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gdb/
authorjkratoch <jkratoch>
Mon, 5 Jul 2010 17:57:49 +0000 (17:57 +0000)
committerjkratoch <jkratoch>
Mon, 5 Jul 2010 17:57:49 +0000 (17:57 +0000)
Fix attaching to PIEs prelinked on the disk after the process was
started.
* solib-svr4.c (svr4_exec_displacement): New variable arch_size.
Verify it against bfd_get_arch_size.  Try to match arbitrary
displacement for the phdrs comparison.

gdb/testsuite/
* gdb.base/break-interp.exp: Run $binpie with new value "ATTACH", new
code for it.  New variable relink_args.
(prelinkYES): Call prelinkNO.
(test_attach): Accept new parameter relink_args.  Re-prelink the binary
in such case.  Move the core code to ...
(test_attach_gdb): ... a new function.  Send GDB command "file".
Extend expected "Attaching to " string.

gdb/ChangeLog
gdb/solib-svr4.c
gdb/testsuite/ChangeLog
gdb/testsuite/gdb.base/break-interp.exp

index 4ce5331..ceaff6c 100644 (file)
@@ -1,3 +1,12 @@
+2010-07-05  Jan Kratochvil  <jan.kratochvil@redhat.com>
+           Joel Brobecker  <brobecker@adacore.com>
+
+       Fix attaching to PIEs prelinked on the disk after the process was
+       started.
+       * solib-svr4.c (svr4_exec_displacement): New variable arch_size.
+       Verify it against bfd_get_arch_size.  Try to match arbitrary
+       displacement for the phdrs comparison.
+
 2010-07-02  Tom Tromey  <tromey@redhat.com>
 
        PR exp/11780:
index d031303..4a837ca 100644 (file)
@@ -1775,13 +1775,187 @@ svr4_exec_displacement (CORE_ADDR *displacementp)
         really do not match.  */
       int phdrs_size, phdrs2_size, ok = 1;
       gdb_byte *buf, *buf2;
+      int arch_size;
 
