Re: [PATCH 1/1] tests/tcg/aarch64: Add bti mmap smoke test

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> This tests PROT_BTI, and also does not require special
> compiler support.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tests/tcg/aarch64/bti-2.c         | 108 ++++++++++++++++++++++++++++++
>  tests/tcg/aarch64/Makefile.target |   7 +-
>  2 files changed, 113 insertions(+), 2 deletions(-)
>  create mode 100644 tests/tcg/aarch64/bti-2.c
>
> diff --git a/tests/tcg/aarch64/bti-2.c b/tests/tcg/aarch64/bti-2.c
> new file mode 100644
> index 0000000000..6dc8908b5a
> --- /dev/null
> +++ b/tests/tcg/aarch64/bti-2.c
> @@ -0,0 +1,108 @@
> +/*
> + * Branch target identification, basic notskip cases.
> + */
> +
> +#include <stdio.h>
> +#include <signal.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +
> +#ifndef PROT_BTI
> +#define PROT_BTI  0x10
> +#endif
> +
> +static void skip2_sigill(int sig, siginfo_t *info, void *vuc)
> +{
> +    ucontext_t *uc = vuc;
> +    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)    \
> +    "mov x1, #1\n\t"     \
> +    "adr x16, 1f\n\t"    \
> +    "br x16\n"           \
> +"1: " DEST "\n\t"        \
> +    "mov x1, #0"
> +
> +#define BTYPE_2(DEST)    \
> +    "mov x1, #1\n\t"     \
> +    "adr x16, 1f\n\t"    \
> +    "blr x16\n"          \
> +"1: " DEST "\n\t"        \
> +    "mov x1, #0"
> +
> +#define BTYPE_3(DEST)    \
> +    "mov x1, #1\n\t"     \
> +    "adr x15, 1f\n\t"    \
> +    "br x15\n"           \
> +"1: " DEST "\n\t"        \
> +    "mov x1, #0"
> +
> +#define TEST(WHICH, DEST, EXPECT) \
> +    WHICH(DEST) "\n"              \
> +    ".if " #EXPECT "\n\t"         \
> +    "eor x1, x1," #EXPECT "\n"    \
> +    ".endif\n\t"                  \
> +    "add x0, x0, x1\n\t"
> +
> +extern char test_begin[], test_end[];
> +
> +asm("\n"
> +"test_begin:\n\t"
> +    BTI_C "\n\t"
> +    "mov x2, x30\n\t"
> +    "mov x0, #0\n\t"
> +
> +    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)
> +
> +    "ret x2\n"
> +"test_end:"
> +);
> +
> +int main()
> +{
> +    struct sigaction sa;
> +
> +    void *p = mmap(0, getpagesize(),
> +                   PROT_EXEC | PROT_READ | PROT_WRITE | PROT_BTI,
> +                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +    if (p == MAP_FAILED) {
> +        perror("mmap");
> +        return 1;
> +    }
> +
> +    memset(&sa, 0, sizeof(sa));
> +    sa.sa_sigaction = skip2_sigill;
> +    sa.sa_flags = SA_SIGINFO;
> +    if (sigaction(SIGILL, &sa, NULL) < 0) {
> +        perror("sigaction");
> +        return 1;
> +    }
> +
> +    memcpy(p, test_begin, test_end - test_begin);
> +    return ((int (*)(void))p)();
> +}
> diff --git a/tests/tcg/aarch64/Makefile.target b/tests/tcg/aarch64/Makefile.target
> index 491683e91d..d7d33e293c 100644
> --- a/tests/tcg/aarch64/Makefile.target
> +++ b/tests/tcg/aarch64/Makefile.target
> @@ -26,11 +26,14 @@ run-plugin-pauth-%: QEMU_OPTS += -cpu max
>  endif
>  
>  # BTI Tests
> +# bti-1 tests the elf notes, so we require special compiler support.
>  ifneq ($(DOCKER_IMAGE)$(CROSS_CC_HAS_ARMV8_BTI),)
>  AARCH64_TESTS += bti-1
> -bti-%: CFLAGS += -mbranch-protection=standard
> -bti-%: LDFLAGS += -nostdlib
> +bti-1: CFLAGS += -mbranch-protection=standard
> +bti-1: LDFLAGS += -nostdlib
>  endif
> +# bti-2 tests PROT_BTI, so no special compiler support required.
> +AARCH64_TESTS += bti-2


LGTM

Acked-by: Alex Bennée <alex.bennee@linaro.org>

(I assume this just rolls up with your existing BTI patches).

-- 
Alex Bennée