srctree

Jakub Konka parent ca6f41ee 720dd800
elf+riscv: implement enough to get basic hello world in C working

inlinesplit
src/link/Elf/Atom.zig added: 226, removed: 3, total 223
@@ -442,6 +442,10 @@ pub fn scanRelocs(self: Atom, elf_file: *Elf, code: ?[]const u8, undefs: anytype
error.RelocFailure => has_reloc_errors = true,
else => |e| return e,
},
.riscv64 => riscv.scanReloc(self, elf_file, rel, symbol, code, &it) catch |err| switch (err) {
error.RelocFailure => has_reloc_errors = true,
else => |e| return e,
},
else => return error.UnsupportedCpuArch,
}
}
@@ -776,6 +780,12 @@ pub fn resolveRelocsAlloc(self: Atom, elf_file: *Elf, code: []u8) RelocError!voi
=> has_reloc_errors = true,
else => |e| return e,
},
.riscv64 => riscv.resolveRelocAlloc(self, elf_file, rel, target, args, &it, code, &stream) catch |err| switch (err) {
error.RelocFailure,
error.RelaxFailure,
=> has_reloc_errors = true,
else => |e| return e,
},
else => return error.UnsupportedCpuArch,
}
}
@@ -953,6 +963,10 @@ pub fn resolveRelocsNonAlloc(self: Atom, elf_file: *Elf, code: []u8, undefs: any
error.RelocFailure => has_reloc_errors = true,
else => |e| return e,
},
.riscv64 => riscv.resolveRelocNonAlloc(self, elf_file, rel, target, args, &it, code, &stream) catch |err| switch (err) {
error.RelocFailure => has_reloc_errors = true,
else => |e| return e,
},
else => return error.UnsupportedCpuArch,
}
}
@@ -1756,6 +1770,202 @@ const aarch64 = struct {
const aarch64_util = @import("../aarch64.zig");
};
 
const riscv = struct {
fn scanReloc(
atom: Atom,
elf_file: *Elf,
rel: elf.Elf64_Rela,
symbol: *Symbol,
code: ?[]const u8,
it: *RelocsIterator,
) !void {
_ = code;
_ = it;
 
const r_type: elf.R_RISCV = @enumFromInt(rel.r_type());
 
switch (r_type) {
.@"64" => {
try atom.scanReloc(symbol, rel, dynAbsRelocAction(symbol, elf_file), elf_file);
},
 
.HI20 => {
try atom.scanReloc(symbol, rel, absRelocAction(symbol, elf_file), elf_file);
},
 
.CALL_PLT => if (symbol.flags.import) {
symbol.flags.needs_plt = true;
},
 
.GOT_HI20 => {
symbol.flags.needs_got = true;
},
 
.PCREL_HI20,
.PCREL_LO12_I,
.PCREL_LO12_S,
.LO12_I,
.ADD32,
.SUB32,
=> {},
 
else => try atom.reportUnhandledRelocError(rel, elf_file),
}
}
 
fn resolveRelocAlloc(
atom: Atom,
elf_file: *Elf,
rel: elf.Elf64_Rela,
target: *const Symbol,
args: ResolveArgs,
it: *RelocsIterator,
code: []u8,
stream: anytype,
) !void {
const r_type: elf.R_RISCV = @enumFromInt(rel.r_type());
const r_offset = std.math.cast(usize, rel.r_offset) orelse return error.Overflow;
const cwriter = stream.writer();
 
const P, const A, const S, const GOT, const G, const TP, const DTP, const ZIG_GOT = args;
_ = TP;
_ = DTP;
_ = ZIG_GOT;
 
switch (r_type) {
.NONE => unreachable,
 
.@"64" => {
try atom.resolveDynAbsReloc(
target,
rel,
dynAbsRelocAction(target, elf_file),
elf_file,
cwriter,
);
},
 
