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Generate RBP column when needed

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This commit is contained in:
Théophile Bastian 2019-04-01 18:51:06 +02:00
parent fc8c9c45d6
commit 180e32a4b3
7 changed files with 303 additions and 104 deletions
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55
DwarfSynth/Frontend.ml
View file

@ -10,25 +10,46 @@ let pp_int64_hex ppx number =
List.iter pp_short @@ List.map (fun x ->
Int64.(shift_right number (16*x))) [3;2;1;0]
let pp_cfa_change ppx addr pos = Simplest.(
exception LostTrackCfaDisp
let pp_cfa_change ppx addr reg_pos = Simplest.(
let num_len num =
let str_rep = Format.sprintf "%+d" num in
String.length str_rep
in
let print_row cfa_reg int64_offset =
let offset = Int64.to_int int64_offset in
let post_offset_spaces = String.make (6 - num_len offset) ' ' in
Format.fprintf ppx "%a %s%+d%sc-8@."
pp_int64_hex addr cfa_reg offset post_offset_spaces
let print_row cfa_reg cfa_int64_offset rbp_offset =
let cfa_offset = Int64.to_int cfa_int64_offset in
let post_cfa_offset_spaces = String.make (6 - num_len cfa_offset) ' ' in
let rbp_str = (match rbp_offset with
| None -> "u "
| Some off64 ->
let off = Int64.to_int off64 in
Format.sprintf "c%+d%s" off (String.make (5 - num_len off) ' ')
) in
Format.fprintf ppx "%a %s%+d%s%sc-8@."
pp_int64_hex addr cfa_reg cfa_offset post_cfa_offset_spaces rbp_str
in
match pos with
| RspOffset offset ->
print_row "rsp" offset
| RbpOffset offset ->
print_row "rbp" offset
| CfaLostTrack ->
Format.fprintf ppx "%a u u@." pp_int64_hex addr
let cfa_pos, rbp_pos = reg_pos in
(try
let cfa_reg, cfa_offset = (match cfa_pos with
| RspOffset offset ->
"rsp", offset
| RbpOffset offset ->
"rbp", offset
| CfaLostTrack ->
raise LostTrackCfaDisp
) in
let rbp_offset = (match rbp_pos with
| RbpUndef -> None
| RbpCfaOffset off -> Some off
) in
print_row cfa_reg cfa_offset rbp_offset
with LostTrackCfaDisp ->
Format.fprintf ppx "%a u u u@." pp_int64_hex addr
)
)
let pp_pre_dwarf_readelf ppx (pre_dwarf: Simplest.subroutine_cfa_map) =
@ -36,10 +57,10 @@ let pp_pre_dwarf_readelf ppx (pre_dwarf: Simplest.subroutine_cfa_map) =
Simplest.StrMap.iter (fun fde_name entry ->
Format.fprintf ppx "FDE %s pc=%a..%a@."
fde_name pp_int64_hex entry.beg_pos pp_int64_hex entry.end_pos;
let cfa_entry = entry.cfa_changes_fde in
if not (Simplest.AddrMap.is_empty cfa_entry) then (
Format.fprintf ppx " LOC CFA ra@." ;
Simplest.AddrMap.iter (pp_cfa_change ppx) cfa_entry ;
let reg_entry = entry.reg_changes_fde in
if not (Simplest.AddrMap.is_empty reg_entry) then (
Format.fprintf ppx " LOC CFA rbp ra@." ;
Simplest.AddrMap.iter (pp_cfa_change ppx) reg_entry ;
Format.fprintf ppx "@.")
)
pre_dwarf

