}
}
}
+{ package cfi_directive;
+ # CFI directives annotate instructions that are significant for
+ # stack unwinding procedure compliant with DWARF specification,
+ # see http://dwarfstd.org/. Besides naturally expected for this
+ # script platform-specific filtering function, this module adds
+ # three auxiliary synthetic directives not recognized by [GNU]
+ # assembler:
+ #
+ # - .cfi_push to annotate push instructions in prologue, which
+ # translates to .cfi_adjust_cfa_offset (if needed) and
+ # .cfi_offset;
+ # - .cfi_pop to annotate pop instructions in epilogue, which
+ # translates to .cfi_adjust_cfa_offset (if needed) and
+ # .cfi_restore;
+ # - [and most notably] .cfi_cfa_expression which encodes
+ # DW_CFA_def_cfa_expression and passes it to .cfi_escape as
+ # byte vector;
+ #
+ # CFA expressions were introduced in DWARF specification version
+ # 3 and describe how to deduce CFA, Canonical Frame Address. This
+ # becomes handy if your stack frame is variable and you can't
+ # spare register for [previous] frame pointer. Suggested directive
+ # syntax is made-up mix of DWARF operator suffixes [subset of]
+ # and references to registers with optional bias. Following example
+ # describes offloaded *original* stack pointer at specific offset
+ # from *current* stack pointer:
+ #
+ # .cfi_cfa_expression %rsp+40,deref,+8
+ #
+ # Final +8 has everything to do with the fact that CFA is defined
+ # as reference to top of caller's stack, and on x86_64 call to
+ # subroutine pushes 8-byte return address. In other words original
+ # stack pointer upon entry to a subroutine is 8 bytes off from CFA.
+
+ # Below constants are taken from "DWARF Expressions" section of the
+ # DWARF specification, section is numbered 7.7 in versions 3 and 4.
+ my %DW_OP_simple = ( # no-arg operators, mapped directly
+ deref => 0x06, dup => 0x12,
+ drop => 0x13, over => 0x14,
+ pick => 0x15, swap => 0x16,
+ rot => 0x17, xderef => 0x18,
+
+ abs => 0x19, and => 0x1a,
+ div => 0x1b, minus => 0x1c,
+ mod => 0x1d, mul => 0x1e,
+ neg => 0x1f, not => 0x20,
+ or => 0x21, plus => 0x22,
+ shl => 0x24, shr => 0x25,
+ shra => 0x26, xor => 0x27,
+ );
+
+ my %DW_OP_complex = ( # used in specific subroutines
+ constu => 0x10, # uleb128
+ consts => 0x11, # sleb128
+ plus_uconst => 0x23, # uleb128
+ lit0 => 0x30, # add 0-31 to opcode
+ reg0 => 0x50, # add 0-31 to opcode
+ breg0 => 0x70, # add 0-31 to opcole, sleb128
+ regx => 0x90, # uleb28
+ fbreg => 0x91, # sleb128
+ bregx => 0x92, # uleb128, sleb128
+ piece => 0x93, # uleb128
+ );
+
+ # Following constants are defined in x86_64 ABI supplement, for
+ # example avaiable at https://www.uclibc.org/docs/psABI-x86_64.pdf,
+ # see section 3.7 "Stack Unwind Algorithm".
+ my %DW_reg_idx = (
+ "%rax"=>0, "%rdx"=>1, "%rcx"=>2, "%rbx"=>3,
+ "%rsi"=>4, "%rdi"=>5, "%rbp"=>6, "%rsp"=>7,
+ "%r8" =>8, "%r9" =>9, "%r10"=>10, "%r11"=>11,
+ "%r12"=>12, "%r13"=>13, "%r14"=>14, "%r15"=>15
+ );
+
+ my ($cfa_reg, $cfa_rsp);
+
+ # [us]leb128 format is variable-length integer representation base
+ # 2^128, with most significant bit of each byte being 0 denoting
+ # *last* most significat digit. See "Variable Length Data" in the
+ # DWARF specification, numbered 7.6 at least in versions 3 and 4.
+ sub sleb128 {
+ use integer; # get right shift extend sign
+
+ my $val = shift;
+ my $sign = ($val < 0) ? -1 : 0;
+ my @ret = ();
+
+ while(1) {
+ push @ret, $val&0x7f;
+
+ # see if remaining bits are same and equal to most
+ # significant bit of the current digit, if so, it's
+ # last digit...
+ last if (($val>>6) == $sign);
+
+ @ret[-1] |= 0x80;
+ $val >>= 7;
+ }
+
+ return @ret;
+ }
+ sub uleb128 {
+ my $val = shift;
+ my @ret = ();
+
+ while(1) {
+ push @ret, $val&0x7f;
+
+ # see if it's last significant digit...
