Commit 62faca1c authored by Chang S. Bae's avatar Chang S. Bae Committed by Dave Hansen
Browse files

selftests/x86/amx: Add a ptrace test 



Include a test case to validate the XTILEDATA injection to the target.

Also, it ensures the kernel's ability to copy states between different
XSAVE formats.

Refactor the memcmp() code to be usable for the state validation.

Signed-off-by: default avatarChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20230227210504.18520-3-chang.seok.bae%40intel.com
parent b1588884

tools/testing/selftests/x86/amx.c

+105 −3
Original line number Diff line number Diff line
@@ -14,8 +14,10 @@ 
#include <sys/auxv.h>

#include <sys/mman.h>

#include <sys/shm.h>

#include <sys/ptrace.h>

#include <sys/syscall.h>

#include <sys/wait.h>

#include <sys/uio.h>



#include "../kselftest.h" /* For __cpuid_count() */
@@ -583,6 +585,13 @@ static void test_dynamic_state(void) 
	_exit(0);

}



static inline int __compare_tiledata_state(struct xsave_buffer *xbuf1, struct xsave_buffer *xbuf2)

{

	return memcmp(&xbuf1->bytes[xtiledata.xbuf_offset],

		      &xbuf2->bytes[xtiledata.xbuf_offset],

		      xtiledata.size);

}



/*

 * Save current register state and compare it to @xbuf1.'

 *
@@ -599,9 +608,7 @@ static inline bool __validate_tiledata_regs(struct xsave_buffer *xbuf1) 
		fatal_error("failed to allocate XSAVE buffer\n");



	xsave(xbuf2, XFEATURE_MASK_XTILEDATA);

	ret = memcmp(&xbuf1->bytes[xtiledata.xbuf_offset],

		     &xbuf2->bytes[xtiledata.xbuf_offset],

		     xtiledata.size);

	ret = __compare_tiledata_state(xbuf1, xbuf2);



	free(xbuf2);
@@ -826,6 +833,99 @@ static void test_context_switch(void) 
	free(finfo);

}



/* Ptrace test */



/*

 * Make sure the ptracee has the expanded kernel buffer on the first

 * use. Then, initialize the state before performing the state

 * injection from the ptracer.

 */

static inline void ptracee_firstuse_tiledata(void)

{

	load_rand_tiledata(stashed_xsave);

	init_xtiledata();

}



/*

 * Ptracer injects the randomized tile data state. It also reads

 * before and after that, which will execute the kernel's state copy

 * functions. So, the tester is advised to double-check any emitted

 * kernel messages.

 */

static void ptracer_inject_tiledata(pid_t target)

{

	struct xsave_buffer *xbuf;

	struct iovec iov;



	xbuf = alloc_xbuf();

	if (!xbuf)

		fatal_error("unable to allocate XSAVE buffer");



	printf("\tRead the init'ed tiledata via ptrace().\n");



	iov.iov_base = xbuf;

	iov.iov_len = xbuf_size;



	memset(stashed_xsave, 0, xbuf_size);



	if (ptrace(PTRACE_GETREGSET, target, (uint32_t)NT_X86_XSTATE, &iov))

		fatal_error("PTRACE_GETREGSET");



	if (!__compare_tiledata_state(stashed_xsave, xbuf))

		printf("[OK]\tThe init'ed tiledata was read from ptracee.\n");

	else

		printf("[FAIL]\tThe init'ed tiledata was not read from ptracee.\n");



	printf("\tInject tiledata via ptrace().\n");



	load_rand_tiledata(xbuf);



	memcpy(&stashed_xsave->bytes[xtiledata.xbuf_offset],

	       &xbuf->bytes[xtiledata.xbuf_offset],

	       xtiledata.size);



	if (ptrace(PTRACE_SETREGSET, target, (uint32_t)NT_X86_XSTATE, &iov))

		fatal_error("PTRACE_SETREGSET");



	if (ptrace(PTRACE_GETREGSET, target, (uint32_t)NT_X86_XSTATE, &iov))

		fatal_error("PTRACE_GETREGSET");



	if (!__compare_tiledata_state(stashed_xsave, xbuf))

		printf("[OK]\tTiledata was correctly written to ptracee.\n");

	else

		printf("[FAIL]\tTiledata was not correctly written to ptracee.\n");

}



static void test_ptrace(void)

{

	pid_t child;

	int status;



	child = fork();

	if (child < 0) {

		err(1, "fork");

	} else if (!child) {

		if (ptrace(PTRACE_TRACEME, 0, NULL, NULL))

			err(1, "PTRACE_TRACEME");



		ptracee_firstuse_tiledata();



		raise(SIGTRAP);

		_exit(0);

	}



	do {

		wait(&status);

	} while (WSTOPSIG(status) != SIGTRAP);



	ptracer_inject_tiledata(child);



	ptrace(PTRACE_DETACH, child, NULL, NULL);

	wait(&status);

	if (!WIFEXITED(status) || WEXITSTATUS(status))

		err(1, "ptrace test");

}



int main(void)

{

	/* Check hardware availability at first */
@@ -846,6 +946,8 @@ int main(void) 
	ctxtswtest_config.num_threads = 5;

	test_context_switch();



	test_ptrace();



	clearhandler(SIGILL);

	free_stashed_xsave();