From da729c5ccde6eeccae539cbe51a285bc84769b3d Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Mon, 7 Mar 2022 14:06:09 -0700 Subject: [PATCH] Implement gdbarch_stack_frame_destroyed_p for aarch64 The internal AdaCore testsuite has a test that checks that an out-of-scope watchpoint is deleted. This fails on some aarch64 configurations, reporting an extra stop: (gdb) continue Continuing. Thread 3 hit Watchpoint 2: result Old value = 64 New value = 0 0x0000000040021648 in pck.get_val (seed=0, off_by_one=false) at [...]/pck.adb:13 13 end Get_Val; I believe what is happening here is that the variable is stored at: DW_AT_location : 2 byte block: 91 7c (DW_OP_fbreg: -4) and the extra stop is reported just before a return, when the ldp instruction is executed: 0x0000000040021644 <+204>: ldp x29, x30, [sp], #48 0x0000000040021648 <+208>: ret This instruction modifies the frame base calculation, and so the test picks up whatever memory is pointed to in the callee frame. Implementing the gdbarch hook gdbarch_stack_frame_destroyed_p fixes this problem. As usual with this sort of patch, it has passed internal testing, but I don't have a good way to try it with dejagnu. So, I don't know whether some existing test covers this. I suspect there must be one, but it's also worth noting that this test passes for aarch64 in some configurations -- I don't know what causes one to fail and another to succeed. --- gdb/aarch64-tdep.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c index 3f3a65240c0..b714f6194b6 100644 --- a/gdb/aarch64-tdep.c +++ b/gdb/aarch64-tdep.c @@ -3396,6 +3396,25 @@ aarch64_cannot_store_register (struct gdbarch *gdbarch, int regnum) || regnum == AARCH64_PAUTH_CMASK_REGNUM (tdep->pauth_reg_base)); } +/* Implement the stack_frame_destroyed_p gdbarch method. */ + +static int +aarch64_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc) +{ + CORE_ADDR func_start, func_end; + if (!find_pc_partial_function (pc, NULL, &func_start, &func_end)) + return 0; + + enum bfd_endian byte_order_for_code = gdbarch_byte_order_for_code (gdbarch); + uint32_t insn = read_memory_unsigned_integer (pc, 4, byte_order_for_code); + + aarch64_inst inst; + if (aarch64_decode_insn (insn, &inst, 1, nullptr) != 0) + return 0; + + return streq (inst.opcode->name, "ret"); +} + /* Initialize the current architecture based on INFO. If possible, re-use an architecture from ARCHES, which is a list of architectures already created during this debugging session. @@ -3602,6 +3621,9 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_long_double_format (gdbarch, floatformats_ia64_quad); set_gdbarch_type_align (gdbarch, aarch64_type_align); + /* Detect whether PC is at a point where the stack has been destroyed. */ + set_gdbarch_stack_frame_destroyed_p (gdbarch, aarch64_stack_frame_destroyed_p); + /* Internal <-> external register number maps. */ set_gdbarch_dwarf2_reg_to_regnum (gdbarch, aarch64_dwarf_reg_to_regnum); -- 2.30.2