.ADD32 => riscv_util.writeAddend(i32, .add, code[r_offset..][0..4], S + A),
.SUB32 => riscv_util.writeAddend(i32, .sub, code[r_offset..][0..4], S + A),
 
.HI20 => {
const value: u32 = @bitCast(math.cast(i32, S + A) orelse return error.Overflow);
riscv_util.writeInstU(code[r_offset..][0..4], value);
},
 
.LO12_I => {
const value: u32 = @bitCast(math.cast(i32, S + A) orelse return error.Overflow);
riscv_util.writeInstI(code[r_offset..][0..4], value);
},
 
.GOT_HI20 => {
assert(target.flags.has_got);
const disp: u32 = @bitCast(math.cast(i32, G + GOT + A - P) orelse return error.Overflow);
riscv_util.writeInstU(code[r_offset..][0..4], disp);
},
 
.CALL_PLT => {
// TODO: relax
const disp: u32 = @bitCast(math.cast(i32, S + A - P) orelse return error.Overflow);
riscv_util.writeInstU(code[r_offset..][0..4], disp); // auipc
riscv_util.writeInstI(code[r_offset + 4 ..][0..4], disp); // jalr
},
 
.PCREL_HI20 => {
const disp: u32 = @bitCast(math.cast(i32, S + A - P) orelse return error.Overflow);
riscv_util.writeInstU(code[r_offset..][0..4], disp);
},
 
.PCREL_LO12_I,
.PCREL_LO12_S,
=> {
assert(A == 0); // according to the spec
// We need to find the paired reloc for this relocation.
// TODO: should we search forward too?
const file_ptr = atom.file(elf_file).?;
const pos = it.pos;
const pair = while (it.prev()) |pair| {
if (target.address(.{}, elf_file) == atom.address(elf_file) + pair.r_offset) {
break pair;
}
} else unreachable; // TODO error
it.pos = pos;
const target_ = switch (file_ptr) {
.zig_object => |x| elf_file.symbol(x.symbol(pair.r_sym())),
.object => |x| elf_file.symbol(x.symbols.items[pair.r_sym()]),
else => unreachable,
};
const S_ = @as(i64, @intCast(target_.address(.{}, elf_file)));
const A_ = pair.r_addend;
const P_ = @as(i64, @intCast(atom.address(elf_file) + pair.r_offset));
const G_ = @as(i64, @intCast(target_.gotAddress(elf_file))) - GOT;
const disp = switch (@as(elf.R_RISCV, @enumFromInt(pair.r_type()))) {
.PCREL_HI20 => math.cast(i32, S_ + A_ - P_) orelse return error.Overflow,
.GOT_HI20 => math.cast(i32, G_ + GOT + A_ - P_) orelse return error.Overflow,
else => unreachable,
};
relocs_log.debug(" [{x} => {x}]", .{ P_, disp + P_ });
switch (r_type) {
.PCREL_LO12_I => riscv_util.writeInstI(code[r_offset..][0..4], @bitCast(disp)),
.PCREL_LO12_S => riscv_util.writeInstS(code[r_offset..][0..4], @bitCast(disp)),
else => unreachable,
}
},
 
else => try atom.reportUnhandledRelocError(rel, elf_file),
}
}
 
fn resolveRelocNonAlloc(
atom: Atom,
elf_file: *Elf,
rel: elf.Elf64_Rela,
target: *const Symbol,
args: ResolveArgs,
it: *RelocsIterator,
code: []u8,
stream: anytype,
) !void {
_ = target;
_ = it;
 
const r_type: elf.R_RISCV = @enumFromInt(rel.r_type());
const r_offset = std.math.cast(usize, rel.r_offset) orelse return error.Overflow;
const cwriter = stream.writer();
 
_, const A, const S, const GOT, _, _, const DTP, _ = args;
_ = GOT;
_ = DTP;
 
switch (r_type) {
.NONE => unreachable,
 
.@"32" => try cwriter.writeInt(i32, @as(i32, @intCast(S + A)), .little),
.@"64" => try cwriter.writeInt(i64, S + A, .little),
 
