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

[Zhuojia Shen]

On 05/17/2023 12:51 PM -0700, Richard Henderson wrote:
> 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.

Will do.

> 
>  +++ 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.
> 

Thanks!  Will update in the second patch.

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

Tests for CVAP and CVADP require different CFLAGS; I'll merge them into
2 tests.

> 
> 
> r~
>