1 files changed, 105 insertions, 0 deletions
diff --git a/third_party/rust/crash-context/src/linux/getcontext/x86_64.rs b/third_party/rust/crash-context/src/linux/getcontext/x86_64.rs
new file mode 100644
index 0000000000..2ecbf2c24c
--- /dev/null
+++ b/third_party/rust/crash-context/src/linux/getcontext/x86_64.rs
@@ -0,0 +1,105 @@
+/* The x64 implementation of breakpad_getcontext was derived in part
+from the implementation of libunwind which requires the following
+notice. */
+/* libunwind - a platform-independent unwind library
+   Copyright (C) 2008 Google, Inc
+    Contributed by Paul Pluzhnikov <ppluzhnikov@google.com>
+   Copyright (C) 2010 Konstantin Belousov <kib@freebsd.org>
+
+This file is part of libunwind.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
+
+// Oof, unfortunately android libc and normal linux libc don't have the same
+// fpregs offset in ucontext_t, but asm! in Rust is...not convenient for only
+// adding certain lines/blocks of asm based using cfg https://github.com/rust-lang/rust/issues/15701
+// and they're not really inputs, just literals, so...yah
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+
+// Unfortunately, the asm! macro has a few really annoying limitations at the
+// moment
+//
+// 1. const operands are unstable
+// 2. cfg attributes can't be used inside the asm macro at all
+//
+// and the worst part is we need it for literally only 1 thing, using a different
+// offset to the fpstate in ucontext depending on whether we are targeting android
+// or not :(
+macro_rules! asm_func {
+    ($offset:expr) => {
+        std::arch::global_asm! {
+            ".text",
+            ".global crash_context_getcontext",
+            ".hidden crash_context_getcontext",
+            ".align 4",
+            ".type crash_context_getcontext, @function",
+        "crash_context_getcontext:",
+            ".cfi_startproc",
+            // Callee saved: RBX, RBP, R12-R15
+            "movq %r12, 0x48(%rdi)",
+            "movq %r13, 0x50(%rdi)",
+            "movq %r14, 0x58(%rdi)",
+            "movq %r15, 0x60(%rdi)",
+            "movq %rbp, 0x78(%rdi)",
+            "movq %rbx, 0x80(%rdi)",
+
+            // Save argument registers
+            "movq %r8,  0x28(%rdi)",
+            "movq %r9,  0x30(%rdi)",
+            "movq %rdi, 0x68(%rdi)",
+            "movq %rsi, 0x70(%rdi)",
+            "movq %rdx, 0x88(%rdi)",
+            "movq %rax, 0x90(%rdi)",
+            "movq %rcx, 0x98(%rdi)",
+
+            // Save fp state
+            stringify!(leaq $offset(%rdi),%r8),
+            "movq %r8, 0xe0(%rdi)",
+            "fnstenv (%r8)",
+            "stmxcsr 0x18(%r8)",
+
+            // Exclude this call
+            "leaq 8(%rsp), %rax",
+            "movq %rax, 0xa0(%rdi)",
+
+            "movq 0(%rsp), %rax",
+            "movq %rax, 0xa8(%rdi)",
+
+            // Save signal mask: sigprocmask(SIGBLOCK, NULL, &uc->uc_sigmask)
+            "leaq 0x128(%rdi), %rdx",  // arg3
+            "xorq %rsi, %rsi",  // arg2 NULL
+            "xorq %rdi, %rdi",  // arg1 SIGBLOCK == 0
+            "call sigprocmask@PLT",
+
+            // Always return 0 for success, even if sigprocmask failed.
+            "xorl %eax, %eax",
+            "ret",
+            ".cfi_endproc",
+            ".size crash_context_getcontext, . - crash_context_getcontext",
+            options(att_syntax)
+        }
+    };
+}
+
+#[cfg(target_os = "linux")]
+asm_func!(0x1a8);
+#[cfg(target_os = "android")]
+asm_func!(0x130);