2011-11-14 Stan Shebs <stan@codesourcery.com>

Kwok Cheung Yeung  <kcy@codesourcery.com>

	* NEWS: Document shorter fast tracepoints and qTMinFTPILen packet.
	* i386-tdep.c (i386_fast_tracepoint_valid_at): Query target for
	the minimum instruction size for fast tracepoints.
	* target.h (struct target_ops): Add new method
	to_get_min_fast_tracepoint_insn_len.
	(target_get_min_fast_tracepoint_insn_len): New.
	* target.c (update_current_target): Set up new target operation.
	* remote.c (remote_write_bytes_aux): Fix typo.
	(remote_get_min_fast_tracepoint_insn_len): New.
	(init_remote_ops): Initialize new field.

	* gdb.texinfo (Create and Delete Tracepoints): Describe what is
	needed to get shorter fast tracepoints.
	(Tracepoint Packets): Document new qTMinFTPILen packet.

	* linux-x86-low.c (small_jump_insn): New.
	(i386_install_fast_tracepoint_jump_pad): Add arguments for
	trampoline and error message, build a trampoline and issue a small
	jump instruction to it.
	(x86_install_fast_tracepoint_jump_pad): Add arguments for
	trampoline and error message.
	(x86_get_min_fast_tracepoint_insn_len): New.
	(the_low_target): Add call to x86_get_min_fast_tracepoint_insn_len.
	* linux-low.h (struct linux_target_ops): Add arguments to
	install_fast_tracepoint_jump_pad operation, add new operation.
	* linux-low.c (linux_install_fast_tracepoint_jump_pad): Add
	arguments.
	(linux_get_min_fast_tracepoint_insn_len): New function.
	(linux_target_op): Add new operation.
	* tracepoint.c (gdb_trampoline_buffer): New IPA variable.
	(gdb_trampoline_buffer_end): Ditto.
	(gdb_trampoline_buffer_error): Ditto.
	(struct ipa_sym_addresses): Add fields for new IPA variables.
	(symbol_list): Add entries for new IPA variables.
	(struct tracepoint): Add fields to hold the address range of the
	trampoline used by the tracepoint.
	(trampoline_buffer_head): New static variable.
	(trampoline_buffer_tail): Ditto.
	(claim_trampoline_space): New function.
	(have_fast_tracepoint_trampoline_buffer): New function.
	(clone_fast_tracepoint): Fill in trampoline fields of tracepoint
	structure.
	(install_fast_tracepoint): Ditto, also add error buffer argument.
	(cmd_qtminftpilen): New function.
	(handle_tracepoint_query): Add response to qTMinFTPILen packet.
	(fast_tracepoint_from_trampoline_address): New function.
	(fast_tracepoint_collecting): Handle trampoline as part of jump
	pad space.
	(set_trampoline_buffer_space): New function.
	(initialize_tracepoint): Initialize new IPA variables.
	* target.h (struct target_ops): Add arguments to
	install_fast_tracepoint_jump_pad operation, add new
	get_min_fast_tracepoint_insn_len operation.
	(target_get_min_fast_tracepoint_insn_len): New.
	(install_fast_tracepoint_jump_pad): Add arguments.
	* server.h (IPA_BUFSIZ): Define.
	* linux-i386-ipa.c: Include extra header files.
	(initialize_fast_tracepoint_trampoline_buffer): New function.
	(initialize_low_tracepoint): Call it.
	* server.h (set_trampoline_buffer_space): Declare.
	(claim_trampoline_space): Ditto.
	(have_fast_tracepoint_trampoline_buffer): Ditto.

	* gdb.trace/ftrace.c: New.
	* gdb.trace/ftrace.exp: New.

gdb/gdbserver/linux-i386-ipa.c

@@ -19,6 +19,8 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "server.h"
+#include <stdint.h>
+#include <sys/mman.h>
 
 /* GDB register numbers.  */
 
@@ -191,8 +193,62 @@ supply_static_tracepoint_registers (struct regcache *regcache,
    may use it proper at some point.  */
 const char *gdbserver_xmltarget;
 
+/* Attempt to allocate memory for trampolines in the first 64 KiB of
+   memory to enable smaller jump patches.  */
+
+static void
+initialize_fast_tracepoint_trampoline_buffer (void)
+{
+  const CORE_ADDR buffer_end = 64 * 1024;
+  /* Ensure that the buffer will be at least 1 KiB in size, which is
+     enough space for over 200 fast tracepoints.  */
+  const int min_buffer_size = 1024;
+  char buf[IPA_BUFSIZ];
+  CORE_ADDR mmap_min_addr = buffer_end + 1;
+  ULONGEST buffer_size;
+  FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r");
+
+  if (!f)
+    {    
+      snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s",
+		strerror (errno));
+      set_trampoline_buffer_space (0, 0, buf);
+      return;
+    }
+
+  if (fgets (buf, IPA_BUFSIZ, f))
+    sscanf (buf, "%llu", &mmap_min_addr);
+      
+  fclose (f);
+      
+  buffer_size = buffer_end - mmap_min_addr;
+
+  if (buffer_size >= min_buffer_size)
+    {
+      if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size,
+		PROT_READ | PROT_EXEC | PROT_WRITE,
+		MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
+		-1, 0)
+	  != MAP_FAILED)
+	set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL);
+      else
+	{
+	  snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s",
+		    strerror (errno));
+	  set_trampoline_buffer_space (0, 0, buf);
+	}
+    }
+  else
+    {
+      snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less",
+		(int) mmap_min_addr, (int) buffer_end - min_buffer_size);
+      set_trampoline_buffer_space (0, 0, buf);
+    }
+}
+
 void
 initialize_low_tracepoint (void)
 {
   init_registers_i386_linux ();
+  initialize_fast_tracepoint_trampoline_buffer ();
 }