.ADD8 => riscv_util.writeAddend(i8, .add, code[r_offset..][0..1], S + A),
.SUB8 => riscv_util.writeAddend(i8, .sub, code[r_offset..][0..1], S + A),
.ADD16 => riscv_util.writeAddend(i16, .add, code[r_offset..][0..2], S + A),
.SUB16 => riscv_util.writeAddend(i16, .sub, code[r_offset..][0..2], S + A),
.ADD32 => riscv_util.writeAddend(i32, .add, code[r_offset..][0..4], S + A),
.SUB32 => riscv_util.writeAddend(i32, .sub, code[r_offset..][0..4], S + A),
.ADD64 => riscv_util.writeAddend(i64, .add, code[r_offset..][0..8], S + A),
.SUB64 => riscv_util.writeAddend(i64, .sub, code[r_offset..][0..8], S + A),
 
.SET8 => mem.writeInt(i8, code[r_offset..][0..1], @as(i8, @truncate(S + A)), .little),
.SET16 => mem.writeInt(i16, code[r_offset..][0..2], @as(i16, @truncate(S + A)), .little),
.SET32 => mem.writeInt(i32, code[r_offset..][0..4], @as(i32, @truncate(S + A)), .little),
 
.SET6 => riscv_util.writeSetSub6(.set, code[r_offset..][0..1], S + A),
.SUB6 => riscv_util.writeSetSub6(.sub, code[r_offset..][0..1], S + A),
 
else => try atom.reportUnhandledRelocError(rel, elf_file),
}
}
 
const riscv_util = @import("../riscv.zig");
};
 
const ResolveArgs = struct { i64, i64, i64, i64, i64, i64, i64, i64 };
 
const RelocError = error{
@@ -1796,10 +2006,11 @@ const elf = std.elf;
const eh_frame = @import("eh_frame.zig");
const log = std.log.scoped(.link);
const math = std.math;
const mem = std.mem;
const relocs_log = std.log.scoped(.link_relocs);
const relocation = @import("relocation.zig");
 
const Allocator = std.mem.Allocator;
const Allocator = mem.Allocator;
const Atom = @This();
const Elf = @import("../Elf.zig");
const Fde = eh_frame.Fde;
 
src/link/Elf/eh_frame.zig added: 226, removed: 3, total 223
@@ -319,6 +319,7 @@ fn resolveReloc(rec: anytype, sym: *const Symbol, rel: elf.Elf64_Rela, elf_file:
switch (cpu_arch) {
.x86_64 => try x86_64.resolveReloc(rec, elf_file, rel, P, S + A, contents[offset..]),
.aarch64 => try aarch64.resolveReloc(rec, elf_file, rel, P, S + A, contents[offset..]),
.riscv64 => try riscv.resolveReloc(rec, elf_file, rel, P, S + A, contents[offset..]),
else => return error.UnsupportedCpuArch,
}
}
@@ -577,6 +578,17 @@ const aarch64 = struct {
}
};
 
const riscv = struct {
fn resolveReloc(rec: anytype, elf_file: *Elf, rel: elf.Elf64_Rela, source: i64, target: i64, data: []u8) !void {
const r_type: elf.R_RISCV = @enumFromInt(rel.r_type());
switch (r_type) {
.NONE => {},
.@"32_PCREL" => std.mem.writeInt(i32, data[0..4], @as(i32, @intCast(target - source)), .little),
else => try reportInvalidReloc(rec, elf_file, rel),
}
}
};
 
fn reportInvalidReloc(rec: anytype, elf_file: *Elf, rel: elf.Elf64_Rela) !void {
var err = try elf_file.addErrorWithNotes(1);
try err.addMsg(elf_file, "invalid relocation type {} at offset 0x{x}", .{