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https://github.com/ziglang/zig.git
synced 2026-01-21 06:45:24 +00:00
linux: rework getcontext to closer match the specification (saved IP/SP match the state after it would return)
debug: fixup ucontext_t check
This commit is contained in:
kcbanner
parent
89ef004646
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caa334712f
@ -136,7 +136,7 @@ pub fn dumpCurrentStackTrace(start_addr: ?usize) void {
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pub const StackTraceContext = blk: {
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if (native_os == .windows) {
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break :blk std.os.windows.CONTEXT;
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} else if (@hasDecl(os.system, "ucontext_t")) {
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} else if (StackIterator.supports_context) {
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break :blk os.ucontext_t;
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} else {
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break :blk void;
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@ -394,28 +394,51 @@ fn gpRegisterOffset(comptime reg_index: comptime_int) usize {
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return @offsetOf(ucontext_t, "mcontext") + @offsetOf(mcontext_t, "gregs") + @sizeOf(usize) * reg_index;
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}
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pub inline fn getcontext(context: *ucontext_t) usize {
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noinline fn getContextReturnAddress() usize {
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return @returnAddress();
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}
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pub fn getContextInternal() callconv(.Naked) void {
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asm volatile (
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\\ movl %%edi, (%[edi_offset])(%[context])
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\\ movl %%esi, (%[esi_offset])(%[context])
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\\ movl %%ebp, (%[ebp_offset])(%[context])
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\\ movl %%esp, (%[esp_offset])(%[context])
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\\ movl %%ebx, (%[ebx_offset])(%[context])
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\\ movl %%edx, (%[edx_offset])(%[context])
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\\ movl %%ecx, (%[ecx_offset])(%[context])
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\\ movl %%eax, (%[eax_offset])(%[context])
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\\ movl $0, (%[flags_offset])(%%edx)
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\\ movl $0, (%[link_offset])(%%edx)
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\\ movl %%edi, (%[edi_offset])(%%edx)
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\\ movl %%esi, (%[esi_offset])(%%edx)
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\\ movl %%ebp, (%[ebp_offset])(%%edx)
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\\ movl %%ebx, (%[ebx_offset])(%%edx)
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\\ movl %%edx, (%[edx_offset])(%%edx)
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\\ movl %%ecx, (%[ecx_offset])(%%edx)
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\\ movl %%eax, (%[eax_offset])(%%edx)
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\\ movl (%%esp), %%ecx
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\\ movl %%ecx, (%[eip_offset])(%%edx)
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\\ leal 4(%%esp), %%ecx
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\\ movl %%ecx, (%[esp_offset])(%%edx)
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\\ xorl %%ecx, %%ecx
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\\ movw %%fs, %%cx
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\\ movl %%ecx, (%[fs_offset])(%[context])
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\\ leal (%[regspace_offset])(%[context]), %%ecx
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\\ movl %%ecx, (%[fpregs_offset])(%[context])
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\\ movl %%ecx, (%[fs_offset])(%%edx)
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\\ leal (%[regspace_offset])(%%edx), %%ecx
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\\ movl %%ecx, (%[fpregs_offset])(%%edx)
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\\ fnstenv (%%ecx)
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\\ fldenv (%%ecx)
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\\ call getcontext_read_eip
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\\ getcontext_read_eip: pop %%ecx
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\\ movl %%ecx, (%[eip_offset])(%[context])
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\\ pushl %%ebx
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\\ pushl %%esi
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\\ xorl %%ebx, %%ebx
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\\ movl %[sigaltstack], %%eax
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\\ leal (%[stack_offset])(%%edx), %%ecx
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\\ int $0x80
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\\ cmpl $0, %%eax
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\\ jne return
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\\ movl %[sigprocmask], %%eax
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\\ xorl %%ecx, %%ecx
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\\ leal (%[sigmask_offset])(%%edx), %%edx
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\\ movl %[sigset_size], %%esi
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\\ int $0x80
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\\ return:
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\\ popl %%esi
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\\ popl %%ebx
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:
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: [context] "{edi}" (context),
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: [flags_offset] "p" (@offsetOf(ucontext_t, "flags")),
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[link_offset] "p" (@offsetOf(ucontext_t, "link")),
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[edi_offset] "p" (comptime gpRegisterOffset(REG.EDI)),
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[esi_offset] "p" (comptime gpRegisterOffset(REG.ESI)),
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[ebp_offset] "p" (comptime gpRegisterOffset(REG.EBP)),
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@ -428,18 +451,24 @@ pub inline fn getcontext(context: *ucontext_t) usize {
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[fs_offset] "p" (comptime gpRegisterOffset(REG.FS)),
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[fpregs_offset] "p" (@offsetOf(ucontext_t, "mcontext") + @offsetOf(mcontext_t, "fpregs")),
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[regspace_offset] "p" (@offsetOf(ucontext_t, "regspace")),
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[sigaltstack] "i" (@intFromEnum(linux.SYS.sigaltstack)),
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[stack_offset] "p" (@offsetOf(ucontext_t, "stack")),
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[sigprocmask] "i" (@intFromEnum(linux.SYS.rt_sigprocmask)),
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[sigmask_offset] "p" (@offsetOf(ucontext_t, "sigmask")),
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[sigset_size] "i" (linux.NSIG / 8),
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: "memory", "eax", "ecx", "edx"
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);
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}
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pub inline fn getcontext(context: *ucontext_t) usize {
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// This method is used so that getContextInternal can control
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// its prologue in order to read ESP from a constant offset.