-      buf = read_program_header (-1, &phdrs_size, NULL);
+      buf = read_program_header (-1, &phdrs_size, &arch_size);
       buf2 = read_program_headers_from_bfd (exec_bfd, &phdrs2_size);
-      if (buf != NULL && buf2 != NULL
-         && (phdrs_size != phdrs2_size
-             || memcmp (buf, buf2, phdrs_size) != 0))
-       ok = 0;
+      if (buf != NULL && buf2 != NULL)
+       {
+         enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
+
+         /* We are dealing with three different addresses.  EXEC_BFD
+            represents current address in on-disk file.  target memory content
+            may be different from EXEC_BFD as the file may have been prelinked
+            to a different address after the executable has been loaded.
+            Moreover the address of placement in target memory can be
+            different from what the program headers in target memory say - this
+            is the goal of PIE.
+
+            Detected DISPLACEMENT covers both the offsets of PIE placement and
+            possible new prelink performed after start of the program.  Here
+            relocate BUF and BUF2 just by the EXEC_BFD vs. target memory
+            content offset for the verification purpose.  */
+
+         if (phdrs_size != phdrs2_size
+             || bfd_get_arch_size (exec_bfd) != arch_size)
+           ok = 0;
+         else if (arch_size == 32 && phdrs_size >= sizeof (Elf32_External_Phdr)
+                  && phdrs_size % sizeof (Elf32_External_Phdr) == 0)
+           {
+             Elf_Internal_Ehdr *ehdr2 = elf_tdata (exec_bfd)->elf_header;
+             Elf_Internal_Phdr *phdr2 = elf_tdata (exec_bfd)->phdr;
+             CORE_ADDR displacement = 0;
+             int i;
+
+             /* DISPLACEMENT could be found more easily by the difference of
+                ehdr2->e_entry.  But we haven't read the ehdr yet, and we
+                already have enough information to compute that displacement
+                with what we've read.  */
+
+             for (i = 0; i < ehdr2->e_phnum; i++)
+               if (phdr2[i].p_type == PT_LOAD)
+                 {
+                   Elf32_External_Phdr *phdrp;
+                   gdb_byte *buf_vaddr_p, *buf_paddr_p;
+                   CORE_ADDR vaddr, paddr;
+                   CORE_ADDR displacement_vaddr = 0;
+                   CORE_ADDR displacement_paddr = 0;
+
+                   phdrp = &((Elf32_External_Phdr *) buf)[i];
+                   buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr;
+                   buf_paddr_p = (gdb_byte *) &phdrp->p_paddr;
+
+                   vaddr = extract_unsigned_integer (buf_vaddr_p, 4,
+                                                     byte_order);
+                   displacement_vaddr = vaddr - phdr2[i].p_vaddr;
+
+                   paddr = extract_unsigned_integer (buf_paddr_p, 4,
+                                                     byte_order);
+                   displacement_paddr = paddr - phdr2[i].p_paddr;
+
+                   if (displacement_vaddr == displacement_paddr)
+                     displacement = displacement_vaddr;
+
+                   break;
+                 }
+
+             /* Now compare BUF and BUF2 with optional DISPLACEMENT.  */
+
+             for (i = 0; i < phdrs_size / sizeof (Elf32_External_Phdr); i++)
+               {
+                 Elf32_External_Phdr *phdrp;
+                 Elf32_External_Phdr *phdr2p;
+                 gdb_byte *buf_vaddr_p, *buf_paddr_p;
+                 CORE_ADDR vaddr, paddr;
+
+                 phdrp = &((Elf32_External_Phdr *) buf)[i];
+                 buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr;
+                 buf_paddr_p = (gdb_byte *) &phdrp->p_paddr;
+                 phdr2p = &((Elf32_External_Phdr *) buf2)[i];
+
+                 /* PT_GNU_STACK is an exception by being never relocated by
+                    prelink as its addresses are always zero.  */
+
+                 if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0)
+                   continue;
+
+                 /* Check also other adjustment combinations - PR 11786.  */
+
+                 vaddr = extract_unsigned_integer (buf_vaddr_p, 4, byte_order);
+                 vaddr -= displacement;
+                 store_unsigned_integer (buf_vaddr_p, 4, byte_order, vaddr);
+
+                 paddr = extract_unsigned_integer (buf_paddr_p, 4, byte_order);
+                 paddr -= displacement;
+                 store_unsigned_integer (buf_paddr_p, 4, byte_order, paddr);
+
+                 if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0)
+                   continue;
+
+                 ok = 0;
+                 break;
+               }
+           }
+         else if (arch_size == 64 && phdrs_size >= sizeof (Elf64_External_Phdr)
+                  && phdrs_size % sizeof (Elf64_External_Phdr) == 0)
+           {
+             Elf_Internal_Ehdr *ehdr2 = elf_tdata (exec_bfd)->elf_header;
+             Elf_Internal_Phdr *phdr2 = elf_tdata (exec_bfd)->phdr;
+             CORE_ADDR displacement = 0;
+             int i;
+
+             /* DISPLACEMENT could be found more easily by the difference of
+                ehdr2->e_entry.  But we haven't read the ehdr yet, and we
+                already have enough information to compute that displacement
+                with what we've read.  */
+
+             for (i = 0; i < ehdr2->e_phnum; i++)
+               if (phdr2[i].p_type == PT_LOAD)
+                 {
+                   Elf64_External_Phdr *phdrp;
+                   gdb_byte *buf_vaddr_p, *buf_paddr_p;
+                   CORE_ADDR vaddr, paddr;
+                   CORE_ADDR displacement_vaddr = 0;
+                   CORE_ADDR displacement_paddr = 0;
+
+                   phdrp = &((Elf64_External_Phdr *) buf)[i];
+                   buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr;
+                   buf_paddr_p = (gdb_byte *) &phdrp->p_paddr;
+
+                   vaddr = extract_unsigned_integer (buf_vaddr_p, 8,
+                                                     byte_order);
+                   displacement_vaddr = vaddr - phdr2[i].p_vaddr;
+
+                   paddr = extract_unsigned_integer (buf_paddr_p, 8,
+                                                     byte_order);
+                   displacement_paddr = paddr - phdr2[i].p_paddr;
+
+                   if (displacement_vaddr == displacement_paddr)
+                     displacement = displacement_vaddr;
+
+                   break;
+                 }
+
+             /* Now compare BUF and BUF2 with optional DISPLACEMENT.  */
+
+             for (i = 0; i < phdrs_size / sizeof (Elf64_External_Phdr); i++)
+               {
+                 Elf64_External_Phdr *phdrp;
+                 Elf64_External_Phdr *phdr2p;
+                 gdb_byte *buf_vaddr_p, *buf_paddr_p;
+                 CORE_ADDR vaddr, paddr;
+
+                 phdrp = &((Elf64_External_Phdr *) buf)[i];
+                 buf_vaddr_p = (gdb_byte *) &phdrp->p_vaddr;
+                 buf_paddr_p = (gdb_byte *) &phdrp->p_paddr;
+                 phdr2p = &((Elf64_External_Phdr *) buf2)[i];
+
+                 /* PT_GNU_STACK is an exception by being never relocated by
+                    prelink as its addresses are always zero.  */
+
+                 if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0)
+                   continue;
+
+                 /* Check also other adjustment combinations - PR 11786.  */
+
+                 vaddr = extract_unsigned_integer (buf_vaddr_p, 8, byte_order);
+                 vaddr -= displacement;
+                 store_unsigned_integer (buf_vaddr_p, 8, byte_order, vaddr);
+
+                 paddr = extract_unsigned_integer (buf_paddr_p, 8, byte_order);
+                 paddr -= displacement;
+                 store_unsigned_integer (buf_paddr_p, 8, byte_order, paddr);
+
+                 if (memcmp (phdrp, phdr2p, sizeof (*phdrp)) == 0)
+                   continue;
+
+                 ok = 0;
+                 break;
+               }
+           }
+         else
+           ok = 0;
+       }
 
