[PATCH] readelf: Handle signedness of DW_FORM_implicit_const and DW_AT_const_value.
Mark Wielaard
mark@klomp.org
Wed Jun 13 12:51:00 GMT 2018
We only handles DW_FORM_sdata as a signed form, but DW_FORM_implicit_const
is also signed by default. For DW_AT_const_value we can do a little better.
GCC encodes some const_values with signed forms, even though the type
is unsigned. Lookup the (base) type of the DIE and display the const value
as their (signed) type/size (if we can determine that).
Add a new testcase run-readelf-const-values.sh that shows that.
With the new testcase the const values would come out as follows:
name (string) "i"
const_value (implicit_const) 18446744073709551615
name (string) "j"
const_value (implicit_const) 18446744073709551615
name (string) "sc"
const_value (sdata) -2
name (string) "uc"
const_value (sdata) -2
name (string) "ss"
const_value (sdata) -16
name (string) "us"
const_value (sdata) -16
name (string) "si"
const_value (sdata) -3
name (string) "ui"
const_value (sdata) -94967296
name (string) "sl"
const_value (sdata) -1
name (string) "ul"
const_value (sdata) -1
With this patch they show up as:
name (string) "i"
const_value (implicit_const) -1
name (string) "j"
const_value (implicit_const) -1
name (string) "sc"
const_value (sdata) -2
name (string) "uc"
const_value (sdata) 254 (-2)
name (string) "ss"
const_value (sdata) -16
name (string) "us"
const_value (sdata) 65520 (-16)
name (string) "si"
const_value (sdata) -3
name (string) "ui"
const_value (sdata) 4200000000 (-94967296)
name (string) "sl"
const_value (sdata) -1
name (string) "ul"
const_value (sdata) 18446744073709551615 (-1)
(for signed/unsigned int char, short and long)
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
src/ChangeLog | 7 ++
src/readelf.c | 122 ++++++++++++++----
tests/ChangeLog | 9 ++
tests/Makefile.am | 2 +
tests/run-readelf-const-values.sh | 230 ++++++++++++++++++++++++++++++++++
tests/run-readelf-zdebug-rel.sh | 2 +-
tests/testfile-const-values.debug.bz2 | Bin 0 -> 1540 bytes
7 files changed, 350 insertions(+), 22 deletions(-)
create mode 100755 tests/run-readelf-const-values.sh
create mode 100755 tests/testfile-const-values.debug.bz2
diff --git a/src/ChangeLog b/src/ChangeLog
index fd45405..5f381cf 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2018-06-13 Mark Wielaard <mark@klomp.org>
+
+ * readelf.c (die_type_sign_bytes): New function.
+ (attr_callback): Recognized DW_FORM_implicit_cost as signed. Use
+ die_type_sign_bytes to lookup the signedness and size of const
+ values.
+
2018-06-11 Mark Wielaard <mark@klomp.org>
* readelf.c (print_form_data): Don't reuse readp and readendp when
diff --git a/src/readelf.c b/src/readelf.c
index 3b477ab..5e7061d 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -6869,6 +6869,33 @@ print_debug_frame_section (Dwfl_Module *dwflmod, Ebl *ebl, GElf_Ehdr *ehdr,
}
+/* Returns the signedness (or false if it cannot be determined) and
+ the byte size (or zero if it cannot be gotten) of the given DIE
+ DW_AT_type attribute. Uses dwarf_peel_type and dwarf_aggregate_size. */
+static void
+die_type_sign_bytes (Dwarf_Die *die, bool *is_signed, int *bytes)
+{
+ Dwarf_Attribute attr;
+ Dwarf_Die type;
+
+ *bytes = 0;
+ *is_signed = false;
+
+ if (dwarf_peel_type (dwarf_formref_die (dwarf_attr_integrate (die,
+ DW_AT_type,
+ &attr), &type),
+ &type) == 0)
+ {
+ Dwarf_Word val;
+ *is_signed = (dwarf_formudata (dwarf_attr (&type, DW_AT_encoding,
+ &attr), &val) == 0
+ && (val == DW_ATE_signed || val == DW_ATE_signed_char));
+
+ if (dwarf_aggregate_size (&type, &val) == 0)
+ *bytes = val;
+ }
+}
+
struct attrcb_args
{
Dwfl_Module *dwflmod;
@@ -7300,36 +7327,89 @@ attr_callback (Dwarf_Attribute *attrp, void *arg)
}
else
{
- Dwarf_Sword snum = 0;
- if (form == DW_FORM_sdata)
- if (unlikely (dwarf_formsdata (attrp, &snum) != 0))
- goto attrval_out;
-
if (as_hex_id)
{
printf (" %*s%-20s (%s) 0x%.16" PRIx64 "\n",
(int) (level * 2), "", dwarf_attr_name (attr),
