Add support for detecting register-stack overrun on IA64.

tglsfdc · tglsfdc · commit 17b38fae86f0 · 2010-11-06T22:59:31.000-04:00
Per recent investigation, the register stack can grow faster than the
regular stack depending on compiler and choice of options.  To avoid
crashes we must check both stacks in check_stack_depth().

Back-patch to all supported versions.
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
@@ -97,6 +97,12 @@ static int	max_stack_depth_bytes = 2048 * 1024;
 /* Do not make static so PL/Java can modifiy it */
 char	   *stack_base_ptr = NULL;
 
+/*
+ * On IA64 we also have to remember the register stack base.
+ */
+#if defined(__ia64__) || defined(__ia64)
+char	   *register_stack_base_ptr = NULL;
+#endif
 
 /*
  * Flag to mark SIGHUP. Whenever the main loop comes around it
@@ -2288,6 +2294,35 @@ ProcessInterrupts(void)
 }
 
 
+/*
+ * IA64-specific code to fetch the AR.BSP register for stack depth checks.
+ *
+ * We currently support gcc and icc here.
+ */
+#if defined(__ia64__) || defined(__ia64)
+
+#include <asm/ia64regs.h>
+
+static __inline__ char *
+ia64_get_bsp(void)
+{
+	char	   *ret;
+
+#ifndef __INTEL_COMPILER
+	/* the ;; is a "stop", seems to be required before fetching BSP */
+	__asm__ __volatile__(
+		";;\n"
+		"	mov	%0=ar.bsp	\n"
+:		"=r"(ret));
+#else
+  ret = (char *) __getReg(_IA64_REG_AR_BSP);
+#endif
+  return ret;
+}
+
+#endif /* IA64 */
+
+
 /*
  * check_stack_depth: check for excessively deep recursion
  *
@@ -2335,6 +2370,27 @@ check_stack_depth(void)
 				 errmsg("stack depth limit exceeded"),
 				 errhint("Increase the configuration parameter \"max_stack_depth\".")));
 	}
+
+	/*
+	 * On IA64 there is a separate "register" stack that requires its own
+	 * independent check.  For this, we have to measure the change in the
+	 * "BSP" pointer from PostgresMain to here.  Logic is just as above,
+	 * except that we know IA64's register stack grows up.
+	 *
+	 * Note we assume that the same max_stack_depth applies to both stacks.
+	 */
+#if defined(__ia64__) || defined(__ia64)
+	stack_depth = (long) (ia64_get_bsp() - register_stack_base_ptr);
+
+	if (stack_depth > max_stack_depth_bytes &&
+		register_stack_base_ptr != NULL)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_STATEMENT_TOO_COMPLEX),
+				 errmsg("stack depth limit exceeded"),
+				 errhint("Increase the configuration parameter \"max_stack_depth\".")));
+	}
+#endif /* IA64 */
 }
 
 /* GUC assign hook to update max_stack_depth_bytes from max_stack_depth */
@@ -2491,6 +2547,9 @@ PostgresMain(int argc, char *argv[], const char *username)
 
 	/* Set up reference point for stack depth checking */
 	stack_base_ptr = &stack_base;
+#if defined(__ia64__) || defined(__ia64)
+	register_stack_base_ptr = ia64_get_bsp();
+#endif
 
 	/* Compute paths, if we didn't inherit them from postmaster */
 	if (my_exec_path[0] == '\0')
