There was a report that the hardware breakpoints and watch points weren't reporting the debug architecture version as expected, they were reporting a version of 0 which is not defined in the architecture. This happens when running in a KVM guest if the host has a debug architecture version not supported by KVM, it in turn confuses GDB which rejects any debug architecture version it does not know about.

Add a test that covers that situation and while we're at it reports the debug architecture version and number of slots available to aid with figuring out problems that may arise.

Signed-off-by: Mark Brown broonie@kernel.org --- tools/testing/selftests/arm64/abi/ptrace.c | 32 +++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/abi/ptrace.c b/tools/testing/selftests/arm64/abi/ptrace.c index be952511af22..abe4d58d731d 100644 --- a/tools/testing/selftests/arm64/abi/ptrace.c +++ b/tools/testing/selftests/arm64/abi/ptrace.c @@ -20,7 +20,7 @@

#include "../../kselftest.h"

-#define EXPECTED_TESTS 7 +#define EXPECTED_TESTS 11

#define MAX_TPIDRS 2

@@ -132,6 +132,34 @@ static void test_tpidr(pid_t child) } }

+static void test_hw_debug(pid_t child, int type, const char *type_name) +{ + struct user_hwdebug_state state; + struct iovec iov; + int slots, arch, ret; + + iov.iov_len = sizeof(state); + iov.iov_base = &state; + + /* Should be able to read the values */ + ret = ptrace(PTRACE_GETREGSET, child, type, &iov); + ksft_test_result(ret == 0, "read_%s\n", type_name); + + if (ret == 0) { + /* Low 8 bits is the number of slots, next 4 bits the arch */ + slots = state.dbg_info & 0xff; + arch = (state.dbg_info >> 8) & 0xf; + + ksft_print_msg("%s version %d with %d slots\n", type_name, + arch, slots); + + /* Zero is not currently architecturally valid */ + ksft_test_result(arch, "%s_arch_set\n", type_name); + } else { + ksft_test_result_skip("%s_arch_set\n"); + } +} + static int do_child(void) { if (ptrace(PTRACE_TRACEME, -1, NULL, NULL)) @@ -207,6 +235,8 @@ static int do_parent(pid_t child) ksft_print_msg("Parent is %d, child is %d\n", getpid(), child);

test_tpidr(child); + test_hw_debug(child, NT_ARM_HW_WATCH, "NT_ARM_HW_WATCH"); + test_hw_debug(child, NT_ARM_HW_BREAK, "NT_ARM_HW_BREAK");

ret = EXIT_SUCCESS;

--- base-commit: e8d018dd0257f744ca50a729e3d042cf2ec9da65 change-id: 20230414-arm64-test-hw-breakpoint-83fe02f607fc

Best regards,