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smol
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CRC32C-based hash (thanks Intel) (Python part is still TODO)

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pull/17/head
PoroCYon 3 years ago
parent d7135e3fe9
commit 1e17d11774
6 changed files with 125 additions and 43 deletions
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  1. 5
      .gitignore
  2. 34
      rt/loader32.asm
  3. 45
      rt/loader64.asm
  4. 36
      smol/emit.py
  5. 31
      smol/shared.py
  6. 17
      smold.py

5
.gitignore vendored
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@ -1,5 +1,6 @@
/bin
/obj
__pycache__
smol-*-*-*/
*.tar.xz
smol-20*-*-*/
smol*.tar.xz

34
rt/loader32.asm
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@ -104,34 +104,44 @@ _smol_start:
add esi, ebx
push ecx
%ifndef USE_HASH16
; source in eax, result in eax
%ifdef USE_CRC32C_HASH
push -1
pop eax
%else
%ifndef USE_HASH16
push ebx
push 33
push 5381
pop eax
pop ebx
%else
%else
xor eax, eax
%endif
%endif
xor ecx, ecx
%endif
.nexthashiter:
;
xchg eax, ecx
lodsb
or al, al
xchg eax, ecx
jz short .breakhash
%ifndef USE_HASH16
%ifdef USE_CRC32C_HASH
crc32 eax, cl
%else
%ifndef USE_HASH16
push edx
mul ebx
pop edx
; add eax, ecx
%else
%else
ror ax, 2
; add ax, cx
%endif
%endif
add eax, ecx
%endif
jmp short .nexthashiter
.breakhash:
@ -173,16 +183,16 @@ _smol_start:
cmp al, STT_GNU_IFUNC
jne short .no_ifunc
;int3
%ifdef IFUNC_CORRECT_CCONV
%ifdef IFUNC_CORRECT_CCONV
; call destroys stuff, but we only need to preserve edi
; for our purposes anyway. we do need one push to align the
; stack to 16 bytes
push edi
call ecx
pop edi
%else
%else
call ecx
%endif
%endif
db 0x3c ; cmp al, <next byte == xchg ecx,eax> --> jump over next insn
.no_ifunc:
xchg ecx, eax
@ -287,14 +297,14 @@ repne scasd
cmp al, STT_GNU_IFUNC
jne short .no_ifunc
;int3
%ifdef IFUNC_CORRECT_CCONV
%ifdef IFUNC_CORRECT_CCONV
; call destroys stuff, but we only need to preserve edi
; for our purposes anyway. we do need one push to align the
; stack to 16 bytes
push edi
call ecx
pop edi
%else
%else
call ecx
%endif
db 0x3c ; cmp al, <next byte == xchg ecx,eax> --> jump over next insn