25
DwarfSynth/PreCBinding.ml
View file

@ -6,7 +6,9 @@ exception InvalidPreDwarf of string
type pre_c_pre_dwarf_entry = {
location: int64;
cfa_offset: int64;
cfa_offset_reg: int
cfa_offset_reg: int;
rbp_defined: bool;
rbp_offset: int64 (* Assumed to be offset of CFA *)
}
type pre_c_pre_dwarf_fde = {
@ -32,7 +34,9 @@ type pre_c_pre_dwarf = {
let empty_entry = {
location = Int64.zero;
cfa_offset = Int64.zero;
cfa_offset_reg = 0
cfa_offset_reg = 0;
rbp_defined = false;
rbp_offset = Int64.zero
}
(** Empty default value for `pre_c_pre_dwarf_fde` *)
@ -57,17 +61,24 @@ module MapTool (MapT: Map.S) = struct
end
let convert_pre_c_entry loc entry : pre_c_pre_dwarf_entry =
let offset, offset_reg = (match entry with
let cfa_entry, rbp_entry = entry in
let cfa_offset, cfa_offset_reg = (match cfa_entry with
| RspOffset off -> off, 7
| RbpOffset off -> off, 6
| CfaLostTrack ->
raise (InvalidPreDwarf
("CfaLostTrack should be filtered out beforehand"))
) in
let rbp_defined, rbp_offset = (match rbp_entry with
| RbpUndef -> false, Int64.zero
| RbpCfaOffset off -> true, off
) in
{
location = loc;
cfa_offset = offset;
cfa_offset_reg = offset_reg;
cfa_offset = cfa_offset;
cfa_offset_reg = cfa_offset_reg;
rbp_defined = rbp_defined;
rbp_offset = rbp_offset
}
module AddrMapTool = MapTool(AddrMap)
@ -79,11 +90,11 @@ let convert_pre_c_entries entries : pre_c_pre_dwarf_entry array =
let convert_pre_c_fde name entry : pre_c_pre_dwarf_fde option =
try
Some {
num = AddrMap.cardinal entry.cfa_changes_fde;
num = AddrMap.cardinal entry.reg_changes_fde;
initial_location = entry.beg_pos;
end_location = entry.end_pos;
name = name;
entries = convert_pre_c_entries entry.cfa_changes_fde
entries = convert_pre_c_entries entry.reg_changes_fde
}
with InvalidPreDwarf reason -> (
Format.eprintf "FAILED subroutine %s: %s@." name reason ;

