VAX_32: - if (h != NULL) + if (h != NULL && ELF_ST_VISIBILITY (h->other) == STV_DEFAULT) { /* Make sure a plt entry is created for this symbol if it turns out to be a function defined by a dynamic object. */ @@ -1465,7 +1475,10 @@ elf_vax_relocate_section (bfd *output_bf case R_VAX_GOT32: /* Relocation is to the address of the entry for this symbol in the global offset table. */ - if (h == NULL || h->got.offset == (bfd_vma) -1 || h->forced_local) + if (h == NULL + || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT + || h->got.offset == (bfd_vma) -1 + || h->forced_local) break; /* Relocation is the offset of the entry for this symbol in @@ -1527,7 +1540,9 @@ elf_vax_relocate_section (bfd *output_bf /* Resolve a PLTxx reloc against a local symbol directly, without using the procedure linkage table. */ - if (h == NULL || h->forced_local) + if (h == NULL + || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT + || h->forced_local) break; if (h->plt.offset == (bfd_vma) -1 @@ -1581,7 +1596,9 @@ elf_vax_relocate_section (bfd *output_bf case R_VAX_PC8: case R_VAX_PC16: case R_VAX_PC32: - if (h == NULL || h->forced_local) + if (h == NULL + || ELF_ST_VISIBILITY (h->other) != STV_DEFAULT + || h->forced_local) break; /* Fall through. */ case R_VAX_8: diff -up --recursive --new-file binutils-2.19.51-20090531.macro/gas/config/tc-vax.c binutils-2.19.51-20090531/gas/config/tc-vax.c --- binutils-2.19.51-20090531.macro/gas/config/tc-vax.c 2009-04-02 04:25:28.000000000 +0000 +++ binutils-2.19.51-20090531/gas/config/tc-vax.c 2009-06-01 23:23:15.000000000 +0000 @@ -396,23 +396,20 @@ md_estimate_size_before_relax (fragS *fr || S_IS_WEAK (fragP->fr_symbol) || S_IS_EXTERNAL (fragP->fr_symbol))) { - if (p[0] & 0x10) - { - if (flag_want_pic) - as_fatal ("PIC reference to %s is indirect.\n", - S_GET_NAME (fragP->fr_symbol)); - } + /* Indirect references cannot go through the GOT or PLT, + let's hope they'll become local in the final link. */ + if ((ELF_ST_VISIBILITY (S_GET_OTHER (fragP->fr_symbol)) + != STV_DEFAULT) + || (p[0] & 0x10)) + reloc_type = BFD_RELOC_32_PCREL; + else if (((unsigned char *) fragP->fr_opcode)[0] == VAX_CALLS + || ((unsigned char *) fragP->fr_opcode)[0] == VAX_CALLG + || ((unsigned char *) fragP->fr_opcode)[0] == VAX_JSB + || ((unsigned char *) fragP->fr_opcode)[0] == VAX_JMP + || S_IS_FUNCTION (fragP->fr_symbol)) + reloc_type = BFD_RELOC_32_PLT_PCREL; else - { - if (((unsigned char *) fragP->fr_opcode)[0] == VAX_CALLS - || ((unsigned char *) fragP->fr_opcode)[0] == VAX_CALLG - || ((unsigned char *) fragP->fr_opcode)[0] == VAX_JSB - || ((unsigned char *) fragP->fr_opcode)[0] == VAX_JMP - || S_IS_FUNCTION (fragP->fr_symbol)) - reloc_type = BFD_RELOC_32_PLT_PCREL; - else - reloc_type = BFD_RELOC_32_GOT_PCREL; - } + reloc_type = BFD_RELOC_32_GOT_PCREL; } #endif switch (RELAX_STATE (fragP->fr_subtype)) _______________________________________________ Linux-Vax mailing list Linux-Vax(a)mail.pergamentum.com http://mail.pergamentum.com/mailman/listinfo/linux-vax

1 0