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|
-- | Writer assembler to an object file.
module Language.Elna.PrinterWriter
( riscv32Elf
) where
import Data.Word (Word8)
import Data.ByteString (ByteString)
import qualified Data.ByteString as ByteString
import qualified Data.ByteString.Builder as ByteString.Builder
import qualified Data.ByteString.Lazy as LazyByteString
import Data.Vector (Vector)
import qualified Data.Vector as Vector
import Language.Elna.Object.Elf
( ByteOrder(..)
, Elf32_Addr
, Elf32_Ehdr(..)
, Elf32_Half
, Elf32_Word
, Elf32_Sym(..)
, ElfMachine(..)
, ElfType(..)
, ElfVersion(..)
, ElfIdentification(..)
, ElfClass(..)
, ElfData(..)
, Elf32_Shdr(..)
, ElfSectionType(..)
, ElfSymbolBinding(..)
, ElfSymbolType(..)
, Elf32_Rel(..)
, ElfWriter(..)
, ElfHeaderResult(..)
, elf32Sym
, elfHeaderSize
, elfSectionsSize
, stInfo
, rInfo
, elf32Rel
, shfInfoLink
, addSectionHeader
)
import System.IO (Handle)
import qualified Language.Elna.Architecture.RiscV as RiscV
import qualified Data.Text.Encoding as Text.Encoding
import Control.Monad.IO.Class (MonadIO(..))
import Control.Monad.Trans.State (get)
data UnresolvedRelocation = UnresolvedRelocation ByteString Elf32_Addr Word8
data UnresolvedRelocations = UnresolvedRelocations (Vector UnresolvedRelocation) Elf32_Word
riscv32Elf :: Vector RiscV.Instruction -> Handle -> ElfWriter Elf32_Ehdr
riscv32Elf code objectHandle = text
>>= uncurry symrel
>>= strtab
>> shstrtab
>>= riscv32Header
where
shstrtab :: ElfWriter Elf32_Half
shstrtab = do
ElfHeaderResult{..} <- ElfWriter get
let stringTable = sectionNames <> ".shstrtab\0"
nextHeader = Elf32_Shdr
{ sh_type = SHT_STRTAB
, sh_size = fromIntegral $ ByteString.length stringTable
, sh_offset = elfSectionsSize sectionHeaders
, sh_name = fromIntegral $ ByteString.length sectionNames
, sh_link = 0
, sh_info = 0
, sh_flags = 0
, sh_entsize = 0
, sh_addralign = 1
, sh_addr = 0
}
liftIO $ ByteString.hPut objectHandle stringTable
addSectionHeader ".shstrtab" nextHeader
pure $ fromIntegral $ Vector.length sectionHeaders
riscv32Header :: Elf32_Half -> ElfWriter Elf32_Ehdr
riscv32Header shstrndx = do
ElfHeaderResult{..} <- ElfWriter get
pure $ Elf32_Ehdr
{ e_version = EV_CURRENT
, e_type = ET_REL
, e_shstrndx = shstrndx
, e_shoff = elfSectionsSize sectionHeaders
, e_shnum = fromIntegral (Vector.length sectionHeaders)
, e_shentsize = 40
, e_phoff = 0
, e_phnum = 0
, e_phentsize = 32
, e_machine = EM_RISCV
, e_ident = ElfIdentification ELFCLASS32 ELFDATA2LSB
, e_flags = 0x4 -- EF_RISCV_FLOAT_ABI_DOUBLE
, e_entry = 0
, e_ehsize = fromIntegral elfHeaderSize
}
takeStringZ stringTable Elf32_Sym{ st_name }
= ByteString.takeWhile (/= 0)
$ ByteString.drop (fromIntegral st_name) stringTable
resolveRelocation (ElfHeaderResult stringTable entries) unresolvedRelocation
| UnresolvedRelocation symbolName offset type' <- unresolvedRelocation
, Just entry <- Vector.findIndex ((== symbolName) . takeStringZ stringTable) entries =
Right $ Elf32_Rel
{ r_offset = offset
, r_info = rInfo (fromIntegral entry) type'
}
| otherwise = Left unresolvedRelocation
symtab entries = do
ElfHeaderResult{..} <- ElfWriter get
let encodedSymbols = LazyByteString.toStrict
$ ByteString.Builder.toLazyByteString
$ foldMap (elf32Sym LSB) entries
symHeader = Elf32_Shdr
{ sh_type = SHT_SYMTAB
, sh_size = fromIntegral $ ByteString.length encodedSymbols
, sh_offset = elfSectionsSize sectionHeaders
, sh_name = fromIntegral $ ByteString.length sectionNames
, sh_link = fromIntegral $ Vector.length sectionHeaders + 2
, sh_info = 1
, sh_flags = 0
, sh_entsize = 16
, sh_addralign = 4
, sh_addr = 0
}
liftIO $ ByteString.hPut objectHandle encodedSymbols
addSectionHeader ".symtab" symHeader
pure $ fromIntegral $ Vector.length sectionHeaders
symrel symbols relocations = do
let UnresolvedRelocations relocationList index = relocations
ElfHeaderResult stringTable entries = symbols
sectionHeadersLength <- symtab entries
