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From: Luis Machado <luis.machado@arm.com>
To: Simon Marchi <simon.marchi@polymtl.ca>, gdb-patches@sourceware.org
Subject: Re: [PATCH 00/24] Fix reading and writing pseudo registers in non-current frames
Date: Wed, 8 Nov 2023 11:57:37 +0000	[thread overview]
Message-ID: <9a693dcc-9213-4300-a4ee-25820bfada78@arm.com> (raw)
In-Reply-To: <20231108051222.1275306-1-simon.marchi@polymtl.ca>

Hi Simon,

On 11/8/23 05:00, Simon Marchi wrote:
> This series fixes reading/writing pseudo registers from/to non-current
> frames (that is, frames other than frame 0).  Currently, we get this:
> 
>     (gdb) frame 0
>     #0  break_here_asm () at /home/smarchi/src/binutils-gdb/gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S:38
>     38              pop %rbx
>     (gdb) p/x $rbx
>     $1 = 0x2021222324252627
>     (gdb) p/x $ebx
>     $2 = 0x24252627
>     (gdb) frame 1
>     #1  0x000055555555517d in caller () at /home/smarchi/src/binutils-gdb/gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S:58
>     58              call callee
>     (gdb) p/x $rbx
>     $3 = 0x1011121314151617
>     (gdb) p/x $ebx
>     $4 = 0x24252627
> 
> This is a bit surprising, we would expect the last value to be
> 0x14151617, the bottom half of the rbx value from frame 1 (the currently
> selected frame at that point).  Instead, we got the bottom half of the
> rbx value from frame 0.  This is because pseudo registers are always
> read/written from/to the current thread's regcache.
> 
> This series fixes this (as well as writing to pseudo registers) by
> making it so pseudo registers are read/written using a frame.
> 
> Simon Marchi (24):
>   gdb: don't handle i386 k registers as pseudo registers
>   gdb: use reg_buffer_common throughout gdbsupport/common-regcache.h
>   gdb: make store_integer take an array_view
>   gdb: simplify conditions in
>     regcache::{read,write,raw_collect,raw_supply}_part
>   gdb: change regcache interface to use array_view
>   gdb: fix bugs in {get,put}_frame_register_bytes
>   gdb: make put_frame_register take an array_view
>   gdb: change value_of_register and value_of_register_lazy to take the
>     next frame
>   gdb: remove frame_register
>   gdb: make put_frame_register take the next frame
>   gdb: make put_frame_register_bytes take the next frame
>   gdb: make get_frame_register_bytes take the next frame
>   gdb: add value::allocate_register
>   gdb: read pseudo register through frame
>   gdb: change parameter name in frame_unwind_register_unsigned
>     declaration
>   gdb: rename gdbarch_pseudo_register_write to
>     gdbarch_deprecated_pseudo_register_write
>   gdb: add gdbarch_pseudo_register_write that takes a frame
>   gdb: migrate i386 and amd64 to the new gdbarch_pseudo_register_write
>   gdb: make aarch64_za_offsets_from_regnum return za_offsets
>   gdb: add missing raw register read in
>     aarch64_sme_pseudo_register_write
>   gdb: migrate aarch64 to new gdbarch_pseudo_register_write
>   gdb: migrate arm to gdbarch_pseudo_register_read_value
>   gdb: migrate arm to new gdbarch_pseudo_register_write
>   gdb/testsuite: add tests for unwinding of pseudo registers
> 
>  gdb/aarch64-tdep.c                            | 297 +++++-----
>  gdb/alpha-tdep.c                              |  11 +-
>  gdb/amd64-tdep.c                              |  82 +--
>  gdb/arch/arm-get-next-pcs.c                   |   6 +-
>  gdb/arch/arm-get-next-pcs.h                   |   5 +-
>  gdb/arch/arm.c                                |   2 +-
>  gdb/arch/arm.h                                |   4 +-
>  gdb/arm-linux-tdep.c                          |  11 +-
>  gdb/arm-tdep.c                                | 145 +++--
>  gdb/avr-tdep.c                                |   3 +-
>  gdb/bfin-tdep.c                               |   3 +-
>  gdb/csky-tdep.c                               |   4 +-
>  gdb/defs.h                                    |  39 +-
>  gdb/dwarf2/expr.c                             |  22 +-
>  gdb/dwarf2/frame.c                            |   5 +-
>  gdb/eval.c                                    |   3 +-
>  gdb/findvar.c                                 |  50 +-
>  gdb/frame-unwind.c                            |   3 +-
>  gdb/frame.c                                   | 174 +++---
>  gdb/frame.h                                   |  28 +-
>  gdb/frv-tdep.c                                |   3 +-
