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[PATCH] libebl: Add sym_func_value hook.
- From: Mark Wielaard <mjw at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Sun, 15 Jun 2014 11:30:35 +0200
- Subject: [PATCH] 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.
Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
backends/ChangeLog | 5 +++++
backends/arm_init.c | 1 +
backends/arm_symbol.c | 8 ++++++++
libdwfl/ChangeLog | 4 ++++
libdwfl/dwfl_module_getsym.c | 4 ++--
libebl/ChangeLog | 7 +++++++
libebl/Makefile.am | 3 ++-
libebl/ebl-hooks.h | 5 ++++-
libebl/eblsymfuncval.c | 43 +++++++++++++++++++++++++++++++++++++++++++
libebl/libebl.h | 13 ++++++++++++-
src/ChangeLog | 4 ++++
src/elflint.c | 20 +++++++++++++-------
12 files changed, 105 insertions(+), 12 deletions(-)
create mode 100644 libebl/eblsymfuncval.c
diff --git a/backends/ChangeLog b/backends/ChangeLog
index bc5b843..64b669e 100644
--- a/backends/ChangeLog
+++ b/backends/ChangeLog
@@ -1,3 +1,8 @@
+2014-06-14 Mark Wielaard <mjw@redhat.com>
+
+ * arm_init.c (arm_init): Hook sym_func_value.
+ * arm_symbol.c (arm_sym_func_value): New function.
+
2014-05-19 Mark Wielaard <mjw@redhat.com>
* arm_init.c (arm_init): Hook check_reloc_target_type.
diff --git a/backends/arm_init.c b/backends/arm_init.c
index 92e6cd5..e2e20e4 100644
--- a/backends/arm_init.c
+++ b/backends/arm_init.c
@@ -64,6 +64,7 @@ arm_init (elf, machine, eh, ehlen)
HOOK (eh, return_value_location);
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;
diff --git a/backends/arm_symbol.c b/backends/arm_symbol.c
index cd467ff..49fca55 100644
--- a/backends/arm_symbol.c
+++ b/backends/arm_symbol.c
@@ -129,3 +129,11 @@ arm_check_reloc_target_type (Ebl *ebl __attribute__ ((unused)), Elf64_Word sh_ty
{
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;
+}
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index ac92a21..888b400 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,7 @@
+2014-06-14 Mark Wielaard <mjw@redhat.com>
+
+ * dwfl_module_getsym.c (__libdwfl_getsym): Call ebl_sym_func_value.
+
2014-06-11 Mark Wielaard <mjw@redhat.com>
* dwfl_frame.c (__libdwfl_process_free): Reset dwfl->attacherr.
diff --git a/libdwfl/dwfl_module_getsym.c b/libdwfl/dwfl_module_getsym.c
index 917d062..fb192d7 100644
--- a/libdwfl/dwfl_module_getsym.c
+++ b/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 ndx, GElf_Sym *sym, GElf_Addr *addr,
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
diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index 7198d5e..1c7a2ba 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,10 @@
+2014-06-14 Mark Wielaard <mjw@redhat.com>
+
+ * Makefile.am (gen_SOURCES): Add eblsymfuncval.c.
+ * ebl-hooks.h (sym_func_value): New hook.
+ * eblsymfuncval.c: New file.
+ * libebl.h (sym_func_value): New hook.
+
2014-05-19 Mark Wielaard <mjw@redhat.com>
* Makefile.am (gen_SOURCES): Add eblcheckreloctargettype.c.
diff --git a/libebl/Makefile.am b/libebl/Makefile.am
index ec4477b..889c21b 100644
--- a/libebl/Makefile.am
+++ b/libebl/Makefile.am
@@ -55,7 +55,8 @@ gen_SOURCES = eblopenbackend.c eblclosebackend.c eblstrtab.c \
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)
diff --git a/libebl/ebl-hooks.h b/libebl/ebl-hooks.h
index 65c62ec..160a821 100644
--- a/libebl/ebl-hooks.h
+++ b/libebl/ebl-hooks.h
@@ -187,9 +187,12 @@ bool EBLHOOK(unwind) (Ebl *ebl, Dwarf_Addr pc, ebl_tid_registers_t *setfunc,
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 *);
diff --git a/libebl/eblsymfuncval.c b/libebl/eblsymfuncval.c
new file mode 100644
index 0000000..c0b322f
--- /dev/null
+++ b/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 <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <libeblP.h>
+#include <assert.h>
+
+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);
+}
diff --git a/libebl/libebl.h b/libebl/libebl.h
index d05751f..bc1f491 100644
--- a/libebl/libebl.h
+++ b/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_Addr pc, ebl_tid_registers_t *setfunc,
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
diff --git a/src/ChangeLog b/src/ChangeLog
index 7e68036..75341a3 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2014-06-14 Mark Wielaard <mjw@redhat.com>
+
+ * elflint (check_symtab): Check againt ebl_sym_func_value st_value.
+
2014-05-27 Mark Wielaard <mjw@redhat.com>
* readelf.c (print_debug): Skip section if name is NULL.
diff --git a/src/elflint.c b/src/elflint.c
index bf6d044..1334ec0 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -768,12 +768,18 @@ section [%2d] '%s': symbol %zu: function in COMMON section is nonsense\n"),
{
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 in COMMON section is nonsense\n"),
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: referenced section [%2d] '%s' does not have SHF_
{
/* 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 symbol but no TLS program header entry\n"),
}
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 ("\
--
1.9.3