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// The unused &getContextInternal input is required so the function is included in the binary.
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return asm volatile (
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\\ call os.linux.x86.getContextInternal
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: [ret] "={eax}" (-> usize),
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: [context] "{edx}" (context),
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[getContextInternal] "X" (&getContextInternal),
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: "memory", "ecx"
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);
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// TODO: Read CS/SS registers?
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// TODO: Store mxcsr state, need an actual definition of fpstate for that
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// TODO: `flags` isn't present in the getcontext man page, figure out what to write here
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context.flags = 0;
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context.link = null;
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const altstack_result = linux.sigaltstack(null, &context.stack);
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if (altstack_result != 0) return altstack_result;
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return linux.sigprocmask(0, null, &context.sigmask);
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}
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@ -400,35 +400,53 @@ fn gpRegisterOffset(comptime reg_index: comptime_int) usize {
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return @offsetOf(ucontext_t, "mcontext") + @offsetOf(mcontext_t, "gregs") + @sizeOf(usize) * reg_index;
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}
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pub inline fn getcontext(context: *ucontext_t) usize {
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fn getContextInternal() callconv(.Naked) void {
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// TODO: Read GS/FS registers?
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asm volatile (
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\\ movq %%r8, (%[r8_offset])(%[context])
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\\ movq %%r9, (%[r9_offset])(%[context])
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\\ movq %%r10, (%[r10_offset])(%[context])
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\\ movq %%r11, (%[r11_offset])(%[context])
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\\ movq %%r12, (%[r12_offset])(%[context])
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\\ movq %%r13, (%[r13_offset])(%[context])
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\\ movq %%r14, (%[r14_offset])(%[context])
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\\ movq %%r15, (%[r15_offset])(%[context])
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\\ movq %%rdi, (%[rdi_offset])(%[context])
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\\ movq %%rsi, (%[rsi_offset])(%[context])
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\\ movq %%rbp, (%[rbp_offset])(%[context])
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\\ movq %%rbx, (%[rbx_offset])(%[context])
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\\ movq %%rdx, (%[rdx_offset])(%[context])
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\\ movq %%rax, (%[rax_offset])(%[context])
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\\ movq %%rcx, (%[rcx_offset])(%[context])
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\\ movq %%rsp, (%[rsp_offset])(%[context])
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\\ leaq (%%rip), %%rcx
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\\ movq %%rcx, (%[rip_offset])(%[context])
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\\ movq $0, (%[flags_offset])(%%rdi)
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\\ movq $0, (%[link_offset])(%%rdi)
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\\ movq %%r8, (%[r8_offset])(%%rdi)
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\\ movq %%r9, (%[r9_offset])(%%rdi)
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\\ movq %%r10, (%[r10_offset])(%%rdi)
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\\ movq %%r11, (%[r11_offset])(%%rdi)
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\\ movq %%r12, (%[r12_offset])(%%rdi)
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\\ movq %%r13, (%[r13_offset])(%%rdi)
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\\ movq %%r14, (%[r14_offset])(%%rdi)
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\\ movq %%r15, (%[r15_offset])(%%rdi)
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\\ movq %%rdi, (%[rdi_offset])(%%rdi)
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\\ movq %%rsi, (%[rsi_offset])(%%rdi)
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\\ movq %%rbp, (%[rbp_offset])(%%rdi)
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\\ movq %%rbx, (%[rbx_offset])(%%rdi)
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\\ movq %%rdx, (%[rdx_offset])(%%rdi)
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\\ movq %%rax, (%[rax_offset])(%%rdi)
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\\ movq %%rcx, (%[rcx_offset])(%%rdi)
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\\ movq (%%rsp), %%rcx
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\\ movq %%rcx, (%[rip_offset])(%%rdi)
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\\ leaq 8(%%rsp), %%rcx
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\\ movq %%rcx, (%[rsp_offset])(%%rdi)