ElfHeaderResult{..} <- ElfWriter get
let encodedRelocations = LazyByteString.toStrict
$ ByteString.Builder.toLazyByteString
$ Vector.foldMap (either (const mempty) (elf32Rel LSB))
$ resolveRelocation symbols <$> relocationList
relHeader = Elf32_Shdr
{ sh_type = SHT_REL
, sh_size = fromIntegral $ ByteString.length encodedRelocations
, sh_offset = elfSectionsSize sectionHeaders
, sh_name = fromIntegral $ ByteString.length sectionNames
, sh_link = sectionHeadersLength
, sh_info = index
, sh_flags = shfInfoLink
, sh_entsize = 8
, sh_addralign = 4
, sh_addr = 0
}
liftIO $ ByteString.hPut objectHandle encodedRelocations
addSectionHeader ".rel.text" relHeader
pure stringTable
strtab stringTable = do
ElfHeaderResult{..} <- ElfWriter get
let strHeader = Elf32_Shdr
{ sh_type = SHT_STRTAB
, sh_size = fromIntegral $ ByteString.length stringTable
, sh_offset = elfSectionsSize sectionHeaders
, sh_name = fromIntegral $ ByteString.length sectionNames
, sh_link = 0
, sh_info = 0
, sh_flags = 0
, sh_entsize = 0
, sh_addralign = 1
, sh_addr = 0
}
liftIO $ ByteString.hPut objectHandle stringTable
addSectionHeader ".strtab" strHeader
text = do
ElfHeaderResult{..} <- ElfWriter get
let textTabIndex = fromIntegral $ Vector.length sectionHeaders
initialHeaders = ElfHeaderResult "\0"
$ Vector.singleton
$ Elf32_Sym
{ st_value = 0
, st_size = 0
, st_shndx = 0
, st_other = 0
, st_name = 0
, st_info = 0
}
(symbolResult, size, relocations) <- symbolEntry textTabIndex code
(initialHeaders, 0, mempty)
let newHeader = Elf32_Shdr
{ sh_type = SHT_PROGBITS
, sh_size = size
, sh_offset = elfSectionsSize sectionHeaders
, sh_name = fromIntegral $ ByteString.length sectionNames
, sh_link = 0
, sh_info = 0
, sh_flags = 0b110
, sh_entsize = 0
, sh_addralign = 4
, sh_addr = 0
}
addSectionHeader ".text" newHeader
pure (symbolResult, UnresolvedRelocations relocations $ fromIntegral $ Vector.length sectionHeaders)
symbolEntry
:: Elf32_Half
-> Vector RiscV.Instruction
-> (ElfHeaderResult Elf32_Sym, Elf32_Addr, Vector UnresolvedRelocation)
-> ElfWriter (ElfHeaderResult Elf32_Sym, Elf32_Addr, Vector UnresolvedRelocation)
symbolEntry shndx instructions (ElfHeaderResult names entries, offset, relocations) = do
let (encoded, size, updatedRelocations) =
Vector.foldl' encodeInstruction (mempty, offset, relocations) instructions
newEntry = Elf32_Sym
{ st_value = offset
, st_size = fromIntegral size
, st_shndx = shndx
, st_other = 0
, st_name = fromIntegral $ ByteString.length names
, st_info = stInfo STB_GLOBAL STT_FUNC
}
printEntry = Elf32_Sym
{ st_value = 0
, st_size = 0
, st_shndx = 0
, st_other = 0
, st_name = fromIntegral (ByteString.length names) + 7
, st_info = stInfo STB_GLOBAL STT_FUNC
}
liftIO $ ByteString.hPut objectHandle $ LazyByteString.toStrict encoded
let newResult = ElfHeaderResult (names <> "_start\0printi\0")
$ Vector.snoc (Vector.snoc entries newEntry) printEntry
pure (newResult, size, updatedRelocations)
encodeInstruction (instructions, offset, relocations) instruction =
let unresolvedRelocation = case instruction of
RiscV.RelocatableInstruction _ instructionType
| RiscV.Higher20 _ symbolName <- instructionType
-> Just -- R_RISCV_HI20
$ UnresolvedRelocation (Text.Encoding.encodeUtf8 symbolName) offset 26
| RiscV.Lower12I _ _ _ symbolName <- instructionType
-> Just -- R_RISCV_LO12_I
$ UnresolvedRelocation (Text.Encoding.encodeUtf8 symbolName) offset 27
| RiscV.Lower12S symbolName _ _ _ <- instructionType
-> Just -- R_RISCV_LO12_S
$ UnresolvedRelocation (Text.Encoding.encodeUtf8 symbolName) offset 28
RiscV.CallInstruction symbolName
-> Just -- R_RISCV_CALL_PLT
$ UnresolvedRelocation (Text.Encoding.encodeUtf8 symbolName) offset 19
RiscV.Instruction _ _ -> Nothing
encoded = ByteString.Builder.toLazyByteString
$ RiscV.instruction instruction
in
( instructions <> encoded
, offset + fromIntegral (LazyByteString.length encoded)
, maybe relocations (Vector.snoc relocations) unresolvedRelocation
)
|
