merge revision(s) r45517,r45544,r45924:

	signal.c: check stack overflow by SP

	* signal.c (check_stack_overflow): raise SystemStackError if SP
  register and fault address is in the same page, on x86 linux.
  [EXPERIMENTAL]
	* signal.c (check_stack_overflow): Don't use ucontext_t if ucontext.h
	  is not available.
	  Fixes build on Android (x86).


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46367 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 30 insertions, 2 deletions

diff --git a/signal.c b/signal.c
index 96277e322c..d82f4c7e2b 100644
--- a/signal.c
+++ b/signal.c
@@ -628,21 +628,49 @@ rb_get_next_signal(void)
 
 
 #if defined(USE_SIGALTSTACK) || defined(_WIN32)
+NORETURN(void ruby_thread_stack_overflow(rb_thread_t *th));
+#if defined(HAVE_UCONTEXT_H) && defined __linux__ && (defined __i386__ || defined __x86_64__)
+# define USE_UCONTEXT_REG 1
+#endif
+#ifdef USE_UCONTEXT_REG
+static void
+check_stack_overflow(const uintptr_t addr, const ucontext_t *ctx)
+{
+# if defined REG_RSP
+    const greg_t sp = ctx->uc_mcontext.gregs[REG_RSP];
+# else
+    const greg_t sp = ctx->uc_mcontext.gregs[REG_ESP];
+# endif
+    enum {pagesize = 4096};
+    const uintptr_t sp_page = (uintptr_t)sp / pagesize;
+    const uintptr_t fault_page = addr / pagesize;
+
+    /* SP in ucontext is not decremented yet when `push` failed, so
+     * the fault page can be the next. */
+    if (sp_page == fault_page || sp_page == fault_page + 1) {
+	ruby_thread_stack_overflow(GET_THREAD());
+    }
+}
+#else
 static void
 check_stack_overflow(const void *addr)
 {
     int ruby_stack_overflowed_p(const rb_thread_t *, const void *);
-    NORETURN(void ruby_thread_stack_overflow(rb_thread_t *th));
     rb_thread_t *th = GET_THREAD();
     if (ruby_stack_overflowed_p(th, addr)) {
 	ruby_thread_stack_overflow(th);
     }
 }
+#endif
 #ifdef _WIN32
 #define CHECK_STACK_OVERFLOW() check_stack_overflow(0)
 #else
 #define FAULT_ADDRESS info->si_addr
-#define CHECK_STACK_OVERFLOW() check_stack_overflow(FAULT_ADDRESS)
+# ifdef USE_UCONTEXT_REG
+# define CHECK_STACK_OVERFLOW() check_stack_overflow((uintptr_t)FAULT_ADDRESS, ctx)
+#else
+# define CHECK_STACK_OVERFLOW() check_stack_overflow(FAULT_ADDRESS)
+#endif
 #define MESSAGE_FAULT_ADDRESS " at %p", FAULT_ADDRESS
 #endif
 #else