309
DwarfSynth/Simplest.ml
View file

@ -12,20 +12,31 @@ type cfa_pos =
| RbpOffset of memory_offset
| CfaLostTrack
type cfa_changes_fde = cfa_pos AddrMap.t
type rbp_pos =
| RbpUndef
| RbpCfaOffset of memory_offset
type reg_pos = cfa_pos * rbp_pos
type reg_changes_fde = reg_pos AddrMap.t
type subroutine_cfa_data = {
cfa_changes_fde: cfa_changes_fde;
reg_changes_fde: reg_changes_fde;
beg_pos: memory_address;
end_pos: memory_address;
}
type block_local_state = {
rbp_vars: BStd.Var.Set.t
}
module StrMap = Map.Make(String)
type subroutine_cfa_map = subroutine_cfa_data StrMap.t
module TIdMap = Map.Make(BStd.Tid)
exception InvalidSub
exception UnexpectedRbpSet
let pp_cfa_pos ppx = function
| RspOffset off -> Format.fprintf ppx "RSP + (%s)" (Int64.to_string off)
@ -200,57 +211,186 @@ let is_single_free_reg expr =
| _ -> None
)
let process_def def (cur_cfa: cfa_pos)
: (cfa_pos option) =
let lose_track = Some (CfaLostTrack) in
let process_def (local_state: block_local_state) def (cur_reg: reg_pos)
: (reg_pos option * block_local_state) =
let lose_track = Some CfaLostTrack in
(match cur_cfa, Regs.X86_64.of_var (BStd.Def.lhs def) with
| RspOffset(cur_offset), Some reg when reg = Regs.X86_64.rsp ->
let exp = BStd.Def.rhs def in
(match is_single_free_reg exp with
| Some (bil_var, dw_var) when dw_var = Regs.X86_64.rsp ->
let interpreted = interpret_var_expr bil_var cur_offset exp in
(match interpreted with
| None -> lose_track
| Some new_offset ->
Some (RspOffset(new_offset))
)
| _ -> lose_track
)
| RspOffset(cur_offset), Some reg when reg = Regs.X86_64.rbp ->
(* We have CFA=rsp+k and a line %rbp <- [expr]. Might be a %rbp <- %rsp *)
let exp = BStd.Def.rhs def in
(match is_single_free_reg exp with
| Some (bil_var, dw_var) when dw_var = Regs.X86_64.rsp ->
(* We have %rbp := F(%rsp) *)
(* FIXME we wish to have %rbp := %rsp. An ugly and non-robust test to
check that would be interpret F(0), expecting that F is at worst
affine - then a restult of 0 means that %rbp := %rsp + 0 *)
let interpreted = interpret_var_expr bil_var (Int64.zero) exp in
(match interpreted with
| Some offset when offset = Int64.zero ->
Some (RbpOffset(cur_offset))
| _ ->
(* Previous instruction was rsp-indexed, here we put something weird
in %rbp, let's keep indexing with rsp and do nothing *)
None
)
| _ -> None
)
| RbpOffset(cur_offset), Some reg when reg = Regs.X86_64.rbp ->
let cur_cfa, cur_rbp = cur_reg in
let out_cfa =
(match cur_cfa, Regs.X86_64.of_var (BStd.Def.lhs def) with
| RspOffset(cur_offset), Some reg when reg = Regs.X86_64.rsp ->
let exp = BStd.Def.rhs def in
(match is_single_free_reg exp with
| Some (bil_var, dw_var) when dw_var = Regs.X86_64.rsp ->
let interpreted = interpret_var_expr bil_var cur_offset exp in
(match interpreted with
| None -> lose_track
| Some new_offset ->
Some (RspOffset(new_offset))
)
| _ -> lose_track
)
| RspOffset(cur_offset), Some reg when reg = Regs.X86_64.rbp ->
(* We have CFA=rsp+k and a line %rbp <- [expr].
Might be a %rbp <- %rsp *)
let exp = BStd.Def.rhs def in
(match is_single_free_reg exp with
| Some (bil_var, dw_var) when dw_var = Regs.X86_64.rsp ->
(* We have %rbp := F(%rsp) *)
(* FIXME we wish to have %rbp := %rsp. An ugly and non-robust test to
check that would be interpret F(0), expecting that F is at worst
affine - then a restult of 0 means that %rbp := %rsp + 0 *)
let interpreted = interpret_var_expr bil_var (Int64.zero) exp in
(match interpreted with
| Some offset when offset = Int64.zero ->
Some (RbpOffset(cur_offset))
| _ ->
(* Previous instruction was rsp-indexed, here we put something
weird in %rbp, let's keep indexing with rsp and do nothing *)
None
)
| _ -> None
)
| RbpOffset(cur_offset), Some reg when reg = Regs.X86_64.rbp ->
(* Assume we are overwriting %rbp with something — we must revert to
some rsp-based indexing *)
(* FIXME don't assume the rsp offset will always be 8, find a smart way
to figure this out *)
Some (RspOffset(Int64.of_int 8))
| _ -> None)
| _ -> None)
in
let process_jmp jmp (cur_cfa: cfa_pos)
: (cfa_pos option) =
let is_rbp_save_expr expr local_state =
let free_vars = BStd.Exp.free_vars expr in
let card = BStd.Var.Set.length free_vars in
let has_mem_var = BStd.Var.Set.exists
~f:(fun x -> BStd.Var.name x = "mem")
free_vars in
let free_x86_regs = Regs.X86_64.map_varset free_vars in
let has_rsp_var = free_x86_regs
|> Regs.DwRegOptSet.exists
(fun x -> match x with
| Some x when x = Regs.X86_64.rsp -> true
| _ -> false) in
