From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 1978A3855014; Sun, 27 Jun 2021 18:00:47 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1978A3855014 From: "ahmedsayeed1982 at yahoo dot com" To: gdb-prs@sourceware.org Subject: [Bug tdep/27369] ARC: Stepping over atomic instruction sequences loops infinitely Date: Sun, 27 Jun 2021 18:00:46 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gdb X-Bugzilla-Component: tdep X-Bugzilla-Version: HEAD X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: ahmedsayeed1982 at yahoo dot com X-Bugzilla-Status: RESOLVED X-Bugzilla-Resolution: FIXED X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: 10.2 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gdb-prs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-prs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 27 Jun 2021 18:00:47 -0000 https://sourceware.org/bugzilla/show_bug.cgi?id=3D27369 Ahmed Sayeed changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ahmedsayeed1982 at yahoo d= ot com --- Comment #4 from Ahmed Sayeed --- Here, we are at line 7. Using the "next" command leads no where. However, setting a breakpoint on line 9 and issuing "continue" works. Looking at the assembly instructions reveals that we're dealing with the critical section entry code [1] that should never be interrupted, in this case by the debugger's implicit breakpoints: ------8<------- ... 1 add_s r0,r13,0x38 2 mov_s r3,1 3 llock r2,[r0] <-. 4 brne.nt r2,0,14 --. | 5 scond r3,[r0] | | 6 bne -10 --|--' 7 brne_s r2,0,84 <-' ... ------>8------- Lines 3 until 5 (inclusive) are supposed to be executed atomically. Therefo= re, GDB should never (implicitly) insert a breakpoint on lines 4 and 5, else the program will try to acquire the lock again by jumping back to line 3 and gets stuck in an infinite loop. The solution is to make GDB aware of these patterns so it inserts breakpoin= ts after the sequence -- line 6 in this example. http://toblek.xyz/ --=20 You are receiving this mail because: You are on the CC list for the bug.=