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Implement stack probes for x86 #2440

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merged 1 commit into from
May 8, 2019
Merged

Implement stack probes for x86 #2440

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1 change: 1 addition & 0 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -643,6 +643,7 @@ set(ZIG_STD_FILES
"special/build_runner.zig"
"special/builtin.zig"
"special/compiler_rt.zig"
"special/compiler_rt/stack_probe.zig"
"special/compiler_rt/arm/aeabi_fcmp.zig"
"special/compiler_rt/arm/aeabi_dcmp.zig"
"special/compiler_rt/addXf3.zig"
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11 changes: 11 additions & 0 deletions src/codegen.cpp
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Expand Up @@ -399,6 +399,15 @@ static void add_uwtable_attr(CodeGen *g, LLVMValueRef fn_val) {
}
}

static void add_probe_stack_attr(CodeGen *g, LLVMValueRef fn_val) {
// Windows already emits its own stack probes
if (g->zig_target->os != OsWindows &&
(g->zig_target->arch == ZigLLVM_x86 ||
g->zig_target->arch == ZigLLVM_x86_64)) {
addLLVMFnAttrStr(fn_val, "probe-stack", "__zig_probe_stack");
}
}

static LLVMLinkage to_llvm_linkage(GlobalLinkageId id) {
switch (id) {
case GlobalLinkageIdInternal:
Expand Down Expand Up @@ -587,6 +596,8 @@ static LLVMValueRef fn_llvm_value(CodeGen *g, ZigFn *fn_table_entry) {
addLLVMFnAttr(fn_table_entry->llvm_value, "sspstrong");
addLLVMFnAttrStr(fn_table_entry->llvm_value, "stack-protector-buffer-size", "4");
}

add_probe_stack_attr(g, fn_table_entry->llvm_value);
}
} else {
maybe_import_dll(g, fn_table_entry->llvm_value, linkage);
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6 changes: 6 additions & 0 deletions src/main.cpp
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Expand Up @@ -18,6 +18,12 @@

#include <stdio.h>

// Define this symbol here so that we can link with the zig objects during the
// compiler bootstrap phase
extern "C" {
void __zig_probe_stack(void) { }
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@LemonBoy why was this needed? I tried removing this and it seems to work fine

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I needed that in order not to do a fresh rebuild when I first added the stack probe annotation, you can safely remove it now.

}

static int print_error_usage(const char *arg0) {
fprintf(stderr, "See `%s --help` for detailed usage information\n", arg0);
return EXIT_FAILURE;
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125 changes: 15 additions & 110 deletions std/special/compiler_rt.zig
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@@ -1,10 +1,17 @@
const builtin = @import("builtin");
const is_test = builtin.is_test;

const stack_probe = @import("compiler_rt/stack_probe.zig");

comptime {
const linkage = if (is_test) builtin.GlobalLinkage.Internal else builtin.GlobalLinkage.Weak;
const strong_linkage = if (is_test) builtin.GlobalLinkage.Internal else builtin.GlobalLinkage.Strong;

switch (builtin.arch) {
.i386, .x86_64 => @export("__zig_probe_stack", @import("compiler_rt/stack_probe.zig").zig_probe_stack, linkage),
else => { }
}

@export("__lesf2", @import("compiler_rt/comparesf2.zig").__lesf2, linkage);
@export("__ledf2", @import("compiler_rt/comparedf2.zig").__ledf2, linkage);
@export("__letf2", @import("compiler_rt/comparetf2.zig").__letf2, linkage);
Expand Down Expand Up @@ -191,20 +198,20 @@ comptime {
@export("__aeabi_dcmpun", @import("compiler_rt/comparedf2.zig").__unorddf2, linkage);
}
if (builtin.os == builtin.Os.windows) {
if (!builtin.link_libc) {
@export("_chkstk", @import("compiler_rt/stack_probe.zig")._chkstk, strong_linkage);
@export("__chkstk", @import("compiler_rt/stack_probe.zig").__chkstk, strong_linkage);
@export("___chkstk", @import("compiler_rt/stack_probe.zig").___chkstk, strong_linkage);
@export("__chkstk_ms", @import("compiler_rt/stack_probe.zig").__chkstk_ms, strong_linkage);
@export("___chkstk_ms", @import("compiler_rt/stack_probe.zig").___chkstk_ms, strong_linkage);
}

