From: Mark Wielaard Date: Sun, 15 Jun 2014 11:30:35 +0200 Subject: libebl: Add sym_func_value hook. The ARM EABI says that the zero bit of function symbol st_value indicates whether the symbol points to a THUMB or ARM function. Add a new ebl hook to adjust the st_value in such a case so that we get the actual value that the symbol points to. It isn't easily possible to reuse the existing resolve_sym_value for this purpose, so we end up with another hook that can be used from dwfl_module_getsym and elflint. Index: elfutils-0.159/backends/arm_init.c =================================================================== --- elfutils-0.159.orig/backends/arm_init.c +++ elfutils-0.159/backends/arm_init.c @@ -78,6 +78,7 @@ arm_init (elf, machine, eh, ehlen) eh->return_value_location = arm_return_value_location_hard; HOOK (eh, abi_cfi); HOOK (eh, check_reloc_target_type); + HOOK (eh, sym_func_value); /* We only unwind the core integer registers. */ eh->frame_nregs = 16; Index: elfutils-0.159/backends/arm_symbol.c =================================================================== --- elfutils-0.159.orig/backends/arm_symbol.c +++ elfutils-0.159/backends/arm_symbol.c @@ -129,3 +129,11 @@ arm_check_reloc_target_type (Ebl *ebl __ { return sh_type == SHT_ARM_EXIDX; } + +/* ARM EABI says that the low bit indicates whether the function + symbol value is a THUMB function or not. Mask it off. */ +GElf_Addr +arm_sym_func_value (Ebl *ebl __attribute__ ((unused)), GElf_Addr val) +{ + return val & ~(GElf_Addr)1; +} Index: elfutils-0.159/libdwfl/dwfl_module_getsym.c =================================================================== --- elfutils-0.159.orig/libdwfl/dwfl_module_getsym.c +++ elfutils-0.159/libdwfl/dwfl_module_getsym.c @@ -1,5 +1,5 @@ /* Find debugging and symbol information for a module in libdwfl. - Copyright (C) 2006-2013 Red Hat, Inc. + Copyright (C) 2006-2014 Red Hat, Inc. This file is part of elfutils. This file is free software; you can redistribute it and/or modify @@ -119,7 +119,7 @@ __libdwfl_getsym (Dwfl_Module *mod, int descriptors). */ char *ident; - GElf_Addr st_value = sym->st_value; + GElf_Addr st_value = ebl_sym_func_value (mod->ebl, sym->st_value); *resolved = false; if (! adjust_st_value && mod->e_type != ET_REL && alloc && (GELF_ST_TYPE (sym->st_info) == STT_FUNC Index: elfutils-0.159/libebl/Makefile.am =================================================================== --- elfutils-0.159.orig/libebl/Makefile.am +++ elfutils-0.159/libebl/Makefile.am @@ -55,7 +55,8 @@ gen_SOURCES = eblopenbackend.c eblcloseb eblsysvhashentrysize.c eblauxvinfo.c eblcheckobjattr.c \ ebl_check_special_section.c ebl_syscall_abi.c eblabicfi.c \ eblstother.c eblinitreg.c ebldwarftoregno.c eblnormalizepc.c \ - eblunwind.c eblresolvesym.c eblcheckreloctargettype.c + eblunwind.c eblresolvesym.c eblcheckreloctargettype.c \ + eblsymfuncval.c libebl_a_SOURCES = $(gen_SOURCES) Index: elfutils-0.159/libebl/ebl-hooks.h =================================================================== --- elfutils-0.159.orig/libebl/ebl-hooks.h +++ elfutils-0.159/libebl/ebl-hooks.h @@ -187,9 +187,12 @@ bool EBLHOOK(unwind) (Ebl *ebl, Dwarf_Ad bool *signal_framep); /* Returns true if the value can be resolved to an address in an - allocated section, which will be returned in *SHNDXP. + allocated section, which will be returned in *ADDR. (e.g. function descriptor resolving) */ bool EBLHOOK(resolve_sym_value) (Ebl *ebl, GElf_Addr *addr); +/* Returns the real value of a symbol function address or offset. */ +GElf_Addr EBLHOOK(sym_func_value) (Ebl *ebl, GElf_Addr val); + /* Destructor for ELF backend handle. */ void EBLHOOK(destr) (struct ebl *); Index: elfutils-0.159/libebl/eblsymfuncval.c =================================================================== --- /dev/null +++ elfutils-0.159/libebl/eblsymfuncval.c @@ -0,0 +1,43 @@ +/* Turn a symbol function value into a real function address or offset. + Copyright (C) 2014 Red Hat, Inc. + This file is part of elfutils. + + This file is free software; you can redistribute it and/or modify + it under the terms of either + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at + your option) any later version + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at + your option) any later version + + or both in parallel, as here. + + elfutils 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. + + You should have received copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see . */ + +#ifdef HAVE_CONFIG_H +# include +#endif + +#include +#include + +GElf_Addr +ebl_sym_func_value (Ebl *ebl, GElf_Addr val) +{ + if (ebl == NULL || ebl->sym_func_value == NULL) + return val; + + return ebl->sym_func_value (ebl, val); +} Index: elfutils-0.159/libebl/libebl.h =================================================================== --- elfutils-0.159.orig/libebl/libebl.h +++ elfutils-0.159/libebl/libebl.h @@ -1,5 +1,5 @@ /* Interface for libebl. - Copyright (C) 2000-2010, 2013 Red Hat, Inc. + Copyright (C) 2000-2010, 2013, 2014 Red Hat, Inc. This file is part of elfutils. This file is free software; you can redistribute it and/or modify @@ -448,6 +448,17 @@ extern bool ebl_unwind (Ebl *ebl, Dwarf_ extern bool ebl_resolve_sym_value (Ebl *ebl, GElf_Addr *addr) __nonnull_attribute__ (2); +/* Returns the real value of a symbol function address or offset + (e.g. when the st_value contains some flag bits that need to be + masked off). This is different from ebl_resolve_sym_value which + only works for actual symbol addresses (in non-ET_REL files) that + might resolve to an address in a different section. + ebl_sym_func_value is called to turn the given value into the a + real address or offset (the original value might not be a real + address). This works for both ET_REL when the value is a section + offset or ET_EXEC or ET_DYN symbol values, which are addresses. */ +extern GElf_Addr ebl_sym_func_value (Ebl *ebl, GElf_Addr val); + #ifdef __cplusplus } #endif Index: elfutils-0.159/src/elflint.c =================================================================== --- elfutils-0.159.orig/src/elflint.c +++ elfutils-0.159/src/elflint.c @@ -768,12 +768,18 @@ section [%2d] '%s': symbol %zu: function { GElf_Addr sh_addr = (ehdr->e_type == ET_REL ? 0 : destshdr->sh_addr); + GElf_Addr st_value; + if (GELF_ST_TYPE (sym->st_info) == STT_FUNC + || (GELF_ST_TYPE (sym->st_info) == STT_GNU_IFUNC)) + st_value = ebl_sym_func_value (ebl, sym->st_value); + else + st_value = sym->st_value; if (GELF_ST_TYPE (sym->st_info) != STT_TLS) { if (! ebl_check_special_symbol (ebl, ehdr, sym, name, destshdr)) { - if (sym->st_value - sh_addr > destshdr->sh_size) + if (st_value - sh_addr > destshdr->sh_size) { /* GNU ld has severe bugs. When it decides to remove empty sections it leaves symbols referencing them @@ -798,7 +804,7 @@ section [%2d] '%s': symbol %zu: function section [%2d] '%s': symbol %zu: st_value out of bounds\n"), idx, section_name (ebl, idx), cnt); } - else if ((sym->st_value - sh_addr + else if ((st_value - sh_addr + sym->st_size) > destshdr->sh_size) ERROR (gettext ("\ section [%2d] '%s': symbol %zu does not fit completely in referenced section [%2d] '%s'\n"), @@ -818,12 +824,12 @@ section [%2d] '%s': symbol %zu: referenc { /* For object files the symbol value must fall into the section. */ - if (sym->st_value > destshdr->sh_size) + if (st_value > destshdr->sh_size) ERROR (gettext ("\ section [%2d] '%s': symbol %zu: st_value out of bounds of referenced section [%2d] '%s'\n"), idx, section_name (ebl, idx), cnt, (int) xndx, section_name (ebl, xndx)); - else if (sym->st_value + sym->st_size + else if (st_value + sym->st_size > destshdr->sh_size) ERROR (gettext ("\ section [%2d] '%s': symbol %zu does not fit completely in referenced section [%2d] '%s'\n"), @@ -852,20 +858,20 @@ section [%2d] '%s': symbol %zu: TLS symb } else { - if (sym->st_value + if (st_value < destshdr->sh_offset - phdr->p_offset) ERROR (gettext ("\ section [%2d] '%s': symbol %zu: st_value short of referenced section [%2d] '%s'\n"), idx, section_name (ebl, idx), cnt, (int) xndx, section_name (ebl, xndx)); - else if (sym->st_value + else if (st_value > (destshdr->sh_offset - phdr->p_offset + destshdr->sh_size)) ERROR (gettext ("\ section [%2d] '%s': symbol %zu: st_value out of bounds of referenced section [%2d] '%s'\n"), idx, section_name (ebl, idx), cnt, (int) xndx, section_name (ebl, xndx)); - else if (sym->st_value + sym->st_size + else if (st_value + sym->st_size > (destshdr->sh_offset - phdr->p_offset + destshdr->sh_size)) ERROR (gettext ("\