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[PATCH v2] Skip vDSO when reading SO list (PR 8882)
- From: Andreas Arnez <arnez at linux dot vnet dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Cc: Ulrich Weigand <uweigand at de dot ibm dot com>, jan dot kratochvil at redhat dot com
- Date: Tue, 24 Sep 2013 19:47:09 +0200
- Subject: [PATCH v2] Skip vDSO when reading SO list (PR 8882)
- Authentication-results: sourceware.org; auth=none
Suppress the warning when the vDSO's pathname from the SO list in a core
file can not be accessed. The glibc's dynamic loader uses empty-string
literals for both the executable as well as the vDSO, and the compiler
collates both of them to a single string literal. Thus the vDSO's
l_name address matches the main executable's. This property is used as
a criteria for identifying and silently skipping the vDSO.
This version includes a small test case and follows Jan's proposal of
moving the suppression logic after the pathname read has already failed.
OK to apply?
ChangeLog:
2013-09-24 Andreas Arnez <arnez@linux.vnet.ibm.com>
* solib-svr4.c (svr4_read_so_list): Skip the vDSO when reading
link map entries.
testsuite/ChangeLog:
2013-09-24 Andreas Arnez <arnez@linux.vnet.ibm.com>
* gdb.base/corefile.exp: Add a check to assure warning-free
core-file load.
Index: gdb/gdb/solib-svr4.c
===================================================================
--- gdb.orig/gdb/solib-svr4.c
+++ gdb/gdb/solib-svr4.c
@@ -1310,6 +1310,7 @@ static int
svr4_read_so_list (CORE_ADDR lm, CORE_ADDR prev_lm,
struct so_list ***link_ptr_ptr, int ignore_first)
{
+ struct so_list *first = NULL;
CORE_ADDR next_lm;
for (; lm != 0; prev_lm = lm, lm = next_lm)
@@ -1349,6 +1350,7 @@ svr4_read_so_list (CORE_ADDR lm, CORE_AD
{
struct svr4_info *info = get_svr4_info ();
+ first = new;
info->main_lm_addr = new->lm_info->lm_addr;
do_cleanups (old_chain);
continue;
@@ -1359,8 +1361,16 @@ svr4_read_so_list (CORE_ADDR lm, CORE_AD
SO_NAME_MAX_PATH_SIZE - 1, &errcode);
if (errcode != 0)
{
- warning (_("Can't read pathname for load map: %s."),
- safe_strerror (errcode));
+ /* If this entry's l_name address matches that of the
+ inferior executable, then this is not a normal shared
+ object, but (most likely) a vDSO. In this case, silently
+ skip it; otherwise emit a warning. */
+ if (! (first != NULL
+ && new->lm_info->l_name == first->lm_info->l_name))
+ {
+ warning (_("Can't read pathname for load map: %s."),
+ safe_strerror (errcode));
+ }
do_cleanups (old_chain);
continue;
}
Index: gdb/gdb/testsuite/gdb.base/corefile.exp
===================================================================
--- gdb.orig/gdb/testsuite/gdb.base/corefile.exp
+++ gdb/gdb/testsuite/gdb.base/corefile.exp
@@ -255,3 +255,19 @@ if ![is_remote target] {
gdb_exit
}
+
+# Test warning-free core file load. E.g., a Linux vDSO used to
+# trigger this warning:
+# warning: Can't read pathname for load map: Input/output error.
+
+clean_restart ${testfile}
+
+set test "core-file warning-free"
+gdb_test_multiple "core-file $corefile" $test {
+ -re "warning: .*\r\n.*\r\n$gdb_prompt $" {
+ fail $test
+ }
+ -re "\r\n$gdb_prompt $" {
+ pass $test
+ }
+}