--- /dev/null
+# Copyright 2026 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Test that GDB can unwind using a .debug_frame section generated by
+# the DWARF assembler.
+#
+# This test is amd64-specific, but could be ported to other
+# architectures if needed.
+
+load_lib dwarf.exp
+
+require dwarf2_support is_x86_64_m64_target
+
+standard_testfile .S -dw.S
+
+# AMD64 DWARF register numbers.
+set rax 0
+set rbp 6
+set rsp 7
+set r12 12
+set r13 13
+set r14 14
+set rip 16
+
+foreach_with_prefix is_64 { false true } {
+ set asm_file [standard_output_file ${testfile}-${is_64}-dw.S]
+
+ Dwarf::assemble $asm_file {
+ frame {
+ declare_labels cie_label
+
+ cie_label: CIE {
+ return_address_register $::rip
+ data_alignment_factor -8
+ is_64 $::is_64
+ } {
+ DW_CFA_def_cfa $::rsp 8
+ DW_CFA_offset $::rip 1
+ }
+
+ # FDE for main
+ FDE $cie_label main main_len {
+ is_64 $::is_64
+ } {
+ DW_CFA_set_loc main_after_push_rbp
+ DW_CFA_def_cfa_offset 16
+ DW_CFA_offset $::rbp 2
+ DW_CFA_set_loc main_after_set_rbp
+ DW_CFA_def_cfa_register $::rbp
+ }
+
+ # FDE for caller
+ FDE $cie_label caller caller_len {
+ is_64 $::is_64
+ } {
+ DW_CFA_set_loc caller_after_push_rbp
+ DW_CFA_def_cfa_offset 16
+ DW_CFA_offset $::rbp 2
+ DW_CFA_set_loc caller_after_set_rbp
+ DW_CFA_def_cfa_register $::rbp
+ }
+
+ # FDE for callee
+ FDE $cie_label callee callee_len {
+ is_64 $::is_64
+ } {
+ DW_CFA_set_loc callee_after_push_rbp
+ DW_CFA_def_cfa_offset 16
+ DW_CFA_offset $::rbp 2
+ DW_CFA_set_loc callee_after_set_rbp
+ DW_CFA_def_cfa_register $::rbp
+
+ DW_CFA_set_loc callee_body
+ DW_CFA_offset $::r12 3
+ DW_CFA_register $::r13 $::rax
+
+ # r14's value is computed by an arbitrary expression.
+ DW_CFA_val_expression $::r14 {
+ DW_OP_constu 0x99aabbcc
+ }
+ }
+ }
+ }
+
+ if { [prepare_for_testing "failed to prepare" ${testfile}-${is_64} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ continue
+ }
+
+ # Stop in caller before the call, to capture rbp.
+ if { ![runto caller_call_callee] } {
+ continue
+ }
+
+ set caller_rbp [get_hexadecimal_valueof "\$rbp" "UNKNOWN"]
+
+ # Stop inside callee.
+ gdb_breakpoint callee_body
+ gdb_continue_to_breakpoint "callee_body"
+
+ # Verify backtrace shows the full call chain.
+ gdb_test "bt" "#0.*callee.*\r\n#1.*caller.*\r\n#2.*main.*"
+
+ # Select caller's frame and check saved registers.
+ gdb_test "frame 1" "#1.*caller.*"
+
+ # r12 was saved on the stack by callee.
+ gdb_test "p/x \$r12" "= 0x11223344"
+
+ # r13 was saved in rax by callee.
+ gdb_test "p/x \$r13" "= 0x55667788"
+
+ # r14's value is computed by a DWARF expression.
+ gdb_test "p/x \$r14" "= 0x99aabbcc"
+
+ # rbp should match what caller had.
+ gdb_test "p/x \$rbp" "= ${caller_rbp}"
+}
variable _loc_addr_size
variable _loc_offset_size
+ # Variables used when generating a .debug_frame section.
+ variable _frame_addr_size
+ variable _frame_offset_size
+
proc _process_one_constant {name value} {
variable _constants
variable _FORM
}
# We only try to shorten some very common things.
- # FIXME: CFA?
switch -exact -- $prefix {
TAG {
# Create two procedures for the tag. These call
} $name $name $handler]
}
+ CFA {
+ # Create procs for DW_CFA_* instructions, used in
+ # .debug_frame CIE/FDE bodies.
