[v7,6/6] tests/tcg/aarch64: Add bti smoke test

Message ID 20190803210803.5701-7-richard.henderson@linaro.org
State New
Headers show
Series
  • target/arm: Implement ARMv8.5-BTI for linux-user
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Commit Message

Richard Henderson Aug. 3, 2019, 9:08 p.m.
This will build with older toolchains, without the upstream support
for -mbranch-protection.  Such a toolchain will produce a warning
in such cases,

ld: warning: /tmp/ccyZt0kq.o: unsupported GNU_PROPERTY_TYPE (5) \
type: 0xc0000000

but the still places the note at the correct location in the binary
for processing by the runtime loader.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 tests/tcg/aarch64/bti-1.c         | 77 +++++++++++++++++++++++++++++++
 tests/tcg/aarch64/bti-crt.inc.c   | 69 +++++++++++++++++++++++++++
 tests/tcg/aarch64/Makefile.target |  3 ++
 tests/tcg/aarch64/bti.ld          | 15 ++++++
 4 files changed, 164 insertions(+)
 create mode 100644 tests/tcg/aarch64/bti-1.c
 create mode 100644 tests/tcg/aarch64/bti-crt.inc.c
 create mode 100644 tests/tcg/aarch64/bti.ld

-- 
2.17.1

Comments

Peter Maydell Aug. 20, 2019, 3:31 p.m. | #1
On Sat, 3 Aug 2019 at 22:08, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> This will build with older toolchains, without the upstream support

> for -mbranch-protection.  Such a toolchain will produce a warning

> in such cases,

>

> ld: warning: /tmp/ccyZt0kq.o: unsupported GNU_PROPERTY_TYPE (5) \

> type: 0xc0000000

>

> but the still places the note at the correct location in the binary

> for processing by the runtime loader.


Is there some way to suppress these warnings ? 'make check-tcg'
output includes

  BUILD   TCG tests for aarch64-linux-user
  BUILD   aarch64 guest-tests with aarch64-linux-gnu-gcc
/usr/lib/gcc-cross/aarch64-linux-gnu/7/../../../../aarch64-linux-gnu/bin/ld:
warning: /tmp/cccZ8Fk7.o: unsupported GNU_PROPERTY_TYPE (5) type:
0xc0000000
/usr/lib/gcc-cross/aarch64-linux-gnu/7/../../../../aarch64-linux-gnu/bin/ld:
warning: .note.gnu.build-id section discarded, --build-id ignored.
  RUN     TCG tests for aarch64-linux-user

and these are going to come up in the merge-testing search
for warnings in the build logs...

thanks
-- PMM
Richard Henderson Aug. 20, 2019, 4:34 p.m. | #2
On 8/20/19 8:31 AM, Peter Maydell wrote:
> Is there some way to suppress these warnings ? 'make check-tcg'

> output includes

> 

>   BUILD   TCG tests for aarch64-linux-user

>   BUILD   aarch64 guest-tests with aarch64-linux-gnu-gcc

> /usr/lib/gcc-cross/aarch64-linux-gnu/7/../../../../aarch64-linux-gnu/bin/ld:

> warning: /tmp/cccZ8Fk7.o: unsupported GNU_PROPERTY_TYPE (5) type:

> 0xc0000000

> /usr/lib/gcc-cross/aarch64-linux-gnu/7/../../../../aarch64-linux-gnu/bin/ld:

> warning: .note.gnu.build-id section discarded, --build-id ignored.

>   RUN     TCG tests for aarch64-linux-user

> 

> and these are going to come up in the merge-testing search

> for warnings in the build logs...


The only way is to use a newer ld.

Sadly, bfd doesn't really distinguish between warnings and errors when it comes
to printing, so there's no "-w" flag as for gcc.

I suppose we should just disable this test by default for now.  I'll note that
despite the warnings, you got a binary that runs as expected.