let has_rbp_var = free_x86_regs
|> Regs.DwRegOptSet.exists
(fun x -> match x with
| Some x when x = Regs.X86_64.rbp -> true
| _ -> false) in
let has_intermed_rbp_var = free_vars
|> BStd.Var.Set.inter local_state.rbp_vars
|> BStd.Var.Set.is_empty
|> not in
(card = 3 && has_mem_var && has_rsp_var &&
(has_rbp_var || has_intermed_rbp_var))
in
let is_pop_expr expr =
let free_vars = BStd.Exp.free_vars expr in
let free_x86_regs = Regs.X86_64.map_varset free_vars in
(match Regs.DwRegOptSet.cardinal free_x86_regs with
| 2 ->
let reg = free_x86_regs
|> Regs.DwRegOptSet.filter
(fun x -> match x with None -> false | Some _ -> true)
|> Regs.DwRegOptSet.choose in
let has_mem_var = BStd.Var.Set.exists
~f:(fun x -> BStd.Var.name x = "mem")
free_vars in
(match reg, has_mem_var with
| Some dw_var, true when dw_var = Regs.X86_64.rsp -> true
| _ -> false)
| _ -> false
)
in
let is_rbp_expr expr =
let free_vars = BStd.Exp.free_vars expr in
let free_x86_regs = Regs.X86_64.map_varset free_vars in
(match Regs.DwRegOptSet.cardinal free_x86_regs with
| 1 ->
let reg = Regs.DwRegOptSet.choose free_x86_regs in
(match reg with
| Some dwreg when dwreg = Regs.X86_64.rbp -> true
| _ -> false)
| _ -> false)
in
let gather_rbp_intermed_var def cur_state =
(* If `def` is `some intermed. var <- rbp`, add this information in the
local state *)
(match is_rbp_expr @@ BStd.Def.rhs def with
| true ->
let lhs_var = BStd.Def.lhs def in
if (BStd.Var.is_virtual lhs_var
&& BStd.Var.typ lhs_var = BStd.reg64_t) then
(
(* This `def` is actually of the type we want to store. *)
let n_rbp_vars = BStd.Var.Set.add cur_state.rbp_vars lhs_var in
{ cur_state with rbp_vars = n_rbp_vars }
)
else
cur_state
| false -> cur_state
)
in
let out_rbp, new_state =
(match cur_rbp with
| RbpUndef ->
let cur_state = gather_rbp_intermed_var def local_state in
(* We assume that an expression is saving %rbp on the stack at the
address %rip when the current def is an expression of the kind
`MEM <- F(MEM, %rip, v)` where `v` is either `%rbp` or some
intermediary variable holding `%rbp`.
This approach is sound when %rbp is saved using a `push`, but
probably wrong when saved using a `mov` on some stack-space allocated
previously (eg. for multiple registers saved at once).
It would be far better to actually read the position at which `v` is
saved, but this requires parsing the actual rhs expression, which is
not easily done: FIXME
*)
let new_rbp =
if (BStd.Var.name @@ BStd.Def.lhs def = "mem"
&& is_rbp_save_expr (BStd.Def.rhs def) cur_state)
then
(match cur_cfa with
| RspOffset off ->
Some (RbpCfaOffset (Int64.mul Int64.minus_one off))
| _ -> raise UnexpectedRbpSet
)
else
None
in
new_rbp, cur_state
| RbpCfaOffset offs ->
(* We go back to RbpUndef when encountering something like a `pop rbp`,
that is, RBP <- f(RSP, mem) *)
(match Regs.X86_64.of_var (BStd.Def.lhs def),
is_pop_expr @@ BStd.Def.rhs def with
| Some reg, true when reg = Regs.X86_64.rbp ->
Some RbpUndef, local_state
| _ -> None, local_state
)
)
in
(match out_cfa, out_rbp with
| None, None -> None
| Some cfa, None -> Some (cfa, cur_rbp)
| None, Some rbp -> Some (cur_cfa, rbp)
| Some cfa, Some rbp -> Some (cfa, rbp)),
new_state
let process_jmp jmp (cur_reg: reg_pos)
: (reg_pos option) =
let cur_cfa, cur_rbp = cur_reg in
let gen_change = match cur_cfa with
| RspOffset cur_offset -> (fun off ->
let new_offset = Int64.add cur_offset (Int64.of_int off) in
Some (RspOffset(new_offset))
Some (RspOffset(new_offset), cur_rbp)
)
| _ -> (fun _ -> None)
in
@ -261,30 +401,34 @@ let process_jmp jmp (cur_cfa: cfa_pos)
| _ -> None
let process_blk
next_instr_graph (block_init: cfa_pos) blk : (cfa_changes_fde * cfa_pos) =
(** Extracts the CFA changes of a block. *)
next_instr_graph (block_init: reg_pos) blk : (reg_changes_fde * reg_pos) =
(** Extracts the registers (CFA+RBP) changes of a block. *)
let apply_offset cur_addr_opt ((accu:cfa_changes_fde), cur_cfa) = function
| None -> (accu, cur_cfa)
| Some pos ->
let cur_addr = (match cur_addr_opt with
| None -> assert false
| Some x -> to_int64_addr x) in
(AddrSet.fold (fun n_addr cur_accu ->
AddrMap.add n_addr pos cur_accu)
(AddrMap.find cur_addr next_instr_graph)
accu),
pos
let apply_offset cur_addr_opt ((accu:reg_changes_fde), cur_reg, local_state)
= function
| None -> (accu, cur_reg, local_state)
| Some reg_pos ->
let cur_addr = (match cur_addr_opt with
| None -> assert false
| Some x -> to_int64_addr x) in
(AddrSet.fold (fun n_addr cur_accu ->