+
+ # DW_CFA_advance_loc, DW_CFA_offset and
+ # DW_CFA_restore encode the operand in the low 6
+ # bits of the opcode byte. They need special
+ # handling and are predefined below.
+ switch -exact -- $name {
+ DW_CFA_advance_loc -
+ DW_CFA_offset -
+ DW_CFA_restore {
+ }
+
+ default {
+ # Standard CFA instruction: emit opcode
+ # byte then delegate to handler.
+ set handler _handle_default_CFA
+ if {[llength [info procs _handle_$name]] > 0} {
+ set handler _handle_$name
+ }
+
+ # tclint-disable-next-line command-args
+ proc $name {args} [format {
+ _op .byte $Dwarf::_constants(%s) %s
+ %s {*}$args
+ } $name $name $handler]
+ }
+ }
+ }
+
default {
return
}
# error.
}
+ # DW_CFA_advance_loc, DW_CFA_offset and DW_CFA_restore encode the
+ # operand in the low 6 bits of the opcode byte. They need special
+ # handling, so they are defined here rather than generated.
+ proc DW_CFA_advance_loc {delta} {
+ _op .byte \
+ "$Dwarf::_constants(DW_CFA_advance_loc) + $delta" DW_CFA_advance_loc
+ }
+
+ proc DW_CFA_offset {register offset} {
+ _op .byte \
+ "$Dwarf::_constants(DW_CFA_offset) + $register" DW_CFA_offset
+ _op .uleb128 $offset "offset"
+ }
+
+ proc DW_CFA_restore {register} {
+ _op .byte \
+ "$Dwarf::_constants(DW_CFA_restore) + $register" DW_CFA_restore
+ }
+
+ # Helper to emit a DWARF expression block (ULEB128 length followed
+ # by the expression bytes) inside a .debug_frame CIE or FDE body.
+ # BODY is a Tcl code containing DW_OP_* calls.
+ proc _emit_cfa_expression {body} {
+ set start [new_label "cfa_expr_start"]
+ set end [new_label "cfa_expr_end"]
+ _op .uleb128 "$end - $start" "expression length"
+ define_label $start
+
+ # Pass 5 as the DWARF version, since we need to pass something, but it
+ # doesn't matter. The DWARF version is checked only for DW_OP_* ops
+ # that don't make sense in CFI.
+ _location $body 5 $Dwarf::_frame_addr_size $Dwarf::_frame_offset_size
+ define_label $end
+ }
+
+ #
+ # Handlers for DW_CFA_* instructions.
+ #
+ # A handler is only needed if the instruction requires operands.
+ # Generic code handles emitting the opcode byte itself, so a
+ # handler should not do this.
+ #
+ # Handlers are found by name when processing the .def file. If a
+ # handler isn't found, the default (_handle_default_CFA) is used.
+ #
+
+ proc _handle_default_CFA {} {
+ # Do nothing; if arguments are passed, Tcl will cause an
+ # error.
+ }
+
+ proc _handle_DW_CFA_set_loc {address} {
+ _op .${Dwarf::_frame_addr_size}byte $address "address"
+ }
+
+ proc _handle_DW_CFA_advance_loc1 {delta} {
+ _op .byte $delta "delta"
+ }
+
+ proc _handle_DW_CFA_advance_loc2 {delta} {
+ _op .2byte $delta "delta"
+ }
+
+ proc _handle_DW_CFA_advance_loc4 {delta} {
+ _op .4byte $delta "delta"
+ }
+
+ proc _handle_DW_CFA_offset_extended {register offset} {
+ _op .uleb128 $register "register"
+ _op .uleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_restore_extended {register} {
+ _op .uleb128 $register "register"
+ }
+
+ proc _handle_DW_CFA_undefined {register} {
+ _op .uleb128 $register "register"
+ }
+
+ proc _handle_DW_CFA_same_value {register} {
+ _op .uleb128 $register "register"
+ }
+
+ proc _handle_DW_CFA_register {register1 register2} {
+ _op .uleb128 $register1 "register"
+ _op .uleb128 $register2 "register"
+ }
+
+ proc _handle_DW_CFA_def_cfa {register offset} {
+ _op .uleb128 $register "register"
+ _op .uleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_def_cfa_register {register} {
+ _op .uleb128 $register "register"
+ }
+
+ proc _handle_DW_CFA_def_cfa_offset {offset} {
+ _op .uleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_def_cfa_expression {body} {
+ _emit_cfa_expression $body
+ }
+
+ proc _handle_DW_CFA_expression {register body} {
+ _op .uleb128 $register "register"
+ _emit_cfa_expression $body
+ }
+
+ proc _handle_DW_CFA_offset_extended_sf {register offset} {
+ _op .uleb128 $register "register"
+ _op .sleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_def_cfa_sf {register offset} {
+ _op .uleb128 $register "register"
+ _op .sleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_def_cfa_offset_sf {offset} {
+ _op .sleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_val_offset {register offset} {
+ _op .uleb128 $register "register"
+ _op .uleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_val_offset_sf {register offset} {
+ _op .uleb128 $register "register"
+ _op .sleb128 $offset "offset"
+ }
+
+ proc _handle_DW_CFA_val_expression {register body} {
+ _op .uleb128 $register "register"
