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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org> To: gdb-prs@sourceware.org Subject: [Bug breakpoints/27205] [-m32] FAIL: gdb.base/longjmp.exp: next over longjmp(1) Date: Sat, 23 Jan 2021 06:38:40 +0000 [thread overview] Message-ID: <bug-27205-4717-Fy0IU0sgtZ@http.sourceware.org/bugzilla/> (raw) In-Reply-To: <bug-27205-4717@http.sourceware.org/bugzilla/> https://sourceware.org/bugzilla/show_bug.cgi?id=27205 --- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> --- The failure to access memory is due to glibc having pointer encryption (aka "pointer mangling" or "pointer guard") of the long jump buffer. So, when we're trying to read pc from the long jump buffer in i386_get_longjmp_target, we get an encrypted pointer, and don't decrypt it. This issue has been known for a bit, see https://sourceware.org/legacy-ml/gdb-patches/2008-04/msg00127.html. Possibly error mode could be improved: if we can detect that pc is not in a text segment or displaced stepping buffer, we return 0 in i386_get_longjmp_target, and revert to single stepping. Anyway, the reason we're exercising i386_get_longjmp_target is that this fails: ... /* If we set the longjmp breakpoint via a SystemTap probe, then use it to extract the arguments. The destination PC is the third argument to the probe. */ arg_value = probe_safe_evaluate_at_pc (frame, 2); ... I double checked on openSUSE Leap 15.2 and there this works, so I'll try to figure out what's the difference. -- You are receiving this mail because: You are on the CC list for the bug.
next prev parent reply other threads:[~2021-01-23 6:38 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-19 15:51 [Bug breakpoints/27205] New: " vries at gcc dot gnu.org 2021-01-23 6:38 ` vries at gcc dot gnu.org [this message] 2021-01-23 9:02 ` [Bug breakpoints/27205] " vries at gcc dot gnu.org 2021-01-23 9:30 ` vries at gcc dot gnu.org 2021-01-23 9:50 ` vries at gcc dot gnu.org 2021-01-27 14:31 ` vries at gcc dot gnu.org 2021-01-28 9:59 ` cvs-commit at gcc dot gnu.org 2021-01-28 10:02 ` vries at gcc dot gnu.org
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