1 files changed, 68 insertions, 0 deletions
diff --git a/third_party/rust/crash-context/src/linux/getcontext/x86.rs b/third_party/rust/crash-context/src/linux/getcontext/x86.rs
new file mode 100644
index 0000000000..cb823e1182
--- /dev/null
+++ b/third_party/rust/crash-context/src/linux/getcontext/x86.rs
@@ -0,0 +1,68 @@
+// 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:",
+            "movl 4(%esp), %eax",   // eax = uc
+
+            // Save register values
+            "movl %ecx, 0x3c(%eax)",
+            "movl %edx, 0x38(%eax)",
+            "movl %ebx, 0x34(%eax)",
+            "movl %edi, 0x24(%eax)",
+            "movl %esi, 0x28(%eax)",
+            "movl %ebp, 0x2c(%eax)",
+
+            "movl (%esp), %edx",   /* return address */
+            "lea  4(%esp), %ecx",  /* exclude return address from stack */
+            "mov  %edx, 0x4c(%eax)",
+            "mov  %ecx, 0x30(%eax)",
+
+            "xorl %ecx, %ecx",
+            "movw %fs, %cx",
+            "mov  %ecx, 0x18(%eax)",
+
+            "movl $0, 0x40(%eax)",
+
+            // Save floating point state to fpregstate, then update
+            // the fpregs pointer to point to it
+            stringify!(leal $offset(%eax),%ecx),
+            "fnstenv (%ecx)",
+            "fldenv  (%ecx)",
+            "mov %ecx, 0x60(%eax)",
+
+            // Save signal mask: sigprocmask(SIGBLOCK, NULL, &uc->uc_sigmask)
+            "leal 0x6c(%eax), %edx",
+            "xorl %ecx, %ecx",
+            "push %edx",   /* &uc->uc_sigmask */
+            "push %ecx",   /* NULL */
+            "push %ecx",   /* SIGBLOCK == 0 on i386 */
+            "call sigprocmask@PLT",
+            "addl $12, %esp",
+
+            "movl $0, %eax",
+            "ret",
+
+            ".size crash_context_getcontext, . - crash_context_getcontext",
+            options(att_syntax)
+        }
+    };
+}
+
+#[cfg(target_os = "linux")]
+asm_func!(0xec);
+#[cfg(target_os = "android")]
+asm_func!(0x74);