diff mbox series

[v6,6/6] tests/tcg/aarch64: Add bti smoke test

Message ID 20190605205706.569-7-richard.henderson@linaro.org (mailing list archive)
State New, archived
Headers show
Series linux-user/aarch64: Support PROT_BTI | expand

Commit Message

Richard Henderson June 5, 2019, 8:57 p.m. UTC 
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 ++
 3 files changed, 149 insertions(+)
 create mode 100644 tests/tcg/aarch64/bti-1.c
 create mode 100644 tests/tcg/aarch64/bti-crt.inc.c

Comments

Dave Martin June 6, 2019, 10:21 a.m. UTC | #1 
On Wed, Jun 05, 2019 at 09:57:06PM +0100, Richard Henderson 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.
> 
> 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 ++
>  3 files changed, 149 insertions(+)
>  create mode 100644 tests/tcg/aarch64/bti-1.c
>  create mode 100644 tests/tcg/aarch64/bti-crt.inc.c
> 
> 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.

FYI, GCC9 has it.

> + */
> +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");

Note, this won't be enough to generate the PT_GNU_PROPERTY entry in the
program header table using older tools.

This may be work-round-able with a linker script, but I haven't looked
into it.

> diff --git a/tests/tcg/aarch64/Makefile.target b/tests/tcg/aarch64/Makefile.target
> index 2bb914975b..21da3bc37f 100644
> --- a/tests/tcg/aarch64/Makefile.target
> +++ b/tests/tcg/aarch64/Makefile.target
> @@ -18,4 +18,7 @@ run-fcvt: fcvt
>  AARCH64_TESTS += pauth-1
>  run-pauth-%: QEMU += -cpu max
>  
> +AARCH64_TESTS += bti-1
> +bti-1: LDFLAGS += -nostartfiles -nodefaultlibs -nostdlib
> +

Doesn't -nostdlib imply -nodefaultlibs and -nostartfiles?

Cheers
---Dave
Richard Henderson June 6, 2019, 2:24 p.m. UTC | #2 
On 6/6/19 5:21 AM, Dave Martin wrote:
>> +/*
>> + * 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.
> 
> FYI, GCC9 has it.

Thanks.

>> + */
>> +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");
> 
> Note, this won't be enough to generate the PT_GNU_PROPERTY entry in the
> program header table using older tools.
> 
> This may be work-round-able with a linker script, but I haven't looked
> into it.

Yes, a linker script can create such an entry.

>> +AARCH64_TESTS += bti-1
>> +bti-1: LDFLAGS += -nostartfiles -nodefaultlibs -nostdlib
>> +
> 
> Doesn't -nostdlib imply -nodefaultlibs and -nostartfiles?

I don't believe so, but I'll double-check.


r~
diff mbox series

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 2bb914975b..21da3bc37f 100644
--- a/tests/tcg/aarch64/Makefile.target
+++ b/tests/tcg/aarch64/Makefile.target
@@ -18,4 +18,7 @@  run-fcvt: fcvt
 AARCH64_TESTS += pauth-1
 run-pauth-%: QEMU += -cpu max
 
+AARCH64_TESTS += bti-1
+bti-1: LDFLAGS += -nostartfiles -nodefaultlibs -nostdlib
+
 TESTS:=$(AARCH64_TESTS)