+ _emit_cfa_expression $body
+ }
+
# This is a miniature assembler for location expressions. It is
# suitable for use in the attributes to a DIE.
#
debug_str_offsets_end:
}
+ # Emit a DWARF .debug_frame section.
+ #
+ # BODY is Tcl code that emits the CIEs and FDEs which make up the
+ # section. It is evaluated in the caller's context.
+ #
+ # Within BODY, the following commands are available:
+ #
+ # CIE options body
+ # -- emit a Common Information Entry. See _frame_CIE for details.
+ #
+ # FDE cie_label initial_location address_range body
+ # -- emit a Frame Description Entry. See _frame_FDE for details.
+ proc frame { body } {
+ _section .debug_frame
+
+ with_override Dwarf::CIE Dwarf::_frame_CIE {
+ with_override Dwarf::FDE Dwarf::_frame_FDE {
+ uplevel $Dwarf::_level $body
+ }
+ }
+ }
+
+ # Available as proc CIE when in the body of proc debug_frame.
+ #
+ # OPTIONS is a list of option-name/option-value pairs. Supported
+ # options are (default values are shown in parentheses):
+ #
+ # is_64 (false)
+ # -- if true, emit a 64-bit CIE.
+ #
+ # cie_id (default)
+ # -- the CIE id value. When "default", uses 0xffffffff for
+ # 32-bit and 0xffffffffffffffff for 64-bit. Should typically not be
+ # used unless trying to craft an invalid CIE.
+ #
+ # version (4)
+ # -- the CIE version number. Note that this is version independent
+ # from the DWARF version. DWARF 4 and 5 both use .debug_frame
+ # version 4.
+ #
+ # augmentation ("")
+ # -- the augmentation string.
+ #
+ # addr_size (default)
+ # -- the address size in bytes. When "default", use 8 for 64-bit
+ # targets and 4 for 32-bit targets.
+ #
+ # segment_selector_size (0)
+ # -- the segment selector size in bytes.
+ #
+ # code_alignment_factor (1)
+ # -- the code alignment factor.
+ #
+ # data_alignment_factor (1)
+ # -- the data alignment factor.
+ #
+ # return_address_register (0)
+ # -- the number of the "column" containing the return address.
+ #
+ # BODY is Tcl code that emits the CIE's initial instructions using
+ # DW_CFA_* operations. It is evaluated in the caller's context.
+ proc _frame_CIE {options body} {
+ parse_options {
+ { is_64 false }
+ { cie_id default }
+ { version 4 }
+ { augmentation "" }
+ { addr_size default }
+ { segment_selector_size 0 }
+ { code_alignment_factor 1 }
+ { data_alignment_factor 1 }
+ { return_address_register 0 }
+ }
+
+ if { $is_64 } {
+ set Dwarf::_frame_offset_size 8
+ } else {
+ set Dwarf::_frame_offset_size 4
+ }
+
+ if { $cie_id == "default" } {
+ if { $is_64 } {
+ set cie_id 0xffffffffffffffff
+ } else {
+ set cie_id 0xffffffff
+ }
+ }
+
+ if {$addr_size == "default"} {
+ if {[is_64_target]} {
+ set Dwarf::_frame_addr_size 8
+ } else {
+ set Dwarf::_frame_addr_size 4
+ }
+ } else {
+ set Dwarf::_frame_addr_size $addr_size
+ }
+
+ declare_labels cie_post_length cie_end
+
+ # Length.