>  gdb/gdbarch-gen.h                             |  28 +-
>  gdb/gdbarch.c                                 |  40 +-
>  gdb/gdbarch_components.py                     |  29 +-
>  gdb/guile/scm-frame.c                         |   3 +-
>  gdb/h8300-tdep.c                              |   3 +-
>  gdb/i386-tdep.c                               | 380 ++++--------
>  gdb/i386-tdep.h                               |  15 +-
>  gdb/i387-tdep.c                               |  16 +-
>  gdb/ia64-tdep.c                               |  18 +-
>  gdb/infcmd.c                                  |   6 +-
>  gdb/loongarch-tdep.c                          |   3 +-
>  gdb/m32c-tdep.c                               |   3 +-
>  gdb/m68hc11-tdep.c                            |   3 +-
>  gdb/m68k-tdep.c                               |  17 +-
>  gdb/mep-tdep.c                                |   3 +-
>  gdb/mi/mi-main.c                              |   3 +-
>  gdb/mips-tdep.c                               |  29 +-
>  gdb/msp430-tdep.c                             |   3 +-
>  gdb/nat/aarch64-hw-point.c                    |   3 +-
>  gdb/nat/aarch64-scalable-linux-ptrace.c       |  20 +-
>  gdb/nat/linux-btrace.c                        |   3 +-
>  gdb/nds32-tdep.c                              |   8 +-
>  gdb/python/py-frame.c                         |   3 +-
>  gdb/python/py-unwind.c                        |   4 +-
>  gdb/regcache.c                                | 548 +++++++++++-------
>  gdb/regcache.h                                | 113 +++-
>  gdb/riscv-tdep.c                              |  13 +-
>  gdb/rl78-tdep.c                               |   3 +-
>  gdb/rs6000-tdep.c                             |  21 +-
>  gdb/s12z-tdep.c                               |   2 +-
>  gdb/s390-tdep.c                               |   3 +-
>  gdb/sh-tdep.c                                 |   9 +-
>  gdb/sparc-tdep.c                              |   3 +-
>  gdb/sparc64-tdep.c                            |   3 +-
>  gdb/std-regs.c                                |  11 +-
>  .../gdb.arch/aarch64-pseudo-unwind-asm.S      |  82 +++
>  .../gdb.arch/aarch64-pseudo-unwind.c          |  33 ++
>  .../gdb.arch/aarch64-pseudo-unwind.exp        |  90 +++
>  .../gdb.arch/amd64-pseudo-unwind-asm.S        |  66 +++
>  gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c  |  33 ++
>  .../gdb.arch/amd64-pseudo-unwind.exp          |  91 +++
>  .../gdb.arch/arm-pseudo-unwind-asm.S          |  81 +++
>  .../gdb.arch/arm-pseudo-unwind-legacy-asm.S   |  84 +++
>  .../gdb.arch/arm-pseudo-unwind-legacy.c       |  33 ++
>  .../gdb.arch/arm-pseudo-unwind-legacy.exp     |  86 +++
>  gdb/testsuite/gdb.arch/arm-pseudo-unwind.c    |  33 ++
>  gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp  |  88 +++
>  gdb/valops.c                                  |  31 +-
>  gdb/value.c                                   | 149 +++++
>  gdb/value.h                                   |  64 +-
>  gdb/xtensa-tdep.c                             |   3 +-
>  gdbserver/linux-arm-low.cc                    |   4 +-
>  gdbserver/regcache.cc                         |  69 ++-
>  gdbserver/regcache.h                          |   6 +-
>  gdbsupport/common-regcache.cc                 |   2 +-
>  gdbsupport/common-regcache.h                  |  58 +-
>  gdbsupport/rsp-low.cc                         |   8 +
>  gdbsupport/rsp-low.h                          |   2 +
>  79 files changed, 2324 insertions(+), 1144 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-pseudo-unwind-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.c
>  create mode 100644 gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.exp
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-pseudo-unwind-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-pseudo-unwind.c
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-pseudo-unwind.exp
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy-asm.S
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.c
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind-legacy.exp
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind.c
>  create mode 100644 gdb/testsuite/gdb.arch/arm-pseudo-unwind.exp
> 
> 
> base-commit: 1185b5b79a12ba67eb60bee3f75babf7a222fde0

I haven't tracked the particular patch that causes this, but for aarch64 systems supporting SVE
(and probably SME as well) I'm seeing internal errors related to one assertion:

Running gdb/testsuite/gdb.arch/aarch64-pseudo-unwind.exp ...
PASS: gdb.arch/aarch64-pseudo-unwind.exp: continue to breakpoint: continue to callee
PASS: gdb.arch/aarch64-pseudo-unwind.exp: callee, before change: p/x $v8.q.u
PASS: gdb.arch/aarch64-pseudo-unwind.exp: callee, before change: p/x $s8.u
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: set $s8.u = 0x34353637 (GDB internal error)
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: callee, after change: p/x $v8.q.u
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: callee, after change: p/x $s8.u
PASS: gdb.arch/aarch64-pseudo-unwind.exp: up
PASS: gdb.arch/aarch64-pseudo-unwind.exp: caller, before change: p/x $v8.q.u
PASS: gdb.arch/aarch64-pseudo-unwind.exp: caller, before change: p/x $s8.u
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: set $s8.u = 0x44454647 (GDB internal error)
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: caller, after change: p/x $v8.q.u
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: caller, after change: p/x $s8.u
PASS: gdb.arch/aarch64-pseudo-unwind.exp: down
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: callee, after change in caller: p/x $v8.q.u
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: callee, after change in caller: p/x $s8.u
PASS: gdb.arch/aarch64-pseudo-unwind.exp: continue to breakpoint: continue to break_here_c
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: p/x value
Running gdb/testsuite/gdb.arch/aarch64-fp.exp ...
PASS: gdb.arch/aarch64-fp.exp: set the breakpoint after setting the fp registers
PASS: gdb.arch/aarch64-fp.exp: continue until breakpoint
PASS: gdb.arch/aarch64-fp.exp: check register q0 value
PASS: gdb.arch/aarch64-fp.exp: check register q1 value
PASS: gdb.arch/aarch64-fp.exp: check register v0 value
PASS: gdb.arch/aarch64-fp.exp: check register v1 value
PASS: gdb.arch/aarch64-fp.exp: check register fpsr value
PASS: gdb.arch/aarch64-fp.exp: check register fpcr value
FAIL: gdb.arch/aarch64-fp.exp: bfloat16: set h0.bf to 129 (GDB internal error)
FAIL: gdb.arch/aarch64-fp.exp: bfloat16: h0 fields are valid
FAIL: gdb.arch/aarch64-fp.exp: bfloat16: set v0.h.bf[0] to 0 (GDB internal error)
FAIL: gdb.arch/aarch64-fp.exp: bfloat16: v0.h.s[0] is 0
FAIL: gdb.arch/aarch64-fp.exp: bfloat16: set v0.h.bf[0] to 129 (GDB internal error)
FAIL: gdb.arch/aarch64-fp.exp: bfloat16: v0.h.s[0] is 129

The failure mode is:

set $s8.u = 0x34353637^M
../../../repos/binutils-gdb/gdb/frame.c:1441: internal-error: put_frame_register: Assertion `buf.size () == size' failed.^M
A problem internal to GDB has been detected,^M
further debugging may prove unreliable.^M
----- Backtrace -----^M
FAIL: gdb.arch/aarch64-pseudo-unwind.exp: set $s8.u = 0x34353637 (GDB internal error)
Resyncing due to internal error.
0xaaaaabd6e08f gdb_internal_backtrace_1^M
        ../../../repos/binutils-gdb/gdb/bt-utils.c:122^M
0xaaaaabd6e08f _Z22gdb_internal_backtracev^M
        ../../../repos/binutils-gdb/gdb/bt-utils.c:168^M
0xaaaaac315307 internal_vproblem^M
        ../../../repos/binutils-gdb/gdb/utils.c:396^M
0xaaaaac31556f _Z15internal_verrorPKciS0_St9__va_list^M
        ../../../repos/binutils-gdb/gdb/utils.c:476^M
0xaaaaac8604e3 _Z18internal_error_locPKciS0_z^M
        ../../../repos/binutils-gdb/gdbsupport/errors.cc:58^M
0xaaaaabec89c7 _Z18put_frame_register14frame_info_ptriN3gdb10array_viewIKhEE^M
        ../../../repos/binutils-gdb/gdb/frame.c:1441^M
0xaaaaabc55243 aarch64_pseudo_write_1^M
        ../../../repos/binutils-gdb/gdb/aarch64-tdep.c:3316^M
0xaaaaabc5c943 aarch64_pseudo_write^M
        ../../../repos/binutils-gdb/gdb/aarch64-tdep.c:3414^M
0xaaaaabce0913 _Z29gdbarch_pseudo_register_writeP7gdbarch14frame_info_ptriN3gdb10array_viewIKhEE^M
        ../../../repos/binutils-gdb/gdb/gdbarch.c:1927^M
0xaaaaabec892f _Z18put_frame_register14frame_info_ptriN3gdb10array_viewIKhEE^M
        ../../../repos/binutils-gdb/gdb/frame.c:1462^M
0xaaaaabed0fa7 _Z24put_frame_register_bytes14frame_info_ptrimN3gdb10array_viewIKhEE^M
        ../../../repos/binutils-gdb/gdb/frame.c:1592^M
0xaaaaac33092b _Z12value_assignP5valueS0_^M
        ../../../repos/binutils-gdb/gdb/valops.c:1260^M
0xaaaaabe8fcdf _ZN10expression8evaluateEP4type6noside^M
        ../../../repos/binutils-gdb/gdb/eval.c:111^M
0xaaaaac0cba9f set_command^M
        ../../../repos/binutils-gdb/gdb/printcmd.c:1542^M
0xaaaaabd9d91b _Z8cmd_funcP16cmd_list_elementPKci^M
        ../../../repos/binutils-gdb/gdb/cli/cli-decode.c:2735^M
0xaaaaac2af583 _Z15execute_commandPKci^M
        ../../../repos/binutils-gdb/gdb/top.c:575^M
0xaaaaabe97413 _Z15command_handlerPKc^M
        ../../../repos/binutils-gdb/gdb/event-top.c:552^M
0xaaaaabe9869f _Z20command_line_handlerOSt10unique_ptrIcN3gdb13xfree_deleterIcEEE^M
        ../../../repos/binutils-gdb/gdb/event-top.c:788^M
0xaaaaabe97f17 gdb_rl_callback_handler^M
        ../../../repos/binutils-gdb/gdb/event-top.c:259^M
0xaaaaac3ce363 rl_callback_read_char^M
        ../../../../repos/binutils-gdb/readline/readline/callback.c:290^M
0xaaaaabe96e93 gdb_rl_callback_read_char_wrapper_noexcept^M
        ../../../repos/binutils-gdb/gdb/event-top.c:195^M
0xaaaaabe97d7b gdb_rl_callback_read_char_wrapper^M
        ../../../repos/binutils-gdb/gdb/event-top.c:234^M
0xaaaaac2ea1f7 stdin_event_handler^M
        ../../../repos/binutils-gdb/gdb/ui.c:155^M
0xaaaaac860ecf gdb_wait_for_event^M
        ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:694^M
0xaaaaac8618af gdb_wait_for_event^M
        ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:593^M
0xaaaaac8618af _Z16gdb_do_one_eventi^M
        ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:264^M
0xaaaaabffe02f start_event_loop^M
        ../../../repos/binutils-gdb/gdb/main.c:407^M
0xaaaaabffe02f captured_command_loop^M
        ../../../repos/binutils-gdb/gdb/main.c:471^M
0xaaaaabfffc73 captured_main^M
        ../../../repos/binutils-gdb/gdb/main.c:1324^M
0xaaaaabfffc73 _Z8gdb_mainP18captured_main_args^M
        ../../../repos/binutils-gdb/gdb/main.c:1343^M
0xaaaaabc3b457 main^M
        ../../../repos/binutils-gdb/gdb/gdb.c:39^M

It is also worth noting that the v registers are *not* pseudo-registers when the aarch64-fpu feature is used. If SVE
is available though, then that means the v registers are pseudo-registers as well. You can tell them apart by their types.

Real register (no SVE support):

type = union aarch64v {
    vnd d;
    vns s;
    vnh h;
    vnb b;
    vnq q;
}

Pseudo-register (SVE support):

union __gdb_builtin_type_vnv {
    __gdb_builtin_type_vnd d;
    __gdb_builtin_type_vns s;
    __gdb_builtin_type_vnh h;
    __gdb_builtin_type_vnb b;
    __gdb_builtin_type_vnq q;
}

Please let me know if you want me to narrow this down or provide more info.

