https://gcc.gnu.org/g:946c17e456d3a3c3d3baceffd245e7bbb580f7ed
commit r14-11253-g946c17e456d3a3c3d3baceffd245e7bbb580f7ed
Author: Ilya Leoshkevich <i...@linux.ibm.com>
Date: Wed Jan 8 00:17:07 2025 +0100
asan: Fix missing FakeStack flag cleanup
The FakeStack flag is not zeroed out when can_store_by_pieces()
returns false. Over time, this causes FakeStack::Allocate() to perform
the maximum number of loop iterations, significantly slowing down the
instrumented program.
Link:
https://inbox.sourceware.org/gcc-patches/20250109001702.154685-1-...@linux.ibm.com/
Signed-off-by: Ilya Leoshkevich <i...@linux.ibm.com>
gcc/ChangeLog:
* asan.cc (asan_emit_stack_protection): Always zero the flag
unless it is cleared by the __asan_stack_free_N() libcall.
(cherry picked from commit 13d971601175541146fda54682cde4d3f9cd2759)
Diff:
---
gcc/asan.cc | 37 ++++++++++++++++++-------------------
1 file changed, 18 insertions(+), 19 deletions(-)
diff --git a/gcc/asan.cc b/gcc/asan.cc
index 386aeec81557..268bb9fe0707 100644
--- a/gcc/asan.cc
+++ b/gcc/asan.cc
@@ -2100,28 +2100,13 @@ asan_emit_stack_protection (rtx base, rtx pbase,
unsigned int alignb,
mem = adjust_address (mem, VOIDmode, base_align_bias);
emit_move_insn (mem, gen_int_mode (ASAN_STACK_RETIRED_MAGIC, ptr_mode));
unsigned HOST_WIDE_INT sz = asan_frame_size >> ASAN_SHADOW_SHIFT;
+ bool asan_stack_free_emitted_p = false;
if (use_after_return_class < 5
&& can_store_by_pieces (sz, builtin_memset_read_str, &c,
BITS_PER_UNIT, true))
- {
- /* Emit:
- memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
- **SavedFlagPtr(FakeStack, class_id) = 0
- */
- store_by_pieces (shadow_mem, sz, builtin_memset_read_str, &c,
- BITS_PER_UNIT, true, RETURN_BEGIN);
-
- unsigned HOST_WIDE_INT offset
- = (1 << (use_after_return_class + 6));
- offset -= GET_MODE_SIZE (ptr_mode);
- mem = gen_rtx_MEM (ptr_mode, base);
- mem = adjust_address (mem, ptr_mode, offset);
- rtx addr = gen_reg_rtx (ptr_mode);
- emit_move_insn (addr, mem);
- addr = convert_memory_address (Pmode, addr);
- mem = gen_rtx_MEM (QImode, addr);
- emit_move_insn (mem, const0_rtx);
- }
+ /* Emit memset (ShadowBase, kAsanStackAfterReturnMagic, ShadowSize). */
+ store_by_pieces (shadow_mem, sz, builtin_memset_read_str, &c,
+ BITS_PER_UNIT, true, RETURN_BEGIN);
else if (use_after_return_class >= 5
|| !set_storage_via_setmem (shadow_mem,
GEN_INT (sz),
@@ -2138,6 +2123,20 @@ 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),
orig_addr, ptr_mode);
+ asan_stack_free_emitted_p = true;
+ }
+ if (!asan_stack_free_emitted_p)
+ {
+ /* Emit **SavedFlagPtr (FakeStack, class_id) = 0. */
+ unsigned HOST_WIDE_INT offset = (1 << (use_after_return_class + 6));
+ offset -= GET_MODE_SIZE (ptr_mode);
+ mem = gen_rtx_MEM (ptr_mode, base);
+ mem = adjust_address (mem, ptr_mode, offset);
+ rtx addr = gen_reg_rtx (ptr_mode);
+ emit_move_insn (addr, mem);
+ addr = convert_memory_address (Pmode, addr);
+ mem = gen_rtx_MEM (QImode, addr);
+ emit_move_insn (mem, const0_rtx);
}
lab = gen_label_rtx ();
emit_jump (lab);