switch (builtin.arch) {
builtin.Arch.i386 => {
if (!builtin.link_libc) {
@export("_chkstk", _chkstk, strong_linkage);
@export("__chkstk_ms", __chkstk_ms, linkage);
}
@export("_aulldiv", @import("compiler_rt/aulldiv.zig")._aulldiv, strong_linkage);
@export("_aullrem", @import("compiler_rt/aullrem.zig")._aullrem, strong_linkage);
},
builtin.Arch.x86_64 => {
if (!builtin.link_libc) {
@export("__chkstk", __chkstk, strong_linkage);
@export("___chkstk_ms", ___chkstk_ms, linkage);
}
// The "ti" functions must use @Vector(2, u64) parameter types to adhere to the ABI
// that LLVM expects compiler-rt to have.
@export("__divti3", @import("compiler_rt/divti3.zig").__divti3_windows_x86_64, linkage);
Expand Down Expand Up @@ -492,108 +499,6 @@ nakedcc fn __aeabi_memcmp() noreturn {
unreachable;
}

// _chkstk (_alloca) routine - probe stack between %esp and (%esp-%eax) in 4k increments,
// then decrement %esp by %eax. Preserves all registers except %esp and flags.
// This routine is windows specific
// http://msdn.microsoft.com/en-us/library/ms648426.aspx
nakedcc fn _chkstk() align(4) void {
@setRuntimeSafety(false);

asm volatile (
\\ push %%ecx
\\ push %%eax
\\ cmp $0x1000,%%eax
\\ lea 12(%%esp),%%ecx
\\ jb 1f
\\ 2:
\\ sub $0x1000,%%ecx
\\ test %%ecx,(%%ecx)
\\ sub $0x1000,%%eax
\\ cmp $0x1000,%%eax
\\ ja 2b
\\ 1:
\\ sub %%eax,%%ecx
\\ test %%ecx,(%%ecx)
\\ pop %%eax
\\ pop %%ecx
\\ ret
);
}

nakedcc fn __chkstk() align(4) void {
@setRuntimeSafety(false);

asm volatile (
\\ push %%rcx
\\ push %%rax
\\ cmp $0x1000,%%rax
\\ lea 24(%%rsp),%%rcx
\\ jb 1f
\\2:
\\ sub $0x1000,%%rcx
\\ test %%rcx,(%%rcx)
\\ sub $0x1000,%%rax
\\ cmp $0x1000,%%rax
\\ ja 2b
\\1:
\\ sub %%rax,%%rcx
\\ test %%rcx,(%%rcx)
\\ pop %%rax
\\ pop %%rcx
\\ ret
);
}

// _chkstk routine
// This routine is windows specific
// http://msdn.microsoft.com/en-us/library/ms648426.aspx
nakedcc fn __chkstk_ms() align(4) void {
@setRuntimeSafety(false);

asm volatile (
\\ push %%ecx
\\ push %%eax
\\ cmp $0x1000,%%eax
\\ lea 12(%%esp),%%ecx
\\ jb 1f
\\ 2:
\\ sub $0x1000,%%ecx
\\ test %%ecx,(%%ecx)
\\ sub $0x1000,%%eax
\\ cmp $0x1000,%%eax
\\ ja 2b
\\ 1:
\\ sub %%eax,%%ecx
\\ test %%ecx,(%%ecx)
\\ pop %%eax
\\ pop %%ecx
\\ ret
);
}

nakedcc fn ___chkstk_ms() align(4) void {
@setRuntimeSafety(false);

asm volatile (
\\ push %%rcx
\\ push %%rax
\\ cmp $0x1000,%%rax
\\ lea 24(%%rsp),%%rcx
\\ jb 1f
\\2:
\\ sub $0x1000,%%rcx
\\ test %%rcx,(%%rcx)
\\ sub $0x1000,%%rax
\\ cmp $0x1000,%%rax
\\ ja 2b
\\1:
\\ sub %%rax,%%rcx
\\ test %%rcx,(%%rcx)
\\ pop %%rax
\\ pop %%rcx
\\ ret
);
}

extern fn __divmodsi4(a: i32, b: i32, rem: *i32) i32 {
@setRuntimeSafety(is_test);
Expand Down
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