Commit be7cacfbbe
Changed files (5)
src/codegen.cpp
@@ -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:
@@ -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);
src/main.cpp
@@ -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) { }
+}
+
static int print_error_usage(const char *arg0) {
fprintf(stderr, "See `%s --help` for detailed usage information\n", arg0);
return EXIT_FAILURE;
std/special/compiler_rt/stack_probe.zig
@@ -0,0 +1,206 @@
+const builtin = @import("builtin");
+
+// Zig's own stack-probe routine (available only on x86 and x86_64)
+pub nakedcc fn zig_probe_stack() void {
+ @setRuntimeSafety(false);
+
+ // Versions of the Linux kernel before 5.1 treat any access below SP as
+ // invalid so let's update it on the go, otherwise we'll get a segfault
+ // instead of triggering the stack growth.
+
+ switch (builtin.arch) {
+ .x86_64 => {
+ // %rax = probe length, %rsp = stack pointer
+ asm volatile (
+ \\ push %%rcx
+ \\ mov %%rax, %%rcx
+ \\ cmp $0x1000,%%rcx
+ \\ jb 2f
+ \\ 1:
+ \\ sub $0x1000,%%rsp
+ \\ orl $0,16(%%rsp)
+ \\ sub $0x1000,%%rcx
+ \\ cmp $0x1000,%%rcx
+ \\ ja 1b
+ \\ 2:
+ \\ sub %%rcx, %%rsp
+ \\ orl $0,16(%%rsp)
+ \\ add %%rax,%%rsp
+ \\ pop %%rcx
+ \\ ret
+ );
+ },
+ .i386 => {
+ // %eax = probe length, %esp = stack pointer
+ asm volatile (
+ \\ push %%ecx
+ \\ mov %%eax, %%ecx
+ \\ cmp $0x1000,%%ecx
+ \\ jb 2f
+ \\ 1:
+ \\ sub $0x1000,%%esp
+ \\ orl $0,8(%%esp)
+ \\ sub $0x1000,%%ecx
+ \\ cmp $0x1000,%%ecx
+ \\ ja 1b
+ \\ 2:
+ \\ sub %%ecx, %%esp
+ \\ orl $0,8(%%esp)
+ \\ add %%eax,%%esp
+ \\ pop %%ecx
+ \\ ret
+ );
+ },
+ else => { }
+ }
+
+ unreachable;
+}
+
+fn win_probe_stack_only() void {
+ @setRuntimeSafety(false);
+
+ switch (builtin.arch) {
+ .x86_64 => {
+ 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
+ );
+ },
+ .i386 => {
+ 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
+ );
+ },
+ else => { }
+ }
+
+ unreachable;
+}
+
+fn win_probe_stack_adjust_sp() void {
+ @setRuntimeSafety(false);
+
+ switch (builtin.arch) {
+ .x86_64 => {
+ asm volatile (
+ \\ push %%rcx
+ \\ cmp $0x1000,%%rax
+ \\ lea 16(%%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)
+ \\
+ \\ lea 8(%%rsp),%%rax
+ \\ mov %%rcx,%%rsp
+ \\ mov -8(%%rax),%%rcx
+ \\ push (%%rax)
+ \\ sub %%rsp,%%rax
+ \\ ret
+ );
+ },
+ .i386 => {
+ asm volatile (
+ \\ push %%ecx
+ \\ cmp $0x1000,%%eax
+ \\ lea 8(%%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)
+ \\
+ \\ lea 4(%%esp),%%eax
+ \\ mov %%ecx,%%esp
+ \\ mov -4(%%eax),%%ecx
+ \\ push (%%eax)
+ \\ sub %%esp,%%eax
+ \\ ret
+ );
+ },
+ else => { },
+ }
+
+ unreachable;
+}
+
+// Windows has a multitude of stack-probing functions with similar names and
+// slightly different behaviours: some behave as alloca() and update the stack
+// pointer after probing the stack, other do not.
+//
+// Function name | Adjusts the SP? |
+// | x86 | x86_64 |
+// ----------------------------------------
+// _chkstk (_alloca) | yes | yes |
+// __chkstk | yes | no |
+// __chkstk_ms | no | no |
+// ___chkstk (__alloca) | yes | yes |
+// ___chkstk_ms | no | no |
+
+pub nakedcc fn _chkstk() void {
+ @setRuntimeSafety(false);
+ @inlineCall(win_probe_stack_adjust_sp);
+}
+pub nakedcc fn __chkstk() void {
+ @setRuntimeSafety(false);
+ switch (builtin.arch) {
+ .i386 => @inlineCall(win_probe_stack_adjust_sp),
+ .x86_64 => @inlineCall(win_probe_stack_only),
+ else => unreachable
+ }
+}
+pub nakedcc fn ___chkstk() void {
+ @setRuntimeSafety(false);
+ @inlineCall(win_probe_stack_adjust_sp);
+}
+pub nakedcc fn __chkstk_ms() void {
+ @setRuntimeSafety(false);
+ @inlineCall(win_probe_stack_only);
+}
+pub nakedcc fn ___chkstk_ms() void {
+ @setRuntimeSafety(false);
+ @inlineCall(win_probe_stack_only);
+}
std/special/compiler_rt.zig
@@ -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);
@@ -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);
@@ -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);
CMakeLists.txt
@@ -644,6 +644,7 @@ 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"