       xfree (buf);
       xfree (buf2);
index 7d08148..a9da37f 100644 (file)
@@ -1,3 +1,14 @@
+2010-07-05  Jan Kratochvil  <jan.kratochvil@redhat.com>
+           Joel Brobecker  <brobecker@adacore.com>
+
+       * gdb.base/break-interp.exp: Run $binpie with new value "ATTACH", new
+       code for it.  New variable relink_args.
+       (prelinkYES): Call prelinkNO.
+       (test_attach): Accept new parameter relink_args.  Re-prelink the binary
+       in such case.  Move the core code to ...
+       (test_attach_gdb): ... a new function.  Send GDB command "file".
+       Extend expected "Attaching to " string.
+
 2010-07-02  Tom Tromey  <tromey@redhat.com>
 
        * gdb.base/bitops.exp: Remove extraneous "pass".
index 4742889..a1f8105 100644 (file)
@@ -154,6 +154,12 @@ proc prelinkYES {arg {name ""}} {
     if {$name == ""} {
        set name [file tail $arg]
     }
+
+    # Try to unprelink it first so that if it has been already prelinked before
+    # we get different address now and the result is not affected by the
+    # previous $arg state..
+    prelinkNO $arg "$name pre-unprelink"
+
     set test "prelink $name"
     set command "exec /usr/sbin/prelink -qNR --no-exec-shield $arg"
     verbose -log "command is $command"
@@ -325,38 +331,12 @@ proc test_core {file displacement} {
     set pf_prefix $old_ldprefix
 }
 
-proc test_attach {file displacement} {
-    global board_info gdb_prompt expect_out
-
-    gdb_exit
-
-    set test "sleep function started"
-
-    set command "${file} sleep"
-    set res [remote_spawn host $command];
-    if { $res < 0 || $res == "" } {
-       perror "Spawning $command failed."
-       fail $test
-       return
-    }
-    set pid [exp_pid -i $res]
-    gdb_expect {
-       -re "sleeping\r\n" {
-           pass $test
-       }
-       eof {
-           fail "$test (eof)"
-           return
-       }
-       timeout {
-           fail "$test (timeout)"
-           return
-       }
-    }
+proc test_attach_gdb {file pid displacement prefix} {
+    global gdb_prompt expect_out
 
     global pf_prefix
     set old_ldprefix $pf_prefix
-    lappend pf_prefix "attach:"
+    lappend pf_prefix "$prefix:"
 
     gdb_exit
     gdb_start
@@ -364,9 +344,13 @@ proc test_attach {file displacement} {
     # Print the "PIE (Position Independent Executable) displacement" message.
     gdb_test_no_output "set verbose on"
 
+    if {$file != ""} {
+       gdb_test "file $file" "Reading symbols from .*done\\." "file"
+    }
+
     set test "attach"
     gdb_test_multiple "attach $pid" $test {
-       -re "Attaching to process $pid\r\n" {
+       -re "Attaching to (program: .*, )?process $pid\r\n" {
            # Missing "$gdb_prompt $" is intentional.
            pass $test
        }
@@ -402,11 +386,56 @@ proc test_attach {file displacement} {
     gdb_test "bt" "#\[0-9\]+ +\[^\r\n\]*\\mlibfunc\\M\[^\r\n\]*\r\n#\[0-9\]+ +\[^\r\n\]*\\mmain\\M.*" "attach main bt"
     gdb_exit
 
