Commit d81090ed authored by Athira Rajeev's avatar Athira Rajeev Committed by Michael Ellerman
Browse files

selftests/powerpc: EBB selftest for MMCR0 control for PMU SPRs in ISA v3.1 



With the MMCR0 control bit (PMCCEXT) in ISA v3.1, read access to
group B registers is restricted when MMCR0 PMCC=0b00. In other
platforms (like power9), the older behaviour works where group B
PMU SPRs are readable.

Patch creates a selftest which verifies that the test takes a
SIGILL when attempting to read PMU registers via helper function
"dump_ebb_state" for ISA v3.1.

Signed-off-by: default avatarAthira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: default avatarNageswara R Sastry &lt;rnsastry@linux.ibm.com <mailto:rnsastry@linux.ibm.com&gt;>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1621950703-1532-3-git-send-email-atrajeev@linux.vnet.ibm.com
parent 45677c9a

tools/testing/selftests/powerpc/pmu/ebb/Makefile

+1 −1
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@@ -24,7 +24,7 @@ TEST_GEN_PROGS := reg_access_test event_attributes_test cycles_test \ 
	 fork_cleanup_test ebb_on_child_test			\

	 ebb_on_willing_child_test back_to_back_ebbs_test	\

	 lost_exception_test no_handler_test			\

	 cycles_with_mmcr2_test

	 cycles_with_mmcr2_test regs_access_pmccext_test



top_srcdir = ../../../../../..

include ../../../lib.mk

tools/testing/selftests/powerpc/pmu/ebb/regs_access_pmccext_test.c

0 → 100644
+63 −0
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// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright 2021, Athira Rajeev, IBM Corp.

 */



#include <stdio.h>

#include <stdlib.h>

#include <setjmp.h>

#include <signal.h>



#include "ebb.h"





/*

 * Test that closing the EBB event clears MMCR0_PMCC and

 * sets MMCR0_PMCCEXT preventing further read access to the

 * group B PMU registers.

 */



static int regs_access_pmccext(void)

{

	struct event event;



	SKIP_IF(!ebb_is_supported());



	event_init_named(&event, 0x1001e, "cycles");

	event_leader_ebb_init(&event);



	FAIL_IF(event_open(&event));



	ebb_enable_pmc_counting(1);

	setup_ebb_handler(standard_ebb_callee);

	ebb_global_enable();

	FAIL_IF(ebb_event_enable(&event));



	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));



	while (ebb_state.stats.ebb_count < 1)

		FAIL_IF(core_busy_loop());



	ebb_global_disable();

	event_close(&event);



	FAIL_IF(ebb_state.stats.ebb_count == 0);



	/*

	 * For ISA v3.1, verify the test takes a SIGILL when reading

	 * PMU regs after the event is closed. With the control bit

	 * in MMCR0 (PMCCEXT) restricting access to group B PMU regs,

	 * sigill is expected.

	 */

	if (have_hwcap2(PPC_FEATURE2_ARCH_3_1))

		FAIL_IF(catch_sigill(dump_ebb_state));

	else

		dump_ebb_state();



	return 0;

}



int main(void)

{

	return test_harness(regs_access_pmccext, "regs_access_pmccext");

}