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std.os.linux.pie: Remove .weak/.hidden usage in inline assembly. #21260

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std.os.linux.pie: Remove .weak/.hidden usage in inline assembly. #21260

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a330aaa
std.DynLib: Remove an outdated TODO.
alexrp Aug 28, 2024
a7c52c8
std.os.linux: Rename start_pie.zig to pie.zig.
alexrp Aug 28, 2024
6c9cc09
std.os.linux.pie: Remove `.weak`/`.hidden` usage in inline assembly.
alexrp Aug 28, 2024
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8 changes: 1 addition & 7 deletions lib/std/dynamic_library.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -83,15 +83,9 @@ const RDebug = extern struct {
r_ldbase: usize,
};

/// TODO make it possible to reference this same external symbol 2x so we don't need this
/// helper function.
pub fn get_DYNAMIC() ?[*]elf.Dyn {
return @extern([*]elf.Dyn, .{ .name = "_DYNAMIC", .linkage = .weak });
}

pub fn linkmap_iterator(phdrs: []elf.Phdr) error{InvalidExe}!LinkMap.Iterator {
_ = phdrs;
const _DYNAMIC = get_DYNAMIC() orelse {
const _DYNAMIC = @extern([*]elf.Dyn, .{ .name = "_DYNAMIC", .linkage = .weak }) orelse {
// No PT_DYNAMIC means this is either a statically-linked program or a
// badly corrupted dynamically-linked one.
return .{ .current = null };
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2 changes: 1 addition & 1 deletion lib/std/os/linux.zig
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Expand Up @@ -115,7 +115,7 @@ pub const user_desc = arch_bits.user_desc;
pub const getcontext = arch_bits.getcontext;

pub const tls = @import("linux/tls.zig");
pub const pie = @import("linux/start_pie.zig");
pub const pie = @import("linux/pie.zig");
pub const BPF = @import("linux/bpf.zig");
pub const IOCTL = @import("linux/ioctl.zig");
pub const SECCOMP = @import("linux/seccomp.zig");
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28 changes: 0 additions & 28 deletions lib/std/os/linux/start_pie.zig → lib/std/os/linux/pie.zig
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Expand Up @@ -42,29 +42,21 @@ const R_RELATIVE = switch (builtin.cpu.arch) {
inline fn getDynamicSymbol() [*]elf.Dyn {
return switch (builtin.cpu.arch) {
.x86 => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ call 1f
\\ 1: pop %[ret]
\\ lea _DYNAMIC-1b(%[ret]), %[ret]
: [ret] "=r" (-> [*]elf.Dyn),
),
.x86_64 => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ lea _DYNAMIC(%%rip), %[ret]
: [ret] "=r" (-> [*]elf.Dyn),
),
.arc => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ add %[ret], pcl, _DYNAMIC@pcl
: [ret] "=r" (-> [*]elf.Dyn),
),
// Work around the limited offset range of `ldr`
.arm, .armeb, .thumb, .thumbeb => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ ldr %[ret], 1f
\\ add %[ret], pc
\\ b 2f
Expand All @@ -74,8 +66,6 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
),
// A simple `adr` is not enough as it has a limited offset range
.aarch64, .aarch64_be => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ adrp %[ret], _DYNAMIC
\\ add %[ret], %[ret], #:lo12:_DYNAMIC
: [ret] "=r" (-> [*]elf.Dyn),
Expand All @@ -88,8 +78,6 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
: [ret] "=r" (-> [*]elf.Dyn),
),
.hexagon => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ jump 1f
\\ .word _DYNAMIC - .
\\ 1:
Expand All @@ -102,23 +90,17 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
: "r1"
),
.loongarch32, .loongarch64 => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ la.local %[ret], _DYNAMIC
: [ret] "=r" (-> [*]elf.Dyn),
),
// Note that the - 8 is needed because pc in the second lea instruction points into the
// middle of that instruction. (The first lea is 6 bytes, the second is 4 bytes.)
.m68k => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ lea _DYNAMIC - . - 8, %[ret]
\\ lea (%[ret], %%pc), %[ret]
: [ret] "=r" (-> [*]elf.Dyn),
),
.mips, .mipsel => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ bal 1f
\\ .gpword _DYNAMIC
\\ 1:
Expand All @@ -129,8 +111,6 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
: "lr"
),
.mips64, .mips64el => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ .balign 8
\\ bal 1f
\\ .gpdword _DYNAMIC
Expand All @@ -142,8 +122,6 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
: "lr"
),
.powerpc, .powerpcle => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ bl 1f
\\ .long _DYNAMIC - .
\\ 1:
Expand All @@ -155,8 +133,6 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
: "lr", "r4"
),
.powerpc64, .powerpc64le => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ bl 1f
\\ .quad _DYNAMIC - .
\\ 1:
Expand All @@ -168,14 +144,10 @@ inline fn getDynamicSymbol() [*]elf.Dyn {
: "lr", "r4"
),
.riscv32, .riscv64 => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ lla %[ret], _DYNAMIC
: [ret] "=r" (-> [*]elf.Dyn),
),
.s390x => asm volatile (
\\ .weak _DYNAMIC
\\ .hidden _DYNAMIC
\\ larl %[ret], 1f
\\ ag %[ret], 0(%[ret])
\\ b 2f
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4 changes: 2 additions & 2 deletions lib/std/start.zig
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Expand Up @@ -288,8 +288,8 @@ fn _start() callconv(.Naked) noreturn {
,
.csky =>
// The CSKY ABI assumes that `gb` is set to the address of the GOT in order for
// position-independent code to work. We depend on this in `std.os.linux.start_pie`
// to locate `_DYNAMIC` as well.
// position-independent code to work. We depend on this in `std.os.linux.pie` to locate
// `_DYNAMIC` as well.
\\ grs t0, 1f
\\ 1:
\\ lrw gb, 1b@GOTPC
Expand Down
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