-    remote_exec host "kill -9 $pid"
-
     set pf_prefix $old_ldprefix
 }
 
+proc test_attach {file displacement {relink_args ""}} {
+    global board_info
+
+    gdb_exit
+
+    set test "sleep function started"
+
+    set command "${file} sleep"
+    set res [remote_spawn host $command];
+    if { $res < 0 || $res == "" } {
+       perror "Spawning $command failed."
+       fail $test
+       return
+    }
+    set pid [exp_pid -i $res]
+    gdb_expect {
+       -re "sleeping\r\n" {
+           pass $test
+       }
+       eof {
+           fail "$test (eof)"
+           return
+       }
+       timeout {
+           fail "$test (timeout)"
+           return
+       }
+    }
+
+    if {$relink_args == ""} {
+       test_attach_gdb "" $pid $displacement "attach"
+    } else {
+       # These could be rather passed as arguments.
+       global exec interp_saved interp
+
+       foreach relink {YES NO} {
+           if {[prelink$relink $relink_args [file tail $exec]]
+               && [copy $interp_saved $interp]} {
+               # /proc/PID/exe cannot be loaded as it is "EXECNAME (deleted)".
+               test_attach_gdb $exec $pid $displacement "attach-relink$relink"
+           }
+       }
+    }
+
+    remote_exec host "kill -9 $pid"
+}
+
 proc test_ld {file ifmain trynosym displacement} {
     global srcdir subdir gdb_prompt expect_out
 
@@ -615,7 +644,10 @@ foreach ldprelink {NO YES} {
        set old_binprefix $pf_prefix
        foreach binprelink {NO YES} {
            foreach binsepdebug {NO IN SEP} {
-               foreach binpie {NO YES} {
+               # "ATTACH" is like "YES" but it is modified during run.
+               # It cannot be used for problem reproducibility after the
+               # testcase ends.
+               foreach binpie {NO YES ATTACH} {
                    # This combination is not possible, non-PIE (fixed address)
                    # binary cannot be prelinked to any (other) address.
                    if {$binprelink == "YES" && $binpie == "NO"} {
@@ -634,7 +666,7 @@ foreach ldprelink {NO YES} {
                    if {$binsepdebug != "NO"} {
                        lappend opts {debug}
                    }
-                   if {$binpie == "YES"} {
+                   if {$binpie != "NO"} {
                        lappend opts {additional_flags=-fPIE -pie}
                    }
                    if {[build_executable ${test}.exp [file tail $exec] $srcfile $opts] == -1} {
@@ -682,16 +714,48 @@ foreach ldprelink {NO YES} {
                        lappend dests $dest
                    }
 
-                   if {[prelink$binprelink "--dynamic-linker=$interp --ld-library-path=$dir $exec $interp [concat $dests]" [file tail $exec]]
+                   if {$binpie == "NO"} {
+                       set displacement "NONE"
+                   } elseif {$binprelink == "NO"} {
+                       set displacement "NONZERO"
+                   } else {
+                       set displacement "ZERO"
+                   }
+
+                   set relink_args "--dynamic-linker=$interp --ld-library-path=$dir $exec $interp [concat $dests]"
+                   if {[prelink$binprelink $relink_args [file tail $exec]]
                        && [copy $interp_saved $interp]} {
-                       if {$binpie == "NO"} {
-                           set displacement "NONE"
-                       } elseif {$binprelink == "NO"} {
-                           set displacement "NONZERO"
+                       if {$binpie != "ATTACH"} {
+                           test_ld $exec 1 [expr {$binsepdebug == "NO"}] $displacement
                        } else {
-                           set displacement "ZERO"
+                           # If the file has been randomly prelinked it must
+                           # be "NONZERO".  We could see "ZERO" only if it was
+                           # unprelinked and it is now running at the same
+                           # address - which is 0 but executable can never run
+                           # at address 0.
+
+                           set displacement "NONZERO"
+                           test_attach $exec $displacement $relink_args
+
+                           # ATTACH means that executables and libraries have
+                           # been modified after they have been run.  They
+                           # cannot be reused for problem reproducibility after
+                           # the testcase ends in the ATTACH case.  Therefore
+                           # they are rather deleted not to confuse after the
+                           # run finishes.
+                           set exec_debug [system_debug_get $exec]
+                           if {$exec_debug != ""} {
+                               # `file delete [glob "${exec_debug}*"]' does not work.
+                               foreach f [glob "${exec_debug}*"] {
+                                   file delete $f
+                               }
+                           }
+                           file delete -force $dir
+                           # `file delete [glob "${exec}*"]' does not work.
+                           foreach f [glob "${exec}*"] {
+                               file delete $f
+                           }
                        }
-                       test_ld $exec 1 [expr {$binsepdebug == "NO"}] $displacement
                    }
                }
            }