diff options
Diffstat (limited to 'usr/src/cmd/sgs/libld/common/relocate.c')
| -rw-r--r-- | usr/src/cmd/sgs/libld/common/relocate.c | 77 |
1 files changed, 66 insertions, 11 deletions
diff --git a/usr/src/cmd/sgs/libld/common/relocate.c b/usr/src/cmd/sgs/libld/common/relocate.c index 5c2ca2b711..64cc687204 100644 --- a/usr/src/cmd/sgs/libld/common/relocate.c +++ b/usr/src/cmd/sgs/libld/common/relocate.c @@ -1007,6 +1007,22 @@ ld_reloc_plt(Rel_desc *rsp, Ofl_desc *ofl) } /* + * Round up to the next power of 2. Used to ensure section alignments that can + * be used for copy relocation symbol alignments are sane values. + */ +static Word +nlpo2(Word val) +{ + val--; + val |= (val >> 1); + val |= (val >> 2); + val |= (val >> 4); + val |= (val >> 8); + val |= (val >> 16); + return (++val); +} + +/* * process GLOBAL undefined and ref_dyn_need symbols. */ static uintptr_t @@ -1056,7 +1072,7 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) /* * If the reference isn't to an object (normally because a .type - * directive hasn't defined in some assembler source), then simply apply + * directive wasn't defined in some assembler source), then apply * a generic relocation (this has a tendency to result in text * relocations). */ @@ -1074,7 +1090,7 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) /* * Prepare for generating a copy relocation. * - * If this symbol is one of an alias pair, we need to insure both + * If this symbol is one of an alias pair, we need to ensure both * symbols become part of the output (the strong symbol will be used to * maintain the symbols state). And, if we did raise the precedence of * a symbol we need to check and see if this is a weak symbol. If it is @@ -1131,10 +1147,16 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) * to the executables .bss at runtime. */ if (!(RELAUX_GET_USYM(rsp)->sd_flags & FLG_SY_MVTOCOMM)) { - Word rtype = rsp->rel_rtype; + Word rtype = rsp->rel_rtype, w2align; Copy_rel cr; /* + * Diagnose the original copy reference, as this symbol + * information will be overridden with the new destination. + */ + DBG_CALL(Dbg_syms_copy_reloc(ofl, sdp, 0)); + + /* * Indicate that the symbol(s) against which we're relocating * have been moved to the executables common. Also, insure that * the symbol(s) remain marked as global, as the shared object @@ -1171,9 +1193,7 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) } /* - * Assign the symbol to the bss and insure sufficient alignment - * (we don't know the real alignment so we have to make the - * worst case guess). + * Assign the symbol to the bss. */ _sdp = RELAUX_GET_USYM(rsp); stval = _sdp->sd_sym->st_value; @@ -1181,9 +1201,37 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) return (S_ERROR); _sdp->sd_shndx = _sdp->sd_sym->st_shndx = SHN_COMMON; _sdp->sd_flags |= FLG_SY_SPECSEC; - _sdp->sd_sym->st_value = - (_sdp->sd_sym->st_size < (ld_targ.t_m.m_word_align * 2)) ? - ld_targ.t_m.m_word_align : ld_targ.t_m.m_word_align * 2; + + /* + * Ensure the symbol has sufficient alignment. The symbol + * definition has no alignment information that can be used, + * hence we use a heuristic. Historically, twice the native + * word alignment was sufficient for any data type, however, + * the developer may have requested larger alignments (pragma + * align). The most conservative approach is to use a power + * of two alignment, determined from the alignment of the + * section containing the symbol definition. Note that this + * can result in some bloat to the .bss as the not every item + * of copied data might need the section alignment. + * + * COMMON symbols carry their alignment requirements in the + * symbols st_value field. This alignment is applied to the + * symbol when it is eventually transformed into .bss. + */ + w2align = ld_targ.t_m.m_word_align * 2; + if (_sdp->sd_sym->st_size < w2align) + _sdp->sd_sym->st_value = ld_targ.t_m.m_word_align; + else { + Shdr *shdr; + Word isalign; + + if (_sdp->sd_isc && + ((shdr = _sdp->sd_isc->is_shdr) != NULL) && + ((isalign = shdr->sh_addralign) != 0)) + _sdp->sd_sym->st_value = nlpo2(isalign); + else + _sdp->sd_sym->st_value = w2align; + } /* * Whether or not the symbol references initialized data we @@ -1213,7 +1261,13 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) rsp->rel_rtype = rtype; /* - * If this symbol is a protected symbol, warn it. + * If this symbol is a protected symbol, warn the user. A + * potential issue exists as the copy relocated symbol within + * the executable can be visible to others, whereas the shared + * object that defined the original copy data symbol is pre- + * bound to reference it's own definition. Any modification + * of the symbols data could lead to inconsistencies for the + * various users. */ if (_sdp->sd_flags & FLG_SY_PROT) { Conv_inv_buf_t inv_buf; @@ -1224,7 +1278,8 @@ reloc_exec(Rel_desc *rsp, Ofl_desc *ofl) ld_targ.t_m.m_r_copy, 0, &inv_buf), _sdp->sd_file->ifl_name, _sdp->sd_name); } - DBG_CALL(Dbg_syms_reloc(ofl, sdp)); + DBG_CALL(Dbg_syms_copy_reloc(ofl, _sdp, + _sdp->sd_sym->st_value)); } return (ld_add_actrel(NULL, rsp, ofl)); } |