Commit cb5aa637 authored by Mark Brown's avatar Mark Brown Committed by Catalin Marinas
Browse files

kselftest/arm64: Add a smoke test for ptracing hardware break/watch points 



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: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230414-arm64-test-hw-breakpoint-v2-1-90a19e3b1059@kernel.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 44c026a7

tools/testing/selftests/arm64/abi/ptrace.c

+31 −1
Original line number Diff line number Diff line
@@ -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;