[packages/gdb.git] / gdb-bz614659-prelink-dynbss.patch

http://sourceware.org/ml/gdb-patches/2010-07/msg00237.html
Subject: [patch] Fix regression on prelinked executables

Hi,

there is a regression since gdb-7.0 for a combination of:
 * prelinked
 * main executable
 * using separate debug info
 * using copy relocations

It is since a patch for both PIE and (AFAIK) OSX support:
	[commit] syms_from_objfile: Relativize also MAINLINE
	http://sourceware.org/ml/gdb-patches/2010-01/msg00080.html

which started to use problematic addr_info_make_relative even for main
executables.  prelink<->gdb discussion at:
	https://bugzilla.redhat.com/show_bug.cgi?id=614659

Currently in the unfortunately executables GDB has invalid displcement for
symbols in .bss:
	int bssvar, *bssvarp = &bssvar;
	(gdb) p &bssvar
	$1 = (int *) 0x600b54
	(gdb) p bssvarp
	$2 = (int *) 0x600b50

<abstract-higher-point-of-view>
addr_info_make_relative could just simply subtract entry point address and
provide single CORE_ADDR objfile->offset (instead of the current
section_offsets array with offsets specific for each section).  Linux systems
use always single offset for the whole objfile.  AFAIK these per-section
offsets are there for some embedded targets.  Curiously GDB already uses at
many places
	baseaddr = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
instead of using offset for the appropriate section at that place and nobody
complains.
</abstract-higher-point-of-view>

No regressions on {x86_64,x86_64-m32,i686}-fedora13-linux-gnu.

Proposing for the gdb-7.2 branch.  I had problems fixing up my crashing X.


Thanks,
Jan


gdb/
2010-07-15  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* symfile.c (addr_section_name): New function.
	(addrs_section_compar): Use it.
	(addr_info_make_relative): Use it.  Move variable sect_name into a more
	inner block.  Make ".dynbss" and ".sdynbss" checks more strict.

gdb/testsuite/
2010-07-15  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.base/prelink-lib.c (copyreloc): New initialized variable.
	* gdb.base/prelink.c (copyreloc, bssvar, bssvarp): New variables.
	(main): Use copyreloc.
	* gdb.base/prelink.exp (split debug of executable)
	(.dynbss vs. .bss address shift): New tests.

--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -547,6 +547,23 @@ relative_addr_info_to_section_offsets (struct section_offsets *section_offsets,
     }
 }
 
+/* Transform section name S for a name comparison.  prelink can split section
+   `.bss' into two sections `.dynbss' and `.bss' (in this order).  Similarly
+   prelink can split `.sbss' into `.sdynbss' and `.sbss'.  Use virtual address
+   of the new `.dynbss' (`.sdynbss') section as the adjacent new `.bss'
+   (`.sbss') section has invalid (increased) virtual address.  */
+
+static const char *
+addr_section_name (const char *s)
+{
+  if (strcmp (s, ".dynbss") == 0)
+    return ".bss";
+  if (strcmp (s, ".sdynbss") == 0)
+    return ".sbss";
+
+  return s;
+}
+
 /* qsort comparator for addrs_section_sort.  Sort entries in ascending order by
    their (name, sectindex) pair.  sectindex makes the sort by name stable.  */
 
@@ -557,7 +574,7 @@ addrs_section_compar (const void *ap, const void *bp)
   const struct other_sections *b = *((struct other_sections **) bp);
   int retval, a_idx, b_idx;
 
-  retval = strcmp (a->name, b->name);
+  retval = strcmp (addr_section_name (a->name), addr_section_name (b->name));
   if (retval)
     return retval;
 
@@ -641,14 +658,16 @@ addr_info_make_relative (struct section_addr_info *addrs, bfd *abfd)
 
   while (*addrs_sorted)
     {
-      const char *sect_name = (*addrs_sorted)->name;
+      const char *sect_name = addr_section_name ((*addrs_sorted)->name);
 
       while (*abfd_addrs_sorted
-	     && strcmp ((*abfd_addrs_sorted)->name, sect_name) < 0)
+	     && strcmp (addr_section_name ((*abfd_addrs_sorted)->name),
+			sect_name) < 0)
 	abfd_addrs_sorted++;
 
       if (*abfd_addrs_sorted
-	  && strcmp ((*abfd_addrs_sorted)->name, sect_name) == 0)
+	  && strcmp (addr_section_name ((*abfd_addrs_sorted)->name),
+		     sect_name) == 0)
 	{
 	  int index_in_addrs;
 