dwarf_form_name (form), num);
}
- else if (valuestr == NULL)
- {
- printf (" %*s%-20s (%s)",
- (int) (level * 2), "", dwarf_attr_name (attr),
- dwarf_form_name (form));
- if (form == DW_FORM_sdata)
- printf (" %" PRIdMAX "\n", (intmax_t) snum);
- else
- printf (" %" PRIuMAX "\n", (uintmax_t) num);
- }
else
{
- printf (" %*s%-20s (%s) %s",
- (int) (level * 2), "", dwarf_attr_name (attr),
- dwarf_form_name (form), valuestr);
- if (form == DW_FORM_sdata)
- printf (" (%" PRIdMAX ")\n", (intmax_t) snum);
+ Dwarf_Sword snum = 0;
+ bool is_signed;
+ int bytes = 0;
+ if (attr == DW_AT_const_value)
+ die_type_sign_bytes (cbargs->die, &is_signed, &bytes);
+ else
+ is_signed = (form == DW_FORM_sdata
+ || form == DW_FORM_implicit_const);
+
+ if (is_signed)
+ if (unlikely (dwarf_formsdata (attrp, &snum) != 0))
+ goto attrval_out;
+
+ if (valuestr == NULL)
+ {
+ printf (" %*s%-20s (%s) ",
+ (int) (level * 2), "", dwarf_attr_name (attr),
+ dwarf_form_name (form));
+ }
+ else
+ {
+ printf (" %*s%-20s (%s) %s (",
+ (int) (level * 2), "", dwarf_attr_name (attr),
+ dwarf_form_name (form), valuestr);
+ }
+
+ switch (bytes)
+ {
+ case 1:
+ if (is_signed)
+ printf ("%" PRId8, (int8_t) snum);
+ else
+ printf ("%" PRIu8, (uint8_t) num);
+ break;
+
+ case 2:
+ if (is_signed)
+ printf ("%" PRId16, (int16_t) snum);
+ else
+ printf ("%" PRIu16, (uint16_t) num);
+ break;
+
+ case 4:
+ if (is_signed)
+ printf ("%" PRId32, (int32_t) snum);
+ else
+ printf ("%" PRIu32, (uint32_t) num);
+ break;
+
+ case 8:
+ if (is_signed)
+ printf ("%" PRId64, (int64_t) snum);
+ else
+ printf ("%" PRIu64, (uint64_t) num);
+ break;
+
+ default:
+ if (is_signed)
+ printf ("%" PRIdMAX, (intmax_t) snum);
+ else
+ printf ("%" PRIuMAX, (uintmax_t) num);
+ break;
+ }
+
+ /* Make clear if we switched from a signed encoding to
+ an unsigned value. */
+ if (attr == DW_AT_const_value
+ && (form == DW_FORM_sdata || form == DW_FORM_implicit_const)
+ && !is_signed)
+ printf (" (%" PRIdMAX ")", (intmax_t) num);
+
+ if (valuestr == NULL)
+ printf ("\n");
else
- printf (" (%" PRIuMAX ")\n", (uintmax_t) num);
+ printf (")\n");
}
}
break;
diff --git a/tests/ChangeLog b/tests/ChangeLog
index e5df211..4abbd12 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,12 @@
+2018-06-13 Mark Wielaard <mark@klomp.org>
+
+ * run-readelf-const-values.sh: New test.
+ * testfile-const-values.debug.bz2: New test file.
+ * run-readelf-zdebug-rel.sh: Adjust expected const_value.
+ * Makefile.am (TESTS): Add run-readelf-const-values.sh.
+ (EXTRA_DIST): Add run-readelf-const-values.sh and
+ testfile-const-values.debug.bz2.
+
2018-06-08 Mark Wielaard <mark@klomp.org>
* varlocs.c (print_expr): Error on bad DW_OP_GNU_parameter_ref
diff --git a/tests/Makefile.am b/tests/Makefile.am
index b45ecdc..2d63da6 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -94,6 +94,7 @@ TESTS = run-arextract.sh run-arsymtest.sh run-ar.sh newfile test-nlist \
run-addrscopes.sh run-strings-test.sh run-funcscopes.sh \
run-find-prologues.sh run-allregs.sh run-addrcfi.sh \
run-nm-self.sh run-readelf-self.sh run-readelf-info-plus.sh \
+ run-readelf-const-values.sh \
run-varlocs-self.sh run-exprlocs-self.sh \
run-readelf-test1.sh run-readelf-test2.sh run-readelf-test3.sh \
run-readelf-test4.sh run-readelf-twofiles.sh \
@@ -199,6 +200,7 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh run-ar.sh \
run-ranlib-test3.sh run-ranlib-test4.sh \
run-addrscopes.sh run-strings-test.sh run-funcscopes.sh \
run-nm-self.sh run-readelf-self.sh run-readelf-info-plus.sh \
+ run-readelf-const-values.sh testfile-const-values.debug.bz2 \
run-addrcfi.sh \
run-varlocs-self.sh run-exprlocs-self.sh \
run-find-prologues.sh run-allregs.sh run-native-test.sh \
diff --git a/tests/run-readelf-const-values.sh b/tests/run-readelf-const-values.sh
new file mode 100755
index 0000000..0a6356f
--- /dev/null
+++ b/tests/run-readelf-const-values.sh
@@ -0,0 +1,230 @@
+#! /bin/sh
+# Test for displaying DW_AT_const_types with the "correct" sign.