+ if { $is_64 } {
+ _op .4byte 0xffffffff "length 1/2"
+ _op .8byte "$cie_end - $cie_post_length" "length 2/2"
+ } else {
+ _op .4byte "$cie_end - $cie_post_length" "length"
+ }
+
+ define_label $cie_post_length
+
+ # CIE_id
+ _op .${Dwarf::_frame_offset_size}byte $cie_id "CIE_id"
+
+ # Version.
+ _op .byte $version "version"
+
+ # Augmentation string.
+ _op .ascii [_quote $augmentation] "augmentation"
+
+ # Address size.
+ _op .byte $Dwarf::_frame_addr_size "address_size"
+
+ # Segment selector size.
+ _op .byte 0 "segment_size"
+
+ # Code alignment factor.
+ _op .uleb128 $code_alignment_factor "code_alignment_factor"
+
+ # Data alignment factor.
+ _op .sleb128 $data_alignment_factor "data_alignment_factor"
+
+ # Return address register.
+ _op .uleb128 $return_address_register "return_address_register"
+
+ # Initial instructions.
+ uplevel $Dwarf::_level $body
+
+ # Padding up to the address size. Fill with DW_CFA_nop (zeroes).
+ _op .align $Dwarf::_frame_addr_size "padding"
+
+ define_label $cie_end
+ }
+
+ # Available as proc FDE when in the body of proc debug_frame.
+ #
+ # CIE_LABEL is the label of the CIE this FDE refers to.
+ #
+ # INITIAL_LOCATION is the address of the first instruction covered
+ # by this FDE.
+ #
+ # ADDRESS_RANGE is the number of bytes of instructions covered by
+ # this FDE.
+ #
+ # OPTIONS is a list of option-name/option-value pairs. Supported
+ # options are (default values are shown in parentheses):
+ #
+ # is_64 (false)
+ # -- if true, emit a 64-bit CIE.
+ #
+ # addr_size (default)
+ # -- the address size in bytes. When "default", use 8 for 64-bit
+ # targets and 4 for 32-bit targets.
+ #
+ # BODY is Tcl code that emits the FDE's call frame instructions using
+ # DW_CFA_* operations. It is evaluated in the caller's context.
+ proc _frame_FDE { cie_label initial_location address_range options
+ body } {
+ parse_options {
+ { is_64 false }
+ { addr_size default }
+ }
+
+ if { $is_64 } {
+ set Dwarf::_frame_offset_size 8
+ } else {
+ set Dwarf::_frame_offset_size 4
+ }
+
+ if {$addr_size == "default"} {
+ if {[is_64_target]} {
+ set Dwarf::_frame_addr_size 8
+ } else {
+ set Dwarf::_frame_addr_size 4
+ }
+ } else {
+ set Dwarf::_frame_addr_size $addr_size
+ }
+
+ declare_labels fde_post_length fde_end
+
+ # Length.
+ if { $is_64 } {
+ _op .4byte 0xffffffff "length 1/2"
+ _op .8byte "$fde_end - $fde_post_length" "length 2/2"
+ } else {
+ _op .4byte "$fde_end - $fde_post_length" "length"
+ }
+ define_label $fde_post_length
+
+ # CIE pointer, offset of the CIE into the .debug_frame section.
+ _op .${Dwarf::_frame_offset_size}byte $cie_label "CIE pointer"
+
+ # Initial location.
+ _op .${Dwarf::_frame_addr_size}byte $initial_location "initial_location"
+
+ # Address range.
+ _op .${Dwarf::_frame_addr_size}byte $address_range "address_range"
+
+ # Instructions.
+ uplevel $Dwarf::_level $body
+
+ # Padding up to the address size. Fill with DW_CFA_nop (zeroes).
+ _op .align $Dwarf::_frame_addr_size "padding"
+
+ define_label $fde_end
+ }
+
# The top-level interface to the DWARF assembler.
# OPTIONS is a list with an even number of elements containing
# option-name and option-value pairs.
projects / thirdparty / binutils-gdb.git / commitdiff
