Re: [PATCH v3 2/2] tests/tcg/s390x: Test SIGILL and SIGSEGV handling

["jonathan.albrecht" <jonathan.albrecht@linux.vnet.ibm.com>]

On 2021-06-01 8:22 pm, Ilya Leoshkevich wrote:
> Verify that s390x-specific uc_mcontext.psw.addr is reported correctly.
> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>  tests/tcg/s390x/Makefile.target |   1 +
>  tests/tcg/s390x/signal.c        | 163 ++++++++++++++++++++++++++++++++
>  2 files changed, 164 insertions(+)
>  create mode 100644 tests/tcg/s390x/signal.c
> 
> diff --git a/tests/tcg/s390x/Makefile.target 
> b/tests/tcg/s390x/Makefile.target
> index 241ef28f61..cdb7d85316 100644
> --- a/tests/tcg/s390x/Makefile.target
> +++ b/tests/tcg/s390x/Makefile.target
> @@ -8,3 +8,4 @@ TESTS+=exrl-trtr
>  TESTS+=pack
>  TESTS+=mvo
>  TESTS+=mvc
> +TESTS+=signal
> diff --git a/tests/tcg/s390x/signal.c b/tests/tcg/s390x/signal.c
> new file mode 100644
> index 0000000000..c25d7dd019
> --- /dev/null
> +++ b/tests/tcg/s390x/signal.c
> @@ -0,0 +1,163 @@
> +#include <assert.h>
> +#include <signal.h>
> +#include <string.h>
> +#include <sys/mman.h>
> +#include <ucontext.h>
> +#include <unistd.h>
> +
> +/*
> + * Various instructions that generate SIGILL and SIGSEGV. They could 
> have been
> + * defined in a separate .s file, but this would complicate the build, 
> so the
> + * inline asm is used instead.
> + */
> +
> +void illegal_op(void);
> +void after_illegal_op(void);
> +asm(".globl\tillegal_op\n"
> +    "illegal_op:\t.byte\t0x00,0x00\n"
> +    "\t.globl\tafter_illegal_op\n"
> +    "after_illegal_op:\tbr\t%r14");
> +
> +void stg(void *dst, unsigned long src);
> +asm(".globl\tstg\n"
> +    "stg:\tstg\t%r3,0(%r2)\n"
> +    "\tbr\t%r14");
> +
> +void mvc_8(void *dst, void *src);
> +asm(".globl\tmvc_8\n"
> +    "mvc_8:\tmvc\t0(8,%r2),0(%r3)\n"
> +    "\tbr\t%r14");
> +
> +static void safe_puts(const char *s)
> +{
> +    write(0, s, strlen(s));
> +    write(0, "\n", 1);
> +}
> +
> +enum exception {
> +    exception_operation,
> +    exception_translation,
> +    exception_protection,
> +};
> +
> +static struct {
> +    int sig;
> +    void *addr;
> +    unsigned long psw_addr;
> +    enum exception exception;
> +} expected;
> +
> +static void handle_signal(int sig, siginfo_t *info, void *ucontext)
> +{
> +    void *page;
> +    int err;
> +
> +    if (sig != expected.sig) {
> +        safe_puts("[  FAILED  ] wrong signal");
> +        _exit(1);
> +    }
> +
> +    if (info->si_addr != expected.addr) {
> +        safe_puts("[  FAILED  ] wrong si_addr");
> +        _exit(1);
> +    }
> +
> +    if (((ucontext_t *)ucontext)->uc_mcontext.psw.addr != 
> expected.psw_addr) {
> +        safe_puts("[  FAILED  ] wrong psw.addr");
> +        _exit(1);
> +    }
> +
> +    switch (expected.exception) {

When I try to run 'make test-tcg' gcc 9.3.0 is complaining about a 
missing case:
/home/jalbrecht/src/qemu/tests/tcg/s390x/signal.c: In function 
'handle_signal':
/home/jalbrecht/src/qemu/tests/tcg/s390x/signal.c:70:5: error: 
enumeration value 'exception_operation' not handled in switch 
[-Werror=switch]
    70 |     switch (expected.exception) {
       |     ^~~~~~
cc1: all warnings being treated as errors

> +    case exception_translation:
> +        page = mmap(expected.addr, 4096, PROT_READ | PROT_WRITE,
> +                    MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
> +        if (page != expected.addr) {
> +            safe_puts("[  FAILED  ] mmap() failed");
> +            _exit(1);
> +        }
> +        break;
> +    case exception_protection:
> +        err = mprotect(expected.addr, 4096, PROT_READ | PROT_WRITE);
> +        if (err != 0) {
> +            safe_puts("[  FAILED  ] mprotect() failed");
> +            _exit(1);
> +        }
> +        break;
> +    }
> +}
> +
> +static void check_sigsegv(void *func, enum exception exception,
> +                          unsigned long val)
> +{
> +    int prot;
> +    unsigned long *page;
> +    unsigned long *addr;
> +    int err;
> +
> +    prot = exception == exception_translation ? PROT_NONE : PROT_READ;
> +    page = mmap(NULL, 4096, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +    assert(page != MAP_FAILED);
> +    if (exception == exception_translation) {
> +        /* Hopefully nothing will be mapped at this address. */
> +        err = munmap(page, 4096);
> +        assert(err == 0);
> +    }
> +    addr = page + (val & 0x1ff);
> +
> +    expected.sig = SIGSEGV;
> +    expected.addr = page;
> +    expected.psw_addr = (unsigned long)func;
> +    expected.exception = exception;
> +    if (func == stg) {
> +        stg(addr, val);
> +    } else {
> +        assert(func == mvc_8);
> +        mvc_8(addr, &val);
> +    }
> +    assert(*addr == val);
> +
> +    err = munmap(page, 4096);
> +    assert(err == 0);
> +}
> +
> +int main(void)
> +{
> +    struct sigaction act;
> +    int err;
> +
> +    memset(&act, 0, sizeof(act));
> +    act.sa_sigaction = handle_signal;
> +    act.sa_flags = SA_SIGINFO;
> +    err = sigaction(SIGILL, &act, NULL);
> +    assert(err == 0);
> +    err = sigaction(SIGSEGV, &act, NULL);
> +    assert(err == 0);
> +
> +    safe_puts("[ RUN      ] Operation exception");
> +    expected.sig = SIGILL;
> +    expected.addr = illegal_op;
> +    expected.psw_addr = (unsigned long)after_illegal_op;
> +    expected.exception = exception_operation;
> +    illegal_op();
> +    safe_puts("[       OK ]");
> +
> +    safe_puts("[ RUN      ] Translation exception from stg");
> +    check_sigsegv(stg, exception_translation, 42);
> +    safe_puts("[       OK ]");
> +
> +    safe_puts("[ RUN      ] Translation exception from mvc");
> +    check_sigsegv(mvc_8, exception_translation, 4242);
> +    safe_puts("[       OK ]");
> +
> +    safe_puts("[ RUN      ] Protection exception from stg");
> +    check_sigsegv(stg, exception_protection, 424242);
> +    safe_puts("[       OK ]");
> +
> +    safe_puts("[ RUN      ] Protection exception from mvc");
> +    check_sigsegv(mvc_8, exception_protection, 42424242);
> +    safe_puts("[       OK ]");
> +
> +    safe_puts("[  PASSED  ]");
> +
> +    return 0;
> +}