+# Copyright (C) 2018 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 the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# 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 a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/test-subr.sh
+
+# = s.c
+#
+# int s()
+# {
+# int i = -1;
+# int j = -1;
+#
+# return i - j;
+# }
+#
+# = m.c
+#
+# extern int s();
+#
+# int
+# main ()
+# {
+# const signed char sc = -2;
+# const unsigned char uc = 254;
+#
+# const signed short ss = -16;
+# const unsigned short us = 65520;
+#
+# const signed int si = -3;
+# const unsigned int ui = 4200000000;
+#
+# signed long sl = -1;
+# unsigned long ul = 0xffffffffffffffffUL;
+#
+# return s ();
+# }
+#
+# gcc -gdwarf-5 -O2 -c s.c
+# gcc -gdwarf-4 -O2 -c m.c
+# gcc -o testfile-const-values s.o m.o
+# eu-strip -g -f testfile-const-values.debug testfile-const-values
+
+testfiles testfile-const-values.debug
+
+testrun_compare ${abs_top_builddir}/src/readelf --debug-dump=info testfile-const-values.debug << EOF
+
+DWARF section [28] '.debug_info' at offset 0x2e0:
+ [Offset]
+ Compilation unit at offset 0:
+ Version: 5, Abbreviation section offset: 0, Address size: 8, Offset size: 4
+ Unit type: compile (1)
+ [ c] compile_unit abbrev: 2
+ producer (strp) "GNU C11 7.3.1 20180303 (Red Hat 7.3.1-5) -mtune=generic -march=x86-64 -gdwarf-5 -O2"
+ language (data1) C11 (29)
+ name (string) "s.c"
+ comp_dir (strp) "/home/mark/build/elfutils-obj"
+ low_pc (addr) 0x00000000004004d0
+ high_pc (data8) 3 (0x00000000004004d3)
+ stmt_list (sec_offset) 0
+ [ 2e] subprogram abbrev: 3
+ external (flag_present) yes
+ name (string) "s"
+ decl_file (data1) s.c (1)
+ decl_line (data1) 1
+ type (ref4) [ 5e]
+ low_pc (addr) 0x00000000004004d0
+ high_pc (data8) 3 (0x00000000004004d3)
+ frame_base (exprloc)
+ [ 0] call_frame_cfa
+ call_all_calls (flag_present) yes
+ sibling (ref4) [ 5e]
+ [ 4d] variable abbrev: 1
+ name (string) "i"
+ decl_file (implicit_const) s.c (1)
+ decl_line (data1) 3
+ type (ref4) [ 5e]
+ const_value (implicit_const) -1
+ [ 55] variable abbrev: 1
+ name (string) "j"
+ decl_file (implicit_const) s.c (1)
+ decl_line (data1) 4
+ type (ref4) [ 5e]
+ const_value (implicit_const) -1
+ [ 5e] base_type abbrev: 4
+ byte_size (data1) 4
+ encoding (data1) signed (5)
+ name (string) "int"
+ Compilation unit at offset 102:
+ Version: 4, Abbreviation section offset: 73, Address size: 8, Offset size: 4
+ [ 71] compile_unit abbrev: 1
+ producer (strp) "GNU C11 7.3.1 20180303 (Red Hat 7.3.1-5) -mtune=generic -march=x86-64 -gdwarf-4 -O2"
+ language (data1) C99 (12)
+ name (string) "m.c"
+ comp_dir (strp) "/home/mark/build/elfutils-obj"
+ ranges (sec_offset) range list [ 0]
+ low_pc (addr) 000000000000000000
+ stmt_list (sec_offset) 54
+ [ 8f] subprogram abbrev: 2
+ external (flag_present) yes
+ name (strp) "main"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 4
+ type (ref4) [ 119]
+ low_pc (addr) 0x00000000004003e0
+ high_pc (data8) 7 (0x00000000004003e7)
+ frame_base (exprloc)
+ [ 0] call_frame_cfa
+ GNU_all_call_sites (flag_present) yes
+ sibling (ref4) [ 119]
+ [ b0] variable abbrev: 3
+ name (string) "sc"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 6
+ type (ref4) [ 12c]
+ const_value (sdata) -2
+ [ bb] variable abbrev: 3
+ name (string) "uc"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 7
+ type (ref4) [ 138]
+ const_value (sdata) 254 (-2)
+ [ c6] variable abbrev: 3
