When compiling with -mbackchain -fstack-clash-protection currently no
probes are emitted. This patch adjusts the "allocate_stack" expander
to call anti_adjust_stack_and_probe_stack_clash when needed. In order
to do this I had to export that function from explow.c.
Ok for mainline?
2020-05-08 Andreas Krebbel <kreb...@linux.ibm.com>
* explow.c (anti_adjust_stack_and_probe_stack_clash): Remove
prototype. Remove static.
* explow.h (anti_adjust_stack_and_probe_stack_clash): Add
prototype.
* config/s390/s390.md ("allocate_stack"): Call
anti_adjust_stack_and_probe_stack_clash when stack clash
protection is enabled.
gcc/testsuite/ChangeLog:
2020-05-08 Andreas Krebbel <kreb...@linux.ibm.com>
* gcc.target/s390/stack-clash-3.c: New test.
---
gcc/config/s390/s390.md | 7 ++++++-
gcc/explow.c | 3 +--
gcc/explow.h | 4 ++++
gcc/testsuite/gcc.target/s390/stack-clash-3.c | 17 +++++++++++++++++
4 files changed, 28 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/s390/stack-clash-3.c
diff --git a/gcc/config/s390/s390.md b/gcc/config/s390/s390.md
index cf53ef1b791..908de587e17 100644
--- a/gcc/config/s390/s390.md
+++ b/gcc/config/s390/s390.md
@@ -11007,7 +11007,12 @@
rtx temp = gen_reg_rtx (Pmode);
emit_move_insn (temp, s390_back_chain_rtx ());
- anti_adjust_stack (operands[1]);
+
+ if (flag_stack_clash_protection)
+ anti_adjust_stack_and_probe_stack_clash (operands[1]);
+ else
+ anti_adjust_stack (operands[1]);
+
emit_move_insn (s390_back_chain_rtx (), temp);
emit_move_insn (operands[0], virtual_stack_dynamic_rtx);
diff --git a/gcc/explow.c b/gcc/explow.c
index b838f035870..15c9cfb0318 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -43,7 +43,6 @@ along with GCC; see the file COPYING3. If not see
#include "output.h"
static rtx break_out_memory_refs (rtx);
-static void anti_adjust_stack_and_probe_stack_clash (rtx);
/* Truncate and perhaps sign-extend C as appropriate for MODE. */
@@ -1948,7 +1947,7 @@ emit_stack_clash_protection_probe_loop_end (rtx loop_lab,
rtx end_loop,
allocate/probe beyond that because this probing style does not
guarantee signal handling capability if the guard is hit. */
-static void
+void
anti_adjust_stack_and_probe_stack_clash (rtx size)
{
/* First ensure SIZE is Pmode. */
diff --git a/gcc/explow.h b/gcc/explow.h
index cc44bf8520a..0df8c62b82a 100644
--- a/gcc/explow.h
+++ b/gcc/explow.h
@@ -69,6 +69,10 @@ extern void anti_adjust_stack (rtx);
/* Add some bytes to the stack while probing it. An rtx says how many. */
extern void anti_adjust_stack_and_probe (rtx, bool);
+/* Add some bytes to the stack while probing it. An rtx says how
+ many. Add additional probes to prevent stack clashing attacks. */
+extern void anti_adjust_stack_and_probe_stack_clash (rtx);
+
/* Support for building allocation/probing loops for stack-clash
protection of dyamically allocated stack space. */
extern void compute_stack_clash_protection_loop_data (rtx *, rtx *, rtx *,
diff --git a/gcc/testsuite/gcc.target/s390/stack-clash-3.c
b/gcc/testsuite/gcc.target/s390/stack-clash-3.c
new file mode 100644
index 00000000000..929d3fbb365
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/stack-clash-3.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=z900 -fstack-clash-protection -mbackchain" } */
+
+extern void bar (char *);
+
+void
+foo ()
+{
+ char * mem = __builtin_alloca (20000);
+ bar (mem);
+}
+
+/* For alloca a common code routine emits the probes. Make sure the
+ "probe_stack" expander is used in that case. We want to use mem
+ compares instead of stores. */
+/* { dg-final { scan-assembler-times "cg\t" 5 { target lp64 } } } */
+/* { dg-final { scan-assembler-times "c\t" 5 { target { ! lp64 } } } } */
--
2.17.1