@@ -676,7 +695,6 @@ addr_info_make_relative (struct section_addr_info *addrs, bfd *abfd)
 
   for (i = 0; i < addrs->num_sections && addrs->other[i].name; i++)
     {
-      const char *sect_name = addrs->other[i].name;
       struct other_sections *sect = addrs_to_abfd_addrs[i];
 
       if (sect)
@@ -694,6 +712,9 @@ addr_info_make_relative (struct section_addr_info *addrs, bfd *abfd)
 	}
       else
 	{
+	  /* addr_section_name transformation is not used for SECT_NAME.  */
+	  const char *sect_name = addrs->other[i].name;
+
 	  /* This section does not exist in ABFD, which is normally
 	     unexpected and we want to issue a warning.
 
@@ -704,12 +725,20 @@ addr_info_make_relative (struct section_addr_info *addrs, bfd *abfd)
 	     a warning.  Shared libraries contain just the section
 	     ".gnu.liblist" but it is not marked as loadable there.  There is
 	     no other way to identify them than by their name as the sections
-	     created by prelink have no special flags.  */
+	     created by prelink have no special flags.
+
+	     For the sections `.bss' and `.sbss' see addr_section_name.  */
 
 	  if (!(strcmp (sect_name, ".gnu.liblist") == 0
 		|| strcmp (sect_name, ".gnu.conflict") == 0
-		|| strcmp (sect_name, ".dynbss") == 0
-		|| strcmp (sect_name, ".sdynbss") == 0))
+		|| (strcmp (sect_name, ".bss") == 0
+		    && i > 0
+		    && strcmp (addrs->other[i - 1].name, ".dynbss") == 0
+		    && addrs_to_abfd_addrs[i - 1] != NULL)
+		|| (strcmp (sect_name, ".sbss") == 0
+		    && i > 0
+		    && strcmp (addrs->other[i - 1].name, ".sdynbss") == 0
+		    && addrs_to_abfd_addrs[i - 1] != NULL)))
 	    warning (_("section %s not found in %s"), sect_name,
 		     bfd_get_filename (abfd));
 
--- a/gdb/testsuite/gdb.base/prelink-lib.c
+++ b/gdb/testsuite/gdb.base/prelink-lib.c
@@ -16,6 +16,8 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+int copyreloc = 1;
+
 int
 g (void (*p)(void))
 {
--- a/gdb/testsuite/gdb.base/prelink.c
+++ b/gdb/testsuite/gdb.base/prelink.c
@@ -18,6 +18,11 @@
 
 #include <stdio.h>
 
+extern int copyreloc;
+
+/* Test GDB itself finds `&bssvar' right.   */
+static int bssvar, *bssvarp = &bssvar;
+
 extern void (*h (void)) (void (*)(void));
 
 int
@@ -25,5 +30,6 @@ main (void)
 {
   void (*f) (void (*)(void)) = h ();
   printf ("%p\n", f);
+  printf ("%d\n", copyreloc);
   f (0);
 }
--- a/gdb/testsuite/gdb.base/prelink.exp
+++ b/gdb/testsuite/gdb.base/prelink.exp
@@ -57,6 +57,13 @@ if {$prelink_args == ""} {
     return -1
 }
 
+set test "split debug of executable"
+if [gdb_gnu_strip_debug $binfile] {
+    fail $test
+} else {
+    pass $test
+}
+
 if ![prelink_yes $prelink_args] {
     # Maybe we don't have prelink.
     return -1
@@ -105,3 +112,5 @@ clean_restart $executable
 gdb_test_no_output "set verbose on"
 
