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This commit is contained in:
Rui Ueyama 2020-11-03 20:26:22 +09:00
parent 4421ff5571
commit 6a895c51e6
3 changed files with 89 additions and 84 deletions
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78
main.cc
View File

@ -338,6 +338,82 @@ create_shdrs(ArrayRef<OutputChunk *> output_chunks) {
return vec;
}
static u32 to_phdr_flags(u64 sh_flags) {
u32 ret = PF_R;
if (sh_flags & SHF_WRITE)
ret |= PF_W;
if (sh_flags & SHF_EXECINSTR)
ret |= PF_X;
return ret;
}
static std::vector<OutputPhdr::Entry>
create_phdrs(ArrayRef<OutputChunk *> output_chunks) {
std::vector<OutputPhdr::Entry> entries;
auto add = [&](u32 type, u32 flags, u32 align, std::vector<OutputChunk *> members) {
ELF64LE::Phdr phdr = {};
phdr.p_type = type;
phdr.p_flags = flags;
phdr.p_align = align;
entries.push_back({phdr, members});
};
// Create a PT_PHDR for the program header itself.
add(PT_PHDR, PF_R, 8, {out::phdr});
// Create an PT_INTERP.
if (out::interp)
add(PT_INTERP, PF_R, 1, {out::interp});
// Create PT_LOAD segments.
bool first = true;
bool last_was_bss;
for (OutputChunk *chunk : output_chunks) {
if (!(chunk->shdr.sh_flags & SHF_ALLOC))
break;
u32 flags = to_phdr_flags(chunk->shdr.sh_flags);
bool this_is_bss =
(chunk->shdr.sh_type == SHT_NOBITS && !(chunk->shdr.sh_flags & SHF_TLS));
if (first) {
add(PT_LOAD, flags, PAGE_SIZE, {chunk});
last_was_bss = this_is_bss;
first = false;
continue;
}
if (entries.back().phdr.p_flags != flags || (last_was_bss && !this_is_bss))
add(PT_LOAD, flags, PAGE_SIZE, {chunk});
else
entries.back().members.push_back(chunk);
last_was_bss = this_is_bss;
}
// Create a PT_TLS.
for (int i = 0; i < output_chunks.size(); i++) {
if (output_chunks[i]->shdr.sh_flags & SHF_TLS) {
std::vector<OutputChunk *> vec = {output_chunks[i++]};
while (i < output_chunks.size() && (output_chunks[i]->shdr.sh_flags & SHF_TLS))
vec.push_back(output_chunks[i++]);
add(PT_TLS, to_phdr_flags(output_chunks[i]->shdr.sh_flags), 1, vec);
}
}
for (OutputPhdr::Entry &ent : entries)
for (OutputChunk *chunk : ent.members)
ent.phdr.p_align = std::max(ent.phdr.p_align, chunk->shdr.sh_addralign);
for (OutputPhdr::Entry &ent : entries)
if (ent.phdr.p_type == PT_LOAD)
ent.members.front()->starts_new_ptload = true;
return entries;
}
static u64 set_osec_offsets(ArrayRef<OutputChunk *> output_chunks) {
u64 fileoff = 0;
u64 vaddr = 0x200000;
@ -617,7 +693,7 @@ int main(int argc, char **argv) {
// Create section header and program header contents.
out::shdr->set_entries(create_shdrs(output_chunks));
out::phdr->construct(output_chunks);
out::phdr->set_entries(create_phdrs(output_chunks));
out::symtab->shdr.sh_link = out::strtab->shndx;
// Assign offsets to output sections

18
mold.h
View File

@ -280,18 +280,20 @@ public:
// Program header
class OutputPhdr : public OutputChunk {
public:
OutputPhdr() { shdr.sh_flags = llvm::ELF::SHF_ALLOC; }
void relocate(u8 *buf) override;
void construct(std::vector<OutputChunk *> &sections);
private:
struct Phdr {
struct Entry {
ELF64LE::Phdr phdr;
std::vector<OutputChunk *> members;
};
std::vector<Phdr> entries;
OutputPhdr() { shdr.sh_flags = llvm::ELF::SHF_ALLOC; }
void relocate(u8 *buf) override;
void set_entries(std::vector<Entry> vec) {
shdr.sh_size = vec.size() * sizeof(ELF64LE::Phdr);
entries = std::move(vec);
}
std::vector<Entry> entries;
};
// Sections

77
output_chunks.cc
View File

@ -54,81 +54,8 @@ void OutputEhdr::relocate(u8 *buf) {
hdr->e_shstrndx = out::shstrtab->shndx;
}
static u32 to_phdr_flags(u64 sh_flags) {
u32 ret = PF_R;
if (sh_flags & SHF_WRITE)
ret |= PF_W;
if (sh_flags & SHF_EXECINSTR)
ret |= PF_X;
return ret;
}
void OutputPhdr::construct(std::vector<OutputChunk *> &chunks) {
auto add = [&](u32 type, u32 flags, u32 align, std::vector<OutputChunk *> members) {
ELF64LE::Phdr phdr = {};
phdr.p_type = type;
phdr.p_flags = flags;
phdr.p_align = align;
entries.push_back({phdr, members});
};
// Create a PT_PHDR for the program header itself.
add(PT_PHDR, PF_R, 8, {out::phdr});
// Create an PT_INTERP.
if (out::interp)
add(PT_INTERP, PF_R, 1, {out::interp});
// Create PT_LOAD segments.
bool first = true;
bool last_was_bss;
for (OutputChunk *chunk : chunks) {
if (!(chunk->shdr.sh_flags & SHF_ALLOC))
break;
u32 flags = to_phdr_flags(chunk->shdr.sh_flags);
bool this_is_bss =
(chunk->shdr.sh_type == SHT_NOBITS && !(chunk->shdr.sh_flags & SHF_TLS));
if (first) {
add(PT_LOAD, flags, PAGE_SIZE, {chunk});
last_was_bss = this_is_bss;
first = false;
continue;
}
if (entries.back().phdr.p_flags != flags || (last_was_bss && !this_is_bss))
add(PT_LOAD, flags, PAGE_SIZE, {chunk});
else
entries.back().members.push_back(chunk);
last_was_bss = this_is_bss;
}
// Create a PT_TLS.
for (int i = 0; i < chunks.size(); i++) {
if (chunks[i]->shdr.sh_flags & SHF_TLS) {
std::vector<OutputChunk *> vec = {chunks[i++]};
while (i < chunks.size() && (chunks[i]->shdr.sh_flags & SHF_TLS))
vec.push_back(chunks[i++]);
add(PT_TLS, to_phdr_flags(chunks[i]->shdr.sh_flags), 1, vec);
}
}
for (Phdr &ent : entries)
for (OutputChunk *chunk : ent.members)
ent.phdr.p_align = std::max(ent.phdr.p_align, chunk->shdr.sh_addralign);
for (Phdr &ent : entries)
if (ent.phdr.p_type == PT_LOAD)
ent.members.front()->starts_new_ptload = true;
this->shdr.sh_size = entries.size() * sizeof(ELF64LE::Phdr);
}
void OutputPhdr::relocate(u8 *buf) {
for (Phdr &ent : entries) {
for (Entry &ent : entries) {
OutputChunk *front = ent.members.front();
OutputChunk *back = ent.members.back();
@ -142,7 +69,7 @@ void OutputPhdr::relocate(u8 *buf) {
}
auto *p = (ELF64LE::Phdr *)(buf + shdr.sh_offset);
for (Phdr &ent : entries)
for (Entry &ent : entries)
*p++ = ent.phdr;
}