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BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; PREVIOUSLY_DELIVERED(0.00)[gdb-patches@sourceware.org]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid,gdb.tui:url,sourceware.org:url,plt:email]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_NONE(0.00)[]; RCVD_TLS_ALL(0.00)[] X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org I was investigating TUI behaviour on ppc64-linux using the executable from test-case gdb.tui/basic.exp, and after scrolling in the asm window ended up with: ... +----------------------------------------------------------------------------+ | 0x920 <__libc_start_main@plt+4> b 0x8f0 <__glink_PLTresolve> | | 0x924 <__gmon_start__@plt> li r0,1 | | 0x928 <__gmon_start__@plt+4> b 0x8f0 <__glink_PLTresolve> | | 0x92c <__cxa_finalize@plt> li r0,2 | | 0x930 <__cxa_finalize@plt+4> b 0x8f0 <__glink_PLTresolve> | | 0x934 <._fini> mflr r0 | | 0x938 <._fini+4> std r0,16(r1) | | 0x93c <._fini+8> stdu r1,-112(r1) | | 0x940 <._fini+12> addi r1,r1,112 | | 0x944 <._fini+16> ld r0,16(r1) | | 0x948 <._fini+20> mtlr r0 | | 0x94c <._fini+24> blr | | 0x950 <_IO_stdin_used> .long 0x20001 | | 0x954 .long 0x11b033b | | 0x958 .long 0x18 | | 0x95c .long 0x2 | | 0x960 .long 0xffffff60 | | 0x964 .long 0x48 | | 0x968 .long 0xffffff9c | | 0x96c .long 0x30 | +----------------------------------------------------------------------------+ exec No process (asm) In: L?? PC: ?? (gdb) ... The view corresponds to this objdump -D output: ... Disassembly of section .text: ... 000000000000091c <__libc_start_main@plt>: 91c: 38 00 00 00 li r0,0 920: 4b ff ff d0 b 8f0 <__glink_PLTresolve> 0000000000000924 <__gmon_start__@plt>: 924: 38 00 00 01 li r0,1 928: 4b ff ff c8 b 8f0 <__glink_PLTresolve> 000000000000092c <__cxa_finalize@plt>: 92c: 38 00 00 02 li r0,2 930: 4b ff ff c0 b 8f0 <__glink_PLTresolve> Disassembly of section .fini: 0000000000000934 <._fini>: 934: 7c 08 02 a6 mflr r0 938: f8 01 00 10 std r0,16(r1) 93c: f8 21 ff 91 stdu r1,-112(r1) 940: 38 21 00 70 addi r1,r1,112 944: e8 01 00 10 ld r0,16(r1) 948: 7c 08 03 a6 mtlr r0 94c: 4e 80 00 20 blr Disassembly of section .rodata: 0000000000000950 <_IO_stdin_used>: 950: 00 02 00 01 .long 0x20001 Disassembly of section .eh_frame_hdr: 0000000000000954 <__GNU_EH_FRAME_HDR>: 954: 01 1b 03 3b .long 0x11b033b 958: 00 00 00 18 .long 0x18 95c: 00 00 00 02 .long 0x2 960: ff ff ff 60 .long 0xffffff60 964: 00 00 00 48 .long 0x48 968: ff ff ff 9c .long 0xffffff9c 96c: 00 00 00 30 .long 0x30 ... ISTM that we should not be disassembling the .rodata section. My first thought was to require tui_disassemble to stay in the same section, but after thinking about it a bit more decided that that was too restrictive, and instead went for requiring that we stay in code sections. So, I came up with this fix: ... struct obj_section *section = find_pc_section (pc); if (section != nullptr && (bfd_section_flags (section->the_bfd_section) & SEC_CODE) == 0) return pc; ... Then I stumbled on PR tui/34399, which reports not being able to scroll back up after scrolling down. The problem there is that we disassemble code from a section hole (0x401034-0x402000): ... Section Headers: [Nr] Name Type Address Offset Size EntSize Flags Link Info Align [ 0] NULL 0000000000000000 00000000 0000000000000000 0000000000000000 0 0 0 [ 1] .note.gnu.pr[...] NOTE 0000000000400190 00000190 0000000000000030 0000000000000000 A 0 0 8 [ 2] .note.gnu.bu[...] NOTE 00000000004001c0 000001c0 0000000000000024 0000000000000000 A 0 0 4 [ 3] .text PROGBITS 0000000000401000 00001000 0000000000000034 0000000000000000 AX 0 0 1 [ 4] .rodata PROGBITS 0000000000402000 00002000 0000000000000006 0000000000000000 A 0 0 1 [ 5] .symtab SYMTAB 0000000000000000 00002008 0000000000000078 0000000000000018 6 1 8 [ 6] .strtab STRTAB 0000000000000000 00002080 0000000000000019 0000000000000000 0 0 1 [ 7] .shstrtab STRTAB 0000000000000000 00002099 000000000000004f 0000000000000000 0 0 1 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings), I (info), L (link order), O (extra OS processing required), G (group), T (TLS), C (compressed), x (unknown), o (OS specific), E (exclude), D (mbind), l (large), p (processor specific) ... and once we call tui_find_backward_disassembly_start_address with an address ADDR for which find_pc_section (ADDR - 1) == nullptr, we are stuck in the section hole. Fix this by not disassembling section holes. This is achieved by slightly modifying the earlier fix: ... if (section == nullptr || (bfd_section_flags (section->the_bfd_section) & SEC_CODE) == 0) return pc; ... Tested on x86_64-linux and ppc64-linux. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34399 --- gdb/tui/tui-disasm.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/gdb/tui/tui-disasm.c b/gdb/tui/tui-disasm.c index 5c68312a91b..085a6c2903e 100644 --- a/gdb/tui/tui-disasm.c +++ b/gdb/tui/tui-disasm.c @@ -112,6 +112,15 @@ tui_disassemble (struct gdbarch *gdbarch, { tui_asm_line tal; + /* Don't disassemble: + - non-code sections (not appropriate for disassembly window), and + - section holes (otherwise we can get stuck, unable to scroll back to + the section before the section hole). */ + struct obj_section *section = find_pc_section (pc); + if (section == nullptr + || (bfd_section_flags (section->the_bfd_section) & SEC_CODE) == 0) + return pc; + /* Save the instruction address. */ tal.addr = pc; base-commit: 4ed310516eb76cbf650523a53f733060d3ae71b9 -- 2.51.0