 gdb_test "core-file $objdir/$subdir/prelink.core" "Using PIC \\(Position Independent Code\\) prelink displacement 0x\[^0\]\[0-9a-f\]* for \[^\r\n\]*[file tail ${libfile}].*" "seen displacement message"
+
+gdb_test "p &bssvar == bssvarp" " = 1" ".dynbss vs. .bss address shift"
Commit	Line	Data
51a5ef0f PS	1	http://sourceware.org/ml/gdb-patches/2010-07/msg00237.html
	2	Subject: [patch] Fix regression on prelinked executables
	3
	4	Hi,
	5
	6	there is a regression since gdb-7.0 for a combination of:
	7	* prelinked
	8	* main executable
	9	* using separate debug info
	10	* using copy relocations
	11
	12	It is since a patch for both PIE and (AFAIK) OSX support:
	13	[commit] syms_from_objfile: Relativize also MAINLINE
	14	http://sourceware.org/ml/gdb-patches/2010-01/msg00080.html
	15
	16	which started to use problematic addr_info_make_relative even for main
	17	executables. prelink<->gdb discussion at:
	18	https://bugzilla.redhat.com/show_bug.cgi?id=614659
	19
	20	Currently in the unfortunately executables GDB has invalid displcement for
	21	symbols in .bss:
	22	int bssvar, *bssvarp = &bssvar;
	23	(gdb) p &bssvar
	24	$1 = (int *) 0x600b54
	25	(gdb) p bssvarp
	26	$2 = (int *) 0x600b50
	27
	28	<abstract-higher-point-of-view>
	29	addr_info_make_relative could just simply subtract entry point address and
	30	provide single CORE_ADDR objfile->offset (instead of the current
	31	section_offsets array with offsets specific for each section). Linux systems
	32	use always single offset for the whole objfile. AFAIK these per-section
	33	offsets are there for some embedded targets. Curiously GDB already uses at
	34	many places
	35	baseaddr = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
	36	instead of using offset for the appropriate section at that place and nobody
	37	complains.
	38	</abstract-higher-point-of-view>
	39
	40	No regressions on {x86_64,x86_64-m32,i686}-fedora13-linux-gnu.
	41
	42	Proposing for the gdb-7.2 branch. I had problems fixing up my crashing X.
	43
	44
	45	Thanks,
	46	Jan
	47
	48
	49	gdb/
	50	2010-07-15 Jan Kratochvil <jan.kratochvil@redhat.com>
	51
	52	* symfile.c (addr_section_name): New function.
	53	(addrs_section_compar): Use it.
	54	(addr_info_make_relative): Use it. Move variable sect_name into a more
	55	inner block. Make ".dynbss" and ".sdynbss" checks more strict.
	56
	57	gdb/testsuite/
	58	2010-07-15 Jan Kratochvil <jan.kratochvil@redhat.com>
	59
	60	* gdb.base/prelink-lib.c (copyreloc): New initialized variable.
	61	* gdb.base/prelink.c (copyreloc, bssvar, bssvarp): New variables.
	62	(main): Use copyreloc.
	63	* gdb.base/prelink.exp (split debug of executable)
	64	(.dynbss vs. .bss address shift): New tests.
65
66	--- a/gdb/symfile.c
67	+++ b/gdb/symfile.c
68	@@ -547,6 +547,23 @@ relative_addr_info_to_section_offsets (struct section_offsets *section_offsets,
69	}
70	}
71
72	+/* Transform section name S for a name comparison. prelink can split section
73	+ `.bss' into two sections `.dynbss' and `.bss' (in this order). Similarly
74	+ prelink can split `.sbss' into `.sdynbss' and `.sbss'. Use virtual address
75	+ of the new `.dynbss' (`.sdynbss') section as the adjacent new `.bss'
76	+ (`.sbss') section has invalid (increased) virtual address. */
77	+
78	+static const char *
79	+addr_section_name (const char *s)
80	+{
81	+ if (strcmp (s, ".dynbss") == 0)
82	+ return ".bss";
83	+ if (strcmp (s, ".sdynbss") == 0)
84	+ return ".sbss";
85	+
86	+ return s;
87	+}
88	+
89	/* qsort comparator for addrs_section_sort. Sort entries in ascending order by
90	their (name, sectindex) pair. sectindex makes the sort by name stable. */
91
92	@@ -557,7 +574,7 @@ addrs_section_compar (const void ap, const void bp)
93	const struct other_sections b = ((struct other_sections **) bp);
94	int retval, a_idx, b_idx;
95
96	- retval = strcmp (a->name, b->name);
97	+ retval = strcmp (addr_section_name (a->name), addr_section_name (b->name));
98	if (retval)
99	return retval;
