From 7e4208a3f5d60f43b4a8f02e583fa950b599cd00 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Tue, 13 Feb 2024 09:10:54 +0100 Subject: [gdb/tdep] Fix reverse execution of LDR(immediate) T4 When running test-case gdb.reverse/func-map-to-same-line.exp on arm-linux with target board unix/-mthumb, we run into: ... (gdb) reverse-step func2 () at func-map-to-same-line.c:26 26 { (gdb) FAIL: gdb.reverse/func-map-to-same-line.exp: \ column_info_flag=column-info: step-test: reverse-step into func2 ... The FAIL is caused by incorrect recording of this insn: ... 4f6: f85d 7b04 ldr.w r7, [sp], #4 ... The insn updates the sp, but we don't record this: ... $ gdb -q -batch func-map-to-same-line \ -ex "b *func2+8" \ -ex run \ -ex record \ -ex "set debug record 2" \ -ex stepi Breakpoint 1 at 0x4f6: file func-map-to-same-line.c, line 27. Breakpoint 1, 0xaaaaa4f6 in func2 () at func-map-to-same-line.c:27 27 } /* END FUNC2 */ Process record: arm_process_record addr = 0xaaaaa4f6 Process record: add register num = 15 to record list. Process record: record_full_arch_list_add 0xabc6c460. Process record: add register num = 7 to record list. Process record: record_full_arch_list_add 0xabc3b868. Process record: add register num = 25 to record list. ... [ Note that sp is r13, and we see here only r15 (pc), r7, and r25 (ps). ] The problem is that the specific insn, an LDR(immediate) T4, is not handled in thumb2_record_ld_word. Fix this by detecting the insn in thumb2_record_ld_word, and recording the updated base register. Tested on arm-linux. Reported-By: Thiago Jung Bauermann Approved-By: Luis Machado PR tdep/31278 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31278 --- gdb/arm-tdep.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c index 861d50a..081e934 100644 --- a/gdb/arm-tdep.c +++ b/gdb/arm-tdep.c @@ -14184,6 +14184,14 @@ thumb2_record_ld_word (arm_insn_decode_record *thumb2_insn_r) record_buf[1] = ARM_PS_REGNUM; thumb2_insn_r->reg_rec_count = 2; + if ((thumb2_insn_r->arm_insn & 0xfff00900) == 0xf8500900) + { + /* Detected LDR(immediate), T4, with write-back bit set. Record Rn + update. */ + record_buf[2] = bits (thumb2_insn_r->arm_insn, 16, 19); + thumb2_insn_r->reg_rec_count++; + } + REG_ALLOC (thumb2_insn_r->arm_regs, thumb2_insn_r->reg_rec_count, record_buf); return ARM_RECORD_SUCCESS; -- cgit v1.1