AddrMap.add n_addr reg_pos cur_accu)
(AddrMap.find cur_addr next_instr_graph)
accu),
reg_pos,
local_state
in
let fold_elt (accu, cur_cfa) elt = match elt with
let fold_elt (accu, cur_reg, cur_local_state) elt = match elt with
| `Def(def) ->
let new_offset, new_state = process_def cur_local_state def cur_reg in
apply_offset
(opt_addr_of def) (accu, cur_cfa) @@ process_def def cur_cfa
(opt_addr_of def) (accu, cur_reg, new_state) new_offset
| `Jmp(jmp) ->
apply_offset
(opt_addr_of jmp) (accu, cur_cfa) @@ process_jmp jmp cur_cfa
| _ -> (accu, cur_cfa)
(opt_addr_of jmp) (accu, cur_reg, cur_local_state)
@@ process_jmp jmp cur_reg
| _ -> (accu, cur_reg, cur_local_state)
in
let init_changes = (match opt_addr_of blk with
@ -294,11 +438,14 @@ let process_blk
AddrMap.singleton blk_address block_init
) in
let empty_local_state = {
rbp_vars = BStd.Var.Set.empty
} in
let elts_seq = BStd.Blk.elts blk in
let out, end_cfa = BStd.Seq.fold elts_seq
~init:(init_changes, block_init)
let out_reg, end_reg, _ = BStd.Seq.fold elts_seq
~init:(init_changes, block_init, empty_local_state)
~f:fold_elt in
out, end_cfa
out_reg, end_reg
exception Inconsistent of BStd.tid
@ -356,20 +503,20 @@ let find_last_addr sub =
| None -> Int64.zero
| Some x -> x
let cleanup_fde (fde_changes: cfa_changes_fde) : cfa_changes_fde =
let cleanup_fde (fde_changes: reg_changes_fde) : reg_changes_fde =
(** Cleanup the result of `of_sub`.
Merges entries at the same address, propagates track lost *)
let fold_one addr cfa_change (accu, last_change, lost_track) =
match cfa_change, last_change, lost_track with
let fold_one addr reg_change (accu, last_change, lost_track) =
match reg_change, last_change, lost_track with
| _, _, true -> (accu, None, lost_track)
| CfaLostTrack, _, false ->
(AddrMap.add addr cfa_change accu, None, true)
| cfa_change, Some prev_change, false when cfa_change = prev_change ->
| (CfaLostTrack, _), _, false ->
(AddrMap.add addr reg_change accu, None, true)
| reg_change, Some prev_change, false when reg_change = prev_change ->
(accu, last_change, false)
| cfa_change, _, false ->
(AddrMap.add addr cfa_change accu, Some cfa_change, false)
| reg_change, _, false ->
(AddrMap.add addr reg_change accu, Some reg_change, false)
in
match AddrMap.fold fold_one fde_changes (AddrMap.empty, None, false) with
@ -387,7 +534,9 @@ let process_sub sub : subroutine_cfa_data =
let initial_cfa_rsp_offset = Int64.of_int 8 in
let rec dfs_process
(sub_changes: (cfa_changes_fde * cfa_pos) TIdMap.t) node entry_offset =
(sub_changes: (reg_changes_fde * reg_pos) TIdMap.t)
node
(entry_offset: reg_pos) =
(** Processes one block *)
let cur_blk = CFG.Node.label node in
@ -396,12 +545,12 @@ let process_sub sub : subroutine_cfa_data =
match (TIdMap.find_opt tid sub_changes) with
| None ->
(* Not yet visited: compute the changes *)
let cur_blk_changes, end_cfa =
let cur_blk_changes, end_reg =
process_blk next_instr_graph entry_offset cur_blk in
let n_sub_changes =
TIdMap.add tid (cur_blk_changes, entry_offset) sub_changes in
BStd.Seq.fold (CFG.Node.succs node cfg)
~f:(fun accu child -> dfs_process accu child end_cfa)
~f:(fun accu child -> dfs_process accu child end_reg)
~init:n_sub_changes
| Some (_, former_entry_offset) ->
(* Already visited: check that entry values are matching *)
@ -412,7 +561,7 @@ let process_sub sub : subroutine_cfa_data =
in
let entry_blk = get_entry_blk cfg in
let initial_offset = (RspOffset initial_cfa_rsp_offset) in
let initial_offset = (RspOffset initial_cfa_rsp_offset, RbpUndef) in
let changes_map = dfs_process TIdMap.empty entry_blk initial_offset in
let merged_changes = TIdMap.fold
@ -425,10 +574,10 @@ let process_sub sub : subroutine_cfa_data =
changes_map
AddrMap.empty in
let cfa_changes = cleanup_fde merged_changes in
let reg_changes = cleanup_fde merged_changes in
let output = {
cfa_changes_fde = cfa_changes ;
reg_changes_fde = reg_changes ;
beg_pos = first_addr ;
end_pos = last_addr ;
} in
@ -462,9 +611,11 @@ let of_proj proj : subroutine_cfa_map =
let clean_lost_track_subs pre_dwarf : subroutine_cfa_map =
(** Removes the subroutines on which we lost track from [pre_dwarf] *)
let sub_lost_track sub_name (sub: subroutine_cfa_data) =
not @@ AddrMap.exists (fun addr pos -> (match pos with
not @@ AddrMap.exists (fun addr pos ->
let cfa_pos, _ = pos in
(match cfa_pos with
| RspOffset _ | RbpOffset _ -> false
| CfaLostTrack -> true))
sub.cfa_changes_fde
sub.reg_changes_fde
in
StrMap.filter sub_lost_track pre_dwarf

