From 99f99efb4a7ab2fcae8b3ab6b80959c982a2aa69 Mon Sep 17 00:00:00 2001
From: Zoltan Varga <vargaz@gmail.com>
Date: Thu, 25 Nov 2010 23:36:57 +0100
Subject: [PATCH] Fix stack alignment when resuming from a signal handler in
 the soft debugger. Fixes #647464.

---
 mono/mini/debugger-agent.c   |  5 ++++-
 mono/mini/exceptions-amd64.c | 16 ++++++++++++++++
 mono/mini/mini-amd64.h       |  3 +--
 mono/mini/mini.h             |  1 +
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/mono/mini/debugger-agent.c b/mono/mini/debugger-agent.c
index 751d380b0c198..9286f4937cb86 100644
--- a/mono/mini/debugger-agent.c
+++ b/mono/mini/debugger-agent.c
@@ -3529,8 +3529,11 @@ resume_from_signal_handler (void *sigctx, void *func)
 
 	mono_arch_sigctx_to_monoctx (sigctx, &ctx);
 	memcpy (&tls->handler_ctx, &ctx, sizeof (MonoContext));
+#ifdef MONO_ARCH_HAVE_SETUP_RESUME_FROM_SIGNAL_HANDLER_CTX
+	mono_arch_setup_resume_sighandler_ctx (&ctx, func);
+#else
 	MONO_CONTEXT_SET_IP (&ctx, func);
-
+#endif
 	mono_arch_monoctx_to_sigctx (&ctx, sigctx);
 }
 
diff --git a/mono/mini/exceptions-amd64.c b/mono/mini/exceptions-amd64.c
index a212c836394d0..971e92469579e 100644
--- a/mono/mini/exceptions-amd64.c
+++ b/mono/mini/exceptions-amd64.c
@@ -1458,3 +1458,19 @@ mono_tasklets_arch_restore (void)
 }
 #endif
 
+/*
+ * mono_arch_setup_resume_sighandler_ctx:
+ *
+ *   Setup CTX so execution continues at FUNC.
+ */
+void
+mono_arch_setup_resume_sighandler_ctx (MonoContext *ctx, gpointer func)
+{
+	/* 
+	 * When resuming from a signal handler, the stack should be misaligned, just like right after
+	 * a call.
+	 */
+	if ((((guint64)MONO_CONTEXT_GET_SP (ctx)) % 16) == 0)
+		MONO_CONTEXT_SET_SP (ctx, (guint64)MONO_CONTEXT_GET_SP (ctx) - 8);
+	MONO_CONTEXT_SET_IP (ctx, func);
+}
diff --git a/mono/mini/mini-amd64.h b/mono/mini/mini-amd64.h
index a16f957c2888d..8cf61a7c42888 100644
--- a/mono/mini/mini-amd64.h
+++ b/mono/mini/mini-amd64.h
@@ -376,8 +376,7 @@ typedef struct {
 #define MONO_ARCH_DYN_CALL_PARAM_AREA 0
 
 #define MONO_ARCH_HAVE_LLVM_IMT_TRAMPOLINE 1
-
-#define MONO_ARCH_USE_OP_TAIL_CALL(caller_sig, callee_sig) mono_metadata_signature_equal ((caller_sig), (callee_sig))
+#define MONO_ARCH_HAVE_SETUP_RESUME_FROM_SIGNAL_HANDLER_CTX 1
 
 /* Used for optimization, not complete */
 #define MONO_ARCH_IS_OP_MEMBASE(opcode) ((opcode) == OP_X86_PUSH_MEMBASE)
diff --git a/mono/mini/mini.h b/mono/mini/mini.h
index e68a3d669e532..a6b77626e3c23 100644
--- a/mono/mini/mini.h
+++ b/mono/mini/mini.h
@@ -1709,6 +1709,7 @@ guint8*   mono_arch_get_ip_for_breakpoint       (MonoJitInfo *ji, MonoContext *c
 void     mono_arch_skip_breakpoint              (MonoContext *ctx) MONO_INTERNAL;
 void     mono_arch_skip_single_step             (MonoContext *ctx) MONO_INTERNAL;
 gpointer mono_arch_get_seq_point_info           (MonoDomain *domain, guint8 *code) MONO_INTERNAL;
+void     mono_arch_setup_resume_sighandler_ctx  (MonoContext *ctx, gpointer func) MONO_INTERNAL;
 #endif
 
 MonoJitInfo *mono_arch_find_jit_info            (MonoDomain *domain,