Re: [PATCH] Move static chain and non-local goto init after NOTE_INSN_FUNCTION_BEG (PR sanitize/81186).

["Martin Liška" <mliska@suse.cz>]

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On 06/30/2017 04:03 PM, Michael Matz wrote:
> So you need to find some other solution of setting up the stack for ASAN.  
> And it'd be best if that solution doesn't require inserting code inside 
> the above sequence of parameter setup instructions, and you certainly 
> can't call any functions inside that sequence.  It might mean that you 
> can't track the static chain place or the nonlocal goto save area.  You 
> also don't track the parameter stack slots, right?

Hi.

Hopefully following patch will fix that. I returned to the first version and
saved/restored static_chain register before/after __asan_stack_malloc.

Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.

Thoughts?
Martin

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From b285e7cb1d7f3e35981dec951121db58ce152b3b Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Thu, 13 Jul 2017 13:37:47 +0200
Subject: [PATCH] Move static chain and non-local goto init after
 NOTE_INSN_FUNCTION_BEG

gcc/ChangeLog:

2017-06-27  Martin Liska  <mliska@suse.cz>

        PR sanitize/81186
	* function.c (expand_function_start): Move static chain and non-local
	goto init after NOTE_INSN_FUNCTION_BEG.
	* asan.c (asan_emit_stack_protection): Preserve static chain
	register if we call __asan_stack_malloc_N.

gcc/testsuite/ChangeLog:

2017-06-27  Martin Liska  <mliska@suse.cz>

        PR sanitize/81186
	* gcc.dg/asan/pr81186.c: New test.
---
 gcc/asan.c                          | 12 ++++++++++++
 gcc/function.c                      | 18 +++++++++---------
 gcc/testsuite/gcc.dg/asan/pr81186.c | 18 ++++++++++++++++++
 3 files changed, 39 insertions(+), 9 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/asan/pr81186.c

diff --git a/gcc/asan.c b/gcc/asan.c
index 89c2731e8cd..9cc1d21c1fb 100644
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -1340,6 +1340,16 @@ asan_emit_stack_protection (rtx base, rtx pbase, unsigned int alignb,
       emit_cmp_and_jump_insns (ret, const0_rtx, EQ, NULL_RTX,
 			       VOIDmode, 0, lab,
 			       profile_probability::very_likely ());
+      /* Preserve static chain register in order to not have it clobbered in
+	 __asan_stack_malloc_N function.  */
+      rtx chain = targetm.calls.static_chain (current_function_decl, true);
+      rtx saved_chain;
+      if (chain)
+	{
+	  saved_chain = gen_reg_rtx (Pmode);
+	  emit_move_insn (saved_chain, chain);
+	}
+
       snprintf (buf, sizeof buf, "__asan_stack_malloc_%d",
 		use_after_return_class);
       ret = init_one_libfunc (buf);
@@ -1347,6 +1357,8 @@ asan_emit_stack_protection (rtx base, rtx pbase, unsigned int alignb,
 				     GEN_INT (asan_frame_size
 					      + base_align_bias),
 				     TYPE_MODE (pointer_sized_int_node));
+      if (chain)
+	emit_move_insn (chain, saved_chain);
       /* __asan_stack_malloc_[n] returns a pointer to fake stack if succeeded
 	 and NULL otherwise.  Check RET value is NULL here and jump over the
 	 BASE reassignment in this case.  Otherwise, reassign BASE to RET.  */
diff --git a/gcc/function.c b/gcc/function.c
index f625489205b..5e8a56099a5 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -5220,6 +5220,14 @@ expand_function_start (tree subr)
      In some cases this requires emitting insns.  */
   assign_parms (subr);
 
+  /* The following was moved from init_function_start.
+     The move is supposed to make sdb output more accurate.  */
+  /* Indicate the beginning of the function body,
+     as opposed to parm setup.  */
+  rtx_note *b = emit_note (NOTE_INSN_FUNCTION_BEG);
+
+  gcc_assert (NOTE_P (get_last_insn ()));
+
   /* If function gets a static chain arg, store it.  */
   if (cfun->static_chain_decl)
     {
@@ -5284,15 +5292,7 @@ expand_function_start (tree subr)
       update_nonlocal_goto_save_area ();
     }
 
-  /* The following was moved from init_function_start.
-     The move is supposed to make sdb output more accurate.  */
-  /* Indicate the beginning of the function body,
-     as opposed to parm setup.  */
-  emit_note (NOTE_INSN_FUNCTION_BEG);
-
-  gcc_assert (NOTE_P (get_last_insn ()));
-
-  parm_birth_insn = get_last_insn ();
+  parm_birth_insn = b;
 
   if (crtl->profile)
     {
diff --git a/gcc/testsuite/gcc.dg/asan/pr81186.c b/gcc/testsuite/gcc.dg/asan/pr81186.c
new file mode 100644
index 00000000000..7f0f672ca40
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/asan/pr81186.c
@@ -0,0 +1,18 @@
+/* PR sanitizer/81186 */
+/* { dg-do run } */
+
+int
+main ()
+{
+  __label__ l;
+  void f ()
+  {
+    int a[123];
+
+    goto l;
+  }
+
+  f ();
+l:
+  return 0;
+}
-- 
2.13.2