45
rt/loader64.asm
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@ -1,4 +1,4 @@
; vim: set ft=nasm:
; vim: set ft=nasm et:
%ifndef HASH_END_TYP
%warning "W: HASH_END_TYP not defined, falling back to 16-bit!"
@ -101,6 +101,8 @@ _smol_start:
mov esi, dword [rdx + ST_NAME_OFF]
add rsi, r8;9
%ifndef USE_CRC32C_HASH
; djb2
xor ecx, ecx
push 33
push 5381
@ -108,22 +110,45 @@ _smol_start:
; pop rcx
pop rax
pop rbx
%else
; crc32
push -1
pop rcx
%endif
.nexthashiter:
%ifndef USE_CRC32C_HASH
; djb2
; TODO: optimize register usage a bit more
xchg eax, ecx
%endif
lodsb
or al, al
%ifndef USE_CRC32C_HASH
; djb2
xchg eax, ecx
%endif
jz short .breakhash
%ifndef USE_CRC32C_HASH
; djb2
push rdx
mul ebx
pop rdx
add eax, ecx
%else
; crc32c
crc32 ecx, al
%endif
jmp short .nexthashiter
.breakhash:
%ifdef USE_CRC32C_HASH
; crc32c
cmp r14d, ecx
%else
; djb2
cmp r14d, eax
%endif
je short .hasheq
add rdx, SYMTAB_SIZE
@ -144,7 +169,7 @@ _smol_start:
%ifdef IFUNC_SUPPORT
and cl, ST_INFO__STT_MASK
cmp cl, STT_GNU_IFUNC
%ifdef SKIP_ZERO_VALUE
%ifdef SKIP_ZERO_VALUE
jne short .no_ifunc2
push rdi
push r11
@ -152,25 +177,25 @@ _smol_start:
pop r11
pop rdi
.no_ifunc2:
%else ; !SKIP_ZERO_VALUE
%else ; !SKIP_ZERO_VALUE
je short .ifunc
.no_ifunc:
%endif
%endif
%endif
stosq
cmp HASH_END_TYP [rdi], 0
%ifdef IFUNC_SUPPORT
%ifdef SKIP_ZERO_VALUE
%ifdef SKIP_ZERO_VALUE
jne .next_hash;short .next_hash
%else ; IFUNC_SUPPORT && !SKIP_ZERO_VALUE
%else ; IFUNC_SUPPORT && !SKIP_ZERO_VALUE
jne short .next_hash
%endif
%endif
%else ; !IFUNC_SUPPORT
jne short .next_hash
%endif
%ifdef IFUNC_SUPPORT
%ifndef SKIP_ZERO_VALUE
%ifndef SKIP_ZERO_VALUE
jmp short .break_loop
.ifunc:
;;int3 ; in this call, we lose rax rcx rdx rsi rdi r8 r9 r10 r11
@ -194,7 +219,7 @@ _smol_start:
;pop rcx
jmp short .no_ifunc
.break_loop:
%endif
%endif
%endif
; if USE_DNLOAD_LOADER

36
smol/emit.py
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@ -37,13 +37,16 @@ def sort_imports(libraries, hashfn):
if sys.version_info < (3, 6): return OrderedDict(ll)
else: return dict(ll)
def output_x86(libraries, nx, h16, outf, det):
def output_x86(libraries, nx, hashid, outf, det):
outf.write('; vim: set ft=nasm:\n') # be friendly
if nx: outf.write('%define USE_NX 1\n')
if h16: outf.write('%define USE_HASH16 1\n')
defff = define_for_hash[hashid]
if defff is not None:
outf.write('%define {} 1\n'.format(defff))
if nx:
outf.write('%define USE_NX 1\n')
hashfn = hash_bsd2 if h16 else hash_djb2
hashfn = get_hash_fn(hashid)
if det: libraries = sort_imports(libraries, hashfn)
outf.write('%%define HASH_END_TYP %s\n' %
@ -128,22 +131,25 @@ global {name}
# end output_x86
def output_amd64(libraries, nx, h16, outf, det):
if h16:
def output_amd64(libraries, nx, hashid, outf, det):
if hashid == HASH_BSD2:
error("--hash16 not supported yet for x86_64 outputs.")
if nx: outf.write('%define USE_NX 1\n')
# if h16: outf.write('%define USE_HASH16 1\n')
outf.write('; vim: set ft=nasm:\n')
outf.write('bits 64\n')
defff = define_for_hash[hashid]
if defff is not None:
outf.write('%define {} 1\n'.format(defff))
if nx:
outf.write('%define USE_NX 1\n')
hashfn = hash_djb2 #hash_bsd2 if h16 else hash_djb2
hashfn = get_hash_fn(hashid)
if det: libraries = sort_imports(libraries, hashfn)
outf.write('%%define HASH_END_TYP %s\n' %
fetch_width_from_bits[get_min_check_width(libraries, hashfn)])
outf.write('; vim: set ft=nasm:\n')
outf.write('bits 64\n')
shorts = { l: l.split('.', 1)[0].lower().replace('-', '_') for l in libraries }
outf.write('%include "header64.asm"\n')
@ -208,9 +214,9 @@ global {name}
# end output_amd64
def output(arch, libraries, nx, h16, outf, det):
if arch == 'i386': output_x86(libraries, nx, h16, outf, det)
elif arch == 'x86_64': output_amd64(libraries, nx, h16, outf, det)
def output(arch, libraries, nx, hashid, outf, det):
if arch == 'i386': output_x86(libraries, nx, hashid, outf, det)
elif arch == 'x86_64': output_amd64(libraries, nx, hashid, outf, det)
else:
error("E: cannot emit for arch '%s'" % str(arch))