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\\ pushfq
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\\ popq (%[efl_offset])(%[context])
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\\ leaq (%[fpmem_offset])(%[context]), %%rcx
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\\ movq %%rcx, (%[fpstate_offset])(%[context])
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\\ popq (%[efl_offset])(%%rdi)
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\\ leaq (%[fpmem_offset])(%%rdi), %%rcx
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\\ movq %%rcx, (%[fpstate_offset])(%%rdi)
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\\ fnstenv (%%rcx)
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\\ fldenv (%%rcx)
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\\ stmxcsr (%[mxcsr_offset])(%[context])
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\\ stmxcsr (%[mxcsr_offset])(%%rdi)
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\\ leaq (%[stack_offset])(%%rdi), %%rsi
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\\ movq %%rdi, %%r8
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\\ xorq %%rdi, %%rdi
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\\ movq %[sigaltstack], %%rax
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\\ syscall
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\\ cmpq $0, %%rax
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\\ jne return
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\\ movq %[sigprocmask], %%rax
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\\ xorq %%rsi, %%rsi
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\\ leaq (%[sigmask_offset])(%%r8), %%rdx
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\\ movq %[sigset_size], %%r10
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\\ syscall
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\\ return:
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:
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: [context] "{rdi}" (context),
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: [flags_offset] "p" (@offsetOf(ucontext_t, "flags")),
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[link_offset] "p" (@offsetOf(ucontext_t, "link")),
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[r8_offset] "p" (comptime gpRegisterOffset(REG.R8)),
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[r9_offset] "p" (comptime gpRegisterOffset(REG.R9)),
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[r10_offset] "p" (comptime gpRegisterOffset(REG.R10)),
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@ -450,17 +468,24 @@ pub inline fn getcontext(context: *ucontext_t) usize {
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[fpstate_offset] "p" (@offsetOf(ucontext_t, "mcontext") + @offsetOf(mcontext_t, "fpregs")),
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[fpmem_offset] "p" (@offsetOf(ucontext_t, "fpregs_mem")),
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[mxcsr_offset] "p" (@offsetOf(ucontext_t, "fpregs_mem") + @offsetOf(fpstate, "mxcsr")),
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: "memory", "rcx"
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[sigaltstack] "i" (@intFromEnum(linux.SYS.sigaltstack)),
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[stack_offset] "p" (@offsetOf(ucontext_t, "stack")),
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[sigprocmask] "i" (@intFromEnum(linux.SYS.rt_sigprocmask)),
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[sigmask_offset] "p" (@offsetOf(ucontext_t, "sigmask")),
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[sigset_size] "i" (linux.NSIG / 8),
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: "memory", "rcx", "rdx", "rdi", "rsi", "r8", "r10", "r11"
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);
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}
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pub inline fn getcontext(context: *ucontext_t) usize {
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// This method is used so that getContextInternal can control
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// its prologue in order to read RSP from a constant offset
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// The unused &getContextInternal input is required so the function is included in the binary.
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return asm volatile (
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\\ call os.linux.x86_64.getContextInternal
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: [ret] "={rax}" (-> usize),
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: [context] "{rdi}" (context),
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[getContextInternal] "X" (&getContextInternal),
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: "memory", "rcx", "rdx", "rdi", "rsi", "r8", "r10", "r11"
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);
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// TODO: Read GS/FS registers?
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// TODO: `flags` isn't present in the getcontext man page, figure out what to write here
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context.flags = 0;
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context.link = null;
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const altstack_result = linux.sigaltstack(null, &context.stack);
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if (altstack_result != 0) return altstack_result;
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return linux.sigprocmask(0, null, &context.sigmask);
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}
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