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    Subject[PATCH v4 7/7] selftests: test uaccess logging
    From
    Add a kselftest for the uaccess logging feature.

    Link: https://linux-review.googlesource.com/id/I39e1707fb8aef53747c42bd55b46ecaa67205199
    Signed-off-by: Peter Collingbourne <pcc@google.com>
    ---
    tools/testing/selftests/Makefile | 1 +
    .../testing/selftests/uaccess_buffer/Makefile | 4 +
    .../uaccess_buffer/uaccess_buffer_test.c | 126 ++++++++++++++++++
    3 files changed, 131 insertions(+)
    create mode 100644 tools/testing/selftests/uaccess_buffer/Makefile
    create mode 100644 tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c

    diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
    index c852eb40c4f7..291b62430557 100644
    --- a/tools/testing/selftests/Makefile
    +++ b/tools/testing/selftests/Makefile
    @@ -71,6 +71,7 @@ TARGETS += timers
    endif
    TARGETS += tmpfs
    TARGETS += tpm2
    +TARGETS += uaccess_buffer
    TARGETS += user
    TARGETS += vDSO
    TARGETS += vm
    diff --git a/tools/testing/selftests/uaccess_buffer/Makefile b/tools/testing/selftests/uaccess_buffer/Makefile
    new file mode 100644
    index 000000000000..e6e5fb43ce29
    --- /dev/null
    +++ b/tools/testing/selftests/uaccess_buffer/Makefile
    @@ -0,0 +1,4 @@
    +# SPDX-License-Identifier: GPL-2.0
    +TEST_GEN_PROGS := uaccess_buffer_test
    +
    +include ../lib.mk
    diff --git a/tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c b/tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c
    new file mode 100644
    index 000000000000..051062e4fbf9
    --- /dev/null
    +++ b/tools/testing/selftests/uaccess_buffer/uaccess_buffer_test.c
    @@ -0,0 +1,126 @@
    +// SPDX-License-Identifier: GPL-2.0
    +
    +#include "../kselftest_harness.h"
    +
    +#include <linux/uaccess-buffer.h>
    +#include <sys/prctl.h>
    +#include <sys/utsname.h>
    +
    +FIXTURE(uaccess_buffer)
    +{
    + uint64_t addr;
    +};
    +
    +FIXTURE_SETUP(uaccess_buffer)
    +{
    + ASSERT_EQ(0, prctl(PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR, &self->addr, 0,
    + 0, 0));
    +}
    +
    +FIXTURE_TEARDOWN(uaccess_buffer)
    +{
    + ASSERT_EQ(0, prctl(PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR, 0, 0, 0, 0));
    +}
    +
    +TEST_F(uaccess_buffer, uname)
    +{
    + struct uaccess_descriptor desc;
    + struct uaccess_buffer_entry entries[64];
    + struct utsname un;
    +
    + desc.addr = (uint64_t)(unsigned long)entries;
    + desc.size = 64;
    + self->addr = (uint64_t)(unsigned long)&desc;
    + ASSERT_EQ(0, uname(&un));
    + ASSERT_EQ(0, self->addr);
    +
    + if (desc.size == 63) {
    + ASSERT_EQ((uint64_t)(unsigned long)(entries + 1), desc.addr);
    +
    + ASSERT_EQ((uint64_t)(unsigned long)&un, entries[0].addr);
    + ASSERT_EQ(sizeof(struct utsname), entries[0].size);
    + ASSERT_EQ(UACCESS_BUFFER_FLAG_WRITE, entries[0].flags);
    + } else {
    + /* See override_architecture in kernel/sys.c */
    + ASSERT_EQ(62, desc.size);
    + ASSERT_EQ((uint64_t)(unsigned long)(entries + 2), desc.addr);
    +
    + ASSERT_EQ((uint64_t)(unsigned long)&un, entries[0].addr);
    + ASSERT_EQ(sizeof(struct utsname), entries[0].size);
    + ASSERT_EQ(UACCESS_BUFFER_FLAG_WRITE, entries[0].flags);
    +
    + ASSERT_EQ((uint64_t)(unsigned long)&un.machine,
    + entries[1].addr);
    + ASSERT_EQ(UACCESS_BUFFER_FLAG_WRITE, entries[1].flags);
    + }
    +}
    +
    +static bool handled;
    +
    +static void usr1_handler(int signo)
    +{
    + handled = true;
    +}
    +
    +TEST_F(uaccess_buffer, blocked_signals)
    +{
    + struct uaccess_descriptor desc;
    + struct shared_buf {
    + bool ready;
    + bool killed;
    + } volatile *shared = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE,
    + MAP_ANON | MAP_SHARED, -1, 0);
    + struct sigaction act = {}, oldact;
    + int pid;
    +
    + handled = false;
    + act.sa_handler = usr1_handler;
    + sigaction(SIGUSR1, &act, &oldact);
    +
    + pid = fork();
    + if (pid == 0) {
    + /*
    + * Busy loop to synchronize instead of issuing syscalls because
    + * we need to test the behavior in the case where no syscall is
    + * issued by the parent process.
    + */
    + while (!shared->ready)
    + ;
    + kill(getppid(), SIGUSR1);
    + shared->killed = true;
    + _exit(0);
    + } else {
    + int i;
    +
    + desc.addr = 0;
    + desc.size = 0;
    + self->addr = (uint64_t)(unsigned long)&desc;
    +
    + shared->ready = true;
    + while (!shared->killed)
    + ;
    +
    + /*
    + * The kernel should have IPI'd us by now, but let's wait a bit
    + * longer just in case.
    + */
    + for (i = 0; i != 1000000; ++i)
    + ;
    +
    + ASSERT_FALSE(handled);
    +
    + /*
    + * Returning from the waitpid syscall should trigger the signal
    + * handler. The signal itself may also interrupt waitpid, so
    + * make sure to handle EINTR.
    + */
    + while (waitpid(pid, NULL, 0) == -1)
    + ASSERT_EQ(EINTR, errno);
    + ASSERT_TRUE(handled);
    + }
    +
    + munmap((void *)shared, getpagesize());
    + sigaction(SIGUSR1, &oldact, NULL);
    +}
    +
    +TEST_HARNESS_MAIN
    --
    2.34.1.173.g76aa8bc2d0-goog
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