31
smol/shared.py
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@ -9,6 +9,16 @@ archmagic = {
'x86_64': 62, 62: 'x86_64',
}
HASH_DJB2 = 0
HASH_BSD2 = 1
HASH_CRC32C=2
define_for_hash = {
HASH_DJB2: None
HASH_BSD2: 'USE_HASH16',
HASH_CRC32C: 'USE_CRC32C_HASH'
}
def hash_bsd2(s):
h = 0
@ -24,10 +34,31 @@ def hash_djb2(s):
return h
def hash_crc32c(s):
# crc32 implementation is basically:
# sum = -1; for (; *s; ++s) crc32_instr(&sum, *s); return sum
assert False, "not implemented!" # TODO
def eprintf(*args, **kwargs):
print(*args, file=sys.stderr, **kwargs)
def get_hash_id(h16, c32):
if not h16 and not c32:
return HASH_DJB2
elif h16 and not c32:
return HASH_BSD2
elif not h16 and c32:
return HASH_CRC32C
else:
return False, "??????? (shouldn't happen)"
def get_hash_fn(hid):
return (hash_djb2, hash_bsd2, hash_crc32c)[hid]
def error(*args, **kwargs):
traceback.print_stack()
eprintf(*args, **kwargs)

17
smold.py
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@ -24,8 +24,11 @@ def main():
help="directories to search libraries in")
parser.add_argument('-s', '--hash16', default=False, action='store_true', \
help="Use 16-bit (BSD) hashes instead of 32-bit djb2 hashes. "+\
"Implies -fuse-dnload-loader")
help="Use 16-bit (BSD2) hashes instead of 32-bit djb2 hashes. "+\
"Implies -fuse-dnload-loader. Only usable for 32-bit output.")
parser.add_argument('-c', '--crc32c', default=False, action='store_true', \
help="Use Intel's crc32 intrinsic for hashing. "+\
"Implies -fuse-dnload-loader. Conflicts with `--hash16'.")
parser.add_argument('-n', '--nx', default=False, action='store_true', \
help="Use NX (i.e. don't use RWE pages). Costs the size of one phdr, "+\
"plus some extra bytes on i386.")
@ -118,7 +121,10 @@ def main():
args = parser.parse_args()
if args.hash16:
if args.hash16 and args.crc32c:
error("Cannot combine --hash16 and --crc32c!")
if args.hash16 or args.crc32c:
args.fuse_dnload_loader = True
if args.fskip_zero_value: args.asflags.insert(0, "-DSKIP_ZERO_VALUE")
@ -145,6 +151,9 @@ def main():
error("Unknown/unsupported architecture '%s'" % str(arch))
if args.verbose: eprintf("arch: %s" % str(arch))
if args.hash16 and arch not in ('i386', 3):
error("Cannot use --hash16 for arch `%s' (not i386)" % (arch))
objinput = None
objinputistemp = False
tmp_asm_file = args.output
@ -180,7 +189,7 @@ def main():
symbols[library].append((symbol, reloc))
with os.fdopen(tmp_asm_fd, mode='w') as taf:
output(arch, symbols, args.nx, args.hash16, taf, args.det)
output(arch, symbols, args.nx, get_hash_id(args.hash16, args.crc32c), taf, args.det)
if args.verbose:
eprintf("wrote symtab to %s" % tmp_asm_file)

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