r~

Patch

diff --git a/tests/tcg/aarch64/bti-1.c b/tests/tcg/aarch64/bti-1.c
new file mode 100644
index 0000000000..2aee57ea7a
--- /dev/null
+++ b/tests/tcg/aarch64/bti-1.c
@@ -0,0 +1,77 @@ 
+/*
+ * Branch target identification, basic notskip cases.
+ */
+
+#include "bti-crt.inc.c"
+
+/*
+ * Work around lack of -mbranch-protection=standard in older toolchains.
+ * The signal handler is invoked by the kernel with PSTATE.BTYPE=2, which
+ * means that the handler must begin with a marker like BTI_C.
+ */
+asm("skip2_sigill1:\n\
+	hint	#34\n\
+	b	skip2_sigill2\n\
+.type skip2_sigill1,%function\n\
+.size skip2_sigill1,8");
+
+extern void skip2_sigill1(int sig, siginfo_t *info, ucontext_t *uc)
+    __attribute__((visibility("hidden")));
+
+static void __attribute__((used))
+skip2_sigill2(int sig, siginfo_t *info, ucontext_t *uc)
+{
+    uc->uc_mcontext.pc += 8;
+    uc->uc_mcontext.pstate = 1;
+}
+
+#define NOP       "nop"
+#define BTI_N     "hint #32"
+#define BTI_C     "hint #34"
+#define BTI_J     "hint #36"
+#define BTI_JC    "hint #38"
+
+#define BTYPE_1(DEST) \
+    asm("mov %0,#1; adr x16, 1f; br x16; 1: " DEST "; mov %0,#0" \
+        : "=r"(skipped) : : "x16")
+
+#define BTYPE_2(DEST) \
+    asm("mov %0,#1; adr x16, 1f; blr x16; 1: " DEST "; mov %0,#0" \
+        : "=r"(skipped) : : "x16", "x30")
+
+#define BTYPE_3(DEST) \
+    asm("mov %0,#1; adr x15, 1f; br x15; 1: " DEST "; mov %0,#0" \
+        : "=r"(skipped) : : "x15")
+
+#define TEST(WHICH, DEST, EXPECT) \
+    do { WHICH(DEST); fail += skipped ^ EXPECT; } while (0)
+
+
+int main()
+{
+    int fail = 0;
+    int skipped;
+
+    /* Signal-like with SA_SIGINFO.  */
+    signal_info(SIGILL, skip2_sigill1);
+
+    TEST(BTYPE_1, NOP, 1);
+    TEST(BTYPE_1, BTI_N, 1);
+    TEST(BTYPE_1, BTI_C, 0);
+    TEST(BTYPE_1, BTI_J, 0);
+    TEST(BTYPE_1, BTI_JC, 0);
+
+    TEST(BTYPE_2, NOP, 1);
+    TEST(BTYPE_2, BTI_N, 1);
+    TEST(BTYPE_2, BTI_C, 0);
+    TEST(BTYPE_2, BTI_J, 1);
+    TEST(BTYPE_2, BTI_JC, 0);
+
+    TEST(BTYPE_3, NOP, 1);
+    TEST(BTYPE_3, BTI_N, 1);
+    TEST(BTYPE_3, BTI_C, 1);
+    TEST(BTYPE_3, BTI_J, 0);
+    TEST(BTYPE_3, BTI_JC, 0);
+
+    return fail;
+}
diff --git a/tests/tcg/aarch64/bti-crt.inc.c b/tests/tcg/aarch64/bti-crt.inc.c
new file mode 100644
index 0000000000..bb363853de
--- /dev/null
+++ b/tests/tcg/aarch64/bti-crt.inc.c
@@ -0,0 +1,69 @@ 
+/*
+ * Minimal user-environment for testing BTI.
+ *
+ * Normal libc is not built with BTI support enabled, and so could
+ * generate a BTI TRAP before ever reaching main.
+ */
+
+#include <stdlib.h>
+#include <signal.h>
+#include <ucontext.h>
+#include <asm/unistd.h>
+
+int main(void);
+
+void _start(void)
+{
+    exit(main());
+}
+
+void exit(int ret)
+{
+    register int x0 __asm__("x0") = ret;
+    register int x8 __asm__("x8") = __NR_exit;
+
+    asm volatile("svc #0" : : "r"(x0), "r"(x8));
+    __builtin_unreachable();
+}
+
+/*
+ * Irritatingly, the user API struct sigaction does not match the
+ * kernel API struct sigaction.  So for simplicity, isolate the
+ * kernel ABI here, and make this act like signal.
+ */
+void signal_info(int sig, void (*fn)(int, siginfo_t *, ucontext_t *))
+{
+    struct kernel_sigaction {
+        void (*handler)(int, siginfo_t *, ucontext_t *);
+        unsigned long flags;
+        unsigned long restorer;
+        unsigned long mask;
+    } sa = { fn, SA_SIGINFO, 0, 0 };
+
+    register int x0 __asm__("x0") = sig;
+    register void *x1 __asm__("x1") = &sa;
+    register void *x2 __asm__("x2") = 0;
+    register int x3 __asm__("x3") = sizeof(unsigned long);
+    register int x8 __asm__("x8") = __NR_rt_sigaction;
+
+    asm volatile("svc #0"
+                 : : "r"(x0), "r"(x1), "r"(x2), "r"(x3), "r"(x8) : "memory");
+}
+
+/*
+ * Create the PT_NOTE that will enable BTI in the page tables.
+ * This will be created by the compiler with -mbranch-protection=standard,
+ * but as of 2019-03-29, this is has not been committed to gcc mainline.
+ * This will probably be in GCC10.
+ */
+asm(".section .note.gnu.property,\"a\"\n\
+	.align	3\n\
+	.long	4\n\
+        .long	16\n\
+        .long	5\n\
+        .string	\"GNU\"\n\
+	.long	0xc0000000\n\
+	.long	4\n\
+	.long	1\n\
+        .align  3\n\
+	.previous");
diff --git a/tests/tcg/aarch64/Makefile.target b/tests/tcg/aarch64/Makefile.target
index 31ba9cfcaa..68135c6ee8 100644
--- a/tests/tcg/aarch64/Makefile.target
+++ b/tests/tcg/aarch64/Makefile.target
@@ -18,4 +18,7 @@  run-fcvt: fcvt
 AARCH64_TESTS += pauth-1 pauth-2
 run-pauth-%: QEMU += -cpu max
 
+AARCH64_TESTS += bti-1
+bti-1: LDFLAGS += -nostdlib -Wl,-T,$(AARCH64_SRC)/bti.ld
+
 TESTS:=$(AARCH64_TESTS)
diff --git a/tests/tcg/aarch64/bti.ld b/tests/tcg/aarch64/bti.ld
new file mode 100644
index 0000000000..a5ef98f8a2
--- /dev/null
+++ b/tests/tcg/aarch64/bti.ld
@@ -0,0 +1,15 @@ 
+ENTRY(_start)
+
+PHDRS
+{
+  text PT_LOAD FILEHDR PHDRS;
+  prop 0x6474e553 ;  /* PT_GNU_PROPERTY */
+}
+
+SECTIONS
+{
+  . = 1M + SIZEOF_HEADERS;
+  .note.gnu.property : { *(.note.gnu.property) } :text :prop
+  .text : { *(.text) *(.rodata) } :text
+  /DISCARD/ : { *(.note.gnu.build-id) }
+}