+
+/*
+ * mono_arch_create_sdb_trampoline:
+ *
+ * Return a trampoline which captures the current context, passes it to
+ * debugger_agent_single_step_from_context ()/debugger_agent_breakpoint_from_context (),
+ * then restores the (potentially changed) context.
+ */
+guint8*
+mono_arch_create_sdb_trampoline (gboolean single_step, MonoTrampInfo **info, gboolean aot)
+{
+ int tramp_size = 256;
+ int i, framesize, ctx_offset, cfa_offset, gregs_offset;
+ guint8 *code, *buf;
+ GSList *unwind_ops = NULL;
+ MonoJumpInfo *ji = NULL;
+
+ code = buf = mono_global_codeman_reserve (tramp_size);
+
+ framesize = sizeof (MonoContext);
+ framesize = ALIGN_TO (framesize, MONO_ARCH_FRAME_ALIGNMENT);
+
+ // CFA = sp + 8
+ cfa_offset = 8;
+ mono_add_unwind_op_def_cfa (unwind_ops, code, buf, AMD64_RSP, 8);
+ // IP saved at CFA - 8
+ mono_add_unwind_op_offset (unwind_ops, code, buf, AMD64_RIP, -cfa_offset);
+
+ amd64_push_reg (code, AMD64_RBP);
+ cfa_offset += sizeof(mgreg_t);
+ mono_add_unwind_op_def_cfa_offset (unwind_ops, code, buf, cfa_offset);
+ mono_add_unwind_op_offset (unwind_ops, code, buf, AMD64_RBP, - cfa_offset);
+
+ amd64_mov_reg_reg (code, AMD64_RBP, AMD64_RSP, sizeof(mgreg_t));
+ mono_add_unwind_op_def_cfa_reg (unwind_ops, code, buf, AMD64_RBP);
+ amd64_alu_reg_imm (code, X86_SUB, AMD64_RSP, framesize);
+
+ ctx_offset = 0;
+ gregs_offset = ctx_offset + MONO_STRUCT_OFFSET (MonoContext, gregs);
+
+ /* Initialize a MonoContext structure on the stack */
+ for (i = 0; i < AMD64_NREG; ++i) {
+ if (i != AMD64_RIP && i != AMD64_RSP && i != AMD64_RBP)
+ amd64_mov_membase_reg (code, AMD64_RSP, gregs_offset + (i * sizeof (mgreg_t)), i, sizeof (mgreg_t));
+ }
+ amd64_mov_reg_membase (code, AMD64_R11, AMD64_RBP, 0, sizeof (mgreg_t));
+ amd64_mov_membase_reg (code, AMD64_RSP, gregs_offset + (AMD64_RBP * sizeof (mgreg_t)), AMD64_R11, sizeof (mgreg_t));
+ amd64_lea_membase (code, AMD64_R11, AMD64_RBP, 2 * sizeof (mgreg_t));
+ amd64_mov_membase_reg (code, AMD64_RSP, gregs_offset + (AMD64_RSP * sizeof (mgreg_t)), AMD64_R11, sizeof (mgreg_t));
+ amd64_mov_reg_membase (code, AMD64_R11, AMD64_RBP, sizeof (mgreg_t), sizeof (mgreg_t));
+ amd64_mov_membase_reg (code, AMD64_RSP, gregs_offset + (AMD64_RIP * sizeof (mgreg_t)), AMD64_R11, sizeof (mgreg_t));
+
+ /* Call the single step/breakpoint function in sdb */
+ amd64_lea_membase (code, AMD64_ARG_REG1, AMD64_RSP, ctx_offset);
+
+ if (aot) {
+ if (single_step)
+ code = mono_arch_emit_load_aotconst (buf, code, &ji, MONO_PATCH_INFO_JIT_ICALL_ADDR, "debugger_agent_single_step_from_context");
+ else
+ code = mono_arch_emit_load_aotconst (buf, code, &ji, MONO_PATCH_INFO_JIT_ICALL_ADDR, "debugger_agent_breakpoint_from_context");
+ amd64_call_reg (code, AMD64_R11);
+ } else {
+ if (single_step)
+ amd64_call_code (code, debugger_agent_single_step_from_context);
+ else
+ amd64_call_code (code, debugger_agent_breakpoint_from_context);
+ }
+
+ /* Restore registers from ctx */
+ for (i = 0; i < AMD64_NREG; ++i) {
+ if (i != AMD64_RIP && i != AMD64_RSP && i != AMD64_RBP)
+ amd64_mov_reg_membase (code, AMD64_RSP, i, gregs_offset + (i * sizeof (mgreg_t)), sizeof (mgreg_t));
+ }
+ amd64_mov_reg_membase (code, AMD64_R11, AMD64_RSP, gregs_offset + (AMD64_RBP * sizeof (mgreg_t)), sizeof (mgreg_t));
+ amd64_mov_membase_reg (code, AMD64_RBP, 0, AMD64_R11, sizeof (mgreg_t));
+ amd64_mov_reg_membase (code, AMD64_R11, AMD64_RSP, gregs_offset + (AMD64_RIP * sizeof (mgreg_t)), sizeof (mgreg_t));
+ amd64_mov_membase_reg (code, AMD64_RBP, sizeof (mgreg_t), AMD64_R11, sizeof (mgreg_t));
+
+ amd64_leave (code);
+ amd64_ret (code);
+
+ mono_arch_flush_icache (code, code - buf);
+ g_assert (code - buf <= tramp_size);
+
+ const char *tramp_name = single_step ? "sdb_single_step_trampoline" : "sdb_breakpoint_trampoline";
+ *info = mono_tramp_info_create (tramp_name, buf, code - buf, ji, unwind_ops);
+
+ return buf;
+}