+ name (string) "ss"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 9
+ type (ref4) [ 144]
+ const_value (sdata) -16
+ [ d1] variable abbrev: 3
+ name (string) "us"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 10
+ type (ref4) [ 150]
+ const_value (sdata) 65520 (-16)
+ [ dc] variable abbrev: 3
+ name (string) "si"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 12
+ type (ref4) [ 120]
+ const_value (sdata) -3
+ [ e7] variable abbrev: 3
+ name (string) "ui"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 13
+ type (ref4) [ 15c]
+ const_value (sdata) 4200000000 (-94967296)
+ [ f5] variable abbrev: 3
+ name (string) "sl"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 15
+ type (ref4) [ 161]
+ const_value (sdata) -1
+ [ 100] variable abbrev: 3
+ name (string) "ul"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 16
+ type (ref4) [ 168]
+ const_value (sdata) 18446744073709551615 (-1)
+ [ 10b] GNU_call_site abbrev: 4
+ low_pc (addr) 0x00000000004003e7
+ GNU_tail_call (flag_present) yes
+ abstract_origin (ref4) [ 16f]
+ [ 119] base_type abbrev: 5
+ byte_size (data1) 4
+ encoding (data1) signed (5)
+ name (string) "int"
+ [ 120] const_type abbrev: 6
+ type (ref4) [ 119]
+ [ 125] base_type abbrev: 7
+ byte_size (data1) 1
+ encoding (data1) signed_char (6)
+ name (strp) "signed char"
+ [ 12c] const_type abbrev: 6
+ type (ref4) [ 125]
+ [ 131] base_type abbrev: 7
+ byte_size (data1) 1
+ encoding (data1) unsigned_char (8)
+ name (strp) "unsigned char"
+ [ 138] const_type abbrev: 6
+ type (ref4) [ 131]
+ [ 13d] base_type abbrev: 7
+ byte_size (data1) 2
+ encoding (data1) signed (5)
+ name (strp) "short int"
+ [ 144] const_type abbrev: 6
+ type (ref4) [ 13d]
+ [ 149] base_type abbrev: 7
+ byte_size (data1) 2
+ encoding (data1) unsigned (7)
+ name (strp) "short unsigned int"
+ [ 150] const_type abbrev: 6
+ type (ref4) [ 149]
+ [ 155] base_type abbrev: 7
+ byte_size (data1) 4
+ encoding (data1) unsigned (7)
+ name (strp) "unsigned int"
+ [ 15c] const_type abbrev: 6
+ type (ref4) [ 155]
+ [ 161] base_type abbrev: 7
+ byte_size (data1) 8
+ encoding (data1) signed (5)
+ name (strp) "long int"
+ [ 168] base_type abbrev: 7
+ byte_size (data1) 8
+ encoding (data1) unsigned (7)
+ name (strp) "long unsigned int"
+ [ 16f] subprogram abbrev: 8
+ external (flag_present) yes
+ declaration (flag_present) yes
+ linkage_name (string) "s"
+ name (string) "s"
+ decl_file (data1) m.c (1)
+ decl_line (data1) 1
+EOF
+
+exit 0
diff --git a/tests/run-readelf-zdebug-rel.sh b/tests/run-readelf-zdebug-rel.sh
index ccccd82..3f20078 100755
--- a/tests/run-readelf-zdebug-rel.sh
+++ b/tests/run-readelf-zdebug-rel.sh
@@ -90,7 +90,7 @@ DWARF section [ 4] '.debug_info' at offset 0x58:
decl_file (data1) testfile-zdebug-rel.c (1)
decl_line (data1) 6
type (ref4) [ 9a]
- const_value (sdata) -9
+ const_value (sdata) 18446744073709551607 (-9)
[ 74] variable abbrev: 6
name (string) "b"
decl_file (data1) testfile-zdebug-rel.c (1)
diff --git a/tests/testfile-const-values.debug.bz2 b/tests/testfile-const-values.debug.bz2
new file mode 100755
index 0000000000000000000000000000000000000000..167da166e9fcf88bb548c4c8d0455ebae7d0f54c
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z$bb+AM4)#%gqEfWS|b9XPN1|R=%8&`1O6=Y5J78xu>vv|%ys-GWs)%yrARsHPf_c(
q-CRcdoYN*-f3K-6tt;1DzMX2;a$qtigpXi<#oUoj6eKZqU#I|#!>+Ud
literal 0
HcmV?d00001
--
1.8.3.1
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