5
DwarfSynth/c_bindings/dwarf_write.c
View file

@ -231,6 +231,11 @@ static int write_fde_instruction(struct dwarfw_fde *fde,
return -1;
}
if(cur_entry->rbp_defined)
dwarfw_cie_write_offset(fde->cie, 6, cur_entry->rbp_offset, f);
else
dwarfw_cie_write_undefined(fde->cie, 6, f);
return 0;
}

2
DwarfSynth/c_bindings/dwarf_write.h
View file

@ -41,6 +41,8 @@ struct pre_dwarf_entry {
addr_t location;
reg_t cfa_offset_reg;
offset_t cfa_offset;
int rbp_defined;
offset_t rbp_offset;
};
struct pre_dwarf_fde {

7
DwarfSynth/c_bindings/dwarf_write_stubs.c
View file

@ -94,6 +94,11 @@ offset_t convert_offset_t(value offset) {
return (offset_t) int64_of_value(offset);
}
int convert_bool(value boolval) {
CAMLparam1(boolval);
return Bool_val(boolval);
}
struct pre_dwarf_entry * convert_pre_dwarf_entry(value oc_pde) {
struct pre_dwarf_entry *pde = malloc(sizeof(struct pre_dwarf_entry));
@ -103,6 +108,8 @@ struct pre_dwarf_entry * convert_pre_dwarf_entry(value oc_pde) {
pde->location = convert_addr_t(Field(oc_pde, 0));
pde->cfa_offset = convert_offset_t(Field(oc_pde, 1));
pde->cfa_offset_reg = convert_reg_t(Field(oc_pde, 2));
pde->rbp_defined = convert_bool(Field(oc_pde, 3));
pde->rbp_offset = convert_offset_t(Field(oc_pde, 4));
return pde;
}

4
DwarfSynth/c_bindings/ml_dwarf_write.ml
View file

@ -3,7 +3,9 @@
type pre_c_pre_dwarf_entry = {
location: int64;
cfa_offset: int64;
cfa_offset_reg: int
cfa_offset_reg: int;
rbp_defined: bool;
rbp_offset: int64 (* Assumed to be offset of CFA *)
}
type pre_c_pre_dwarf_fde = {