110 lines
4.1 KiB
Diff
110 lines
4.1 KiB
Diff
commit f250c4d3241c156f8e65398e2af76e3e2ee1ccb5
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Author: philippe <philippe@a5019735-40e9-0310-863c-91ae7b9d1cf9>
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Date: Wed Nov 18 20:56:55 2015 +0000
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Fix incorrect (or infinite loop) unwind on RHEL7 x86 32 bits.
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On RHEL7 x86 32 bits, Valgrind unwinder cannot properly unwind
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the stack just after a thread creation : the unwinder always retrieves
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the same pc/sp/bp.
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See below for an example.
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This has as consequences that some stack traces are bigger than
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needed (i.e. they always fill up the ips array). If
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--merge-recursive-frames is given, then the unwinder enters in an
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infinite loop (as identical frames will be merged, and the ips array
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will never be filled in).
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Thi patch adds an additional exit condition : after unwinding
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a frame, if the previous sp is >= new sp, then unwinding stops.
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Patch has been tested on debian 8/x86, RHEL7/x86.
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0x0417db67 <+55>: mov 0x18(%esp),%ebx
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0x0417db6b <+59>: mov 0x28(%esp),%edi
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0x0417db6f <+63>: mov $0x78,%eax
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0x0417db74 <+68>: mov %ebx,(%ecx)
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0x0417db76 <+70>: int $0x80
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=> 0x0417db78 <+72>: pop %edi
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0x0417db79 <+73>: pop %esi
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0x0417db7a <+74>: pop %ebx
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0x0417db7b <+75>: test %eax,%eax
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Valgrind stacktrace gives:
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==21261== at 0x417DB78: clone (clone.S:110)
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==21261== by 0x424702F: ???
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==21261== by 0x424702F: ???
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==21261== by 0x424702F: ???
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==21261== by 0x424702F: ???
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==21261== by 0x424702F: ???
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==21261== by 0x424702F: ???
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==21261== by 0x424702F: ???
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...
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(till the array of ips is full)
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while gdb stacktrace gives:
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(gdb) bt
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#0 clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:110
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#1 0x00000000 in ?? ()
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(gdb) p $pc
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$2 = (void (*)()) 0x417db78 <clone+72>
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(gdb)
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With the fix, valgrind gives:
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==21261== at 0x417DB78: clone (clone.S:110)
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==21261== by 0x424702F: ???
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which looks more reasonable.
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git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15729 a5019735-40e9-0310-863c-91ae7b9d1cf9
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diff --git a/coregrind/m_stacktrace.c b/coregrind/m_stacktrace.c
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index 8c1e9a4..137e780 100644
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--- a/coregrind/m_stacktrace.c
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+++ b/coregrind/m_stacktrace.c
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@@ -350,6 +350,8 @@ UInt VG_(get_StackTrace_wrk) ( ThreadId tid_if_known,
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uregs.xbp <= fp_max - 1 * sizeof(UWord)/*see comment below*/ &&
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VG_IS_4_ALIGNED(uregs.xbp))
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{
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+ Addr old_xsp;
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+
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/* fp looks sane, so use it. */
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uregs.xip = (((UWord*)uregs.xbp)[1]);
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// We stop if we hit a zero (the traditional end-of-stack
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@@ -382,6 +384,7 @@ UInt VG_(get_StackTrace_wrk) ( ThreadId tid_if_known,
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}
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}
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+ old_xsp = uregs.xsp;
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uregs.xsp = uregs.xbp + sizeof(Addr) /*saved %ebp*/
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+ sizeof(Addr) /*ra*/;
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uregs.xbp = (((UWord*)uregs.xbp)[0]);
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@@ -393,6 +396,12 @@ UInt VG_(get_StackTrace_wrk) ( ThreadId tid_if_known,
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if (debug) VG_(printf)(" cache FPUNWIND >2\n");
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if (debug) unwind_case = "FO";
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if (do_stats) stats.FO++;
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+ if (old_xsp >= uregs.xsp) {
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+ if (debug)
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+ VG_(printf) (" FO end of stack old_xsp %p >= xsp %p\n",
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+ (void*)old_xsp, (void*)uregs.xsp);
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+ break;
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+ }
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} else {
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fp_CF_verif_cache [hash] = xip_verified ^ CFUNWIND;
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if (debug) VG_(printf)(" cache CFUNWIND >2\n");
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@@ -406,6 +415,12 @@ UInt VG_(get_StackTrace_wrk) ( ThreadId tid_if_known,
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} else {
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if (debug) unwind_case = "FF";
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if (do_stats) stats.FF++;
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+ if (old_xsp >= uregs.xsp) {
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+ if (debug)
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+ VG_(printf) (" FF end of stack old_xsp %p >= xsp %p\n",
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+ (void*)old_xsp, (void*)uregs.xsp);
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+ break;
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+ }
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}
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goto unwind_done;
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} else {
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