Re: [PATCH v2] target/arm: allow DC CVA[D]P in user mode emulation

[Richard Henderson <richard.henderson@linaro.org>]

On 5/17/23 10:31, Zhuojia Shen wrote:
> DC CVAP and DC CVADP instructions can be executed in EL0 on Linux,
> either directly when SCTLR_EL1.UCI == 1 or emulated by the kernel (see
> user_cache_maint_handler() in arch/arm64/kernel/traps.c).
> 
> This patch enables execution of the two instructions in user mode
> emulation.
> 
> Signed-off-by: Zhuojia Shen <chaosdefinition@hotmail.com>
> ---
>   target/arm/helper.c               |  6 ++--
>   tests/tcg/aarch64/Makefile.target | 11 ++++++++
>   tests/tcg/aarch64/dcpodp-1.c      | 47 +++++++++++++++++++++++++++++++
>   tests/tcg/aarch64/dcpodp-2.c      | 47 +++++++++++++++++++++++++++++++
>   tests/tcg/aarch64/dcpop-1.c       | 47 +++++++++++++++++++++++++++++++
>   tests/tcg/aarch64/dcpop-2.c       | 47 +++++++++++++++++++++++++++++++
>   6 files changed, 201 insertions(+), 4 deletions(-)
>   create mode 100644 tests/tcg/aarch64/dcpodp-1.c
>   create mode 100644 tests/tcg/aarch64/dcpodp-2.c
>   create mode 100644 tests/tcg/aarch64/dcpop-1.c
>   create mode 100644 tests/tcg/aarch64/dcpop-2.c

I recommend splitting the tests to a second patch.

  +++ b/tests/tcg/aarch64/dcpodp-1.c
> @@ -0,0 +1,47 @@
> +/* Test execution of DC CVADP instruction */
> +
> +#include <asm/hwcap.h>
> +#include <sys/auxv.h>
> +
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +#ifndef HWCAP2_DCPODP
> +#define HWCAP2_DCPODP (1 << 0)
> +#endif
> +
> +static void signal_handler(int sig)
> +{
> +    exit(EXIT_FAILURE);
> +}
> +
> +static int do_dc_cvadp(void)
> +{
> +    struct sigaction sa = {
> +        .sa_handler = signal_handler,
> +    };
> +
> +    if (sigaction(SIGILL, &sa, NULL) < 0) {
> +        perror("sigaction");
> +        return EXIT_FAILURE;
> +    }
> +    if (sigaction(SIGSEGV, &sa, NULL) < 0) {
> +        perror("sigaction");
> +        return EXIT_FAILURE;
> +    }
> +
> +    asm volatile("dc cvadp, %0\n\t" :: "r"(&sa));
> +
> +    return EXIT_SUCCESS;
> +}

...

> diff --git a/tests/tcg/aarch64/dcpodp-2.c b/tests/tcg/aarch64/dcpodp-2.c
> new file mode 100644
> index 0000000000..3245d7883d
> --- /dev/null
> +++ b/tests/tcg/aarch64/dcpodp-2.c
> @@ -0,0 +1,47 @@
> +/* Test execution of DC CVADP instruction on unmapped address */
> +
> +#include <asm/hwcap.h>
> +#include <sys/auxv.h>
> +
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +#ifndef HWCAP2_DCPODP
> +#define HWCAP2_DCPODP (1 << 0)
> +#endif
> +
> +static void signal_handler(int sig)
> +{
> +    exit(EXIT_SUCCESS);
> +}
> +
> +static int do_dc_cvadp(void)
> +{
> +    struct sigaction sa = {
> +        .sa_handler = signal_handler,
> +    };
> +
> +    if (sigaction(SIGILL, &sa, NULL) < 0) {
> +        perror("sigaction");
> +        return EXIT_FAILURE;
> +    }

This isn't: if SIGILL, exit with success.

You don't actually need to register anything for SIGILL, in either test, because SIGILL is 
a fine exit for failure.  So is SIGSEGV for test 1.

Also, you could merge all 4 tests and save some CI time.


r~