100
101	@@ -641,14 +658,16 @@ addr_info_make_relative (struct section_addr_info addrs, bfd abfd)
102
103	while (*addrs_sorted)
104	{
105	- const char sect_name = (addrs_sorted)->name;
106	+ const char sect_name = addr_section_name ((addrs_sorted)->name);
107
108	while (*abfd_addrs_sorted
109	- && strcmp ((*abfd_addrs_sorted)->name, sect_name) < 0)
110	+ && strcmp (addr_section_name ((*abfd_addrs_sorted)->name),
111	+ sect_name) < 0)
112	abfd_addrs_sorted++;
113
114	if (*abfd_addrs_sorted
115	- && strcmp ((*abfd_addrs_sorted)->name, sect_name) == 0)
116	+ && strcmp (addr_section_name ((*abfd_addrs_sorted)->name),
117	+ sect_name) == 0)
118	{
119	int index_in_addrs;
120
121	@@ -676,7 +695,6 @@ addr_info_make_relative (struct section_addr_info addrs, bfd abfd)
122
123	for (i = 0; i < addrs->num_sections && addrs->other[i].name; i++)
124	{
125	- const char *sect_name = addrs->other[i].name;
126	struct other_sections *sect = addrs_to_abfd_addrs[i];
127
128	if (sect)
129	@@ -694,6 +712,9 @@ addr_info_make_relative (struct section_addr_info addrs, bfd abfd)
130	}
131	else
132	{
133	+ /* addr_section_name transformation is not used for SECT_NAME. */
134	+ const char *sect_name = addrs->other[i].name;
135	+
136	/* This section does not exist in ABFD, which is normally
137	unexpected and we want to issue a warning.
138
139	@@ -704,12 +725,20 @@ addr_info_make_relative (struct section_addr_info addrs, bfd abfd)
140	a warning. Shared libraries contain just the section
141	".gnu.liblist" but it is not marked as loadable there. There is
142	no other way to identify them than by their name as the sections
143	- created by prelink have no special flags. */
144	+ created by prelink have no special flags.
145	+
146	+ For the sections `.bss' and `.sbss' see addr_section_name. */
147
148	if (!(strcmp (sect_name, ".gnu.liblist") == 0
149	\|\| strcmp (sect_name, ".gnu.conflict") == 0
150	- \|\| strcmp (sect_name, ".dynbss") == 0
151	- \|\| strcmp (sect_name, ".sdynbss") == 0))
152	+ \|\| (strcmp (sect_name, ".bss") == 0
153	+ && i > 0
154	+ && strcmp (addrs->other[i - 1].name, ".dynbss") == 0
155	+ && addrs_to_abfd_addrs[i - 1] != NULL)
156	+ \|\| (strcmp (sect_name, ".sbss") == 0
157	+ && i > 0
158	+ && strcmp (addrs->other[i - 1].name, ".sdynbss") == 0
159	+ && addrs_to_abfd_addrs[i - 1] != NULL)))
160	warning (_("section %s not found in %s"), sect_name,
161	bfd_get_filename (abfd));
162
163	--- a/gdb/testsuite/gdb.base/prelink-lib.c
164	+++ b/gdb/testsuite/gdb.base/prelink-lib.c
165	@@ -16,6 +16,8 @@
166	along with this program. If not, see <http://www.gnu.org/licenses/>.
167	*/
168
169	+int copyreloc = 1;
170	+
171	int
172	g (void (*p)(void))
173	{
174	--- a/gdb/testsuite/gdb.base/prelink.c
175	+++ b/gdb/testsuite/gdb.base/prelink.c
176	@@ -18,6 +18,11 @@
177
178	#include <stdio.h>
179
180	+extern int copyreloc;
181	+
182	+/* Test GDB itself finds `&bssvar' right. */
183	+static int bssvar, *bssvarp = &bssvar;
184	+
185	extern void (h (void)) (void ()(void));
186
187	int
188	@@ -25,5 +30,6 @@ main (void)
189	{
190	void (f) (void ()(void)) = h ();
191	printf ("%p\n", f);
192	+ printf ("%d\n", copyreloc);
193	f (0);
194	}
195	--- a/gdb/testsuite/gdb.base/prelink.exp
196	+++ b/gdb/testsuite/gdb.base/prelink.exp
197	@@ -57,6 +57,13 @@ if {$prelink_args == ""} {
198	return -1
199	}
200
201	+set test "split debug of executable"
202	+if [gdb_gnu_strip_debug $binfile] {
203	+ fail $test
204	+} else {
205	+ pass $test
206	+}
207	+
208	if ![prelink_yes $prelink_args] {
209	# Maybe we don't have prelink.
210	return -1
211	@@ -105,3 +112,5 @@ clean_restart $executable
212	gdb_test_no_output "set verbose on"
213
214	gdb_test "core-file $objdir/$subdir/prelink.core" "Using PIC \\(Position Independent Code\\) prelink displacement 0x\[^0\]\[0-9a-f\]* for \[^\r\n\][file tail ${libfile}]." "seen displacement message"
215	+
216	+gdb_test "p &bssvar == bssvarp" " = 1" ".dynbss vs. .bss address shift"
217