From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 106B83858C53; Tue, 17 Jan 2023 13:24:51 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 106B83858C53 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1673961891; bh=8xoD0VZK1vtJlgTZ87pmF7aca+YfKpnacK9yvJAFUZY=; h=From:To:Subject:Date:From; b=wH2dCvX5GzR4fNKhZkLhrk1IO1LqZRC6juRAgAmecQJaeW27kJsiAWYqukdUmlH67 hf+oSRY8cPNIbvWNSgaVlI/S6wO6o09bR85u53qVVKtEJsJZ5p5CVHLzQyOf+a1AW7 DNRz2D6u0qAugwYpTF3gVKk1E9kimVbxgH3FDmDw= From: "vries at gcc dot gnu.org" To: gdb-prs@sourceware.org Subject: [Bug tdep/30010] New: [gdb/tdep, aarch64] Incorrect frame address for last insn (non-leaf case) Date: Tue, 17 Jan 2023 13:24:50 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new 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: vries at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone Message-ID: 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 List-Id: https://sourceware.org/bugzilla/show_bug.cgi?id=3D30010 Bug ID: 30010 Summary: [gdb/tdep, aarch64] Incorrect frame address for last insn (non-leaf case) Product: gdb Version: HEAD Status: NEW Severity: normal Priority: P2 Component: tdep Assignee: unassigned at sourceware dot org Reporter: vries at gcc dot gnu.org Target Milestone: --- [ Spinoff from PR29721. ] Consider the following test-case: ... $ cat test.c void foo (const char *s) { } int main (void) { foo ("foo"); return 0; } ... Compiled without debug info: ... $ gcc test.c ... Disassembly of main: ... 0000000000400578
: 400578: a9bf7bfd stp x29, x30, [sp, #-16]! 40057c: 910003fd mov x29, sp 400580: 90000000 adrp x0, 400000 <_init-0x408> 400584: 91192000 add x0, x0, #0x648 400588: 97fffff7 bl 400564 40058c: 52800000 mov w0, #0x0 // = #0 400590: a8c17bfd ldp x29, x30, [sp], #16 400594: d65f03c0 ret ... Now, let's do "info frame" at each insn in main (so, using ni to skip over foo), as well as printing $sp and $fp: ... $ gdb a.out Reading symbols from a.out... (gdb) b *main Breakpoint 1 at 0x400578 (gdb) r Starting program: a.out=20 Breakpoint 1, 0x0000000000400578 in main () (gdb) display /x $sp 1: /x $sp =3D 0xfffffffff3b0 (gdb) display /x $fp 2: /x $fp =3D 0xfffffffff3b0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x400578 in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3b0, args:=20 Locals at 0xfffffffff3b0, Previous frame's sp is 0xfffffffff3b0 (gdb) ni 0x000000000040057c in main () 1: /x $sp =3D 0xfffffffff3a0 2: /x $fp =3D 0xfffffffff3a0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x40057c in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3a0, args:=20 Locals at 0xfffffffff3a0, Previous frame's sp is 0xfffffffff3b0 Saved registers: x29 at 0xfffffffff3a0, x30 at 0xfffffffff3a8 (gdb) ni 0x0000000000400580 in main () 1: /x $sp =3D 0xfffffffff3a0 2: /x $fp =3D 0xfffffffff3a0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x400580 in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3a0, args:=20 Locals at 0xfffffffff3a0, Previous frame's sp is 0xfffffffff3b0 Saved registers: x29 at 0xfffffffff3a0, x30 at 0xfffffffff3a8 (gdb) ni 0x0000000000400584 in main () 1: /x $sp =3D 0xfffffffff3a0 2: /x $fp =3D 0xfffffffff3a0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x400584 in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3a0, args:=20 Locals at 0xfffffffff3a0, Previous frame's sp is 0xfffffffff3b0 Saved registers: x29 at 0xfffffffff3a0, x30 at 0xfffffffff3a8 (gdb) ni 0x0000000000400588 in main () 1: /x $sp =3D 0xfffffffff3a0 2: /x $fp =3D 0xfffffffff3a0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x400588 in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3a0, args:=20 Locals at 0xfffffffff3a0, Previous frame's sp is 0xfffffffff3b0 Saved registers: x29 at 0xfffffffff3a0, x30 at 0xfffffffff3a8 (gdb) ni 0x000000000040058c in main () 1: /x $sp =3D 0xfffffffff3a0 2: /x $fp =3D 0xfffffffff3a0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x40058c in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3a0, args:=20 Locals at 0xfffffffff3a0, Previous frame's sp is 0xfffffffff3b0 Saved registers: x29 at 0xfffffffff3a0, x30 at 0xfffffffff3a8 (gdb) ni 0x0000000000400590 in main () 1: /x $sp =3D 0xfffffffff3a0 2: /x $fp =3D 0xfffffffff3a0 (gdb) info frame Stack level 0, frame at 0xfffffffff3b0: pc =3D 0x400590 in main; saved pc =3D 0xfffff7e5bfa0 Arglist at 0xfffffffff3a0, args:=20 Locals at 0xfffffffff3a0, Previous frame's sp is 0xfffffffff3b0 Saved registers: x29 at 0xfffffffff3a0, x30 at 0xfffffffff3a8 (gdb) ni 0x0000000000400594 in main () 1: /x $sp =3D 0xfffffffff3b0 2: /x $fp =3D 0xfffffffff3b0 (gdb) info frame Stack level 0, frame at 0xfffffffff3c0: pc =3D 0x400594 in main; saved pc =3D 0x4004a4 Arglist at 0xfffffffff3b0, args:=20 Locals at 0xfffffffff3b0, Previous frame's sp is 0xfffffffff3c0 Saved registers: x29 at 0xfffffffff3b0, x30 at 0xfffffffff3b8 (gdb) ni 0x0000fffff7e5bfa0 in __libc_start_main () from /lib64/libc.so.6 1: /x $sp =3D 0xfffffffff3b0 2: /x $fp =3D 0xfffffffff3b0 ... The "frame at" bit lists 0xfffffffff3b0 except at the last insn. The frame address is calculated here in aarch64_make_prologue_cache_1: ... unwound_fp =3D get_frame_register_unsigned (this_frame, cache->framereg); if (unwound_fp =3D=3D 0) return; cache->prev_sp =3D unwound_fp + cache->framesize; ... For insns after the prologue, we have cache->framereg =3D=3D fp and cache->framesize =3D=3D 16, so unwound_fp + cache->framesize gives the wron= g answer once fp has been restored to entry value by the before-last insn. --=20 You are receiving this mail because: You are on the CC list for the bug.=