  parent reply	other threads:[~2023-11-08 11:57 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-08  5:00 Simon Marchi
2023-11-08  5:00 ` [PATCH 01/24] gdb: don't handle i386 k registers as pseudo registers Simon Marchi
2023-11-11 19:29   ` John Baldwin
2023-11-08  5:00 ` [PATCH 02/24] gdb: use reg_buffer_common throughout gdbsupport/common-regcache.h Simon Marchi
2023-11-11 19:42   ` John Baldwin
2023-11-08  5:00 ` [PATCH 03/24] gdb: make store_integer take an array_view Simon Marchi
2023-11-08  5:00 ` [PATCH 04/24] gdb: simplify conditions in regcache::{read,write,raw_collect,raw_supply}_part Simon Marchi
2023-11-08  5:00 ` [PATCH 05/24] gdb: change regcache interface to use array_view Simon Marchi
2023-11-13 13:43   ` Andrew Burgess
2023-11-13 14:00     ` Andrew Burgess
2023-11-13 16:47       ` Simon Marchi
2023-11-08  5:00 ` [PATCH 06/24] gdb: fix bugs in {get,put}_frame_register_bytes Simon Marchi
2023-11-13 15:00   ` Andrew Burgess
2023-11-13 19:51     ` Simon Marchi
2023-11-08  5:00 ` [PATCH 07/24] gdb: make put_frame_register take an array_view Simon Marchi
2023-11-08  5:00 ` [PATCH 08/24] gdb: change value_of_register and value_of_register_lazy to take the next frame Simon Marchi
2023-11-08  5:00 ` [PATCH 09/24] gdb: remove frame_register Simon Marchi
2023-11-08  5:00 ` [PATCH 10/24] gdb: make put_frame_register take the next frame Simon Marchi
2023-11-08  5:00 ` [PATCH 11/24] gdb: make put_frame_register_bytes " Simon Marchi
2023-11-08  5:00 ` [PATCH 12/24] gdb: make get_frame_register_bytes " Simon Marchi
2023-11-08  5:00 ` [PATCH 13/24] gdb: add value::allocate_register Simon Marchi
2023-11-08  5:00 ` [PATCH 14/24] gdb: read pseudo register through frame Simon Marchi
2023-11-11 20:11   ` John Baldwin
2023-11-08  5:00 ` [PATCH 15/24] gdb: change parameter name in frame_unwind_register_unsigned declaration Simon Marchi
2023-11-08  5:01 ` [PATCH 16/24] gdb: rename gdbarch_pseudo_register_write to gdbarch_deprecated_pseudo_register_write Simon Marchi
2023-11-14 12:12   ` Andrew Burgess
2023-11-14 15:16     ` Simon Marchi
2023-11-08  5:01 ` [PATCH 17/24] gdb: add gdbarch_pseudo_register_write that takes a frame Simon Marchi
2023-11-14 12:20   ` Andrew Burgess
2023-11-14 15:20     ` Simon Marchi
2023-11-08  5:01 ` [PATCH 18/24] gdb: migrate i386 and amd64 to the new gdbarch_pseudo_register_write Simon Marchi
2023-11-11 20:16   ` John Baldwin
2023-11-13  2:59     ` Simon Marchi
2023-11-08  5:01 ` [PATCH 19/24] gdb: make aarch64_za_offsets_from_regnum return za_offsets Simon Marchi
2023-11-08  5:01 ` [PATCH 20/24] gdb: add missing raw register read in aarch64_sme_pseudo_register_write Simon Marchi
2023-11-08  5:01 ` [PATCH 21/24] gdb: migrate aarch64 to new gdbarch_pseudo_register_write Simon Marchi
2023-11-08  5:01 ` [PATCH 22/24] gdb: migrate arm to gdbarch_pseudo_register_read_value Simon Marchi
2023-11-08  5:01 ` [PATCH 23/24] gdb: migrate arm to new gdbarch_pseudo_register_write Simon Marchi
2023-11-08  5:01 ` [PATCH 24/24] gdb/testsuite: add tests for unwinding of pseudo registers Simon Marchi
2023-11-08  5:16 ` [PATCH 00/24] Fix reading and writing pseudo registers in non-current frames Simon Marchi
2023-11-09  3:05   ` Simon Marchi
2023-11-08 11:57 ` Luis Machado [this message]
2023-11-08 15:47   ` Simon Marchi
2023-11-08 17:08     ` Luis Machado
2023-11-08 19:34       ` Simon Marchi
2023-11-09 19:04         ` Simon Marchi
2023-11-13 13:10           ` Luis Machado
2023-11-13 15:08             ` Luis Machado
2023-11-11 20:26 ` John Baldwin
2023-11-13  3:03   ` Simon Marchi
2023-12-01 16:27 Simon Marchi
2023-12-01 16:56 ` Simon Marchi
2023-12-14 14:51 ` Luis Machado
2023-12-14 16:20   ` Simon Marchi

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