Re: [PATCH v3 12/12] tests/tcg/s390x: Test unaligned accesses

[Thomas Huth]

On 16/03/2023 00.26, Ilya Leoshkevich wrote:
> Add a number of small test that check whether accessing unaligned
> addresses in various ways leads to a specification exception.
>
> Run these test both in softmmu and user configurations; expect a PGM
> in one case and SIGILL in the other.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
...
> diff --git a/tests/tcg/s390x/pgm-specification.inc 
> b/tests/tcg/s390x/pgm-specification.inc
> new file mode 100644
> index 00000000000..e3899ed4718
> --- /dev/null
> +++ b/tests/tcg/s390x/pgm-specification.inc
> @@ -0,0 +1,90 @@
> +/*
> + * Common code for specification exception testing.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +#ifdef CONFIG_SOFTMMU
> +    .org 0x8d
> +ilc:
> +    .org 0x8e
> +program_interruption_code:
> +    .org 0x150
> +program_old_psw:
> +    .org 0x1D0                         /* program new PSW */
> +    .quad 0x180000000,pgm              /* 64-bit mode */
> +    .org 0x200                         /* lowcore padding */
> +
> +    .globl _start
> +_start:
> +    lpswe start64_psw
> +start64:
> +    CODE
> +    j failure
> +
> +pgm:
> +    chhsi program_interruption_code,0x6          /* PGM_SPECIFICATION? */
> +    jne failure
> +    lg %r0,expected_old_psw+8                    /* ilc adjustment */
> +    llgc %r1,ilc
> +    agr %r0,%r1
> +    stg %r0,expected_old_psw+8
> +    clc expected_old_psw(16),program_old_psw     /* correct location? */
> +    jne failure
> +    lpswe success_psw
> +failure:
> +    lpswe failure_psw
> +
> +    .align 8
> +start64_psw:
> +    .quad 0x180000000,start64          /* 64-bit mode */
> +expected_old_psw:
> +#ifndef EXPECTED_OLD_PSWA
> +#define EXPECTED_OLD_PSWA expected_old_pswa
> +#endif
> +    .quad 0x180000000,EXPECTED_OLD_PSWA
> +success_psw:
> +    .quad 0x2000180000000,0xfff        /* see is_special_wait_psw() */
> +failure_psw:
> +    .quad 0x2000180000000,0            /* disabled wait */
> +    DATA
> +#else
> +#include <assert.h>
> +#include <signal.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +#ifndef EXPECTED_OLD_PSWA
> +extern char expected_old_pswa[];
> +#define EXPECTED_OLD_PSWA (long)expected_old_pswa
> +#endif
> +
> +static void handle_sigill(int sig, siginfo_t *info, void *ucontext)
> +{
> +    if ((long)info->si_addr != EXPECTED_OLD_PSWA) {
> +        _exit(EXIT_FAILURE);
> +    }
> +    _exit(EXIT_SUCCESS);
> +}
> +
> +asm("    .data\n"
> +    "    .align 8\n"
> +    DATA
> +    "    .previous\n");
> +
> +int main(void)
> +{
> +    struct sigaction act;
> +    int err;
> +
> +    memset(&act, 0, sizeof(act));
> +    act.sa_sigaction = handle_sigill;
> +    act.sa_flags = SA_SIGINFO;
> +    err = sigaction(SIGILL, &act, NULL);
> +    assert(err == 0);
> +
> +    asm volatile(CODE);
> +
> +    return EXIT_FAILURE;
> +}
> +#endif

Honestly, this looks like quite a ugly pre-processor magic to me. Wouldn't 
it be possible to have the test code in normal .S files instead and then 
link it once with the C code for the linux-user binaries, and once with the 
assembly startup code for the system binaries?

 Thomas