+ last if (($val >>= 7) == 0);
+
+ @ret[-1] |= 0x80;
+ }
+
+ return @ret;
+ }
+ sub const {
+ my $val = shift;
+
+ if ($val >= 0 && $val < 32) {
+ return ($DW_OP_complex{lit0}+$val);
+ }
+ return ($DW_OP_complex{consts}, sleb128($val));
+ }
+ sub reg {
+ my $val = shift;
+
+ return if ($val !~ m/^(%r\w+)(?:([\+\-])((?:0x)?[0-9a-f]+))?/);
+
+ my $reg = $DW_reg_idx{$1};
+ my $off = eval ("0 $2 $3");
+
+ return (($DW_OP_complex{breg0} + $reg), sleb128($off));
+ # Yes, we use DW_OP_bregX+0 to push register value and not
+ # DW_OP_regX, because latter would require even DW_OP_piece,
+ # which would be a waste under the circumstances. If you have
+ # to use DWP_OP_reg, use "regx:N"...
+ }
+ sub cfa_expression {
+ my $line = shift;
+ my @ret;
+
+ foreach my $token (split(/,\s*/,$line)) {
+ if ($token =~ /^%r/) {
+ push @ret,reg($token);
+ } elsif ($token =~ /(\w+):(\-?(?:0x)?[0-9a-f]+)(U?)/i) {
+ my $i = 1*eval($2);
+ push @ret,$DW_OP_complex{$1}, ($3 ? uleb128($i) : sleb128($i));
+ } elsif (my $i = 1*eval($token) or $token eq "0") {
+ if ($token =~ /^\+/) {
+ push @ret,$DW_OP_complex{plus_uconst},uleb128($i);
+ } else {
+ push @ret,const($i);
+ }
+ } else {
+ push @ret,$DW_OP_simple{$token};
+ }
+ }
+
+ # Finally we return DW_CFA_def_cfa_expression, 15, followed by
+ # length of the expression and of course the expression itself.
+ return (15,scalar(@ret),@ret);
+ }
+ sub re {
+ my ($class, $line) = @_;
+ my $self = {};
+ my $ret;
+
+ if ($$line =~ s/^\s*\.cfi_(\w+)\s+//) {
+ bless $self,$class;
+ $ret = $self;
+ undef $self->{value};
+ my $dir = $1;
+
+ SWITCH: for ($dir) {
+ # What is $cfa_rsp? Effectively it's difference between %rsp
+ # value and current CFA, Canonical Frame Address, which is
+ # why it starts with -8. Recall that CFA is top of caller's
+ # stack...
+ /startproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", -8); last; };
+ /endproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", 0); last; };
+ /def_cfa_register/
+ && do { $cfa_reg = $$line; last; };
+ /def_cfa_offset/
+ && do { $cfa_rsp = -1*eval($$line) if ($cfa_reg eq "%rsp");
+ last;
+ };
+ /adjust_cfa_offset/
+ && do { $cfa_rsp -= 1*eval($$line) if ($cfa_reg eq "%rsp");
+ last;
+ };
+ /def_cfa/ && do { if ($$line =~ /(%r\w+)\s*,\s*(\.+)/) {
+ $cfa_reg = $1;
+ $cfa_rsp = -1*eval($2) if ($cfa_reg eq "%rsp");
+ }
+ last;
+ };
+ /push/ && do { $dir = undef;
+ $cfa_rsp -= 8;
+ if ($cfa_reg eq "%rsp") {
+ $self->{value} = ".cfi_adjust_cfa_offset\t8\n";
+ }
+ $self->{value} .= ".cfi_offset\t$$line,$cfa_rsp";
+ last;
+ };
+ /pop/ && do { $dir = undef;
+ $cfa_rsp += 8;
+ if ($cfa_reg eq "%rsp") {
+ $self->{value} = ".cfi_adjust_cfa_offset\t-8\n";
+ }
+ $self->{value} .= ".cfi_restore\t$$line";
+ last;
+ };
+ /cfa_expression/
+ && do { $dir = undef;
+ $self->{value} = ".cfi_escape\t" .
+ join(",", map(sprintf("0x%02x", $_),
+ cfa_expression($$line)));
+ last;
+ };
+ }
+
+ $self->{value} = ".cfi_$dir\t$$line" if ($dir);
+
+ $$line = "";
+ }
+
+ return $ret;
+ }
+ sub out {
+ my $self = shift;
+ return ($elf ? $self->{value} : undef);
+ }
+}
{ package directive; # pick up directives, which start with .
sub re {
my ($class, $line) = @_;
my $ret;
my $dir;
+ # chain-call to cfi_directive
+ $ret = cfi_directive->re($line) and return $ret;
+
if ($$line =~ /^\s*(\.\w+)/) {
bless $self,$class;
$dir = $1;
projects / openssl.git / commitdiff