From: Matthew Fortune <[email protected]>
Ensure the frame barrier prevents reordering of stack pointer changes.
It is possible for a load/store accessing the stack via a copy of the
stack pointer to be moved across the epilogue meaning that it accesses
stack that is no longer allocated. This leads to a situation where the
code is unsafe in the event of an interrupt where the same stack is
used for interrupt handling.
gcc/
* config/mips/mips.cc (mips_frame_barrier): Upgrade to a full
blockage.
gcc/testsuite/
* gcc.target/mips/frame-barrier-1.c: New test.
Cherry-picked 0c240da6f6032bd19348b97148d25c05ba2e8356
from https://github.com/MIPS/gcc
Signed-off-by: Matthew Fortune <[email protected]>
Signed-off-by: Faraz Shahbazker <[email protected]>
Signed-off-by: Aleksandar Rakic <[email protected]>
Signed-off-by: Eldar Osmanovic <[email protected]>
---
gcc/config/mips/mips.cc | 2 +-
gcc/testsuite/gcc.target/mips/frame-barrier-1.c | 15 +++++++++++++++
2 files changed, 16 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/mips/frame-barrier-1.c
diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
index 3f123523849..fdbb0a764bd 100644
--- a/gcc/config/mips/mips.cc
+++ b/gcc/config/mips/mips.cc
@@ -12391,7 +12391,7 @@ mips_output_function_epilogue (FILE *)
static void
mips_frame_barrier (void)
{
- emit_clobber (gen_frame_mem (BLKmode, stack_pointer_rtx));
+ emit_insn (gen_blockage ());
}
diff --git a/gcc/testsuite/gcc.target/mips/frame-barrier-1.c
b/gcc/testsuite/gcc.target/mips/frame-barrier-1.c
new file mode 100644
index 00000000000..b49dab505df
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/frame-barrier-1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-mabi=32 -march=mips32r2 -mno-abicalls -fno-pic
-fdump-rtl-final" } */
+
+extern void use (char *);
+
+int
+f (int n)
+{
+ char * p = (char *) __builtin_alloca (n);
+
+ use (p);
+ return p[0];
+}
+
+/* { dg-final { scan-rtl-dump-times "UNSPEC_BLOCKAGE" 3 "final" } } */
--
2.43.0
